Limited slip installation instructions with pics

[Hindsight]

The factory service manual is wrong and misleading in a few key places, and since I couldn't find a good thread here or on NASIOC that covered it all, I'm going to create one here.

This covers installing a limited slip diff in the transaxle. It doesn't cover changing out the ring and pinion. In this tutorial, I used a 2007 WRX donor transmission. Instructions should be the same for any kind of LSD but I used a Quaife.

Tools needed (beyond the typical torque wrench, sockets, combination wrenches, etc):
- Dial gauge (not the push kind, but the lever kind like this:)
- Shop press (not required but helpful)
- T70 Torx bit
- Wood shims (like from Home-Depot for installing doors and windows - not required but helpful)
- Brass hammer (plastic hammer might work too)

Parts suggested:
- New o-rings for differential bearing carriers (2 total)
- Input shaft seal
- Driveshaft seals (2 total)
- Differential carrier bearings (2 total)

Remove the drain plug with the Torx bit

With the transmission out of the vehicle, remove the engine mount and rear cover plate (if not already removed).

Remove the two sensors that screw into the left side of the center differential housing (they have electrical connectors on them).

Unbolt and remove the center differential housing. You will have to wiggle the gear selector a little bit to get it out. The center diff housing is the rear-most part of the transmission as seen in this pic:
http://i.imgur.com/Sm3SGOy.jpg

Remove this thrust plate which is just sitting behind the driven gear shown in the picture (the center diff case housing which you just removed helps keep it located):
http://i.imgur.com/yskVBpS.jpg

Next remove the four bolts that hold the pinion shaft in. You can see three of the four bolts in this pic:
http://i.imgur.com/qEWpA1U.jpg

[Hindsight]

Next lay the transmission on it's RIGHT side (passenger side) and remove all the nuts holding the case halves together. All but a few of the nuts should be facing up. The only ones that aren't are the ones that can't be because the dipstick tube is in the way.

Flip the transmission over on it's LEFT side and remove all the bolts you took the nuts off of. Do this carefully so the case halves don't split (just yet). Put a couple of 4x4s or stacked 2x4's under the transmission for support. You will need to be able access parts under the transmission and this will provide clearance. Also, the transmission can be very wobbly no matter what you rest it on so have some wood shims around to wedge in key places to keep it stable). Remove any remaining nuts and bolts facing upward. IMPORTANT: You are only removing nuts and bolts that go all the way through the transmission. There are a few bolt-looking things that hold the synchro selectors in place so don't remove those.

Now, with the transmission on the 2x4s on it's left side, remove the upper (right) side case half by lifting it up and off. It will be glued in place with sealant so you may have to tap it in key locations using a brass hammer. It also tends to get stuck on the guide pins. You should now see this:
http://i.imgur.com/BzXMuyJ.jpg



Remove the driven shaft (that's the top shaft in the above pic) by grabbing it on each and and wiggling around until it lifts up and out. It should now look like this:
http://i.imgur.com/aaykQDd.jpg

Now remove the pinion shaft. It may require more wiggling and maybe some prying at the gear end but be careful when prying not to gouge any aluminum. Once the pinion shaft is out, the differential lifts right up and out:
http://i.imgur.com/K7oTKIY.jpg
http://i.imgur.com/gfATqqv.jpg

Remove the ring gear from the differential. I used an impact gun. The ring gear came right off:
http://i.imgur.com/6MB7XPc.jpg

[Hindsight]

Now put the ring gear on your limited slip. If it's too tight (like mine was), you can heat the ring gear in an oven at about 200, and put the diff in a freezer for 20-30 minutes. Tighten the differential ring gear bolts to 45.6 ft lbs.

