New B5 S4 owner with brake questions

[Andy P]

Morning all,

First post here although some of you might know me/ know of me as I joined the ASN Nurburgring trip recently in the Volvo S40.

The "S4" isn't so much an S4 at the moment but basically a rolling shell project car.

Plans for this are rather different from the norm, although for now I'll keep them under my hat for now

Anyhow, on to the brakes...

My last "fast" car had billet KAD 6 pots, 330mm 2 piece discs with alu bells and they were awesome. Obviously, the car will be doing a fair amount of track work. I want to stick to 17's so have been looking at the biggest disc I can get away with - 345mm.

I just happen to have some 4 pot AP racing calipers (brand new in a box!) laying around so I'll get some brackets made to fit these for now, until some 6 pots come along.

Comparison shots with the KADs-

To keep things as cost effective as possible, I plan to use OEM 345mm one piece discs. What is the difference between the 8P S3 disc and B6/7 S4 disc? I'm correct in thinking the S3 is 5x112 and 345mm? How about bore and offset?

Mock up of the AP caliper on the 321mm B5 disc-

Andy

 

[aragorn]

Ah that cars changed hands a bit then!

The S4 disks have a greater offset than the 8P S3 ones. Infact thats the case with all A4 platform cars when compared with the A3/Golf equivalents.

Not meaning to teach you how to suck eggs, but have you checked the piston diameters on the TVR calipers are suitable for the A4 master cylinder and whatnot?

 

[Andy P]

Yep! The shell has passed hands quite a few times so I've heard. Master cylinder isn't a worry as I'll be running my own fabricated non servo assist floor mounted pedal box with bias adjustment

What's the difference in offset? As the caliper bracket has to be custom made any way, so long as it clears the lower arm it'd work - so long as the bore fits the hub?

As far as I could find out, the 8P S3 discs were 50mm high vs 48mm B5 S4. If it clears the lower arm the S3 would gain an extra 2mm spoke/caliper clearance.

Andy