Diff Groaning After Replacing Everything

[BMWahba]

Just finished my entire rear end overhaul.

Everything is awesome minus one thing. My diff was groaning seriously bad at low speed turns. Sounds like the clutches were just not playing nice at all. When I did the overhaul I decided to keep the diff and get a new diff cover, all new OE fluid (the overly expensive FM fluid), got everything back together. Still groaning.

It sounds terrible lol - I was going to just swap the entire diff out when I had everything apart but the diff looked perfectly fine when I opened it up. Thought the new fluid would fix the issue, but nope. Sad.

curious if anyone has any thoughts on what may have caused my diff to take such a poop. Car has 105k miles. Has anyone had any similar woes?

Pic of my underside to make up for the disappointment.

[GhostGrayM3]

Have no knowledge regarding the noise but just wanted to say ur underside looks fantastic 👌 sooo clean

[heinzboehmer]

Did you do a bunch of figure 8s in a parking lot? I've read it helps distribute the fluid all around and can stop the groaning. Haven't had the issue myself but might be worth a shot.

[mikeetastic]

Man that is a money shot, looks really clean aside from the issue..

[Cubieman]

I would eat my dinner off of the underside of your car! So very jealous

[eacmen]

Did you do a bunch of figure 8s in a parking lot? I've read it helps distribute the fluid all around and can stop the groaning. Haven't had the issue myself but might be worth a shot.

this ^^

Also check the condition of the clutch packs. Jack rear in the air and try to spin one tire while holding the other one. It should break free around 80 lb-ft (i think).

Only other thing is the bushing material used in the rear. Poly?


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[eacmen]

Also which fluid did you use exactly? Was it in castrol bottles or BMW?

Some vendors sell the Castrol SAF-XJ as the BMW fluid. While it has FM in it, its not the original ratio.


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[BMWahba]

Did you do a bunch of figure 8s in a parking lot? I've read it helps distribute the fluid all around and can stop the groaning. Haven't had the issue myself but might be worth a shot.

I haven't tried this yet. I will give it a shot, I rarely have any luck with these easy fixes lol.

Man that is a money shot, looks really clean aside from the issue..

I would eat my dinner off of the underside of your car! So very jealous

Thanks!! It was a labor of love. check my insta for some progress pics.

this ^^

Also check the condition of the clutch packs. Jack rear in the air and try to spin one tire while holding the other one. It should break free around 80 lb-ft (i think).

Only other thing is the bushing material used in the rear. Poly?


Sent from my iPhone using Tapatalk

I am using OE diff bushings. Brand new diff cover. The sound is definitely sounding like it's internal to the diff.
I'll try the clutch pack test. Just trying to wrap my head around how or what is causing something like this.

Also which fluid did you use exactly? Was it in castrol bottles or BMW?

Some vendors sell the Castrol SAF-XJ as the BMW fluid. While it has FM in it, its not the original ratio.


Sent from my iPhone using Tapatalk

I got OE BMW fluid from FCP euro. Clear bottle, grey BMW label.

[antknee]

Yeah my undercarriage looks nothing like that. Horror show actually compared to that. Wow

[jbfrancis3]

Beautiful resto job you did there. Did you have the cover off for an extended period of time? Wondering if it takes time for that visco lock to work the air out - just speculating. Hard imagine anything else would be affected by the work (or lack thereof) done to the diff. If you've driven many miles now, forget it - way beyond my paygrade.

[antknee]

I’m convinced my groaning was the cv joint that connects from the rear driveshaft into the diff. Unlike your car, mine was a bit rusty and the joint had spewed out all its grease. When i did my front shaft seal, that joint was repacked and freed up....that coupled w the new csb and Guibo most, if not all the low speed groaning went away for me. Of course it also could’ve been the new fluid though lol

[Syfon]

Christ, that undercarriage is brand new. Lol that's awesome.

Re the diff, when you took it out for a first drive with the new oe fm fluid, did you go to a carpark and do a series of tight turns in either direction? Apparently this helps the clutch packs become coated properly in the fluid? Idk...

Fwiw, after I reinforced my rear end, I did a similar thing with new oe fm fluid. My diff doesn't grind or groan. I did replace the input/output shaft seals among a heap of other stuff but my diff centre wasn't touched (has ~55k miles) Maybe your diff is just on the way out?

[Ceelooboob]

^^ yup do the figure 8’s. It’s helps coats the clutches to stop the groan.

[Stack]

What diff did you end up going with?

When I installed my 3 way clutch LSD from diffs online via turner

There was a 1000 mile break in period along with the figure 8's and the groaning binding noise went away.

[elbert]

Is that a single post lift? I want to see pics of your garage!

(And def do the figure 8's as posted earlier)