Now you can either re-use your old differential carrier bearings and races or get new ones. New ones are ~$80 each from the dealer and I feel is a good idea to replace them while you are in there. The bearings come with races as a matched set so make SURE you keep track of which race goes with which bearing. If you re-use your old bearings, I have heard you can sometimes finesse them off with a screw driver and some other tools, but be careful. If you suspect you may have damaged them in trying to remove them, don't re-use. To install new ones, just press them on with a shop press. I have heard they may go on by hand with the heat/freeze trick as mentioned above but I didn't try. The old bearing races are not pressed into the side retainers (the splined units on each side of the transmission); they will basically just pull right out. Pull them out and put the new ones in. If you are having trouble, simply remove the side retainers by unscrewing them (first remove the bolt holding their locking tab in place).

Remove the side retainers by removing the bolt and the locking tab, then unscrewing them counter clockwise until they are out. I made this tool to help turn the retainers:
http://i.imgur.com/YmYvuGQ.jpg
http://i.imgur.com/m0XeeDo.jpg

With the side retainers removed, remove and replace the LEFT side retainer o-ring, and simply remove the right retainer o-ring (don't replace it just yet). The reason for this is that the o-ring causes friction and makes it difficult to adjust the bearing tension later.

Put the new races in (or old ones if you are re-using them - ensuring you put the same side back in the same side) and screw the LEFT side retain in just a bit. Maybe 1 full turn after it starts to thread.

Install the new input shaft seal by sliding the old one off and the new one on.

Drop the new differential in, then the pinion shaft, and then the driven shaft. A couple of things about this. There are some shims on the back side of the pinion (where you removed the four bolts early on in the procedure). Be careful not to damage these! These set the height of the pinion and since you are not changing the ring and pinion, you don't need to mess with these. Also note that there is one pinion and one driven shaft bearing that have a hole in them to accept a nub in the case half. It will take some fiddling to get these all lined up properly so both shafts drop in all the way and the gears mesh all the way.

In this shot you can see the nubs I'm talking about for the bearings (circled in red):
http://i.imgur.com/apwy5tP.jpg

Another thing to note: The plate that holds the pinion in (with the four bolts and the shims behind it) can sometimes rotate on you during the job. The holes are drilled such that the shims and the plate can ONLY go on one way. If you are having trouble getting things to fit back in, rotate the shims and plate until their holes line up with the left-side case holes. Lastly, there is a circlip on the driven shaft that can get caught in the wrong place. In the pic below, the circlip is interfering with the pinion shims and plate. Rotate the circlip around so the open area of it is facing the shims and plate and allowing them to have clearance (in the picture below, it shows the WRONG orientation for the circlip - note how the opening is in the wrong place and the lower part of the circlip is coming into contact with the shim.... you would rotate the circlip so the opening moves down so it clears the shim):
http://i.imgur.com/PMhtUNK.jpg

[Hindsight]

Now you should be back to this:
http://i.imgur.com/BzXMuyJ.jpg

Clean off all the old gasket material and wipe the case halves with acetone, then apply a thin bead of your favorite transmission oil proof sealant (I used Hondabond). Next place the right case half back on top and tap it down into place with your first. When doing this, be very careful of those pinion shims.

Once the case is in place, put the bolts in. With the case on it's left side still, all the bolts go in from the top down (nuts on the bottom), with the exception of the ones that can't due to obstructions.

You should torque the nuts, not the bolts, and that will require you to flip the case over to the other side but before you do, thread the right side adjuster in about 5 or 6 turns (just to help support the diff and keep it from rattling around too much)

Torque specs and sequence are shown in the pic below from the factory service manual. Be sure to do them in order. Note the larger bolts are the ones with a star next to them and get torqued first, and tighter. Torque the case halves first and then the pinion plate with the four bolts.
http://i.imgur.com/g0AIyyD.png


With everything torqued and triple checked, flip the case back over onto the left side. Remove the top side adjuster. Now, while turning the input shaft with one hand, turn the left side adjuster in (tightening it) and keep tightening until you feel the side adjuster become difficult to tighten. What you are doing is moving the ring gear upwards, closer to the pinion. When it gets difficult to turn, it means the pinion has bottomed out on the ring gear and you are at zero backlash. Here is a side view of what it looks like. Turning the left side adjuster in moves the ring gear closer to the pinion (first picture below) and loosening it moves it further away (second pic below):
http://i.imgur.com/GOstoDU.png

So now, if you install the right side adjuster, nothing you do to it is going to cause the ring gear to move or change the backlash since that's now set with the left side adjuster. At this point, all the right side adjuster can do is set the bearing preload which is the tension pressing in on the bearings.

