2015 Mustang IRS Components. So it begins.

[edwardb]

As I’ve mentioned in a few threads already, I ordered one of the 20th Anniversary Roadsters. These all will use the new 2015 Mustang IRS components along with a new rear suspension design from Factory Five. My kit is due in August, but I’ve been working to obtain the necessary Mustang center section and knuckles. FF announced they would make these parts available from Ford at an “attractive” price. But as of last week, they are not available and no pricing has been announced. At the recommendation of FF, I started looking for the parts in salvage. How much wear could 2015 parts have on them, anyway? Since this is all quite new, I thought others would be interested in more details.

What I found is that parts are out there as “zero mile takeoffs” from new Mustangs that leave the factory but then go to an aftermarket assembly line for further performance upgrades. The IRS assembly is on a subframe, and one of the common upgrades with a new more powerful drivetrain is to remove this entire assembly and replace with one that will handle the 600-700 HP engines, bigger and stickier tires, etc. Rather than re-using, these new IRS assemblies are being sold into salvage and are available. Strange IMO, but I’ll take new over used any time. MPS Auto Salvage, a pretty well known source for Mustang parts, has them available.

Last week I called MPS and they had just what I was looking for. A new zero miles assembly, the cast iron case recommended by FF, and the 3.55 ratio I’ve decided to use for my build. They offered the complete assembly to me for $1,350 plus shipping. It left Georgia last Thursday, and Conway called today for delivery. Turns out since my 2-car residential garage doesn’t have a loading dock (!!!) there was going to be an upcharge for a lift-gate delivery on top of the surcharge for a residential delivery. Since they were only 30 minutes or so from my house, I hooked up the SE and picked it up myself. Total shipping was $187. Not too bad for a 415 pound pallet from GA to MI. The IRS assembly was covered with cardboard, strapped to the skid, and everything stretch wrapped. All good. I used my shop crane to pick it out of the back of the trailer and get into the garage.

So here are some pics of the delivered IRS assembly. As best I can tell, it’s exactly what I expected. Everything looks new with no signs of any wear or shipping damage. There is a little surface rust on the cast iron case and the steel hubs, but not unexpected. The case will get a nice shiny coat of POR15 once I take it apart. My next step will be to remove the center section and the knuckles and get them ready for assembly to the new chassis. I've already backed out a number of the mounting bolts, and I was able to get the axle nuts loose. Obviously there will be a ton of parts I don’t need. I’m going to hang onto everything until the kit arrives and I make sure I have what I need. But then I’m hoping to make a few bucks off the unused parts. Seems that some of the parts should have some value, especially the CV axles. The subframe itself is a $900 part, but I’m not sure who might be looking for something like that plus wouldn’t be cheap to ship. No matter what, I think this is a relatively good value for what I received.

As delivered:

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3232_zpstnxjuce6.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3232_zpstnxjuce6.jpg.html)

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3231_zpsfpsajfhw.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3231_zpsfpsajfhw.jpg.html)

Center section waiting to be removed:

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3236_zpsaqkoizmg.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3236_zpsaqkoizmg.jpg.html)

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3242_zps2zjyblez.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3242_zps2zjyblez.jpg.html)

[edwardb]

Knuckle and hub assemblies, also waiting to be taken apart:

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3235_zpsspsct0po.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3235_zpsspsct0po.jpg.html)

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3239_zps6fkfhbud.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3239_zps6fkfhbud.jpg.html)

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3237_zpsgseffph6.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3237_zpsgseffph6.jpg.html)

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3238_zpstwvvwj8q.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3238_zpstwvvwj8q.jpg.html)

Interesting tag on the rear cover. No mention of friction modifier.

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3240_zpsti39t7if.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3240_zpsti39t7if.jpg.html)

So now I’m up to four parts on hand for the new Roadster build. The IRS, the wind wings and visors I scored for 50% off at the FF Open House, and a new set of Harbor Freight horns. Don’t laugh. They work great and are cheap. I’ll be driving to FF to pick up the new kit hopefully in early August, based on my current production date. Then the fun really begins. :cool:

[BobCarter]

Well, i'm looking forward to receiving my shipment. Good to know about the last minute warning if my garage does not have a loading dock!
Everything in the photos gives me a sense of confidence. Keep us advised on your progress. I'll let you know how my delivery gores, should see it tomorrow or thursday. Thanks again for the tip on MPS. This takes the largest sourcing issue off the table.
:-)
BC

[2bking]

Nice find, and cheap for what you got. I assume when the upper and lower arms are removed they are replaced by FFR designs. I don't understand the lower A arm geometry that looks to put the A arm in a bind as it rotates through its travel. Otherwise, it looks to be a big improvement over the older design. BTW I don't see any tone rings for ABS. I wonder how ABS could be added if a builder was wanting to do so?

[RRussellTx]

Excellent - That is a great deal! I paid about $50 bucks more for the individual parts and I may or may not have everything we need...



BTW I don't see any tone rings for ABS. I wonder how ABS could be added if a builder was wanting to do so?
There is a spot to mount the ABS at the top of the hub but it looks like the tone ring is on the half shaft that will come with the kit.
43451

There should also be a tag on the bottom of the unit with the ratio mentioned (facing your pallet) - here is my 3.31 tag.
43452

[rmiller64]

Sure looks purdy Paul. Look forward to the build Let me guess next week will be that Coyote & TKO delivery :)

[edwardb]

Nice find, and cheap for what you got. I assume when the upper and lower arms are removed they are replaced by FFR designs. I don't understand the lower A arm geometry that looks to put the A arm in a bind as it rotates through its travel. Otherwise, it looks to be a big improvement over the older design. BTW I don't see any tone rings for ABS. I wonder how ABS could be added if a builder was wanting to do so?

Right. None of the OE arms are used in the FFR design. All new stuff in the kit. I agree the geometry looks a little unusual, but there's obviously a reason it's set up that way. No binding. It moves freely. What's not obvious is some of the pivots have some swivel to them. Not just straight bushings.

Regarding ABS, as RRussell said, there is a mounting point on the top of the knuckle for the ABS sensor and cable. The sensors came with my IRS pallet, but I had them out by the time I took the first pictures. I just took a picture of the knuckle with the ABS sensor in place, showing how it extends into the hub area. I also took a picture of the CV axle end that plugs into this area. Something different is going on here because you can see there aren't tone rings as in former designs. Just did some searching, and found that wheel bearings with a magnetic ABS pulse generator are now being used in some cars. Looks like that's what Ford did here. I believe it's the dark ring right under the tip of the ABS sensor in the first pic.

