Hi guys! I wanted to share my rebuild process on the front differential in my 2004 T1 V8 with locking diff. I've seen a lot of the "crush sleeve" dilemma and not being able to obtain one through VW or ZF. I decided to take a little different approach to the whole thing. Now some may agree or disagree with this method and that's up to you, but I assume no responsibility or liability if you try this.
First and foremost I want to thank @dragline1570 for his help and contribution as well as a local buddy of mine, Tim, that builds drag cars and my father for doing the machine work. None of this would have been remotely possible without them, so THANK YOU!!
Now to the fun stuff!
I won't go into how to remove the front differential since there's plenty of tutorials out there to do that. If you need some assistance, look at these:
So check those videos out if you need some guidance on that.
I had previously "rebuilt" the differential about 2yrs ago following Terry Hightower's videos on youtube. Terry's videos were good but he has since taken those videos down and offers a rebuild service. So if you aren't comfortable rebuilding the diff, send it to Terry for a rebuild. My differential was giving the typical groaning noise so I knew it had to be rebuilt the first time. After rebuilding it and driving it for some time I would hear a knock on acceleration/deceleration with a slight groan. So it was time to take it back out and rebuild it before it was ruined indefinitely. What I had determined after removing the diff was that the backlash was incorrect (too much backlash.)
With putting in new carrier bearings/races and new pinion bearings but no new races on the previous rebuild, I inspected them and decided to leave the carrier bearings/races in place but replace the pinion races and bearings, even though they looked fine.
There are some basic things you'll need:
Dial indicator with magnetic base or some base to mount and be able to measure backlash. It also helps if you have a long reach stem for the indicator.
A flat edge for measuring (long enough to span the width of the differential casing)
Torque wrench that can measure up to 30in/lbs either beam or dial, no clicker styles
Gear marking compound (prussian blue by permatex or GM gear marking compound GM#1052351-what I used) and acid brush for applying compound
Hydraulic press or access to one with a bearing separator
Bearing puller (loan-a-tool)
A Lathe and machining skills or a machine shop
A 1" inner diameter steel nut used for making a solid sleeve or whatever you can use to make the sleeve
Shim stock for making pinion shims
Steel washers big enough to make a new pinion shim undersized if needed
Brake cleaner and mineral spirits along with a brush for cleaning
RTV sealant for differentials and gear oil
Pans for cleaning the differential and internals
Drift for knocking pinion out
Race driver kit (loan-a-tool at the local auto parts suppliers)
3M green scouring pad and razor blade
Basic tools such as breaker bar, torx sockets, metric allen sockets, metric sockets, hammers, impact gun, and 32mm 6pt socket for pinion nut (If you don't have common hand tools, you may not want to attempt rebuilding the diff)
Pinion seal: VW 0AA409189 (I recommend purchasing 2 in case one gets messed up on install) source Parts for VW and Audi Cars Cylinder Heads Injector Pumps Engine Gasket
Axle seals x2: VW 0AA409189A (corteco 1643370159) source www.fcpeuro.com
Carrier bearings x2: Timken LM503349
Carrier races x2: Timken LM503310
Pinion bearings: Timken HM88542 & Timken HM89448
Pinion races: Timken HM88510 & Timken HM89410
Carrier Shims: VW 02b498210 (note: I did not use these nor bought them, however I discovered that this shim set is used in a Golf limited slip diff with the same carrier bearing number, so they might could be used) Here is a cross reference with Timken https://mibearings.com/index.php?mai...ducts_id=95616
Lucas Heavy Duty Oil Stabilizer (I use this to prelube the bearings, it's great stuff but not necessary)
Full synthetic 75w-90 GL5 spec gear oil (2qts)
Axle needle bearing for driver side axle tube: VW 311401301 I didn't replace it as nearly no one does, they just don't seem to wear, but if it is, you'll need this and also a slide hammer)
Before we do anything to the diff, clean the outside of it thoroughly. I like to use purple power.
The first thing to do is measure the current preload on your differential. Take the 32mm socket and torque wrench (you may have to use adapters as mine was a 1/4" beam torque wrench) and rotate the driveshaft flange in both directions and note the value. I did not do this so I conversed with dragline1570 and he came up with 14in/lbs-18in/lbs of rotational force for proper pinion preload.