Now that you are at zero backlash, it's time to take any slop out of the bearing races which may not be 100% seated (no real amount of pressure has been placed on them yet). To do this, thread the right side adjuster in place and tighten it until you feel resistance (this means it's just started to pinch the bearing race against the bearing), then tighten it again until it becomes very difficult to turn by hand (about 1-3 teeth). You can tap the case around the adjuster with a plastic hammer to help (per the FSM). Now back off the right side adjuster a couple of turns to get it away from the bearing so it isn't interfering with anything.

Now that any slop is gone, back off the left side adjuster a turn or two, then repeat the procedure with the left side adjuster to get back to zero backlash (slowly tighten it while you turn the input shaft until you feel resistance).

Subaru says to run the diff at .0051 to .0071 backlash. The teeth of the ring and pinion are tapered in a "V" shape so moving the ring gear away from the pinion creates backlash or free space between the gears. To get to the ballpark, back the left side adjuster off (loosen it) by 3 teeth (teeth of the side adjuster). You can mark the side retainer or case with a sharpie to help. Subaru says that for every tooth you turn the side adjuster, the backlash changes by .0021 so 3 teeth would equal .0021 x 3 = .0063 which is in spec. The reason you can't just do this and call it done is that your starting point of 0 backlash is never going to be truly 0 backlash. When tightening the left adjuster and stopping when it gets "hard to turn", there is a course of about 1-2 full teeth where you could interpret it as "hard to turn". When do I stop?! You don't really know so you just feel it with your best guess, back it off three teeth from there, and then start checking with the dial indicator.

So now that the backlash is set to ballpark, screw in the top side retainer until resistance is felt (which would be 0 preload), then tighten a further 1 tooth to set the proper amount of preload on the bearings. There is no measure for pre-load. Oddly, the 5 speed instructions say to use 1 tooth while the 6 speed says to use 2 teeth, and both 5 and 6 speed side retainers move in and out the same amount for each tooth of adjustment. I stuck to 1 tooth.

Now, to check the backlash accurately, you need to lock the pinion shaft TIGHT. A wrench and socket won't work... too much free play. I tried that and even though I was VERY gentle while checking the backlash and could swear the pinion shaft wasn't moving at all, my readings were larger than when I locked the pinion shaft tight using this method: Put a pair of vise grips on the pinion shaft nut, then rest them against something very firm and stable and put a weight on top of the end of the vise grips like this:
http://i.imgur.com/LfwIFOx.jpg

Now put one of your drive shaft stubs in the right side of the transaxle. Now mount your dial indicator and put it on the face of a tooth as far out as possible (meaning, as far toward the outside of the ring gear as possible). I made a mount of steel bar stock I had and it looks like this all setup:
http://i.imgur.com/iSEmI9L.jpg
http://i.imgur.com/HXdtd3l.jpg

Put the transmission in 4th or 5th gear by moving one of the selectors. It isn't critical that it's 4th or 5th (but higher gears multiply torque less which gives less of a chance of the pinion shaft moving and throwing off your numbers). The shift forks are circled here. You can see three of them. Push in or pull out on one of them to engage a given gear. The middle of the three is 3rd and 4th gear but I forget if in is 3rd or out is 3rd. You can check yourself by trying both, then rotating the input shaft and seeing which gear makes the driveshaft stub rotate faster (that would be 4th).
http://i.imgur.com/f5Y1nzo.png



