Questions about rear differential rebuild (seals, diff cover, etc)

[ewrjontan]

So I will be working on my rear differential out of my '95. Along with doing the axle seals I will also be replacing the cover gasket. Is it necessary to add sealant along with the gasket? I believe loctite 5970 is recommended (https://www.ecstuning.com/b-genuine-...l/83190404517/) but is it necessary with the gasket?


The diff has just under 150K on it. The car hasn't been tracked but will be once I get it all back together again. Is it worth rebuilding everything or just doing the seals? Is the input shaft seal more-or-less similar to doing the axle seals? Is there any sort of grease/lube that should be put on the axle seals or do they go on dry? Can I use some Curil-T? I used that stuff on my rear main seal.

[TostitoBandito]

I didn't use a gasket when I replaced my diff. I just used the black permatex stuff, which is what a lot of people do (anything intended for use on oil pans and transmissions and whatnot will work fine). Just clean off all the old gasket and put a nice bead of that all around. If you choose to use the OEM gasket, I think you can just use that unless Bentley says to use sealer in certain places as well (like on the oil pan and valve cover).

Up to you whether to rebuild, but if you're gonna take it apart at all it's absolutely worth checking to make sure no bolts inside the diff are loose or backing out as they tend to do over time. It makes fun noises when loose bolts start bouncing around inside the diff getting chewed up.

[pbonsalb]

I agree. If pulling the cover, blue loctite or even better, replace and loctite the carrier cap bolts. Bimmerdiffs and others sell them. You can add clutches as well.

[Braymond141]

BMW no longer uses gaskets and calls for sealant only for your differential. Don’t use it, the right sealant will last far longer.

[hc1001]

On someones recommendation, i used toyota FIPG for my diff cover back in 2012. No leaks at all. You can get it at a toyota parts dept or online. I would guess any black RTV would be fine though.

Regarding the halfshaft seals, i cleaned the area with a towel and pressed in the new ones. I didnt do the input shaft seal but hear its the same process.

[ewrjontan]

BMW no longer uses gaskets and calls for sealant only for your differential. Don’t use it, the right sealant will last far longer.

bummer, I already have the gasket any reason to use both? I feel like RTV or any other sealant would be good enough.

[Braymond141]

bummer, I already have the gasket any reason to use both? I feel like RTV or any other sealant would be good enough.

Don't use the gasket.

[ewrjontan]

Got the diff apart yesterday except for the input shaft. If I just do the input shaft seal, is there any reason not to just go ahead, pop the input shaft out and replace the crush sleeve? It sounds like this could get complicated real quick :/

I wasn't able to find anything about the torque specs for the differential internal hardware. Anyone know or know where I can find the specs to make sure everything is tightened? Realoem (as far as I know) doesn't list the hardware for the lsd. Are the cap bolts more-or-less standard? I see that thayermotorsports.com sells them so I am assuming those will fit fine.

[AJLM34A]

If you have not already read through this thread, you might be able to find a lot of the info you need;
https://www.bimmerforums.com/forum/s...36-Diff-Thread

- The paper gasket works fine, or any sealant rated for diff fluid.

- If the input shaft was not leaking, leave it alone.

[NeilM]

bummer, I already have the gasket any reason to use both? I feel like RTV or any other sealant would be good enough.

By using both a paper gasket and sealant then you'd be doubling the number of interfaces for a potential leak.

Like everybody has already said: don't use the crappy paper gasket. Do use decent quality commercial goo-in-a-tube gasket stuff that's made for automotive use. Not RTV silicone. Permatex Form-a-Gasket is perfectly decent.

Neil

[TostitoBandito]

Pretty sure I used this

https://smile.amazon.com/Permatex-82...70_&dpSrc=srch

Works for the diff and any other gasket or supplemental gasket needs.

Funny story, my diff was one of the first things I DIY'd on my car. Not knowing any better, I just cleaned off the cover and slapped it on the new diff. I had a fun slow drip after that, since there was no gasket. Ran it long enough to break in the new diff to where I needed a fluid change and then removed it again and used the black RTV on it.

[ewrjontan]

Any input on axle seals? Do these go in dry, with gear oil or some other sealant? I believe the Bentley says to use gear oil but just curious if things have changed/are done differently now.

[RRSperry]

I'd use oil on them.

[ewrjontan]

Sounds good to me. Rather than make a new thread I figure I would try asking here. What are the torque specs for the subframe bolts/studs that connect the subframe to the body? From what I am seeing they are anywhere from 33 lb/ft, 57 lb/ft, 88 lb/ft or 103 lb/ft...Which one is it? Do the studs AND the bolts use the same value? What about the nut that goes to the stud?

[TostitoBandito]

They're all 57 ft/lb. The studs and bolts are treated the same.