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3246_zpszvjl6ou9.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3246_zpszvjl6ou9.jpg.html)

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3247_zpsr7h1dyoc.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3247_zpsr7h1dyoc.jpg.html)

[edwardb]

Sure looks purdy Paul. Look forward to the build Let me guess next week will be that Coyote & TKO delivery :)

Slow down there big boy... Not planning any more purchases until the kit is here. That's my story and I'm sticking to it. :rolleyes:

[edwardb]

Got everything apart already. Wasn't really that hard. Used a three-jaw puller to get the axles out of the hubs. Came off pretty easily. The CV axles popped out of the diff with a little bump from a crow bar, just like they're supposed to. Then took the diff out of the cradle. Will get everything cleaned up and that designer rust orange color of the diff painted gloss black with a POR15 treatment.

Note this picture also shows a pretty big design difference of the 2015 IRS knuckles compared to the older design. You can see the four bolts on the inside holding the bearing carrier in place vs. the pressed in bearings from the past.

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3248_zpsg9fhoqo4.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3248_zpsg9fhoqo4.jpg.html)

[edwardb]

There should also be a tag on the bottom of the unit with the ratio mentioned (facing your pallet) - here is my 3.31 tag.
43452

Yep. My tag is visible in one of the earlier pictures I posted. Confirms it's 3.55.

[Jazzman]

How did you decide upon the 3.55 gear set as opposed to some other ratio? Even though I have not yet ordered my kit, I am thinking about following your lead and ordering one of these zero mile units while they are still available. I have decided to go with the coyote engine as well. I used the Gear Ratio Calculator that you or someone posted elsewhere on the forum. Tell me if I have these statements right:

1. The higher the gear ratio, the lower the top speed of the car, but the faster acceleration it can provide to get you there.
2. The higher the gear ratio, the more RPM you will have to use to achieve the same speed.
3. The lower the gear ratio, the better the fuel economy.
4. If the previous statements are correct, and my primary goal is cruising and long trips, (not road racing or drag racing), then a balanced, middle of the road approach would seem most prudent; a reasonable balance between acceleration and speed.
5. Since the Ford IRS comes in four ratios (3.15, 3.31, 3.55, and 3.73) it would seem that either 3.31 or 3.55 would be the prudent choices. I'm not sure how much difference there would be in fuel economy in either choice, and I'm really not sure I care!! I am certainly not building this to be an econo-car.

Therefore, I think that I have finally worked myself into the same conclusion you did. The 3.55 seems the best choice.

Ok, so how did I do? Did you use the same basic process, or did I miss something important? Thanks for your counsel.

[CraigS]

Jazzman you are correct. There are a couple of other things to consider. 1-what ratio is your 5th gear, 2-how much power will your engine have, 3-will that power be there at low rpm-say 2000- or will you have to zing it, 4-even if the power is at higher rpm, will the engine run along smoothly in 5th at 1500 or so rpm?

[edwardb]

How did you decide upon the 3.55 gear set as opposed to some other ratio? Even though I have not yet ordered my kit, I am thinking about following your lead and ordering one of these zero mile units while they are still available. I have decided to go with the coyote engine as well. I used the Gear Ratio Calculator that you or someone posted elsewhere on the forum. Tell me if I have these statements right:

1. The higher the gear ratio, the lower the top speed of the car, but the faster acceleration it can provide to get you there.
2. The higher the gear ratio, the more RPM you will have to use to achieve the same speed.
3. The lower the gear ratio, the better the fuel economy.
4. If the previous statements are correct, and my primary goal is cruising and long trips, (not road racing or drag racing), then a balanced, middle of the road approach would seem most prudent; a reasonable balance between acceleration and speed.
5. Since the Ford IRS comes in four ratios (3.15, 3.31, 3.55, and 3.73) it would seem that either 3.31 or 3.55 would be the prudent choices. I'm not sure how much difference there would be in fuel economy in either choice, and I'm really not sure I care!! I am certainly not building this to be an econo-car.

Therefore, I think that I have finally worked myself into the same conclusion you did. The 3.55 seems the best choice.

Ok, so how did I do? Did you use the same basic process, or did I miss something important? Thanks for your counsel.

I agree with these statements, as well as the comments from CraigS. For the Coyote, based on my experience plus the numbers from the calculator, either 3.31 or 3.55 would be the best choices. The final choice is most heavily going to depend on what final drive you select for the transmission, and also how you use the car. I had 3.55 in my Mk3 with a pretty warmed up 306 and a T5Z with .63 5th gear. It was just about a perfect combination. Nice and snappy, if not a little short in 1st. RPM at 70 mph in 5th was about 2,100, which was OK and about as low as that engine was happy with how it was cam'd, etc. For my current Mk4, I changed it up quite a bit. I'm doing 3.27 with a TKO600 and .82 final drive. The much stronger DART 347 carries the 3.27 just fine, and I really like the close spacing between 4th and 5th. There's not a big drop-off like in O/D ratios in the .60's. It's even usable in town driving in the 40-50 mph range. But I did give up a little for cruising. RPM at 70 mph is a little over 2,400. It's fine, and the engine is very happy there. I can slow down a bit, speed up, etc. without having to drop back to 4th. But probably giving up just a bit in economy, although that's not all that important. So kind of putting this together for the latest build, it will be a Coyote with a TKO600. The Coyote has somewhat less HP and torque than the current 347, so going back to 3.55 final drive to keep the "spirited" street cruising alive and well. I'm going with the .64 5th gear, which puts me back into a more pure O/D mode. The calculator shows 2,100 at 70 mph, which I'm fine with. The Coyote should handle that all day long. 3.31 with a .64 5th gear also shows good numbers. It would be slightly softer in the 1st - 4th gears, but 5th cruise at 70 mph would be around 1,950. Still easily handled by the Coyote, and probably slightly better fuel economy. But I just don't think it's a big difference, and I'll take the slightly quicker performance all around. My carb'd SBF engines are not known for economy. Now that I've got the DART 347 dialed in, it is getting 13+ mpg in mixed driving each time I've checked it, so it's not that bad actually. But I'm expecting the Coyote will be much better, especially at highway speeds. But as you said, we don't exactly have these for economy. Hope that all isn't too confusing. Either would be fine IMO.

