V2 Diff rebuild + Gear Ratio Swap

[sapote]

2. The installation tool is nothing but an M14 threaded shaft, to which the insert screws like a glove, it does not have the correct shape to form and expand the insert in place.]

The installation tool is a simple M14 with a stop, nothing special. I believe you have a fake Timesert; real one has the bottom compressed slightly so when the installation tool threaded through it expended and lock to the diff.

[bigjae46]

The V2 is a pain in the ass. There is some adjustability in how much you turn the top plate. So you might have to test it, remove the LSD to make adjustment, retest it. It does loose locking torque so the one that I installed in my friend's car had to be removed, tightened, and reinstalled. And now it's not locking again. I'd stick with a V1. I might have an extra one laying around...just need to install the clutch/steels.

You need a way to hold the LSD carrier and diff case...a really good way because you're putting a lot of torque on some of the fasteners.

The order of operation is...

Set carrier preload
Gear pattern
Backlash
Set pinion preload

There is a lot of installing stuff, removing stuff, reinstalling stuff.

If you have the pinion shim that came with the case, that should work. Haven't had to change it on any of the diffs I've rebuilt. With a 4.10...there is a possibility that you'll need a slightly thicker shim. That would be a PIA!

A 4.10 has a smaller pinion gear. Depending on if its a V1 or V2 - you have to reshim the carrier to move it slight closer to the pinion. If the carrier shims are both 1.7-ish, you probably will need a 1.6mm and 1.8mm shim. Your total shim thickness should be around 3.5mm.

1. Install carrier and LSD with shims - set preload - remove
2. Install pinion races and inner bearing on pinion gear
3. Press outer bearing onto pinion (no crush sleeve, no seal)
4. Press input flange and snug pinion nut
5. Install LSD carrier
6. Set gear pattern (adjust carrier shims)
7. Check backlash - should be really close if you have the gear pattern right
8. Disassemble the diff and press out the pinion
9. Slide crush sleeve over pinion
10. Repeat step #3
11. Set pinion preload
12. Assemble the rest of the diff
13. Check gear pattern and backlash again - x2 check

I use a big milwaukee impact to crush the sleeve. I give it two blasts until you get a hair of drag. Then one blast and check. You're much less likely to over crush the sleeve vs using a breaker bar IMO. Once the bearings start to drag (preload) it ramps up very quickly.

[sapote]

The V2 is a pain in the ass. There is some adjustability in how much you turn the top plate. So you might have to test it, remove the LSD to make adjustment, retest it. It does loose locking torque so the one that I installed in my friend's car had to be removed, tightened, and reinstalled. And now it's not locking again. I'd stick with a V1.

V2 has the threaded lock ring to preload the clutch stack. Once set, it should work just like V1, so I don't know why V2 is not desirable in this regard. Unless the lock ring was not locked and it backed out.
Edited: The lock ring should be torqued to spec to bottom out, and it should not be used to adjust the clutch preload.

On top of the clutch stack, there is a cup washer to preload the clutch in V1 as I remember; does V2 have a similar spring washer? I believe it does in order to preload the clutch.

[S54B32]

The V2 is a pain in the ass. There is some adjustability in how much you turn the top plate. So you might have to test it, remove the LSD to make adjustment, retest it. It does loose locking torque so the one that I installed in my friend's car had to be removed, tightened, and reinstalled. And now it's not locking again. I'd stick with a V1. I might have an extra one laying around...just need to install the clutch/steels.

You need a way to hold the LSD carrier and diff case...a really good way because you're putting a lot of torque on some of the fasteners.

The order of operation is...

Set carrier preload
Gear pattern
Backlash
Set pinion preload

There is a lot of installing stuff, removing stuff, reinstalling stuff.

If you have the pinion shim that came with the case, that should work. Haven't had to change it on any of the diffs I've rebuilt. With a 4.10...there is a possibility that you'll need a slightly thicker shim. That would be a PIA!

A 4.10 has a smaller pinion gear. Depending on if its a V1 or V2 - you have to reshim the carrier to move it slight closer to the pinion. If the carrier shims are both 1.7-ish, you probably will need a 1.6mm and 1.8mm shim. Your total shim thickness should be around 3.5mm.

