B4 Sedan/Avant subframe on Coupe/B3 quattro

[OskarH]

Good afternoon all,
I'm starting to plan my new project for next winter so that I manage to source the most important parts in time. For now im looking into the suspension bits. Does anyone here know if the B4 quattro subframe will bolt up to the floor of the B3 quattro? I know that the supension is compleatly different but I was wondering if the 4 pickup points for the subframe are in the same place? If not, has anyone here tried to fit the subframe to the Coupe or B3 floor plan?

Best regards,
Oskar

[varia]

front will

[OskarH]

Sorry I should have specified which subframe. Its the rear subframe I'm thinking of.

[david1980]

It doesnt fit unfortunately.

[K Simmonds]

There is nothing wrong will well serviced B3 Rear suspension.

Fit and works.

[OskarH]

Thats a bummer. Hopefully its not too far off so that its possible to modify either the subframe itself or the mounts, i will see if I can get hold of a b4/b5 subframe and compare with my b3.

Its true that a b3 rear suspension setup works but due to Swedish regulations i need to change the complete drivetrain including the rear differential drive shafts, the complete braking system and/or suspension/steering in order to have the car registered with the intended engine. I was thinking that if I would just need to fab up some of the fixing points in order to install a b4 or b5 rear subframe it would give me more quite cost effective bolt-on solutions for differentials, brakes etc

[david1980]

The b3 vs b4 is completely different.

Subframe is wider and longer.
Diff is longer
uprights are held on by 4x bolts and a different housing vs 1x nut on the top cap.
Arb is wider

[OskarH]

Hmm, maybe I need to rethink this one. Sounds like the "easiest" way is trying to fit the complete rear portion of the floor from an a4 b5 as they still are quite common around here. Was hopping to be able to just fabricate shock mounts and use some of the b3 mounts to line up the suspension.

Any other ideas of more suitable parts to use? I need to change out the complete differential with driveshafts and discs with calipers in order to get it street legal in Sweden.

[K Simmonds]

Basically you would have to purchase a complete B4 quattro car and cut it up, you could cut up an early B5 but would still need parts from the B4.

This is an insane undertaking and makes to sense even if you had a scrap B4 to use.

Just purchase good quality B3 Suspension parts an the set up works fine...

I you'd rather a B4 then buy one and start with that.

I've been driving these car tor over 25 year's and see no need to a convert a B3 to B4 suspension, it a ridiculous undertaking;

The money could be spent much better elsewhere.

If you want to fit a B4 diff casing to a B3 this can be practically done with a bit of simple fabrication.

[OskarH]

Yeah I think you are right, its not worth the fabrication hours. Also I relly dont want to cut up two old classics in order to create one car. There are too few of these cars on the road already

I think I will have to look inte fitting another differential into the exisisting subframe together with some adapter plates for bigger brakes and some adjustable control arms instead.