Doing a diff rebuild.

[Slideways]

Is everyone replacing their output shaft bolts/washers and flex disc bolts/nuts every time they remove these components? TIS states to replace them each time.

[SandeepM3]

Is everyone replacing their output shaft bolts/washers and flex disc bolts/nuts every time they remove these components? TIS states to replace them each time.

I did not.

[pawelgawel]

Is everyone replacing their output shaft bolts/washers and flex disc bolts/nuts every time they remove these components? TIS states to replace them each time.

just use some lock-tite, no need for new ones every time

[bigjae46]

Just built my 3.91 this weekend. I had the shims that came with the diff. I swapped in new bearings and races. Only adjustment I had to make was swapping the carrier shims which I think I got mixed up.






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[SteelGreyM]

Going well so far. And cleaned my cover while I was at it.

Will be sure to post an update once I am done with the job. Seemed like a scary job when watching the racing diffs diy. But everything is going very smoothly so far.

[bigjae46]

Really need a good press and mandrels to get the bearings on and off.

Making gear contact adjustments isn’t bad at all as long as you can make it with the carrier shims. I 4 bolt the carrier flanges on. Turn the diff on its side, zip off the bolts, pry off the flange, change the shim, put the flange back, zip the bolts on.

The PIA part is messing with the pinion because you have to remove the carrier, press or chisel out the pinion, remove the inner race, change the shim and put it all back together. Takes about 20 minutes but everything is heavy.

I use a bar that I bolt to the input flange and use a large battery impact to set pinion preload. Before the input flange starts to drag, one blast at a time, remove bar, check reload. Once you get a tiny bit of drag it takes very little to go far beyond 14 in/lbs.


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[maupineda]

Seems more people are daring the job. I am receiving my rebuild kit this weekend and plan to change the ring and pinion over the holidays. I bought whole set but maybe will just change the ratio as my V2 diff has only 49K miles. I had the clunk but it does not bother me and not sure I feel like going over the whole experience at once.

[sapote]

I had the clunk but it does not bother me and not sure I feel like going over the whole experience at once.

The clutch slip then side-gear bang into the spiders clunk took the fun out of driving, during take off from stop. I thought about side-gear hammering spiders every time it clunk.

[maupineda]

Yeah, any clunk is disturbing, but mine does it rarely, when going from reverse to forth and back. I will see how it goes as I have all the kit for a full rebuild.

[SteelGreyM]

Seems more people are daring the job. I am receiving my rebuild kit this weekend and plan to change the ring and pinion over the holidays. I bought whole set but maybe will just change the ratio as my V2 diff has only 49K miles. I had the clunk but it does not bother me and not sure I feel like going over the whole experience at once.

Not sure how experienced you are at working on cars but it’s a really annoying job on this one. Mainly because of the rear diff bolts. I don’t know how anyone remove those without scratching off all the undercoating behind them. Anyway, I have a spare can of undercoating handy to touch up the spot. And I would recommend you do as well.

Give yourself at least a week to do the job if you don’t want to rush it and have a bad experience . It is taking me longer than expected. I’m on my 2nd week but had to spend a lot of time waiting for parts.

Oh and remove the driveshaft. I thought I could get away with leaving it connected. For disassembly you can leave it on. But it’s tough enough just to get the diff in by itself I wouldn’t want to mess with lining up the driveshaft too.

And if you’re doing the powerflex poly bushings kit (front diff bushing) line up the notch so that it’s horizontal and closest to the rear of the car. Bet I just saved someone 30-60+ min with this tip alone

Yes. What everyone is saying about the vice is true. Need a good solid one THAT IS BOLTED to a table. You are putting 120lb ft on those carrier bell bolts you do not want it slipping around.

[Thoglan]

Mainly because of the rear diff bolts.

Wait really? Maybe I have small sockets and ratchets or something but I took mine out and replaced with the updated bolts in maybe 5 minutes. No damage done to the wheel well behind them.

[SteelGreyM]

Wait really? Maybe I have small sockets or something but I took mine out and replaced with the updated bolts in maybe 5 minutes. No damage done to the wheel well behind them.

I’m really not sure how you did that as my diff bolts contact the wheel well on the way in/out without the socket on! Very very annoying. I keep a can of undercoating ready just for this job.

[SteelGreyM]

https://www.fcpeuro.com/products/bmw-lubricant-olistamoly-2-ln-584-lo-100g-83190447919

This is the cv joint grease I used. Seems to be the OEM.

[bigjae46]

Give yourself at least a week to do the job if you don’t want to rush it and have a bad experience . It is taking me longer than expected. I’m on my 2nd week but had to spend a lot of time waiting for parts.

Oh and remove the driveshaft. I thought I could get away with leaving it connected. For disassembly you can leave it on. But it’s tough enough just to get the diff in by itself I wouldn’t want to mess with lining up the driveshaft too.

Yes. What everyone is saying about the vice is true. Need a good solid one THAT IS BOLTED to a table. You are putting 120lb ft on those carrier bell bolts you do not want it slipping around.

The torque spec for the 14m ring gear bolts is 100nm + 30 degrees. I’ll admit I’ve used an impact to tighten the crown gear bolts. It’s a big Milwaukee battery impact that can certainly get over 100 ft/lbs.

The first one I did took about 2 weeks. I built my 3.91 in less than 3 hours. Didn’t have to mess with the pinion shim.

Be sure to have a new CV gasket.


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[sapote]

I’m really not sure how you did that as my diff bolts contact the wheel well on the way in/out without the socket on! Very very annoying. I keep a can of undercoating ready just for this job.

Break loose the bolts, then remove the front bushing bolt, then I think you can push the diff forward to give more space between the trunk and the rear bushing bolts.