1. Install carrier and LSD with shims - set preload - remove
2. Install pinion races and inner bearing on pinion gear
3. Press outer bearing onto pinion (no crush sleeve, no seal)
4. Press input flange and snug pinion nut
5. Install LSD carrier
6. Set gear pattern (adjust carrier shims)
7. Check backlash - should be really close if you have the gear pattern right
8. Disassemble the diff and press out the pinion
9. Slide crush sleeve over pinion
10. Repeat step #3
11. Set pinion preload
12. Assemble the rest of the diff
13. Check gear pattern and backlash again - x2 check

I use a big milwaukee impact to crush the sleeve. I give it two blasts until you get a hair of drag. Then one blast and check. You're much less likely to over crush the sleeve vs using a breaker bar IMO. Once the bearings start to drag (preload) it ramps up very quickly.

Can't say much about v1/2 difference, most rebuild v1 or switch to os giken or ZF 008 clutch Style..in my experience there is no general shim thickness. With a new lsd (it's a must) or with new side bearings (right way is also do it here) you have to install the lsd (no crown ring installed) and measure with a analog torque wrench (gauge style type) the friction to know the total shim thickness. Then devide that into 2 and start looking at the gear pattern and backlash to know in what direction you have to shift the carrier. Different bearing brands requires different initial preload. You can find that values in the old bmw manual where 210 diff rebuilds are precisely discriped.
btw the pinion bearing preload needs also be set with such a gauge. For adaption I printed some adapters for input and output flange to attach the wrench, works like a charm.

also like bigjae46 i always stayed with the original pinion shim, but most times the offset that is engraved on the new and old final drive was within +-1. i think the bmw Motorsport 4.10 is very accurate manufactured. But on old e34/39 final drive sets I have seen very different engraved values..so beware.

I highly recommend to look in the TIS manuals for diff rebuild to do it right (or do it twice soon again...)

[maupineda]

The installation tool is a simple M14 with a stop, nothing special. I believe you have a fake Timesert; real one has the bottom compressed slightly so when the installation tool threaded through it expended and lock to the diff.

the install tool IS NOT just an M14, very different.

see how different the tools is, is not round and has cutting threads to form the insert and lock it in place. Also, you CANNOT thread the insert into the tool much.



quality of the kit is high, definitely a quality tool.




I also went for the longest inserts which would provide the most engagement possible. This setup means 7mm or about 4 threads are past the insert which is key to avoid loads pulling the insert out.

[bigjae46]

Can't say much about v1/2 difference, most rebuild v1 or switch to os giken or ZF 008 clutch Style..in my experience there is no general shim thickness. With a new lsd (it's a must) or with new side bearings (right way is also do it here) you have to install the lsd (no crown ring installed) and measure with a analog torque wrench (gauge style type) the friction to know the total shim thickness. Then devide that into 2 and start looking at the gear pattern and backlash to know in what direction you have to shift the carrier. Different bearing brands requires different initial preload. You can find that values in the old bmw manual where 210 diff rebuilds are precisely discriped.
btw the pinion bearing preload needs also be set with such a gauge. For adaption I printed some adapters for input and output flange to attach the wrench, works like a charm.

also like bigjae46 i always stayed with the original pinion shim, but most times the offset that is engraved on the new and old final drive was within +-1. i think the bmw Motorsport 4.10 is very accurate manufactured. But on old e34/39 final drive sets I have seen very different engraved values..so beware.

I highly recommend to look in the TIS manuals for diff rebuild to do it right (or do it twice soon again...)

If you measure carrier preload you have to adjust for the gear ratio. If you swap the LSD unit, likely won’t need a carrier shim adjustment. Of course, always check the gear pattern and backlash to make sure.

[maupineda]

I have been going down the mental rabbit hole about rebuilding the diff, and the more go about it, the more I doubt to venture in it, not for the difficulty of it, but the concerns I have to end up with something that will last very little. I will post my concerns and where those come from. I will indeed change the gears and bearings and seals, but still not sure about clutches and the spring washers.

[maupineda]

So, after thinking about this much and reading the feedback from other as well as doing my own research here are some of the key things to do this right.

1. Pinion depth and preload. To do this, I plant to measure the pinion height from the pinions head to the bearing race on the original pinion bearing and race, and on the new ones. This will tell me exactly how different they are to calculate the the correct thickness for pinion shim. I know this will not accound for preload of the race to the actual bearing, but that is ok as the method is the same to measure both, and the result will be valid. Based on what I have read, BMW differentials have very tight tolerances, and give these parts needed to support mas production needs, the varaition maybe so minimal that the same shims from the original set will work on the new gear set. I think this explains why racing diffs say the same shim can be used most of the time. We will see, if I need to reshim, this will get me where I need to be, I believe this is why some poeple report whinning noise with a 4.1, becuase they may just reuse the pinion shim. Who know, but this will do the trick.