[CHOTIS BILL]

Ok I am jealous. I do have one question which is what is the black link that looks like it goes from the outer bolt in the lower arm up to the top bolt in the knuckle. The only thing I can think of is it might be there to add strength to the knuckle but I doubt that is the reason. As far as adding friction modifier to the diff I believe I has a Torsen LSD and they don’t use it. On the lower A arm geometry it looks to me that the center line of the lower a-arm mounting bolts not being perpendicular to the center line on the car is to give it some anti-squat.

Thanks for all the info,

Bill Lomenick

[jceckard]

My guess for the ABS is the magnet is in the sensor. My bet is the four webs on the end of the half shafts (just above the splines) cause a pulse in the sensor when they pass by. Think guitar string vibrating over a pickup. Of course this is just a guess.

[edwardb]

My guess for the ABS is the magnet is in the sensor. My bet is the four webs on the end of the half shafts (just above the splines) cause a pulse in the sensor when they pass by. Think guitar string vibrating over a pickup. Of course this is just a guess.

Nope. I thought that at first too, but those tabs are a good 1/2 inch away from the ABS sensor when the axle is installed into the hub. I looked at it closer this morning. That dark ring I described before is clearly magnetic. You can observe it with a small screwdriver or knife blade. Check this video. https://www.youtube.com/watch?v=e32t-d32SEg

[jceckard]

Wouldn't the first time that I was wrong. Thanks for the clarification. If I were a cat, curiosity would have killed me a long time ago. :)

[FFRSpec72]

I would be so on this if we could get the challenge rules to change to allow an IRS like this, very nice.

[CHOTIS BILL]

After checking out the cad drawings and other pictures there are several changes made to the IRS which will account for the improvements mentioned. The first major change is the mounting of the spring /shock package. By moving them closer to the wheel and standing them upright will be a major benefit to their motion ratio. You can kind of thinking of it as the difference of trying to wright holding the pencil near the point or holding it near the eraser end. The next thing that caught my eye is the roll center seems to be raised which will make it happier to the front suspension, if the front suspension stayed the same. They also added a rear sway bar which will add adjustability which is always a good starting point. Once I get a car to handle properly I like to adjust the spring/shock package and front sway bar so that I can remove the rear sway bar to maintain as much rear tire compliance as possible.

Bill Lomenick

Another change for the better is the upper control arm has an added element to help take braking forces which the earlier one doesn’t have.

[edwardb]

After checking out the cad drawings and other pictures there are several changes made to the IRS which will account for the improvements mentioned. The first major change is the mounting of the spring /shock package. By moving them closer to the wheel and standing them upright will be a major benefit to their motion ratio. You can kind of thinking of it as the difference of trying to wright holding the pencil near the point or holding it near the eraser end. The next thing that caught my eye is the roll center seems to be raised which will make it happier to the front suspension, if the front suspension stayed the same. They also added a rear sway bar which will add adjustability which is always a good starting point. Once I get a car to handle properly I like to adjust the spring/shock package and front sway bar so that I can remove the rear sway bar to maintain as much rear tire compliance as possible.

Bill Lomenick

Another change for the better is the upper control arm has an added element to help take braking forces which the earlier one doesn’t have.

I'm 99% certain there are no changes to the front suspension. The anniversary edition has the higher end Koni shocks and the Wilwood brake upgrade. But no changes to the current Mk4 geometry. My understanding about the rear sway bar is that it's an available option, but not included as part of the kit. The connection points for it are all there though.

[edwardb]

Wrapping up the tear down and preparation for the 2015 Mustang IRS parts. Thought I would share a few more things. Got out the scale and weighed some of the parts. The knuckle and hub assemblies weigh 17 lbs each. The cast iron diff weighs 94 lbs all up. It wasn't easy to get the thing to sit still on the scale, but I think this is quite close. The fact that I can lift it (barely...) says this weight is in the ballpark. Multiple on-line sources cite the aluminum version is 24 lbs lighter, putting it in the 70 lbs range. Looking at some threads about the older design, appear both numbers are slightly heavier than before. But not much. Finally, even though I won't use them, weighed the CV axles. 43 lbs between the two of them. The new design is 34 spline at the diff, and 32 at the hub. Pretty meaty.

I managed to spill some of the fluid out the axle holes while moving it around. I'm just not smelling the quite distinctive odor of friction modifier. But the Ford instructions clearly state 3.2 pints (1.5L) SAE 75W-85 Premium Synthetic Hypoid Gear Lubricant and 4 oz. Motorcraft XL-3 Additive Friction Modifier. I'm planning to drain and replace the fluid as specified. This diff is a standard clutch-pack style limited slip setup. A Torsen setup is available only in the 3.73 ratio.

Several have asked if the internals are the same as past 8.8 diff, e.g. ring and pinion, bearings, etc. I can't answer specifics, but I'm guessing the answer is mostly no. In multiple searches, I found Ford referring to this new IRS diff as a "Super 8.8" touting its strength compared to past versions. I found a side-by-side pic of the new pinion gear compared to the old. The new is larger and longer. The slightly heavier weight compared to the past is also a clue.

Several have commented about the geometry of the new IRS, including the somewhat unusual looking links between the upper and lower pivot points. I compared the pics and knuckles now in hand with the pictures and drawings FF has provided of the new design installed. None of these short links are in the FF design. In fact, clearly one of the pivot points looks like it gets cut off the knuckles, as in the picture below. I won't be cutting anything until the kit and full instructions are on hand. But interesting.

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3254_zpst90ajaog.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3254_zpst90ajaog.jpg.html)

[BobCarter]

Guesing there is no need to further disassemble the knuckle and hub ***'y?

[BobCarter]

Assembly

[edwardb]

Guessing there is no need to further disassemble the knuckle and hub assembly?

For now, I'm not planning to. The FF IRS parts lists has 10 wheel studs included. Required? Different threads or length? I don't know. If the old ones need to be pressed out and new ones pressed in, then some dis-assembly would be required. We'll see.

