Rear brake options for the avant/sedan:

[Josh-stateside]

Hello everyone

I'm going to mention this for awhile I guess. It helps to explain things. A couple of weeks ago I sourced a 1994 audi 90 v6 quattro sedan. It has a 4/108 bolt pattern. However I am swapping over to 5/112 hopefully very soon. I'm actually picking up some OZ superleggas in 5/112 for it tomorrow.

I can't say that all this information is completely correct. I'm still in the research stages of my new project. However I believe there is a very good chance that these setups will work. Instead of source 75mm rear wheel bearing S2 hubs. I will be transplanting A4 rear suspension parts into my sedan. From all the pictures, and all the information that I found it looks like it will be a simple swap.

I believe the Hub offset and everything else is the same as the S2 avant and sedan setup in Europe. I don't have etka but if you wanted to double check you guys could check to see if the rear rotors on the S2 avant were the same as the A4 units.

So to get to the point I'm looking into options for my rear brakes. Seemingly I am going to just buy A4 rear rotors for now since the previous owner installed new calipers.

However I found two future options:

I believe the A8 rear rotor setup has been mentioned before:

Parts required:
Two Audi A8 269mm x 20mm vented rotors: Audi Part# 4D0-615-601-B
Two Audi A8 caliper brackets: Audi Part# 4D0-615-425-B
2000+ Audi S4 left caliper: Audi Part# 8D0-615-423-C
2000+ Audi S4 right caliper: Audi Part# 8D0-615-424-C
Four 2mm washers: (~$0.05 at a hardware store)

I believe the A8 rear calipers will work too.

Another option:

A4 B6 platform (3.0L engine) carriers (8E0-615-425-A) and A6 255mm x 10mm solid rotors (4B0-615-601-B).

This second setup should allow you to retain your stock rear caliper setup. The only reason why this second setup should be consider I suspect is if you can use your stock rear calipers. It would be pointless to buy A4 rear calipers. As long as the A4 rear rotors have the same hat height as the S2 avants you will be all set.

I'm priety positive that this is the case. However I don't want to give false information.

So what does Option two give you? 10mm. It's not much but it's an option.

256mmx20mm is the 2000+s4 rear rotor setup. You would basically have the same stopping power as the 2000+S4. Unfortunately it might be a little hotter.


Just an option I wanted to mention. There are A4 owners running both setups.

Cheers
Josh

[Mikes2]

If you stay with 4x108, you can use a 256x20mm (Coupe GT) front disc on the rear of the sedan.

[Henka]

Well is it worth going from 245 to 255? I mean, that's just 5mm on the radius? Maybe if my discs were badly worn. I would have wanted something more along the lines of 280mm but 10mm thick...

[s2avant]

Parts required:
Two Audi A8 269mm x 20mm vented rotors: Audi Part# 4D0-615-601-B
Two Audi A8 caliper brackets: Audi Part# 4D0-615-425-B
2000+ Audi S4 left caliper: Audi Part# 8D0-615-423-C
2000+ Audi S4 right caliper: Audi Part# 8D0-615-424-C
Four 2mm washers: (~$0.05 at a hardware store)

Word of warning. This setup does NOT fit on an S2 Avant. I have all the bits and have test fitted it and there is no way the rotors/discs will fit. The hat height is such that when fitted the disc completely covers the mounting holes for the calliper. No amount of spacers or grinding is going to make it fit safely.

It requires a disc with a much lower hat height to make it work. I am currently experimenting with various choices to see if I can come up with a viable parts list to fit the Avant. Perk of my job means I can pretty much order anything "just to try it"

On face value it should all fit and I agree with all the part numbers and everything else Josh has said but in practice it doesn't. Josh is right that this is the way to fit bigger rear brakes on Sedan/Avant models we just need to find a combination that will work.

If anyone has size/hat height info on 5/112 discs from the VAG range then this would greatly help in working it all out.

Ben

[Henka]

Is the A4 rear 245mm discs in the same range, hat height wise? If so, front discs from A6 and A4 can be used - they are like 1mm from the A4 rears.

[Josh-stateside]

Hello everyone. The rear A4 hubs are different than the S2 units. I mounted A4 rear hubs and rear hub carriers on my Sedan and used A4 rear rotors. It works. However it's not the same as the S2 units. Both of those rear brake setups will work with the A4 rear hubs. The problem is that it's created a wider stance by about 10mm. It's not really a problem. I suspect a wheel with a 40et offset would sit very nice in the arches. I have 17/8inch and 35et wheels with 225/45/17s tires and they stick out a bit past the arches. I don't believe I will have problems with the tires rubbing, however I will be rolling the arches. The car is not "dropped" yet so it's hard to tell.