Now move the driveshaft stub clockwise until it stops, note the reading on your dial indicator, then rotate it counterclockwise and note the reading. You want .0051 to .0071 total. The FSM tells you to adjust the RIGHT side adjuster to make any adjustments to the backlash at this point but that's wrong! If you just spin the right side adjuster, you'll only increase or decrease the preload on the bearings. If the backlash is too much, it means the ring gear is too far away from the pinion. If the backlash is too little, it means the ring gear is too close to the pinion. Adjust it by first loosening the right side adjuster a turn or so (to take the load off the bearing and allow you to more easily move the left adjuster), then TIGHTEN the left adjuster to DECREASE backlash or LOOSEN to INCREASE backlash. I start by moving them 1 tooth at a time. After your do this, tighten the right side adjuster until you feel resistance, then tighten one more full tooth to set the bearing pre-load as before. Now re-check your play. Repeat until you have the correct amount of play. Once you are there, you have finished setting backlash and preload.

Now install the right side adjuster o-ring by first marking the tooth against the case with a sharpie to mark your position (which is the proper preload), then loosening it until you can see the o-ring groove, install the new o-ring, then tighten the adjuster until your mark lines up. The point in not putting the o-ring in until last is that it made it easier to feel the resistance for bearing contact and pre-load that you were previously setting.

Install the locking tabs to keep the side adjusters in place. If the tabs don't fit, flip them over. You can now install new driveshaft seals if you want now too.

Some people check the ring and pinion contact pattern. I did this initially but realized that you don't have to if all you are doing is swapping the diff; the pinion height won't change and the backlash is set with the dial indicator.

Lastly, clean up the gasket material for the center diff housing mating surfaces with a razor blade and acetone. You can either get a new paper gasket or just use more liquid gasket maker like Hondabond (don't use both though). Replace the big thrust washer removed earlier in the procedure (don't forget to do this as it's easy to forget). Put the gear selector in place on the shift forks and slide the housing in place and bolt on. Don't force the housing if something feels like it's blocking it. On mine, I had to go in with a screwdriver and gently nudge the big thrust washer a bit left and right to get it to be in whatever perfect orientation the case wanted it. Torque the housing bolts to 18 ft lbs.

Put the drain plug back in and torque to 32 ft lbs if you have an aluminum crush washer or 51 ft lbs for a copper crush washer.

Hope this helps.

[Canadian818]

Wow! Thanks for putting in the work, lots of detail. I Just might try this myself now.

[Ellimist]

Second that - this is awesome! Personally still wondering about some aspects of the backlash, but I'm not sure I can ask a coherent enough question yet that won't waste others time, LOL. In any case, this plus a little more reading and I'm feeling good about doing this myself!... Gonna start saving for the Quaife right away!

[Hindsight]

Thanks guys. I updated to include the torx bit size and all tightening torques.

[Tamra]

Great write up!

[JAubin]

Awesome write up! I'm getting ready to do this soon and it will definitely come in handy.

Some P/Ns if you choose to replace these (for an '02 in my case):
Differential Bearings (2 per) : 806340080
Axle Seal (right) : 806730041
Axle Seal (Left) : 806730042
Axle Seal O-Rings (2 per) : 806975010

[Santiago]

Sticky worthy for sure...many thanks!

[metalmaker12]

Nice job!!!

[Silvertop]

A VERY nice job! Still not sure if I will attempt it myself -- I've always found transmissions a little scary -- but maybe...........!

What I'd love to see is a photo sequence displaying the half-shaft conversion necessary to convert a 5MT for use with a Quaife QDH3Y.

[Harley818]

nice work Hindsight.
I'm waiting to drive it first, then determine what type of LSD I want.
Now I feel a little more confident with your instructions and pics to attempt it myself.

[Mitch Wright]

Thanks for the step by step. One thing I want to add is Remove the steel throw out bearing sleeve. It took me a minute to figure out what was keeping the case together. On my 04 transmission it has 2 set screws that are 180* from each other along with some Locktight. It did take a little effort to get is started with a small slide hammer but once it got moving it came right off.

