LSD Internal Debris

[Steve Corbett]

Looks like my LSD is starting to come apart. Noticed a slight ratcheting feel on the input flange. Have not used this yet, Was checking bearings and seals prior to install. Removed the rear cover and found 3 Allen head bolts I assume are from the LSD Unit itself. Can I pull the output flanges, then the LSD Unit is removable? If I do not mess with the Pinion Nut I will not change the Gear Mesh adjustment, Correct? I looked at the ring and pinion gears and do not see any marks on them, not sure how.

[bmwman91]

Wow, weird. Yeah those definitely look like some of the socket cap screws which hold the springs/clutches inside of the LSD unit. I can't imagine how they worked loose though, unless someone had taken things apart at some point.

You have to pull the output flanges, AND unbolt the bearing covers/races + shims to get the actual LSD unit out. You need to take care in doing this, mark which shim was on which side and generally not mess up the bearings. As long as nothing shifts, you should be able to reassemble.

Here are some pics from when I took a small case diff apart for fun. As you note, the only item there that you will not want to mess with is the pinion gear since a crush spacer sets the pre-load on the bearings.

https://www.r3vlimited.com/board/showthread.php?t=381207

[mitchlikesbikes]

be very tedious in marking what came from where and it should go back together just fine. i would use some gear marking compound and check your gear mesh just to be safe.

those socket cap screws are the ones that hold the cap on the lsd unit that contains the springs/clutches/etc. i replaced mine with better ones from mcmaster carr when i rebuilt mine. depending on how many came loose and what they came into contact with you could have a paperweight on your hands. inspect things carefully before reassembling and running the diff. here is a good link for a diff rebuild with photos that will give you an idea of what you're working with

http://buildraceparty.com/diy-tech-how-to-rebuild-a-bmw-e30-differential/

[ThatOneEuroE30]

Wow, weird. Yeah those definitely look like some of the socket cap screws which hold the springs/clutches inside of the LSD unit. I can't imagine how they worked loose though, unless someone had taken things apart at some point.

You have to pull the output flanges, AND unbolt the bearing covers/races + shims to get the actual LSD unit out. You need to take care in doing this, mark which shim was on which side and generally not mess up the bearings. As long as nothing shifts, you should be able to reassemble.

Here are some pics from when I took a small case diff apart for fun. As you note, the only item there that you will not want to mess with is the pinion gear since a crush spacer sets the pre-load on the bearings.

https://www.r3vlimited.com/board/sho...d.php?t=381207

From my understanding those cap bolts are a notorious fail point usually cause the cap itself to break into pieces. Thayer motorsport offer upgraded bolts that you can buy or if you buy a clutch setup they include them

[mitchlikesbikes]

From my understanding those cap bolts are a notorious fail point usually cause the cap itself to break into pieces. Thayer motorsport offer upgraded bolts that you can buy or if you buy a clutch setup they include them

They also have a really shallow hex that's easy to strip without some patience and a good 6mm socket. Upgraded ones that look like normal bolts have a better hex that's easy to torque down.

[ThatOneEuroE30]

They also have a really shallow hex that's easy to strip without some patience and a good 6mm socket. Upgraded ones that look like normal bolts have a better hex that's easy to torque down.

When I took my old ones out i used an impact screwdriver and a regular cordless impact. It worked great

[Steve Corbett]

Thank you for the replies, I will update when I disassemble. Where can I get the gear marking fluid?

[mitchlikesbikes]

Thank you for the replies, I will update when I disassemble. Where can I get the gear marking fluid?

Any auto parts store should have it. It's called "Prussian blue" by permatex. I ordered mine from amazon because I have prime and was already getting some other stuff.

Amazon also sells thayer motor sports products so you can get any clutches, dog ears, or cap screws that you need from there as well

[TobyB]

...however, look on Thayer's website too-
not everything they sell is on Amazon.
I got the G320 detent repair tools significantly cheaper
directly from Thayer.

fwiw,
t

[SkiFree]

I've been using prussian blue forever, but recently converted to the yellow stuff GM uses. Really impressed.

https://www.amazon.com/Genuine-Fluid-1052351-Marking-Compound/dp/B00BK7MFC8

[mitchlikesbikes]

I've been using prussian blue forever, but recently converted to the yellow stuff GM uses. Really impressed.

https://www.amazon.com/Genuine-Fluid.../dp/B00BK7MFC8

I have heard that the yellow stuff is better, maybe I will try that next time I do some differential shenanigans

[Steve Corbett]

After disassembly, found those 3 cap screws were the last ones holding it together. Previous owner of the car had to know it was shelling out as I only found those 3 of the 8 total. Once I removed output shafts and side seals I removed the LSD and Ring Gear. The side bearings had a white debris, possibly water contamination. I found a deep grove in the bottom of the case, where the cap screws were being ground into it by the ring gear. The pinion bearing feels like it has rocks in it instead of ball bearings. Looks like I am in the market for a different differential.

[redlightpete]

If the gears and the lsd clutches look okay, I’d put new bearings and seals in it. You can measure your old and new bearing thicknesses to know if you need to change any shims to keep the ring and pinion in the original orientation. When I refreshed mine, I didn’t end up needing to change any shims.
Any used diff you buy will probably need pinion bearings anyway.

[Wanganstyle]

After disassembly, found those 3 cap screws were the last ones holding it together. Previous owner of the car had to know it was shelling out as I only found those 3 of the 8 total. Once I removed output shafts and side seals I removed the LSD and Ring Gear. The side bearings had a white debris, possibly water contamination. I found a deep grove in the bottom of the case, where the cap screws were being ground into it by the ring gear. The pinion bearing feels like it has rocks in it instead of ball bearings. Looks like I am in the market for a different differential.

Sounds like you bought a pre-r3vtarded or R3vtard rebuild edition differential.

The bolts come out after the unit has been abused and worn out but still continually pushed past the point of clutch packs grabbing. The sheer heat transfers to the housing and melts the loctite; then the bolts walk out and the top cap will eventually be loose and slam against the heads breaking them off.

Common issue in 1995 m3 only as the factory forgot loctite and the owners are almost as abusive as the average r3vtard bc the cars are too cheap.

If the unit has a destroyed pinion Bearing set and these lovely bolts in the slurry then it’s been abused very hard in the past.

Gear may or may not be damaged; but if one has the skills it’s easily torn down to naked and replaced / built up to perfection spec for Street or circuit use with proven results in competition.

Those who just claim parts are r3vtard ok will continue passing crap around on the secondhand market; sometimes/often making people like the OP suffer.

[Steve Corbett]