[karlos]

Interesting thread. The new IRS looks great, and at $1350 you got a smokin' deal. I have a MKIV on the way with the 'old' IRS. Sourcing the parts to complete the system was also what I first turned my attention to. I spent about $1550 just on the center section alone ($150 for a used center section out of a '94 Lincoln and $1400 for new innards plus labor to put it all together). The knuckles and hubs were another $650. So all told I'm in at about $2200.

For anyone contemplating IRS, you might want to jump on one of these zero-mile takeoffs before they're all gone. I doubt you'll ever find a better deal.

[edwardb]

For anyone contemplating IRS, you might want to jump on one of these zero-mile takeoffs before they're all gone. I doubt you'll ever find a better deal.

I doubt the zero mile takeoffs will be gone anytime soon. The aftermarket mods to new Mustangs is ongoing. But I have no doubt the prices could go up when the sellers see the marketplace demand. Just in the few weeks I've been at this, they've changed from only offering the complete pallet to now offering the individual components in total for more.

[rickscobra]

Seems as though FFR could get us a better deal from Ford. Time will certainly tell. I suppose Edward is correct, the time to buy is now.

[edwardb]

Seems as though FFR could get us a better deal from Ford. Time will certainly tell. I suppose Edward is correct, the time to buy is now.

I too will be very curious to see what the FFR deal is from Ford. What I did was a gamble, and I know it. As I described previously, exact prices for the new stuff that's required is hard to determine at this point. But looking at what parts are available, best I can tell the deal I came up with is around one half retail, if not more. Hard to imagine Ford will let them go through FFR for less than that, but we'll see. The other factor is when I first talked to MPS Auto Salvage a couple weeks ago, I mentioned that FF was switching to the 2015 Mustang IRS components for several of their designs. He said he did a lot of business with FF customers, but this was the first he had heard this. It wasn't long after that the individual parts starting showing up for sale. I don't think it's a coincidence, and if the demand is there, I think we all know what will happen with the prices. But just judging from eBay, MPS isn't the only one selling these take off assemblies.

What I can say is I've never been accused of being patient, so with my kit delivery just a few weeks away I wanted to have these parts on hand. I will also say that wrestling around a 400 lb IRS pallet is some work. I'm a solo act and also a grandpa. You do the math. Now that I have the necessary parts separated, not so bad. But I have a pretty big hunk of leftover metal and parts that hopefully I can get rid of and reduce the price even a little more. In the end, though, building one of these, especially the Anniversary Edition, is not a low budget exercise. So for those with delivery dates still a while away, it could make sense to wait. I think the zero take off option is going to be there as long as there are buyers for the upgraded performance Mustangs, and right now that market seems alive and well.

[karlos]

Anybody know what brake options are available with the 2015 IRS? Do you have to use the OEM brakes off the Mustang? I'm guessing the system as a whole is too new for Wilwood, etc, to have already produced much in the way of aftermarket options, but I could be wrong about that...

[Dragonfire]

The new IRS system should be awesome.

[edwardb]

Anybody know what brake options are available with the 2015 IRS? Do you have to use the OEM brakes off the Mustang? I'm guessing the system as a whole is too new for Wilwood, etc, to have already produced much in the way of aftermarket options, but I could be wrong about that...

The FF IRS announcement says that 2015 Mustang brakes can be used. No other OEM brakes mentioned. The 20th Anniversary announcement shows a Wilwood option that is used for those 20 kits, and says the Wilwood option will be offered separately.

[rickscobra]

Well, to the dozen of us that waited a little too long to order the 20th version, I think we should come up with a name for the, "20th Anniversary not so much" models. LOL September 24 seems like a long way away. Heck, we could have snow by then.

[BobCarter]

My IRS setup arrived today from MPS. looks just like yours Paul. Thanks again for letting us know about you find. This has a great impact on my budget $, and time. Really appreciate your sharing the info.

[edwardb]

My IRS setup arrived today from MPS. looks just like yours Paul. Thanks again for letting us know about you find. This has a great impact on my budget $, and time. Really appreciate your sharing the info.

Great! Glad it worked out for you. Now we just need a chassis to hang that stuff on. :D

[Jazzman]

Paul, What kind of warranty do you get on a "zero mile take off" IRS that you buy from MPS? You are certainly much more experienced than I at evaluating and restoring these parts. Was there any concern that all the rust might indicate enough neglect that there could be hidden issues? If I order one, I don't really expect to be able to "see" anything that might really be a concern. Caveat Emptor?

How difficult is the POR15 process, and how dangerous is it to the parts? How do you keep the cleaner from going where you do NOT want it to go? is sandblasting and powder coating a better long term solution?

Thanks!

[edwardb]

Paul, What kind of warranty do you get on a "zero mile take off" IRS that you buy from MPS? You are certainly much more experienced than I at evaluating and restoring these parts. Was there any concern that all the rust might indicate enough neglect that there could be hidden issues? If I order one, I don't really expect to be able to "see" anything that might really be a concern. Caveat Emptor?

How difficult is the POR15 process, and how dangerous is it to the parts? How do you keep the cleaner from going where you do NOT want it to go? is sandblasting and powder coating a better long term solution?

Thanks!

I'm not aware of (or expecting) any warranty beyond that it is what they say it is and arrives in advertised condition. Not unlike most salvage parts unless there is some agreement otherwise. MPS is a forum vendor over on the other forum, and as best I could determine, is a reputable source. I've never used them before, but my transaction went exactly as it should have and I would use them again if the need arises. I'm convinced the parts are exactly what they say they are. The IRS assembly shows little/no evidence that it's been driven, all the factory tags are in place and still very clean, etc. These 8.8 diffs are pretty tough, especially in our application where the vehicle weight is much less than in a Mustang. The risk of not having a warranty is low IMO. But everyone needs to do what lets them sleep at night. I expect the new parts from Ford, once they're offered, would have some kind of warranty.