39493

[Mulry]

First off, this is a great thread. Thanks for documenting all of this Hindsight. It was super-helpful in getting our LSD installed this weekend.

I have a couple of additions, I'll include them with the photos. I can send you the larger sized ones if you want to incorporate these into the thread itself.

Post 3 describes the "nubs" or dowels that locate the bearings on both the driven gear shafts and the pinion gear shafts. Locating the bearings on those nubs can be difficult, since the nubs are blind when you're putting in the shafts. Here's how I solved that problem:

Before putting the new differential in, mark the location of the nubs on the case with a Sharpie, like this:

47452

Make a similar mark on the bearing on the pinion shaft and on the bearing on the driven shaft. Here's what it looks like on the pinion shaft bearing:

47453

With the differential still out of the case, lay the pinion shaft in the case and rotate the bearing until the nub slots into the divot in the bearing so that you know that the bearing is in the same position in which it will need to be when you do the final assembly.

Unfortunately, when the LSD is in the case, you won't be able to see these marks very easily on the pinion shaft bearing, so we need to mark the face of the bearing someplace where we can easily see it during installation (this isn't a problem on the driven shaft bearing because the LSD isn't in the way on that one). You can use the case location where it intersects the bearing as your reference mark, since you can (a) see that easily and (b) it's not going to move when you install the pinion shaft. With the pinion shaft still in the case, from the step above, mark that location with your Sharpie:

47454

I got Sharpie on both the case and the bearing, so when I removed the pinion shaft to place the LSD in the case, I wiped the Sharpie off the case with a little acetone in order to make it easier to see the line on the bearing during installation.

Next, put the LSD in the case and install the pinion shaft. You should be able to freely rotate the bearing. If you marked it as I did above (and erased the extra Sharpie marking that got on the case), then it will look like this when it's rotated into place correctly:

47455

Since there is some axial play in that bearing (by design), you can slide it along the shaft until the nub fits into its slot (phrasing!) on the bearing, but with this marking, you'll know that the bearing is in the correct rotated location and all you need to do is slide the bearing to engage the nub.

Cheers guys.

[Sgt.Gator]

This should be a Sticky!

[Pearldrummer7]

WOW this is amazing. Wish I had this last year when taking transmissions apart. Great write up, +1 for sticky!

[Mulry]

Who do we need to talk to about getting this stickied? It was a tremendously helpful post for me to do our LSD install and I never would have found it with the forum search tools but Hindsight thankfully mentioned it in another thread for me.

[Hindsight]

I'll shoot the admin a message and see if he'll do it.

[David Hodgkins]

Done! I agree, great write up.

:)

[Pearldrummer7]

Great! Thanks Dave for the sticky and thanks Hindsight for the write up. Now get us one for rebuilding an engine! ;)

[DodgyTim]

Great write up
For those putting in an OBX or other early style LSD into a later model gearbox, the diff output shafts change from female to male, and the seals need to be changed
48967
RHS seal suits female, LHS seal suits male output


48968
Part numbers for seals, the left and right seals are different part numbers

4896948970
Adjustment tool needs to clear the output shaft

[lclevert]

Hi all. I just went through this procedure to install a cusco lsd. These instructions are invaluable. I reassembled everything and set the backlash, but something seems to be binding when I turn the axle shaft. The transmission is dry, so not sure if this is due to a lack of lubrication or there is some other problem. I've gone through the backlash procedure twice and still feel it. I can turn the axle shaft, but it seems to "stick" in places and is not a smooth spin.

Nothing in the transmission looked out of the ordinary. There is one shim on the rear pinion shaft that is back in place. The case went back together without any issues so I think everything inside was seated correctly.

I assume this is not normal, so any suggestions as to what this might be before I split the case again? It is an 03 WRX trans and I installed the cusco type RS lsd.

Thanks

Skip

[Hindsight]

Glad the instructions helped you. The binding is not normal and should not happen. Lack of lubrication won't cause it. does it happen regardless of which gear you move the selectors into? IE does it happen when it's in gear as well as when it's in neutral? If it happens in neutral, then it sounds like there is binding at the ring gear. If there is binding only when it is in gear, then it sounds like there is binding between the input shaft and the drive shaft (binding between 1st-5th gears).

