Never really given this any thought before but im about to change the oil in my rear diff. I've been told by Motul that their Gear 300 oil (75W/90) is good for the gearbox and rear diff unless the rear has a LSD and then to use Motul 90PA (which says it's a SAE 90 oil). I have a MY93 WRX so do a have a rear LSD or not, is this limited to the STis? What oil have you out in your rear diff?

Cheers,

Tony.

 

you do have a limited slip diff, uk cars have them too. its just the front diff that is 'open'.

as for the oil, i pop down to the local subaru dealer and they fill a bottle for me from there drum. they dont know what it is as it has to label etc, but its the proper stuff for rear lsd's.

you need 1 litre if i remember correctly.

hope this helps
ian

 

rear is deffo LSD... jack car up and turn the wheel if the opposite goes the same way then it is lsd, if it goes the opposite way then its open... IMHO.

David

 

as far as i am aware, all legacy and impreza turbo's have rear lsd's as standard. of all the ones ive swapped etc, all lsd's.

ian

 

agree with david, thats the way to check if not sure, but they are deffo lsd's.

 

It's a viscous LSD, other wheel will turn the other way, but slowly, try to go fast and it just loads up.

SOME cars did have plated LSDs with clutch packs and the like, these are rare, only came on early Legacys I think.

Front is open, wouldn't mind a Quaife ATB diff for the front.

PaulI

 

Cheers for that, guess i've got a LSD then. I'll do the jacking the car up check this weekend just to be sure.

Tony.

 

A legacy rear diff is a VC unit, and the diff as a unit ( whole housing ) will not directly fit an impreza as the diff has output shafts. Jap spec Legacy's are the same as imprezas, with the driveshaft sliding into the diff housing. The diffs are interchangeable, using the correct driveshafts etc.
Any I have taken apart ( imprezas included ), are all VC units either way. AFAIK the plate type was only fitted to some sti models ( incl P1 ) Only the plate type rear diffs would require the use of a LSD suitable oil.

 

steve, my STi RA rear diff went straight onto my uk legacy, just swapped the front input flange and mounting pins.

driveshafts were the same though?

 

From ancient memory.... isn't the rear diff a "sealed unit", and the oil only used for the crown wheel/pinion, hence the confusion ?

 

More info here http://www.scoobynet.co.uk/bbs/threa...ThreadID=28498

 

Ok, after reading 5 pages of thread this is what i got out of it:

The centre diff is a viscous coupler (LSD) that doeasn't need servicing i.e sealed.
The rear diff (UK, WRX) is also a viscous coupler (LSD) that is sealed but has oil around the input shafts etc in the housing.

That would mean that i could use the same oil that goes in the gearbox and not a LSD oil. Only the Type Rs, 22bs etc with mechanical rear LSDs would need the LSD oil.

Is this right or am i way off

Tony.

 

tone loc, I believe you are correct,

and whoever said it above, the P1 has the same vc rear diff as all normal imprezas, not the clucth type of the typrs, rsa and 22Bs.

 

That would make a change for me .

Cheers for the reply Adam.

Tony.

 

Perhaps some later cars did have the same type diff as an impreza then Ian. Ive only seen 1992-1994 UK legacy's, ( Although Michaels Legacy RS, Jap spec had impreza style rear diff, and its 1990 ) and they all had output shafts. As for the P1 rear diff. We fitted P1 box and diff, to Michaels legacy. It has a mechanical LSD at the rear.

 

EDITED - I STAND CORRECTED

As for the oil, I used Castrol Syntrax in my rear diff on MY95 WRX.

[Edited by caz1562 - 9/10/2002 2:41:22 PM]