Now drain the oil from the case using the proper sized allen socket. You'll probably notice the pretty shimmer in the oil. Next I used a soft faced hammer and knocked out the axle stubs, they're just held in place with circlips. Note the condition of the flanges where the axle seals ride. If there is a significant groove a redi-sleeve may be needed. If the grooves are too deep the new axle seals may not seal properly. Mine did have a groove but I did not feel that they were so deep that the seals would leak. So far I haven't seen any leakage.
Next I would remove the differential cover bolts and separate the cover (I had to use the soft faced hammer again to knock the cover loose to break the seal.) Now setup the dial indicator and base so you can measure the current backlash. Set the indicator's stem as close to the edge of a tooth and as perpendicular as you can to get a good reading. Zero the indicator and record the backlash by gently moving the crown wheel back and forth. I did not do this, not that it would have mattered because my backlash was incorrect from the previous rebuild. I consulted with dragline1570 on this and he advised that backlash tolerance should be .004"-.008". If you wanted to, at this point you could clean a few teeth of the crown wheel, apply the marking compound, install the cover with the torx bolts and rotate the pinion a few times back and forth at the pinion nut; take the cover back off and see what kind of gear pattern you're getting and make notes plus pictures. Note: one thing that is important to do in order to get a good pattern is to apply some friction to the drive flange. I did this by applying pressure to the drive flange with my hand creating the friction.
At this point we can remove the driver side axle tube. Remove the torx bolt (one was in the cover) and use the soft faced hammer to separate it from the case gently. You should see a carrier shim on that side. Clean it then measure it with the digital calipers and record its thickness and also mark it with the paint pen. I like to do one dot on the shim and one dot on the tube. Now pull out the carrier. There is also a shim on the passenger side. Do the same with the calipers as you did with the drivers side and record it's thickness. The reason for measuring the thickness is to put these shims back in the same side they came out of and to know what the carrier bearing preload should be. Take the thickness of both shims and add them together, this is the total thickness to obtain the proper carrier bearing preload. Mine measured .130". This is important to know if you have to add or subtract the shim thicknesses to obtain proper backlash tolerances. Now that the carrier is out of the way, it's time to measure the pinion depth. Set a flat edge across the width of casing face and take the digital calipers, set them on the flat edge, and measure down to the top of the pinion and record the depth.
It's time to get that impact gun out now. To remove the pinion nut, I take two of the drive shaft xzn bolts and screw them into the flange and take a long beefy flat blade screw driver and run it between them while the shaft of the screwdriver is in contact with the bushing mount to counter-hold the drive flange. After the pinion nut is removed, the pinion seal is visible. Take the digital caliper and measure the depth of the seal. You should see somewhat of a "ledge" above the seal to reference to. I like to take 3 measurements in 3 different spots, now record the pinion seal depth. Ok, so now let's remove the pinion. Just so everyone knows, I was working on a wooden benchtop so nothing will get damaged. I set the differential case face flat on the benchtop so that the unit is vertical. Next I place a steel drift, that can fit into the recess of the pinion shaft end, and use a small 5lb hammer to drive out the pinion. Never hit on the pinion directly as it can be damaged easily.
So now that the pinion is out, set it and the crush sleeve aside somewhere safe for now. You'll now notice the inner pinion bearing floating inside the diff case behind the pinion seal. Take the diff case and flip it 180 degrees. I had a wooden block that I used to set the diff case on to somewhat keep it level and upright while I knocked out the bearing and pinion seal. The block somewhat fit into where the drive flange sits. I used a long cold chisel and knocked on the bearing from inside the case which also moves the pinion seal at the same time (the bearing is up against the pinion seal). So now, all we should have to do is knock out the pinion races. Using the same block, I set the diff case down on a cement floor(the case never made contact with the cement floor). Trying to knock out the inner race on the benchtop wouldn't work because it flexed too much. Using that long cold chisel I knocked on the edges of the race until it came out; note the race part number. Take your time with this. Now I took two 2x4s and placed them on the cement floor to support the diff case and so the facing would't get damaged. Using the cold chisel again, I used the same method to remove the outer bearing race from the housing. Now that we have a bare housing, clean it thoroughly with the mineral spirits the use the brake cleaner to dry out the case.
