1990 CQ rear diff rebuild

[etsola]

Hi there, I have a spare rear diff from a 1990 90 CQ.

I am planning on getting a V8 ring and pinion to make it torsen.

I'd like to change what would be preferable to change once it's open and before I put it on the car. I will most likely rebuild the rear subframe and would do this at the same time.

So, I tried to go through the parts catalog at vagcat or else, but I lack the knowledge of what I'll need ... and is it me or it's missing a whole bunch of things too (I'm pretty sure there are some sort of paper gaskets that seal the flanges but there are no mention of them in the parts catalogues),

So here it is,

Has someone done this and have a parts list to give out ? with OEM parts #.

Other than that, any other recommendation would come in handy.

Cheers

[mcandmar]

You need a torsen diff, both output flanges with securing bolts, and a tube of gasket sealant.

[ralleyquattro]

Don't forget the matching V8 "lage" flange seal, it is specific to the V8.
Otherwise swap the crown and put back together.
You also might want to find a rubber seal large enough to block the diff lock "arm" opening.

Hope this helps.

[mcandmar]

Very good point, i had forgotten about that. I posted some part numbers in the torsen thread here http://www.s2forum.com/forum/showpos...&postcount=154

[etsola]

Thanks for all the advice. I didn't know I needed the flanges.

Just to be sure, this is the same for a CQ than for an S2 ?

I have a CQ.

Cheers

P.S. The corteco part #'s are doubled :

Left side seal for manual locking diff,

017525400A : BASLSFRSX7 : 72x122x10/13 : €20

Left side seal for torsen diff,

017525400C : BASLSFRSX7 : 45x122x12/23 : €56

[mcandmar]

Hmm, i have a vague memory that the inner CV joints are smaller on a coupe vs an S2. Or maybe it was a CQ20v/S2 vs all the 10valves. You would need to double check the parts catalog on that one.

P.S. The corteco part #'s are doubled :

Doh Luckily i snapped a photo of the torsen seal with the box

[etsola]

I'm trying to read the thread you reverred to through.

I know S2 driveshafts (CV axles) are bigger, and the flanges too : 90mm vs 108mm ? (I think).

The V8 flanges are a direct swap for the S2, though will be bigger for CQ (by CQ, I mean 90 CQ w/ 7a motor, 20v).

I will not be able to come across S2 driveshafts easily, they never made them in North America and not sure if there any equivalents in small chassis world available here.

In the post, Porkkis makes an obscure comment about using spacers ... :"I swapped a V8 torsen unit to my B3 80 quattro running the small 90mm rear flanges. No reasonably priced S2 coupe rear driveshafts could be found so I got another RH side small flange and used them on both sides. They need 9,3mm tall 25mm diam spacer bushes with center hole for the M8 bolt to extend the flange shaft length inside the torsen unit. That's all."


I guess I'll have to figure it out. Error404 had the same question in the post, but he ended up using S2 driveshafts (or I think) ...

Cheers

[speeding-g60]

the inner cv flanges for the rear diff come in three flavors.

90mm for 4 cylinder stuff, like CQ from EU.
100mm for N/A 5 cylinder stuff, like CQ USA. USA CQ only ever got the N/A 5cyl, so 100mm.
108mm for forced induction 5 cylinders, like S2 and RS2.

the rest of the internals are all the same except for the breather is different a little bit for some reason.

at least in my limited experience in blowing these rear diffs up.

i have had 2 full sets of S2 axles here in the US, just gotta find them and have them sent is all.

[etsola]

But is there a way to re-use the 100mm flanges from the 7a 90 CQ ?

Thanks for the Replies

Cheere

[Error404]

I would get S2 shafts and use both V8 flanges. You will note the splines on the V8 flanges have a lot more engagement in the diff.

[andy10v]

But is there a way to re-use the 100mm flanges from the 7a 90 CQ ?

Thanks for the Replies

Cheere

Re drill the flanges

034 used to just re drill them, others welded them up and then re drilled.

There are old threads on motorgeek.

http://www.motorgeek.com/viewtopic.php?f=15&t=28023

http://www.motorgeek.com/viewtopic.php?f=15&t=1519

[etsola]

Thanks Andy, that clarifies it.

Either shim them 100mm ones or drill the 108mm ones

Cheers