Just to digress for a minute... I've been poking around on some of the Mustang forums learning about these parts plus sizing up what resale there might be for some of my leftover parts. As guys are upping the power on their new Mustangs, putting on sticky tires, etc. and running drag passes they are apparently popping axles pretty frequently. Multiple threads about this, and the various sources for aftermarket axles. I haven't found one mention yet of guys doing anything with the diffs or breaking them. This is with a 3,500 to 3,700 lb car running 10 second passes in some cases. I'm pretty sure they will hold up to our use. ;)

The rust in the pictures is surface rust only, and is 100% normal for parts of this kind. The diff case is raw cast iron, the hubs are raw steel. They're going to get some surface rust almost from day one. It's possible that since they were taken off and transported around they may have been left out in the rain or exposed to high humidity (came from Georgia in the summertime...), but that's nothing to be concerned about. That's exactly the exposure they get in normal use under a car. Look under your DD, and you'll see the same thing. Look under brand new cars sitting on a dealer lot and you'll see the same thing. I'm going to clean up the diff and put some paint on it just because that's we do with builds like this. These parts are designed for the extreme exposure on the underside of a car, so they should be completely unaffected by any cleaning or painting. Within reason of course. I've already knocked most of the surface rust off the hubs, and don't plan on doing anything more. They are pretty much hidden once the suspension is assembled and the wheels mounted. They will get rusty again, but no matter.

I'm going to use POR15 because it looks good (almost like powder coating), it's extremely durable, and I happen to already have some gloss black on hand. They have degreaser and metal cleaner products I will also use, but nothing particularly special. Just like any paint job, the surface should be clean before application. They say to knock off any loose rust, which I'll do with a little sandpaper or wire wheel. POR15 paints pretty normally, although it does have a pretty strong smell and you don't want to get it on your hands or whatever. Hard to get off! The one negative about POR15 is that it's sensitive to UV light (sun). In this application under the car it will be fine. It needs a topcoat if it's going to regularly have exposure to UV light. But all this talk about POR15... you could just as easily use something like Rust-Oleum or similar from a big box store. It would be fine in this case.

Powder coating isn't necessary IMO, and I wouldn't want to be exposing the diff to the heat involved. Plus with the axles out, the diff internals are open to the outside. I have some rags stuffed in there and will exercise some care while handling. I wouldn't want to have any media or sandblasting done on them though.

One other comment. Factory Five specifically says on their website re: the new 2015 Mustang IRS to use the iron case differential, which is from manual shift Mustangs. But when you talk to them, they will tell you it's OK to use the aluminum case version. They're from automatic shift cars. No doubt the iron case is stronger, but they tech guys are saying the aluminum case is up to the task. About 25 lbs lighter and no rust. Another option guys can consider.

Hope this answers your questions!

[CraigS]

Edward can you tell what type of bushings/bearings on in the hub control arm mount points. I am hoping they are modern style and not the old rubber stuff like the old IRS.

[R Thomas]

In older manual transmissions high gear was direct drive 1:1 because it was believed to be most effective in transmitting power, however you might have noticed lately manufacturers have added 5th and 6th gears in the case of my Mustang both overdrive .80 and .60 in the pursuit of the all important mileage number. My car runs at 1200 rpm on the freeway doing 70 mph with its stock gears. So if you go to a 5-speed and spending a lot of time open highway cruising I would look for a rear for running in 4th at 1:1 and go for the wide gear .68 or so 5th for the highway.

[RRussellTx]

OK, I have some findings and a question.

Based on my research, it looks like all of the 3.73's are part of the GT Performance Package option that includes the M4204MT ($1,150 List Price on FordParts.com) Torsen Differential as opposed to the M4204M ($199 List Price on FordParts.com) LOK Differential.

From what I see, ALL of the 3.73's have the Torsen and ALL of the other gear ration have the LOK.
Also, the M4204MT TORSEN is compatible with the 3.31, 3.55 and the 3.73.

Soooo, does anyone know the difference between LOK and TORSEN Differentials?
And is it worth a smooth grand to upgrade if you are really interested in getting power to the ground?

[edwardb]

Edward can you tell what type of bushings/bearings on in the hub control arm mount points. I am hoping they are modern style and not the old rubber stuff like the old IRS.

I can't say because I don't know anything about nor have ever owned any of the previous IRS components. The 2015 knuckles I just received have a combination of metal and some type of elastomer bushings in the two lower arms. They appear to be in there quite substantially. I don't know if these are intended to be left as is, or replaced with parts provided in the FF IRS kit. I'll find out when the kit arrives. That's all I can say for now.

[edwardb]

In older manual transmissions high gear was direct drive 1:1 because it was believed to be most effective in transmitting power, however you might have noticed lately manufacturers have added 5th and 6th gears in the case of my Mustang both overdrive .80 and .60 in the pursuit of the all important mileage number. My car runs at 1200 rpm on the freeway doing 70 mph with its stock gears. So if you go to a 5-speed and spending a lot of time open highway cruising I would look for a rear for running in 4th at 1:1 and go for the wide gear .68 or so 5th for the highway.

I think this is pretty well known and established information. There are a few builds out there with 4-speed toploader transmissions, same as the originals. But the most common manual transmissions for these builds are T-5-s (with several variants) and TKO500/600. All are 5 speed. All fourth is 1:1. All fifth gears are an overdrive. Different models have different ratios. Some in the .80's, some in the .60's. I know that modern DD's are designed to cruise at very low RPM, some as low as the 1200 you mention. Most performance engines, however, are cam'd to get their torque at a higher RPM, and will not be happy at that speed. Very generally, most need to be kept at 1,900 - 2,000 or higher in some cases. The best O/D and final drive ratios are dependent on a number of factors, and vary a lot from build to build.

[edwardb]

OK, I have some findings and a question.

Based on my research, it looks like all of the 3.73's are part of the GT Performance Package option that includes the M4204MT ($1,150 List Price on FordParts.com) Torsen Differential as opposed to the M4204M ($199 List Price on FordParts.com) LOK Differential.

From what I see, ALL of the 3.73's have the Torsen and ALL of the other gear ration have the LOK.
Also, the M4204MT TORSEN is compatible with the 3.31, 3.55 and the 3.73.

Soooo, does anyone know the difference between LOK and TORSEN Differentials?
And is it worth a smooth grand to upgrade if you are really interested in getting power to the ground?

I believe your information is correct. Only the 3.73 comes from the factory with the Torsen option. But the assembly can be bolted into one of the other ratios. There is a method to setting up the internals in these diffs, involved shims, checking and setting lash, etc. So unless you know what you're doing, probably should be done by a pro.

