Swapping Differential--What Else Should I Do While In There

[Fresh1179]

Hello All,
I am going to be swapping to a 4.10 custom differential here in a month or so, and I was wondering if anyone had some suggestions of items to replace while completing this job. There is a very helpful post about additional items to be replaced when changing the clutch which was enormously helpful, so I figured I would give it a shot with respect to differential swaps. Any suggestions?

[Obioban]

diff mounts, which means a new diff rear cover.
rear lower control arms, IF you're ever going to do them or if they're wearing out
subframe bushings, if you're every going to do them or if they're wearing out
at that point, subframe reenforcement (subframe has to come out to do the bushings)
upgrade to new design rear diff mount bolts (torque to spec and use loctite on these)
repack the bearing between the shaft and diff, replace seal

Hopefully that's sufficiently spiraled "while you're in there"

[tnord]

diff mounts, which means a new diff rear cover.

wait....why would you need a new cover?

if you're getting a new diff I presume new axle seals are already included. I don't know if these axles ever go bad, but now would be the time. I haven't take a diff out of these cars, but I don't know that I could justify dropping the subframe and everything just because the diff is out. once the subframe is out, I'm refreshing every bit of rubber in the rear suspension.

[Arith2]

Turner has their solid mounts preinstalled into a diff cover and just keep the subframe mounts stock. That should solve the whole diff mount issue. You'd have to press the front one in but that's not too much of an issue if all goes well. Might be a slight increase in NVH but you'd be set on the diff bushings. The driveshaft CV sometimes fails so I second that service. I don't think the boot is separate from the CV but I may be wrong. Look into reinforcing your rear. Decide if you can live without as much trunk space. It's a tough choice considering our cars were designed to get groceries quickly.

[Kcalhoun27]

wait....why would you need a new cover?

if you're getting a new diff I presume new axle seals are already included. I don't know if these axles ever go bad, but now would be the time. I haven't take a diff out of these cars, but I don't know that I could justify dropping the subframe and everything just because the diff is out. once the subframe is out, I'm refreshing every bit of rubber in the rear suspension.

The regular diff bushings are pressed in from the factory and no one sells the rubber ones by themselves, i believe. I think i read that the e36 ones fit, but i can say that when i refreshed my rear end, i replaced the cover because i couldnt find the bushings and didnt want poly/solid bushings

[Obioban]

wait....why would you need a new cover?

if you're getting a new diff I presume new axle seals are already included. I don't know if these axles ever go bad, but now would be the time. I haven't take a diff out of these cars, but I don't know that I could justify dropping the subframe and everything just because the diff is out. once the subframe is out, I'm refreshing every bit of rubber in the rear suspension.

You can't buy the mounts separately from the cover, so if you want new OE mounts... new cover it is.

Good point on the seals! I assumed they were included with the new diff, but, if they weren't, they should be done for sure.

The regular diff bushings are pressed in from the factory and no one sells the rubber ones by themselves, i believe. I think i read that the e36 ones fit, but i can say that when i refreshed my rear end, i replaced the cover because i couldnt find the bushings and didnt want poly/solid bushings

The e36 ones fit, but are softer than stock-- so performance downgrade.

Turner has their solid mounts preinstalled into a diff cover and just keep the subframe mounts stock. That should solve the whole diff mount issue. You'd have to press the front one in but that's not too much of an issue if all goes well. Might be a slight increase in NVH but you'd be set on the diff bushings. The driveshaft CV sometimes fails so I second that service. I don't think the boot is separate from the CV but I may be wrong. Look into reinforcing your rear. Decide if you can live without as much trunk space. It's a tough choice considering our cars were designed to get groceries quickly.

Solid mounts would certainly solve the wear "issue" (I don't consider a ~100,000 mile life an issue), but it'll be LOUD LOUD LOUD.

[tnord]

You can't buy the mounts separately from the cover, so if you want new OE mounts... new cover it is.

to me this is one of those idiotic things with this car in particular. if you can buy a new cover with mounts pressed in by Turner, Turner is getting them from somewhere. It's the same thing with the transmission rebuild, apparently nobody sells the parts for the rebuild, yet Turner is selling a $5k rebuilt and REM'd unit.

[jbfrancis3]

You'll want to have a new driveshaft gasket ready to go. Part# 26111229503

[Fresh1179]

Thanks guys. They really punish you on the price of these 5k diffs.


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[CrookedCommie]

Thanks guys. They really punish you on the price of these 5k diffs.


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That's because they costs over $3500 just in parts, not even counting the qualified labor cost. If you can do it cheaper, there's a market for it.

[old///MFanatic]

I would absolutely suggest doing the front differential mount while in there. Part #8
https://www.realoem.com/bmw/enUS/par...-M3&mg=33#30oh

https://www.realoem.com/bmw/enUS/sho...diagId=33_1076

[01SG]

You have to pull the diff back to do both lower camber arms and the upper control arms, so I suggest those, along with ball-joints and sway-bar links, except the latter can be done any time.