On this rebuild, like I said earlier, I reused the carrier bearings and races but I'll go over how I removed the bearings from before to the best of my memory. I cut the bearing cages and removed them along with the rollers. Make sure all of them are removed, the rollers like to fall into the spider gears. Next with the bearing puller there's a recess to get the arms of the puller under the bearing. I believe I used a deep socket just undersized of the bearing to push against the carrier. Save that old bearing housing. Clean up the flanges after the bearings are removed. Now take the new bearing and place it onto the carrier as square as you can. Take the old bearing housing and flip it over and place it on top of the new bearing to use as a driver. Take a hammer and knock on the new bearings until they bottom out.
Now it's time to remove the outer pinion bearing. Make sure the bearing separator's edges are sharp for this. Place the bearing separator as close and square to the bearing taking care not to hit the pinion teeth. After that's setup, place it in the hydraulic press and press off the bearing and pinion shim. She'll pop when she releases so don't freak out too much haha. Set the pinion shim aside after cleaning it thoroughly. If all went well, there shouldn't be an damage to the pinion or pinion shim.
So this is where the fun begins! Clean up the pinion with the mineral spirits. After it's cleaned, it was suggested by my buddy that builds drag cars, to grind down the pinion shaft just enough to slip the pinion bearings on and off. The purpose of this is so that when/if you have to change the shims on the pinion to change pinion depth, you aren't having to press on/off the bearing; that's a pain in the ass! I wasn't too keen on that method but decided to go with it. So, I chucked up the pinion in the lathe and used 100grit sandpaper to grind down the pinion shaft. I did a little at a time, taking the pinion out of the lathe and checking to see when the bearings would slip on/off of the shaft with slight friction. The other method would be to slightly grind out the inner diameter of both pinion bearings to accomplish the same thing, but then you'll have to sacrifice two new bearings (more money). The advantage to this method is the pinion stays in an original condition and the outer bearing will have to be pressed back on. So pick your poison here. I was a little worried about centrifugal force causing the bearings to spin on the pinion shaft, but so far, I haven't had any problems (I've run about 600mi or so on the new rebuild thus far). My buddy said, in his experience, the oil would heat up between the shaft and the bearings locking them into place and that if I had to remove them for another rebuild in the future, they probably would still need to be pressed off. Only time will tell with that, but I hope I never have to rebuild it again!
Now to address the crush sleeve problem. I had seen where dragline1570 reused the old crush washer by cutting it a few mm short and making a spacer to bring the length back to 22mm, which he calculated to be factory length. So I did this as well with my original crush washer. This will work just fine as long as the pinion depth is correct and the gear contact pattern and backlash is within tolerance. When I consulted that solution with Tim, he suggested going with a solid sleeve. His reasoning was that for one, the solid sleeve can be reused whereas the crush sleeve is a one shot deal, not to mention that if you over torqued the pinion nut the sleeve will be crushed too far and now you can't back off the pinion nut for less preload; and we all know about the availability of ZF's crush sleeve. Could you keep making spacers to bring it back? Well yes, to a certain extent, however you're limited to how many times it can be done before the crush sleeve is completely trashed. Another reason to go solid is the force it takes to tighten the crush sleeve versus the solid. With a crush sleeve it takes a LOT of torque to crush that sleeve to get proper preload whereas with the solid, if the length of the sleeve is setup to give proper preload, you could use an impact gun to put it on and no matter how tight you get that nut, that sleeve will not crush, at least it shouldn't. As long as that nut is tight, the preload will stay the same. The final reason that Tim gave is that he's seen crush sleeves actually crush slightly more from high torque applications, although I don't think there's enough in the Touareg for that to happen, but I guess that could still be possible. According to Tim, crush sleeves are a poor design and I have to agree. There is a drawback to a solid sleeve though, not all bearings are the same, not even from the same company. There is variance in the bearings, even though Timken, NTN, etc try to keep it at a minimum it's still there and that can possibly change the preload enough to be out of tolerance. To address that issue, shims may have to be used with a solid sleeve, so it isn't perfect either. So choose which method you want to go with and I applaud and thank dragline1570 for his work!
I decided to go with the solid sleeve method.