The Ford Traction Lok is a clutch style system where the Torsen is a gear style system. No question the Torsen is technically a better system. Do you need to spend the extra money and would you notice the difference? For normal street cruising, probably not. For track use, and apparently especially Auto-X, it is a better setup. I've had regular Traction Lok on my first two builds, and for my purposes and use, it's fine. Not planning to change out the Traction Lok in the new build with the 2015 setup either. I'll spend the money elsewhere. More discussion here FWIW:

http://www.ffcars.com/forums/21-ffr-type-65-coupe/23862-torsen-vs-trac-loc.html

http://www.ffcars.com/forums/17-factory-five-roadsters/206918-traction-lok-vs-limited-slip-diff.html

http://www.ffcars.com/forums/17-factory-five-roadsters/339826-differential-question-torsen-vs-trac-lok.html

http://www.ffcars.com/forums/66-2006-roadster-archives-read-only/161622-torsen-vs-lsd.html

[Jazzman]

I just called MPS Salvage to order the same setup that you bought, and was told they don't have any left. Everything that they had was just purchased by . . . Factory Five!!! I don't know how many IRS "take off's" that is, but MPS doesn't have any more at the moment. They said they often get them, so call them back in a couple of weeks. Or maybe Factory Five is reselling them. Who knows. Since I was just stockpiling parts anyway, that isn't a big deal to me. I'll call in a couple of weeks . . . or three, maybe four.

[rickscobra]

Happy to report that my kit will have all the 20Th Anniversary items short of the badging, silver chassis powder coating, and white powder coated engine compartment panels. This was most welcomed news. Kit should be ready for pick up on 19 September.

[edwardb]

I just called MPS Salvage to order the same setup that you bought, and was told they don't have any left. Everything that they had was just purchased by . . . Factory Five!!! I don't know how many IRS "take off's" that is, but MPS doesn't have any more at the moment. They said they often get them, so call them back in a couple of weeks. Or maybe Factory Five is reselling them. Who knows. Since I was just stockpiling parts anyway, that isn't a big deal to me. I'll call in a couple of weeks . . . or three, maybe four.

Interesting. They still have a number of active listings on eBay. Those were sold too? There is another seller on eBay that is listing them as well. Will be watching to see how this all plays out when the first 2015 Mustang IRS kits start deliveries to builders in the next few weeks.

[edwardb]

I just called MPS Salvage to order the same setup that you bought, and was told they don't have any left. Everything that they had was just purchased by . . . Factory Five!!! I don't know how many IRS "take off's" that is, but MPS doesn't have any more at the moment. They said they often get them, so call them back in a couple of weeks. Or maybe Factory Five is reselling them. Who knows. Since I was just stockpiling parts anyway, that isn't a big deal to me. I'll call in a couple of weeks . . . or three, maybe four.

This morning I received an email from Factory Five offering a 2015 Mustang center section and knuckles/hubs for my 20th Anniversary Roadster kit order. The email said they were zero miles Mustang take-off parts, so clearly these same ones. I won't post the price offered, but it was on par with what I paid directly. I obviously don't know their plan for offering these assemblies to customers needing the pieces. The supply is limited. Maybe others are hearing from them as well?

Also got a message today that my kit is going into production and to call for final details. Looks like my early August date is really going to happen. :D

[Georg]

Me as well got the mail from FF and I added this new option to my 20th anniversary kit order. Will safe a lot of research and trouble I guess - seems to be a great deal...

My completion date was scheduled for end of August. So looking forward to follow your build Paul, guess you will be twice as fast as me since this is my first build. All the best!

Georg

[rickscobra]

I am a happy camper as well. When I called FFR and asked about securing one of the MPS IRS assemblies, they added it to my order One less thing to have to chase down. Now I am looking at tires for the new 18inch wheels. This is going to be a fun adventure. Delivery date is 19 September, but I may well wait till 24 September to pick it up. Will make a great birthday present.

[edwardb]

Yesterday I finished prepping the 2015 Mustang IRS center section for my upcoming build. I drained the fluid by tipping it sideways and out the axle holes. Probably perfectly good fluid, but I'll feel better giving it a fresh start including friction modifier as specified once it's installed. Plugged the open axle holes with clean shop rags, and cleaned everything up. The iron case just took a little wire brushing with various size wheels in a hand drill and then Scotch-Brite. Peeled the stickers off the rear cover (after taking several pictures) and cleaned it up as well. I sprayed clear Dupli-Color engine enamel on the back cover. Then brushed black POR-15 engine enamel on the iron case after a thorough cleaning with POR-15 degreaser and metal prep. I was careful to not get anything very wet and especially around the front seal. My shop crane was handy for this project. That thing is not light and kind of clumsy to move around. Didn't take any pics yet, but also cleaned up the knuckles and hubs. I'm going to put some clear on the knuckles too, but not until I get the kit and instructions. Best I can tell, as mentioned before, the upper arm gets trimmed back a bit.

This was a relatively lightweight clean-up job given the age and basically zero time on the road. But let's just say I have a new found appreciation for you guys that have the patience to harvest real live donor parts with years of rust and grime to clean up. I've avoided much donor work to date, and probably will keep it that way.

So now I just need a chassis to put this stuff in! We're off to Factory Five next week, with our pickup date of Wed, Aug 5, now confirmed. :D

Cleaned and ready for finish:
http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_0113_zpswqqzjogf.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_0113_zpswqqzjogf.jpg.html)

All done. Compare this to the orange rusty look earlier in the thread. Nice improvement.
http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3256_zpsmoqf2oqg.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3256_zpsmoqf2oqg.jpg.html)

Clean and shiny rear cover. I'll be interested to see how that vent is handled. I don't remember seeing how it was plumbed when I saw the new suspension at the Open House.
http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3257_zpsfnnrnugj.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3257_zpsfnnrnugj.jpg.html)

[BobCarter]

Nice cleanup. Looks very good with the paint and clearcoat. I got a couple pictures today of my 20th and i think your kit was also visible. Ill send you the pic when i figure out how to do it. I'm not picking mine up at FFR so I have to wait for Stewarts delivery date.
looking forward to sharing our build activities with each other. Safe travels!
PS I learned that my quick response to Dave Smith's 20th Anniversary announcement put me right behind the FFR donor to the Ohio club. They will receive serial number 1, that put me in with serial number 2. I bet you will be number 3. Very cool.

