Observation & possible solution (LSD)

[tnord]

I have 109k, using castrol with no added FM, and it doesn't make any noise that I notice.

[Tbonem3]

I have 120k on mine, fairly fresh fluid less than 10k and I can both hear and feel it doing its job in a parking lot.

What fluid?

[Tbonem3]

I have 109k, using castrol with no added FM, and it doesn't make any noise that I notice.

So that could be that be cause it's slipping or perhaps you just have a quiet diff that never would benefit from the fm booster.

[Tbonem3]

What is the service interval for the Diff Fluid ?

Idk if was a "lifetime" fluid or not, but 60k would be typical.

[sapote]

My diff has 231k miles on it and is definitely dead, it does not lock properly at all. 🙁

Can you spin one jacked up wheel with gear in neutral (other wheel on ground)?

[PipeUy]

When I got the RACP reinforced I also took the time to service the diff. It had the usual play and I went for this https://racingdiffs.com/products/bmw...d-clutch-plate, the shim did somewhat cure the free play issue but not 100%. But what we saw is that the clutches were in relatively good shape (car has probably over 300k km or 200k miles), so I'm not sure what wears quickly.

The diff made noise at low speeds on tight corners, like parking garages, and it still does with the new clutches. I'm using Liqui Moly 75w140 LSD fluid at the moment, unsure what the car had in it before the "rebuild".

Attached pictures of the old clutches.

[Mattn1192]

So this is aimed at someone like yourself. High mileage, no noise, using, I assume, the oe saf-xj +fm that is in clear bottle with red cap or grey bottle with green cap.

Your LSD is probably dead at this point, or close to (no offense, I had a 170k diff at one point too). Try, if you can afford/want to, the oem castrol fluid in gold bottles (syntrax iirc) -1L on amzn was $16 now up to $25 but still cheap, plus half liter bottle exist as well (need 1.2L). And see if there's any noise. Someone like you should want less slip, is my point.

A sunday fair weather vert for a 50 year old and his wife to cruise to the beach? Nah don't sweat it. You'd want the silence, I imagine.

When I dumped my old fluid, it looked like only half a liter came out. Which is very, very, little. That gave me the assumption that it was prob never changed before.

[Mattn1192]

That is my go to move.

I did this with my car when I first got it 😅 peeled out perfectly fine lol

[Mattn1192]

To test if your high mileage LSD is completely become "opened", jack up only one rear wheel and gear in neutral, no hand brake, try to turn the wheel and if it is turning then it is "opened". This is just a relative test, as a normal working LSD requires much more torque to slip the clutch than we could by turning the wheel.

I’m assuming mine failed test? I jacked up my RR tire & it would clunk when I would move it left to right. But it doesn’t free spin. I’d have to apply a bit of power to turn the wheel completely.

[lemoose]

I’m assuming mine failed test? I jacked up my RR tire & it would clunk when I would move it left to right. But it doesn’t free spin. I’d have to apply a bit of power to turn the wheel completely.

you passed

[Mattn1192]

you passed

i have 161k miles, LSD still functioning? I’ll be dammed 🙏🏽

[lemoose]

i have 161k miles, LSD still functioning? I’ll be dammed 🙏🏽

Not exactly but its a good sign that it isn't completely toast:

This is just a relative test, as a normal working LSD requires much more torque to slip the clutch than we could by turning the wheel.

[Phoenix///M3]

So mine locks like a mother at 99k miles. About 25k miles on current fluid changed by PO and no idea what's in there FM or not but I'm not touching it. Probably ever given limited amount of miles I put on it.

Sent from my SM-G950U using Tapatalk

[Mattn1192]

Not exactly but its a good sign that it isn't completely toast:

[Mattn1192]

How much does it cost to get a new diff or just to rebuild it?