I hope this make sense to everyone. I'll try to find time to get pics online.

[Tommy200rs]

>>> weeks ago I sourced a 1994 audi 90 v6 quattro sedan. It has a 4/108 bolt
>>> I will be transplanting A4 rear suspension parts into my sedan. From all the
>>> pictures, and all the information that I found it looks like it will be a simple swap.

Looks very familiar parts in B4 sedan and avant compared to A4 rear.
Sounds doable.

>>> I don't have etka but if you wanted to double check you
>>> guys could check to see if the rear rotors on the S2 avant
>>> were the same as the A4 units.

disc ET is different

>I believe the A8 rear rotor setup has been mentioned before:
>Parts required:
>Two Audi A8 269mm x 20mm vented rotors: Audi Part# 4D0-615-601-B
>Two Audi A8 caliper brackets: Audi Part# 4D0-615-425-B
>2000+ Audi S4 left caliper: Audi Part# 8D0-615-423-C
>2000+ Audi S4 right caliper: Audi Part# 8D0-615-424-C
>Four 2mm washers: (~$0.05 at a hardware store)

A8 269x20 disc has bad ET also the 280x22 has bad et for B4 sedan/avant

> I believe the A8 rear calipers will work too.
no , the handbrake mechanism is differently routed to Aluminium A8 calipers

>A4 B6 platform (3.0L engine) carriers (8E0-615-425-A) and
> A6 255mm x 10mm solid rotors (4B0-615-601-B).

cooling is bad with those discs

>256mmx20mm is the 2000+s4 rear rotor setup. You would basically
> have the same stopping power as the 2000+S4. Unfortunately
> it might be a little hotter.

Disc is 256x22mm

For B4 type S2 SEDAN and AVANT:
The above suggested calipers are very OK , also carriers ok,
but the disc 254x22 is with bad et. ET problem can be solved with another disc
If you use this setup but the A3 front disc 256x22mm and modify the bolt pattern
and hub hole then it works ok. The hand brake wire is tiny short but it works.

Also with newer 280mmx22 A3 disc and above S4 calipers and S8 carriers it
allmost works but then the handbrake wire is too short and new custom wires
needed.

I have the A3 256mmx22 + neu S4 caliper and neu s4 carrier + carrier shims in my
B4 sedan quattro rear and that works.

There are also forum members who have done the upg with rs2 rear brake parts.
That offers even more brake performance.

[Josh-stateside]

If there was enough interest. A simple two piece rotor could solve the issuse for everyone with a S2 sedan or S2 avant.

Actually they make them for the A4 sedans and avants. You would only have to source a custom hat height for the rotor.

www.ecstuning.com is one company that sells two piece rotors.

[Josh-stateside]

"Re: everything works fine. Just need to mill 8mm off. 4mm ea from carriers & carrier extension..."

For all you S2 sedan and avant guys. There's the best route.

[Henka]

Does it have to be neu-S2 calipers? Won't UR-S4 and A8 calipers do the trick? About handbrake cables - would it be possible to use Audi 100/A6 cables or would they be way too long when going 280mm+? Also, there is a 312mm disc from Golf - wouldn't that work too, apart from the cables issue?

[Henka]

"Re: everything works fine. Just need to mill 8mm off. 4mm ea from carriers & carrier extension..."

For all you S2 sedan and avant guys. There's the best route.

Not sure what you mean here. Who posted the "re:" and what was the question? I looked through this thread but I couldn't find it...

[Henka]

Are UR-S4 units anygood when converting to 280 x 22 or 256 x 22? I mean, can those be combined with some carrier to mount up to a S2 Avant? Thing is, A4/S4 are much more expensive than C4/S4 and C4/S6 units!

[s2avant]

I have finally got my rears sorted. Ended up with 256x22mm.

We used nuS4 callipers and carriers with machined TT rear discs. I'll put together a list of part numbers and more details when I get the car back tomorrow.

Ben

[Henka]

Cool, Billzcat1 gave me a list too, I'll post it and we'll compare numbers. His "kit" or "idea" was for a 280mm which I will go for.

[s2avant95M]

I would be interested in this conversion. Good work.