I'm guessing it is binding in neutral and also when in gear which would point to a ring and pinion issue. What could cause that would be if the ring gear didn't get perfectly seated on the limited slip housing.... IE it isn't laying on it's seat perfectly flat. How tight was the fit of the ring gear on the Cusco? Was it REAL tight? Did you have to freeze the LSD and heat the ring gear to get it on or did it just drop right on? If it didn't just drop right on, there is a chance it isn't sitting on there level. Or maybe you got a piece of dirt or something caught between the ring gear and the diff housing preventing it from laying perfectly flat? To test this, check your backlash at several different points of rotation on the ring gear. I check it where there is no binding, then turn the input shaft with the transmission in gear until there is binding, then check the backlash. If your backlash goes away where it binds, that really suggests the ring gear is not sitting flat.

The other thing could be that the differential carrier bearing races are not sitting level. Did you remove the races? They ride in the removable threaded carrier housings (which is what you tighten and loosen to set the backlash and the preload). In one of the steps above, you are supposed to tighten both of them very tight while tapping on the outside of the case with a platic hammer to try to "set" those races and ensure they are flat. I think this is a long-shot though.... my money is on the ring gear not being level - whether that is due to a problem during the installation (you didn't get it perfectly flat or something is wedged under it), or the Cusco just isn't properly machined flat (fairly unlikely).

[lclevert]

Hindsight, thanks for the quick reply. The binding happens in neutral. When I checked the second time, backlash in a non-binding spot was about 6 thousands. backlash in a binding spot was about 1 thousands. The ring gear slipped on without any problem. No heating required.

Also, the bearing races basically fell out when I removed the threaded carriers, so there doesn't seem to be any binding in the races.

I will first pull out the threaded carriers and races and go through that tightening procedure again since thats the easiest to do. I didn't tap on the case with a hammer when tightening the races. Maybe one of them is not just right and there is a little wiggle somewhere.

Thanks again.

Skip

[Hindsight]

If it comes to pulling the diff out, I would check the total thickness of the ring gear + diff housing using micrometer calipers at several points around the circle (12:00, 2:00, etc). Should be exactly the same all the way around. Unless you dropped your pinion shaft, I don't think there is anything there that could cause this. I would focus on the ring gear and the components attached to it.

[lclevert]

Just to follow this up and to maybe save someone else from doing something stupid...
I opened up the trans and found the problem. After I installed the LSD, closed everything up, set the backlash, I started to reinstall the end section. In doing this I removed all of the center diff parts that will not be used, including the parts on the end of the pinion shaft. I don't have my kit yet, so I didn't install the pinion shaft coupler, and just loosely put the nut back on the shaft. I didn't realize the purpose of this nut was to keep the inner shaft tight with the outer shaft. So, without the coupler the inner pinion shaft was free to slide in and out as it pleased. When I turned the diff shafts forward, the pinion would climb the ring gear and bind. When I turned it in reverse, it would back down the ring gear.

I put it all back together with the pinion shaft parts and everything is working as it should be.

Thanks again for you help hindsight.

Skip

[Hindsight]

No problem - I'm glad you got it figured out so quickly and nothing expensive happened.

[STimedic]

THIS is exactly what I needed! Now, did you use or recommend blue loctite on the ring bolts, because I used blue loctite.

[Hindsight]

I did not. I tried using it on another diff I put together on a Jeep and some of the loctite oozed out between the differential body and the ring gear. As loctite dries, it expands. It expanded enough that, despite the torque on the bolts, it impacted the backlash; the backlash was different on multiple positions of the ring gear. The factory doesnt put loctite on the bolts either so my rule is to leave it off. If I get a diff kit and it comes with pre-applied, dried thread compound on the bolts, I WILL use them, but I will not add loctite. These are my opinions and I am by no means a expert.