[edwardb]

Nice cleanup. Looks very good with the paint and clearcoat. I got a couple pictures today of my 20th and i think your kit was also visible. Ill send you the pic when i figure out how to do it. I'm not picking mine up at FFR so I have to wait for Stewarts delivery date.
looking forward to sharing our build activities with each other. Safe travels!
PS I learned that my quick response to Dave Smith's 20th Anniversary announcement put me right behind the FFR donor to the Ohio club. They will receive serial number 1, that put me in with serial number 2. I bet you will be number 3. Very cool.

Cool! I called right after the details were posted on-line to order mine, and they said someone was already on the phone ordering one. I'll bet that was you at number 2, and have wondered if I would be number 3. Would love to see whatever pics you have. PM sent.

[BobCarter]

Cool! I called right after the details were posted on-line to order mine, and they said someone was already on the phone ordering one. I'll bet that was you at number 2, and have wondered if I would be number 3. Would love to see whatever pics you have. PM sent.

3 pics sent

[CraigS]

Here is my experience w/ the two types of lim slips. In my FFR I had the standard LOK for 3-4 years but decided to upgrade to a TrueTrac (very similar to a Torsen) for autocrosses. Very little difference at the autocrosses but one thing I did definitely notice was more driveline slop. Posted here and found that is a characteristic of those units. Recently my wife traded in her 2010 Mustang GT stick w/ LOK on a 2015 GT stick w/ the Performance Package which includes the 373 Torsen. The first weekend after she had been driving it we go for a ride because she has questions. She had noticed the driveline slop although it is less than in my FFR due to the rubber in the diff mounts and control arms. She also noticed that, when pulling out from a stop and making a 90 degree turn, it makes some noise. The noise she hears is the inside tire spinning slightly as the Torsen locks up. It is more obvious w/ more throttle or w/ gravel on the road. My thinking is that the standard Ford LOK is much nicer on the street w/ nearly no downside unless you drive extremely hard.

[RRussellTx]

Edward can you tell what type of bushings/bearings on in the hub control arm mount points. I am hoping they are modern style and not the old rubber stuff like the old IRS.

CraigS,

I'm concerned about the bushings that that come with the 2015 IRS kit to mount the differential in the chassis. They are not rubber and seem like some kind of poly but they are very light and I think very soft for what they are going to be used for. I see from your posts that you have some experience in this area.

What are your thoughts on the expected lifespan of this part and how it would perform under a high load in a light car?
I REALLY don't want to pull the differential after a year or two of service...

It's probably fine for my use but I would be mad at myself if I did not do some due diligence before I installed the unit?

Here is a pic of the part where I am showing off my manly grip and compressing it a bit to show how soft it is.
http://i827.photobucket.com/albums/zz197/rrusselltx/Mobile%20Uploads/2015-09/A243C148-4FDA-4C10-A41B-79D595E1BB22_zpscwvtcet0.jpg (http://s827.photobucket.com/user/rrusselltx/media/Mobile%20Uploads/2015-09/A243C148-4FDA-4C10-A41B-79D595E1BB22_zpscwvtcet0.jpg.html)

Thoughts or opinions from anyone would be appreciated!

[edwardb]

Well you know from our brief discussion in your build thread that my opinion is these will be OK. But several things occur to me. I don't think the experience with the previous IRS mounting is completely applicable to the new 2015 Mustang setup. The previous design has a vertical flange mount along the center of the rear cover, and two vertical bushing mounts on each side of the nose at the front near the pinion flange. This design, which has been very successful BTW, would seem not as capable to resist twisting forces as the 2015 Mustang setup which has four wide horizontal mounting locations. So I'm not sure how much experience with the old design applies to this one. The other point is these four mounting points are very solidly wedged into the chassis. Trust me when you try to install, you will find out just how tightly it's wedged in there. This too would really resist motion in any direction. More than just the bolts pressing against the sleeves in those bushings. Those are some of the reasons I think it's OK. But I understand your concern and I don't want to take it out again either.

The other thought would be call Factory Five. Try to get feedback from one of the design guys, not just the tech support guys answering the phone. Of course they're not going to tell you they designed and sold us a kit with a defective design. But it may be useful to find out just how much this new setup has been actually tested, and what their experience has been from that testing. Maybe that would give you some confidence. Or not. During the FF Open House, when Dave was unveiling the 20th Anniversary Edition Roadster, he spoke at some length about the new IRS. It's been under development for a while, and he described quite a bit of track testing, beating previous best times, etc. Maybe there's something to be learned from that. Just a thought. I too will be interested in what others think.

I'm not a chemist, but I'm also pretty sure those are poly. For those reading this that don't know, the pictured bushing is one of two for each of the four mounting points. They are pressed into steel tubing welded to the chassis, and have a steel bushing through the center for the mounting bolts. M14 bolts (.55 inches) in the back, M16 (.63 inches) in the front.

[CraigS]

Googling '2015 mustang rear wheel hop' I found this;
https://www.youtube.com/watch?v=dA0kzu4Ukzk
Steeda is stiffening the subrame to body mounts and leaving the diff to subframe mounts alone. You can see the bolt head of the diff mount move quite a bit and also notice that the stock bushings are much larger than the one you picture and have voids in them. My "guess" is yours will be fine.

[RRussellTx]

Thanks guys. I really appreciate your perspective!
I'm going to do some more research this weekend so let me know if anyone else has any thoughts.
Since this IRS is so new I really want to consider everything carefully while I'm at this stage of the build.

[RRussellTx]

I called FFR and confirmed that the Diff bushings are Energy Suspension Poly bushings. I got my hands on a similar set of Energy Suspension bushings to compare the hardness. The ones I have for comparison are the same material as the ones in the kit but they seem a lot harder (more like I am used to). But they had a much smaller ID for the bolt to go through so the bushing was much thicker and therefore firmer. After looking at both and talking to several knowledgable people, I am convinced that the bushings are just fine.

I also was able to get my differential mounted this weekend and I don't think it would be possible with bushings that are very much harder. I also followed some steps that made it a little easier so I thought I would share those here in this thread.

