Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: feeutfo on 02 August 2012, 00:24:06

Title: LSD judder
Post by: feeutfo on 02 August 2012, 00:24:06
... 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?

Title: Re: LSD judder
Post by: 05omegav6 on 02 August 2012, 00:34:00
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 ::)
Title: Re: LSD judder
Post by: joshwyatt on 02 August 2012, 00:37:55
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.
Title: Re: LSD judder
Post by: feeutfo on 02 August 2012, 00:44:19
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. ;D  :y
Title: Re: LSD judder
Post by: waspy on 02 August 2012, 07:09:49
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 :y
Title: Re: LSD judder
Post by: Omegatoy on 02 August 2012, 09:31:50
Millers do a very good lsd oil, sorted at least 4 cars i know of out!! :y
Title: Re: LSD judder
Post by: jb on 02 August 2012, 18:00:49
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.
Title: Re: LSD judder
Post by: aaronjb on 02 August 2012, 18:45:13
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 ;)
Title: Re: LSD judder
Post by: 2woody on 05 August 2012, 23:58:52
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.
Title: Re: LSD judder
Post by: 2woody on 06 August 2012, 00:00:37
This is different to the Monaro banging issue, which is cured by replacing the oil.

Monaro has a differnt type of LSD.
Title: Re: LSD judder
Post by: feeutfo on 06 August 2012, 00:05:26
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. ...?
Title: Re: LSD judder
Post by: 2woody on 06 August 2012, 00:09:38
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.
Title: Re: LSD judder
Post by: aaronjb on 06 August 2012, 00:14:03
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)..
Title: Re: LSD judder
Post by: 2woody on 06 August 2012, 00:24:04
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
Title: Re: LSD judder
Post by: feeutfo on 06 August 2012, 00:26:27
It's going to be a long night. ...wondering if it was 90 that went in, or 80/90. :(
Title: Re: LSD judder
Post by: 2woody on 06 August 2012, 00:27:36
If it still judders, you'll be ok. AFAICT, the damage is pretty instant.
Title: Re: LSD judder
Post by: feeutfo on 06 August 2012, 00:29:36
Well that was my thinking, at one point. It was juddering nicely earlier.

Does temperature come into it? It seems to judder more when hot?
Title: Re: LSD judder
Post by: 2woody on 06 August 2012, 00:31:02
I'll need to think about that one......
Title: Re: LSD judder
Post by: feeutfo on 06 August 2012, 00:33:23
Might not be working when cold. :-\
Title: Re: LSD judder
Post by: aaronjb on 06 August 2012, 00:38:37
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

Cheers for that - I did wonder, that explains it nicely :)

Actually more googling implies the E36 had a plate LSD and the E46 has some kind of hybrid viscous coupled diff, which probably explains why hypoid works (but not - to me, anyway - why you'd need the friction modifier). Anyhoo.. back to Chris's clunking :)
Title: Re: LSD judder
Post by: feeutfo on 06 August 2012, 00:43:18
Just checked. It's an 80/90. :(
Title: Re: LSD judder
Post by: feeutfo on 06 August 2012, 00:44:38
This one. :-[

http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_220229_langId_-1_categoryId_255220#tab2
Title: Re: LSD judder
Post by: feeutfo on 06 August 2012, 00:55:33
Link seems to imply muti grade is ok on friction plate LSD. :-\

http://www.redlineoil.com/product.aspx?pid=41&pcid=4
Title: Re: LSD judder
Post by: feeutfo on 06 August 2012, 19:42:08
Well, compared to Taxi Al's car mine judders like a good en. So not a lot wrong I suppose. :-\
Title: Re: LSD judder
Post by: aaronjb on 06 August 2012, 19:56:14
I ordered the additive today .. have we established that it is or isn't OK to add to your diff? I'm not quite sure, now  :-[
Title: Re: LSD judder
Post by: feeutfo on 06 August 2012, 20:29:45
Have to admit to some fuddlement. :-\