8.8 Rear axle questions and shopping list

[Yama-Bro]

Hi Guys,

I am still several months away from ordering my roadster kit, but in the mean time I have been doing a lot of research and planning. Last weekend, I picked up an axle from an ’89 fox body mustang. I thought I would get it ready to go now so I can speed the build process up. It needs some TLC. Before I start tearing into it, I have some questions for those of you with experience. But first I’ll give you the details of my build plan. The car will be a complete kit. The drive train will be a 302 based engine (most likely a 347) with a Tremec TKO-600 tranny. I'll be running the 3 link. I am planning on running 15” wheels. I am also planning on purchasing Levy’s 4 piston disc brake kit for 15” wheels. For this axle I am basically going to take out the innards and get all new stronger stuff. I posted some pictures at the end of the text.

That leads me to my questions; What can I remove from the axle that I won’t need to reuse? Or what can I get rid of? I don’t want to throw something away and find out I need it later.
1. I know the quad shocks are not used, so I assume I can remove the shocks and cut off the brackets?
2. I am planning on switching to disc brakes. Can I remove everything for the drum brakes all the way down to the plate that is bolted onto the flange that is welded to the axle?
3. Is there any reason to keep the any of the brake lines or the brackets that hold the lines on? Does the kit come with new rear brake line clamps?
4. How about the brackets that are bolted onto the lower control arm brackets (see pics). Are they reused? I assume not.
5. There are two brackets on the front of the diff housing, one above and one below the pinion. They may be some sort of anti-vibration brackets or pinion support. Are they used on the kit?
6. And finally, I assume the two rubber bushings inserted into the diff housing are not used in the completed FFR roadster. I am planning on removing them. Has anyone ever cut off the cast flanges that hold these grommets, just to clean up the axle?

Here’s my shopping list for the axle. Is there anything that you can think of that I am missing?
1. Ford Racing 3.55 Gear Set
2. 31 Spline trak loc diff
3. 31 Spline axles
4. Seal and bearing rebuild kit.
5. Gear lube
6. Disc brake brackets
7. Por-15 paint

Is there anything special I need to watch for when ordering the pinion? I thought I saw there are different versions with different # of splines.

Thanks for you input in advance!

Frank

http://i152.photobucket.com/albums/s169/Yama-Bro/FFR%20Cobra/Rear%20Axle/20160506_200132_zpsdjpl5eka.jpg (http://s152.photobucket.com/user/Yama-Bro/media/FFR%20Cobra/Rear%20Axle/20160506_200132_zpsdjpl5eka.jpg.html)

http://i152.photobucket.com/albums/s169/Yama-Bro/FFR%20Cobra/Rear%20Axle/20160506_200154_zpsqoisurlh.jpg (http://s152.photobucket.com/user/Yama-Bro/media/FFR%20Cobra/Rear%20Axle/20160506_200154_zpsqoisurlh.jpg.html)

[Jeff Kleiner]

1. Yes
2. Yes
3. No and no clamps specifically for the rear end. Most times hard line is run to both corners on the chassis with an individual flex hose to each wheel.
4. Not used
5. Not used
6, Not used with the 3 link. I remove the bushings, pick up rubber stoppers of the correct diameter, drill a hole through the center and run the parking brake cables through then silicone it into the diff "ears":

http://i269.photobucket.com/albums/jj43/jkleiner/Mk4%207276/100_1874.jpg

Doing this nothing further is needed to secure the cables.

Cheers,
Jeff

[CraigS]

One addition to Jeff's answer is this. The right (passenger) side rubber bushing ring is used if you get the VPM 3 link brace so don't cut it off.
http://www.vintageperformancemotorcars.com/

[Avalanche325]

Friction modifier for the lube.

[Yama-Bro]

Excellent. Thanks for the answers, guys!

Jeff, Is that a stock cover? If so, it looks great painted silver. I think I will go that route as opposed to the machined aluminum cover. Way cheaper too.

[dmoran]

You might want to replace the vent. The little cylinder on the top, passenger side of the axle. It looks pretty nasty.

53829

For the girdle, if you use RTV instead of a gasket, make sure to get the kind specifically for "gear oil." It's pretty standard to just use black RTV but since you are changing to trac loc, you'll need friction modifier (as mentioned by Avalanche325) and according to the data sheets, it may eventually break down the black RTV. I used:

53830

It's designed for gear lube with friction modifier, whatever that is.

You mentioned cutting off the top quad shock brackets. I found that they were a PITA and in the way when trying to bolt on and torque the disk brake brackets (I used the FFR Rear Brake kit) I cut them off with a sawzall and it went through them like butter. I read some posts where guys were using grinders and cutoff wheels and it took a long time to get them cut off.

One thing I did that I highly recommend before ordering a kit is to go to FFR build school. You get to work through every phase of the project, see the options available and get so much advice on what's good and what needs work that it's invaluable. I'm sure that I have saved more in dead ends and mistakes then the course cost. Plus it was a fun weekend with some great guys. I ended up not getting the complete kit based on some of the things I saw at build school. I went base and then a la carte on the FFR parts I wanted like suspension, brakes, steering. If you time that with FFR's 50% off on upgrades that they have once in a while, you can save a bit. The rest, a lot of the trim and shiny stuff, I wanted aftermarket parts and not what was in the kit.

Good luck,
Doug

[Jeff Kleiner]

Jeff, Is that a stock cover?

Yes.

Jeff

[cnutting]

Not to hijack the thread, but have a relevant question. As I was test fitting the brake brackets on my rear axle, everything was going so smooth that I ended up just assembling everything. Then moved on to the banana bracket, etc. and I neglected to cut off the quad shock brackets (I bought my rear axle with the kit, everything was all cleaned up and powder coated). It doesn't look like they will interfere with anything, so I am tempted to just leave them as is. I could get in there if need be with a sawzall and get most of them out.

To paraphrase The Clash, should they stay or should they go?

[wallace18]

For sure get the extra brace from vintage. Best money you will spend on a 3 link.

[CraigS]

cutting they definitely won't cause any problems being there. SO it's your choice. Personally, I'd cut them out and touch up the edges w/ black paint. Kind of a shame to mess up the powder coat but no one really sees the axle anyway.

[TexasAviator]

I think with that drive train 31 spline is overkill unless you are hard launching it at the track every weekend.
The alloy shafts in the 28 spline version will save you money for other mods.
The gear set it perfect.
The Other thing i would add is get an extra set of bearings for the carrier, use them as set up bearings to set backlash, then when you use the other new set of bearings that comes with the install kit, take a torch to it slide them on with a gloved hand and let cool. They will slide on without a press.

[CraigS]

Another option for oil is Mobil1 w/o any modifier. that is what I ran in my Ford diff until I swapped to a TrueTrac diff. To add to what TexasA said, an extra set of pinion bearings is really nice for measuring the pinion depth. Grind a little on the inside of the inner race so they are a slip fit on the pinion. Otherwise you need a press for every experiment w/ a different pinion shim. If you but Ford gears, you may get lucky and not need a different pinion shim. I did.