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[feeutfo]

... During slow tight corners under medium to heavy acceleration gives a judder at the back. No wheel spin. If it spins the judder stops afaict.

It has the usual sae90 hypoid, or whatever its called, with an unknown lsd additive. Is it worth filling with a specific LSD dif oil. Or is there something more troubling afoot...? I presume the slip element in the dif is not slipping as it should?

[05omegav6]

Mine bangs abit if you give it beans from a standing start:-\ but think that is just the clutch and drive line. To be expected given 225k on original components and oil

[joshwyatt]

I have x2 LSD's, one on 129k and the other on 126k, both judder slighlty and there's a fairly quiet whine, been like that on all LSD Omega's I've driven.
There is a GM LSD additive, I intend to add it at some point to see if it quitens down.
I'll get you the part no.
It comes in a bottle that looks like eye drops, or similiar.

[feeutfo]

I have x2 LSD's, one on 129k and the other on 126k, both judder slighlty and there's a fairly quiet whine, been like that on all LSD Omega's I've driven.
There is a GM LSD additive, I intend to add it at some point to see if it quitens down.
I'll get you the part no.
It comes in a bottle that looks like eye drops, or similiar.

Yes that might well be appropriate packaging, I shall try not to oblige when filling.  

[waspy]

With what your saying your symptoms are, it sounds the same as what Monaros suffer frrom.
Do an oil change & add friction modifier as per manufactures guide, if the problem's still there, but less so add a little more friction modifier.

It worked for me

[Omegatoy]

Millers do a very good lsd oil, sorted at least 4 cars i know of out!!

[jb]

Friction modifier is getting tired...........usually cured with an oil change with correct gm f. mod added or using a fuch or millers product which is blended specifically for lsd diffs.

[aaronjb]

I was talking to Chris about this earlier (he popped round to help me get the pivot bolts out of that Jag diff - done with the aid of two jack handles and a breaker bar!) .. anyway, I'll have a bottle of this arriving soon: http://www.opieoils.co.uk/p-6320-red-line-limited-slip-differential-friction-modifier-break-in-additive.aspx

I should only need half to stop the M3 diff STFU; when I get it, Chris, pop round and we can do an oil change on your diff and put the rest in yours

[2woody]

No - No - No....

that's EXACTLY what they're supposed to do. Indeed, the judder is perhaps the only way that you can tell it's working properly.

I'd describe it as a judder that's felt when for instance turning right out of a tight tee-junction.

What's happening is that because you're loading the tyres differently, the diff is trying to limit the slip from left to right, which it does right up until the point that the tyre unloads by slipping on the road surface, temporarily equalising the load. It's that cycle repeating that is the judder.

If this effect stops, then it's time for an oil change.

[2woody]

This is different to the Monaro banging issue, which is cured by replacing the oil.

Monaro has a differnt type of LSD.

[feeutfo]

So leave as is.

I am tempted to change the oil for a proper LSD mixed oil, rather than a normal dif oil with additive, just to make sure the mix is correct. ...?

[2woody]

you can't use too much additive.

Just don't use a multigrade diff oil - stick only to a "straight" 90 ( from memory ). Even a whiff of a "hypoid" or multigrade diff oil ( such as 80W90 ) and you might as well throw it away.

I'd get the oil you need from AndyC, just to be sure.

[aaronjb]

What is it about the hypoid oil that ruins the clutch plates (I presume), out of interest?

I ask because the current advice I see on M3 forums for the E46 M3 is to use Castrol Syntrax Limited Slip 75W 140 (Formerly SAF-XJ 75w-140) plus RedLine Limited-Slip Differential Friction Modifier - and I'm presuming the former is a hypoid gear oil.

I realise I'm comparing apples and oranges, but they're both clutch plate diffs AFAIK, and the 'proper' BMW oil is something ridiculous like £50 per 0.5L (and you need three bottles)..

[2woody]

the friction surface on the slip plates is usually a copper-based sintered material. The hypoid compound in the oil binds chemically to the copper, thus stopping it working. Permanently. This means that even an oil change won't correct it. The only option is to replace the plates.

Cone-type LSDs and plate-type LSDs are very often mistaken. Cone will tolerate hypoid compounds.

can't tell from RealOEM

[feeutfo]

It's going to be a long night. ...wondering if it was 90 that went in, or 80/90.