2. Diff carrier and housing preload. I have measured the total shim stack, and is 3.2, to maintain this value un affected, you must not change the carrier width, this is why I think the approach to use the screw cap as a way to adjust breakaway torque is not ideal, as that changes the total carrier width, and thus will require to reshim the unit. again, you can still measure how much you deviate from the original point, and based on that calculate a width delta. for example, if your cap is lets say 1/4 turn from the original position, this will result in 0.375mm width reduction, and so your shim stack will change from lets say my 3.2mm to 2.825mm, all of this on the side of the cap. so using the cap method will result in who knows what shim configuration which may make tricky to find the correct ones, or need to fab custom ones. I have the kit from racing diffs, but hey come in 0.1mm increments, which limits the selection. So, you get it, once you move from a factory setup, you are now open to do the whole setup from scratch. if you stick to the factory setup, you just need to move closer or away of the cronw in 0.1mm increments. this is much more managable.

3. Thre free play shim is a big concern in my mind, I think it adds preload to the big spider gear and planetary gears and this will drive premature wear, also, the rebuild clutch stack I have has the free play bevel washer, and another larger one that goes between the cap and the clutch stack, this will add significan preload if closed to the factory position to not change total width of the carrier unit. To do this, I have seen in videos that some units have super thin shims, I think this is what the factory used depending on dimensional tolerances in the assembly process, or to add more breakaway torque while not changing the with of the unit.

4. Breakaway torque. I have found that a typical value to set this can be 20-25% of the engine torque, in our case, at 365NM, 73-91.25NM. This is consistent for instance in E39 M5 differentials where I found that the factory spec is 75ft/lb or 102NM. The racing diffs kit have you at 125NM in their latest iteration, and the original kit recomendation was 100NM, however, if you set the carrier to 100NM with the latest kit, you will be screwing the cap less, and thus changing the width of the carrier unit having you to change shims.

I have access to TIS (ISAT+) and will pull specs for other 210mm differentials to see if I can find factory recommendations for bearing pre load values.

[bigjae46]

We will see, if I need to reshim, this will get me where I need to be, I believe this is why some poeple report whinning noise with a 4.1, becuase they may just reuse the pinion shim. Who know, but this will do the trick.

You will get more whine as the gear ratio gets shorter. Not an expert but it has something to do with the frequency caused by the gear meshing with a smaller pinion gear.

4. Breakaway torque. I have found that a typical value to set this can be 20-25% of the engine torque, in our case, at 365NM, 73-91.25NM. This is consistent for instance in E39 M5 differentials where I found that the factory spec is 75ft/lb or 102NM. The racing diffs kit have you at 125NM in their latest iteration, and the original kit recomendation was 100NM, however, if you set the carrier to 100NM with the latest kit, you will be screwing the cap less, and thus changing the width of the carrier unit having you to change shims.

We started at 75 ft/lbs and it was an open diff. We had to up the breakaway torque to 90 ft/lbs which makes sense...but its not working again.

Here are the BMW specs:

Pinion preload 12 to 23 in/lbs
Carrier preload 11 to 23 in/lbs
Backlash .0024 to .0055"

Ideal range - I think I got these numbers from Diffsonline???
Pinion preload 14 to 16 in/lbs
Carrier preload 9 to 11 in/lbs
Backlash .003 to .0035"

It can be tricky getting the backlash within .003 to .0035. I originally set the backlash at .003, measured .0037 when I upped the breakaway torque to 90 ft/lbs. I didn't do the tightening of the end plate so no record of how many turns. I want to say it was less than a turn.

The guy is waiting for a ZF unit to come in...we are both sick of messing with it.

[maupineda]

You will get more whine as the gear ratio gets shorter. Not an expert but it has something to do with the frequency caused by the gear meshing with a smaller pinion gear.



We started at 75 ft/lbs and it was an open diff. We had to up the breakaway torque to 90 ft/lbs which makes sense...but its not working again.

Here are the BMW specs:

Pinion preload 12 to 23 in/lbs
Carrier preload 11 to 23 in/lbs
Backlash .0024 to .0055"

Ideal range - I think I got these numbers from Diffsonline???
Pinion preload 14 to 16 in/lbs
Carrier preload 9 to 11 in/lbs
Backlash .003 to .0035"

It can be tricky getting the backlash within .003 to .0035. I originally set the backlash at .003, measured .0037 when I upped the breakaway torque to 90 ft/lbs. I didn't do the tightening of the end plate so no record of how many turns. I want to say it was less than a turn.