First, don't install the steel tube spacers all the way in the bushing before you start. You can get them started in the bushing on the outside of the differential but just press them in about an inch.
Then you can position the differential in place and start the threaded bolts in the rear cover first.
http://thefactoryfiveforum.com/attachment.php?attachmentid=71470&d=1501450765

http://thefactoryfiveforum.com/attachment.php?attachmentid=71469&d=1501450756

Make sure you get a good start on the threads but don't tighten any of them down until you get all 4 of them started. Once you get them all started then you can just tighten them a little at at time depending on which one needs to come in first until they are all tight.

http://thefactoryfiveforum.com/attachment.php?attachmentid=71468&d=1501450749

One other thing that helped when I drilled out the differential was to grind down the tip of a 5/8's bit to a small enough diameter to fit into the existing hole. It might have been fine anyway but with this it was super easy was drilled out in just a few seconds.

http://thefactoryfiveforum.com/attachment.php?attachmentid=71467&d=1501450740

Sorry about being concerned about the bushings but I'm 100% convinced that they are the best option now. Good luck installing yours!

[edwardb]

Excellent follow-up and suggestions! Great information.

[ThickCobra]

Any thoughts as to whether adding chassis lube to the bushings would help? And, should I as a rule use chassis lube on poly bushings elsewhere?

[edwardb]

Any thoughts as to whether adding chassis lube to the bushings would help? And, should I as a rule use chassis lube on poly bushings elsewhere?

Yes, use your chassis lube of choice anywhere there's a Zerk fitting. I use Red Line CV-2 (O'Reilly's) but don't think there's anything magical about the brand to be honest. A little on the center section bushings during installation wouldn't hurt anything. But I'm not sure how much it would help. They're just mechanically very tight.

[CraigS]

I use synthetic grease where ever I feel the need. Oil based grease can attach some types of plastic. Since I am not always sure what exact compound I might be dealing with, I figure synthetic is safe for everything.

[toadster]

All done. Compare this to the orange rusty look earlier in the thread. Nice improvement.
http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3256_zpsmoqf2oqg.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3256_zpsmoqf2oqg.jpg.html)

Clean and shiny rear cover. I'll be interested to see how that vent is handled. I don't remember seeing how it was plumbed when I saw the new suspension at the Open House.
http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3257_zpsfnnrnugj.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3257_zpsfnnrnugj.jpg.html)

Paul - I love going through your build threads, I hope my IRS looks 1/2 as nice as yours... it's time to get workin on my end now!

curious as to which grit Scotch Brite (https://www.amazon.com/gp/search/ref=as_li_qf_sp_sr_il_tl?ie=UTF8&tag=cobradreams-20&keywords=scotch brite&index=aps&camp=1789&creative=9325&linkCode=xm2&linkId=a1144ada6af515b743b64cc30c96d15f) you used - that diff cover SHINES!

3-grades pack
121877 (https://amzn.to/2Uq60FY)

[Aircontroller]

Interesting vid about the Torsen below. Posting for future reference.

The guy narrating the vid made an interesting point that I have to review again regarding calibrating the speedometer for the type of transmission.

https://youtu.be/EVXDor-2IxQ

[Aircontroller]

I had just PM’ed Paul the same compliment!:cool:


Paul - I love going through your build threads, I hope my IRS looks 1/2 as nice as yours... it's time to get workin on my end now!

curious as to which grit Scotch Brite (https://www.amazon.com/gp/search/ref=as_li_qf_sp_sr_il_tl?ie=UTF8&tag=cobradreams-20&keywords=scotch brite&index=aps&camp=1789&creative=9325&linkCode=xm2&linkId=a1144ada6af515b743b64cc30c96d15f) you used - that diff cover SHINES!

3-grades pack
121877 (https://amzn.to/2Uq60FY)

[edwardb]

Thanks guys. Brings back memories of rehabbing that diff for my 20th Anniversary build. Ford Performance wasn't selling the separate pieces yet at that time, so a donor was the only choice. Even though I got lucky and scored a zero mile takeout, still was rusty and crummy right from the start. For the Scotch Brite, don't remember specifically. They were green and from Home Depot, if that helps. Don't think it's particularly critical. Whatever works. For the comments in the video about calibrating your speedometer, not an issue if you're using the common GPS gauges from Speedhut. They'll be right from the start no matter what. Autometer requires a calibration step as I recall. Over a measured distance. But pretty straightforward.

[Aircontroller]

Hey toadster, any chance you can post what worked for you to get the rust out? I’m mighty curious.....Thank you in advance!


Paul - I love going through your build threads, I hope my IRS looks 1/2 as nice as yours... it's time to get workin on my end now!

curious as to which grit Scotch Brite (https://www.amazon.com/gp/search/ref=as_li_qf_sp_sr_il_tl?ie=UTF8&tag=cobradreams-20&keywords=scotch brite&index=aps&camp=1789&creative=9325&linkCode=xm2&linkId=a1144ada6af515b743b64cc30c96d15f) you used - that diff cover SHINES!

3-grades pack
121877 (https://amzn.to/2Uq60FY)

[toadster]

Hey toadster, any chance you can post what worked for you to get the rust out? I’m mighty curious.....Thank you in advance!

I've got a few more hours to go on mine... it was a newer unit from Mike Forte
122884

I moved the unit outside for a few days when I had the garage epoxied, and I thought I had it covered well, but it rained one night... ugh, it turned orange, I grabbed a green scotch brite and quickly realized, it wasn't going to do much other than scuff... Its meant for polishing, not for stripping...

so I took a wire wheel and did a decent job for about 10 minutes... although, I'll probably switch to a corded drill or my dremel to finish, otherwise I'll be killing my rechargeable batteries...

you can see pretty easily what was initially hit with the wheel
122885

the aluminum side shines up nicely, but you need to be careful how much you can cut into the face of the metal with the harder metal wheel
122886

so I'll probably use the dremel with some stripping wheels, and buffing wheels to soften the blow... i'll use POR15 on the case, so not super concerned about the finish, but the aluminum I'll hopefully shine up nicely!

60 Pcs brass steel wire polishing brush Wire Brush Wheel Cup set 1/8" (3mm) Shank for Dremel Rotary Tools Polishing Tools Accessories
122887 (https://amzn.to/2wCB2Rl)


40 Pack 1 inch Abrasive Wheel Buffing Polishing Wheel Set For Dremel Rotary Tool
122888 (https://amzn.to/38RuEUo)

then I'll use the scotchbrite to finish :)