[Bob_n_Cincy]

I did not. I tried using it on another diff I put together on a Jeep and some of the loctite oozed out between the differential body and the ring gear. As loctite dries, it expands. It expanded enough that, despite the torque on the bolts, it impacted the backlash; the backlash was different on multiple positions of the ring gear. The factory doesnt put loctite on the bolts either so my rule is to leave it off. If I get a diff kit and it comes with pre-applied, dried thread compound on the bolts, I WILL use them, but I will not add loctite. These are my opinions and I am by no means a expert.

Hindsight.
I'm sure not an expert when it comes to the MT5 transmission. About a year ago, my 818 with 2006 MT5 with about 400 autocross launches had all the ring gear bolts come loose and punch holes in the case. I have no reason to believe this transmission was ever previously apart.
See my very poor video:

https://www.youtube.com/watch?v=IBGVQCvmhRs

Bob

[Hindsight]

I remember that... scary stuff Bob. I haven't heard of that happening commonly though.... at least I haven't seen reports on NASIOC about it or anything. I don't THINK the service manual calls for any thread compound.

[fastzrex]

Joe, thanks for the list of seal and bearings for this install.

[ssssly]

Anyone happen to know the difference between the 806340030 and 806340080 bearings?

I'm converting a TY755VB1AA, JDM forester 4.44 male output shaft transmission, to a female transmission and doing an LSD upgrade while I am in there.

I know I have to switch to the newer female tranny seals. But I haven't been able to find any info on the difference between the two styles of bearings. Both part numbers are listed on the parts diagram, which generally means one is just a newer part number and either is fine. But every once in a while Subaru will throw you a bit of a loop and there is some tiny change that requires one or the other.

Thanks for the great write up and everyone be well.

[subysouth]

Very thorough write-up. Thanks for this.

ss

[Dave 53]

Been a while since any activity on this post. Seeking additional new advice before trying this.

I track my car and I'm really feeling the open diff on the exit of a few tight second gear turns. An LSD is needed.

The tranny in my car is a 5 speed with 10,000 miles since rebuild. Should I put the LSD in this tranny? No rebuild of any other parts since that was done 10,000 miles ago.

I have a spare 5 speed. Or should I open up the spare, do a total rebuild while it's open (whatever that entails) and install the LSD in that tranny?

I found what seems to be a reputable tranny shop that only works on manual trannies that said he would install the LSD for $500. Should I just pay it? I'm not terribly afraid to try, especially with this write up, but this is new territory for me. How long should this job take? Because if I end up spending 10 hours on it, I would rather just pay to have it done.

[STiPWRD]

$500 to install the LSD is very reasonable, most shops in my area would charge double that. I would put the LSD in the spare 5-speed and do the bearings and seals while you're in there.

Are you running at stock power levels and have you done the "leveling out" mod to lower the back end of the trans? In my experience, running increased power levels over stock and having the back of the trans tilted up (as it comes from FFR) can really reduce the lifetime of the 5-speed due to non-ideal oiling. They are not very strong but they are much much cheaper than the 6-speed. I'm on my 3rd and final 5-speed. When this one breaks, I'm getting a 6-speed.

[Hindsight]

I agree that $500 is very reasonable, but that's only if they do a good job. I know of one guy who had a shop replace his R&P and it blew up 10 miles later.

I also agree that the 5 speed is not very durable on these cars and if I had it to do over again, I would have just gone with a 6 speed.

[Dave 53]

265 whp, so not crazy power. Based on a Flatirons podcast about the 5 vs 6 speed, I'm well within the green zone for a 5 speed. I haven't lowered the rear of the tranny, but I raised the engine a bit to keep the Killer B oil pan from being the lowest point under the car. 10,000+ miles since total rebuild including 13 track days. Wish I had the cash for a 6 speed, but so far, the 5 speed ain't broken (and I've got a spare if it does).

Because of the help of this forum, I'm gonna do this! Winter project.