The guy is waiting for a ZF unit to come in...we are both sick of messing with it.

Super helpful!!!!

do you think is the sheer pump that is broken? To my knowledge the M Variable diffs can lock to 100%

[bigjae46]

Super helpful!!!!

do you think is the sheer pump that is broken? To my knowledge the M Variable diffs can lock to 100%

Don’t know. I have to wonder if the thicker Belleville spring is not allowing the shear pump to work properly? Total guess.

[maupineda]

Don’t know. I have to wonder if the thicker Belleville spring is not allowing the shear pump to work properly? Total guess.

I thought the same, I think you need a flat surface to have sufficient area for the shear pump to press the clutches, the be level spring would affect this for sure

[bigjae46]

I thought the same, I think you need a flat surface to have sufficient area for the shear pump to press the clutches, the be level spring would affect this for sure

I'm thinking the belleville spring dulls the locking effect. Wheel spin engages the pump and presses the clutch stack. A thicker, heavier spring would need to be compressed. The shear pump won't begin to add lock until it overcomes the belleville spring which. Might have to be super duper sideways with a lot of wheel spin to get it to work.

Again, total guess. Not really worth it to me to figure it out. I'll throw just in a V1, OS Giken or a ZF unit into my E90 M3.

[sapote]

2. Diff carrier and housing preload. I have measured the total shim stack, and is 3.2, to maintain this value un affected, you must not change the carrier width, this is why I think the approach to use the screw cap as a way to adjust breakaway torque is not ideal, as that changes the total carrier width, and thus will require to reshim the unit. again, you can still measure how much you deviate from the original point, and based on that calculate a width delta. for example, if your cap is lets say 1/4 turn from the original position, this will result in 0.375mm width reduction, and so your shim stack will change from lets say my 3.2mm to 2.825mm, all of this on the side of the cap. so using the cap method will result in who knows what shim configuration which may make tricky to find the correct ones, or need to fab custom ones. I have the kit from racing diffs, but hey come in 0.1mm increments, which limits the selection. So, you get it, once you move from a factory setup, you are now open to do the whole setup from scratch. if you stick to the factory setup, you just need to move closer or away of the cronw in 0.1mm increments. this is much more managable.

3. Thre free play shim is a big concern in my mind, I think it adds preload to the big spider gear and planetary gears and this will drive premature wear, also, the rebuild clutch stack I have has the free play bevel washer, and another larger one that goes between the cap and the clutch stack, this will add significan preload if closed to the factory position to not change total width of the carrier unit. To do this, I have seen in videos that some units have super thin shims, I think this is what the factory used depending on dimensional tolerances in the assembly process, or to add more breakaway torque while not changing the with of the unit.

.

2. The designer didn't want to use the locking ring as way to adjust the clutch stack preload. It should be torqued until the pump housing is bottomed on the carrier step. In this way, the factory shims for the output flanges should be used as intended. IOW, the final position of the ring should be at the same place marked by the ball as before. To preload the clutch correctly, just add/sub the shims between the clutch stack and the pump.

3. As I mentioned before that using the spring shim as Racing Diff is the wrong way to take out the side-gear plays. I would just use flat shims

[sapote]

2. The designer didn't want to use the locking ring as way to adjust the clutch stack preload. It should be torqued until the pump housing is bottomed on the carrier step. In this way, the factory shims for the output flanges should be used as intended. IOW, the final position of the ring should be at the same place marked by the ball as before. To preload the clutch correctly, just add/sub the shims between the clutch stack and the pump.

To prove my point about non-adjust lock ring, with no clutch stack inside, intall the pump and tighten the lock ring to see if it stopped at the same ball location. When using this way, the bearing on the pump solidly supports the carrier, instead of "floating" on the spring washer or the clutch stack which don't make sense.

Btw, the V2 3-piece spinder shafts are stronger than the V1 two shafts with the notch cut out in the middle. Wonder why they redesign the shafts if we haven't seen they bent or broken.

Initially I thought they designed V2 to improve manufacturing due to ease of adjusting the clutch breakaway torque with adjustable lock ring, but now I believe the ring deph is not adjustable, so why they designed V2? Stronger spider gear shafts, and thicker 1-piece flange for the ring gear for less flex compared to V1 two-piece flange.