[Dave 53]

Trying to split the case halves and I literally think the place the rebuilt it used glue and not a gasket product.

I tried heating the case seam up to 200* and it won't budge.

Looking for tips on breaking the case apart.

Note: It ended up being I missed the 2 "center" bolt. The ones not on the perimeter of the case.

[STiPWRD]

Have any photos? First thing I'd check is that all of the case bolts have been removed. Some of them can be camouflaged along the middle of the case. Next is to make sure you unscrewed the 4 bolts holding the flange on one of the shafts (located in the rear). This flange is attached to both case halves.

[Rob T]

I was just playing with my exploded 5-speed and couldn't get the case apart. I had forgotten to take off the throw-out bearing on the end. It was my first transmission....after I destroyed that, it came apart easy.

[Dave 53]

It was the two camouflaged bolts in the middle. I actually figured it out and came in to report my finding and saw your suggestions. Wish I asked about 3 hours ago.

Thanks for the quick replies!!!!!

[Dave 53]

A summary of my LSD installation experience in hopes of helping others...

1. Pulling the tranny requires removing the clutch slave cylinder. I installed a new seat while the tranny was out and without thinking, I gave the clutch a test press and the peddle went to the floor and stayed there. ****! After spending a ridiculous amount of time trying the bleed it, I figured out what was wrong. Because of the tranny project, the rear end was jack up. Turns out you can't bleed a Subaru clutch if the master cylinder is angled front end down. Once I set the rear down and raise the front end, I was able to bleed it. Don't forget to clamp the slave piston all the way down when bleeding. Better yet, make sure no one presses the clutch peddle while the tranny is out!

2. The case will not split apart unless all the bolts holding it together are out (wish someone told me that when I started).

3. Backlash - Upon reviewing the internet (mostly YouTube), there are a couple of techniques for measuring the backlash. The way I did it is, after taking the rear case off and before cracking open the main case, I measured what the previous builder did for backlash (and preload). I marked the sundial location, then tightened it until backlash was zero and counted how many sundial notches it was - in my case 3.5. It seemed very easy to determine when backlash was zero. For reassembly, I simply set the backlash to 3.5 notches. So, I don't know the exact backlash value - only that it's the same as it was before I opened it (hope the last guy got it right).

4. Getting the bearings off the old diff - One popped off with just a little bit of prying. The other was a bit more stubborn, but with just a little bit of even heating with a MAP torch, it came off.

5. Putting the bearings on the new diff - They didn't slide on at room temperature. I froze the diff for about an hour and heated the bearings in the 200* oven for about 20 minutes. The first one slid about halfway on then got stuck. Follow step 4 above to get it off. Then I froze the diff overnight and heated the bearings for an hour. Both bearings dropped right in.

6. Axle clips - My 5 speed is a 2002. The diff is female and the axle CV is also female, so it uses a stubby axle shaft to connect the two. On the OEM open diff, the axle is retained with a circlip in a thin and shallow grove. The new diff is designed to use a 2mm snap clip (part number 28333AG010). This required making the stub axle grove wider and much deeper. I couldn't figure out if there is a Subaru part number for a stub axle with the grove for the 2mm snap ring vs. the circlip. Four machine shops pointed out that the stub axle is case hardened steel and it's not an easy job to widen / deepen this grove. Two turned the job down and one said it would take him several hours and cost many hundreds of dollars. I found a fourth guy willing to do it for $120.

7. Make sure all three shift forks are in neutral when reassembling the rear case.

While it took me many weeks to complete for personal reasons, the job wasn't as scary as I was expecting. This original sticky post and comments along with a couple of YouTube videos really helped (of course ignoring the obvious YouTube hacks).

[lance corsi]

I opened up the original snap ring groove to accept the circlip by chucking the stub axle in a lathe and while turning at about 25 rpm, I used a cutoff wheel to both widen and deepen the groove until I had it deep and wide enough to allow the circlip to fully compress below the root diameter of the splines. It is not need to be as precise as most might think.