The Project Pad

That's great! I'll buy a new set of S4 pads and check to see if it is good without turning the rotors.

ringbearer wrote:I was able to use a 22mm thick rotor and stock rear UrS4 calipers using B5S4 rear carriers as they were the same dimensionally except designed for the thicker rotor. I went a different route that I am happy with but this looks like a great solution for a cheap RBBK. Good work

Are you sure they were new full thickness pads when you got them to fit over the 22mm rotors. S4 rotors are 20mm thick. I needed an extra 1.5mm of width between the pads so I can get the caliper to drop on the rotor. I even took a C-clamp to make sure I had the piston bottomed out.

Audi C4 S4 Quattro 20v T Rear
ES#2718836 - 857615601KT - Rear Brake Rotors - Pair (269x20) - Restore the stopping power in your vehicle - Genuine Volkswagen Audi - Audi Rear Brake Rotors - Pair (269x20)
Restore the stopping power in your vehicle
Brand: Genuine Volkswagen Audi - Corporate Logo ES#: 2718836 Mfg#: 857615601KT

Here is what I used. Brand new Zimmerman rotors and B5S4 Textar pads.

*rear Apikol B5S4 300mm BBK with stock UrS rear calipers, B5S4 carriers and pads, 300x22 Brake Rotors B6/B7 S4 rear, P/N - 8E0 615 601R, 0.420" spacer for carrier to knuckle, longer bolts for bracket and new (stock length) hoses.

It was just able to clear the rotor, I had to bottom the piston in the caliper for it to work, pull on the ebrake lever once and it wouldn't clear.

Now that's an idea! I wonder if the used caliper I am working with has the E-brake adjustment stuck a out a little and causing me to think that I have to turn the rotors. It sounds like that is a big possibility and I will try it on the new caliper that is coming in today. It doesn't change my bracket since I centered the caliper over the deeper grove on the caliper/bracket. I should find out today. Thanks!

New info. I'm getting deeper into this than I ever wanted or expected but using the B5 S4 pads is better! The pads are thinner than C4 S4's. So that thinner pad on each side might be just perfect so that now I surely won't have to turn down the rotor

C4 S4 pad thickness is.... 1.625mm

B5 S4 pad thickness is .... 1.49mm

That must be the ticket! That will be a perfect scenario if that is the case.

I bought those pads as I tried to use the b5s4 rear calipers but the brake cables point the wrong way. I never measured or looked up the specs but they were the same size for the most part so I ran them. Are you turning the piston while compressing it? Just want to make sure you get it bottomed out. Nice to not machine the new rotors down if you don't have to.

I'm going to wait until I get my hands on the new caliper today. I'm not going to try to mess with the old rusted one. The C4 S4/ V8 / 200 caliper will accept the thinner B5 S4 pad, so that is the way to go.... 300x22mm rotor-original caliper-B5 S4 pads- and adapter. Needs to be verified, but I think that has narrowed it down.

That's what I used, 0.420" spacer centered the carrier to the 300x22mm rotor with the B5S4 RBBK adapter.

Pics are in my thread.

2.5TYPE44 wrote:300x22mm rotor-original caliper-B5 S4 pads- and adapter. Needs to be verified, but I think that has narrowed it down.

So no more 330x22 Rear BBK ..?

I recall reading somewhere that guys were having success using UrS rear calipers and larger rotors (mk1 TT, maybe?) as an upgrade on Cq/S2 cars. Perhaps this uprgrade would also be another option for the B3/B4 cars as well...

mushasho wrote:

2.5TYPE44 wrote:I'm going to wait until I get my hands on the new caliper today. I'm not going to try to mess with the old rusted one. The C4 S4/ V8 / 200 caliper will accept the thinner B5 S4 pad, so that is the way to go.... 300x22mm rotor-original caliper-B5 S4 pads- and adapter. Needs to be verified, but I think that has narrowed it down.

So no more 330x22 Rear BBK ..?

No, No, No, ...... Definitely still going to be using the 330 x 22mm rotor. That was the whole point... To mount the the largest possible size while still being able to run a 17" wheel, keep the parking brake function, have the parts be oem/easily accessible, and cheap, and not worry about piston bore volume size. Through this brake topic discussion, and sharing information, taking lots of measurements, looking up lots of part numbers, and buying several models of rotors and pads, I am 99.99% this is the best option and we don't have to turn the rotors down now. The last final thing that made this all work out right is using the B5 S4 pads. Surprisingly, they fit right into the older calipers from the C4 S4 / V8 / S6 / 200 20v. The key is that these pads are thinner and allow for the 22mm rotors. The B5 S4 pads are better design. The retaining clips hold the pads in better and the pads have a different shape. I bought the B5 and the C4 pads to compare and made sure the B5 pads worked in the older calipers.
So here it is...

2010-2011 S4 rotors 330x22mm $84/pair-local parts store
b5 S4 rear brake pads. $17/set-local parts store
Machined adapter $100/pair-shipped

Total.................................. $201.00. You can't beat it!

The machine shop is suggesting I have the parts dipped in a non toxic liquid As a corrosion inhibitor. They said it is what gun smiths use and would be cheaper than powder coating. trying to keep cost down...


Here are some pics comparing B5 S4 pads vs. C4/C3, showing that they are thinner material, fit in our older calipers, and show that the throat of our older calipers is 23mm which is large enough to accept the 22mm wide rotor.

Wow this is great, nice r&d! If the brackets are machined, why not make them one piece? You could do a nice fillet between the dogleg and the two round spacers to minimize stresses too.

Oh nevermind, they're waterjetted...want to provide CAD

The brackets will be one piece, flat, and dog bone shaped. I don't mind giving out the drawing once I get my initial investment back to make my personal set for my car

I am curious about one last measurement that I don't have access to... Does anyone know what the width of the opening on a b5 s4 rear carrier bracket is? Basically how many mm wide where the rotor rides? None of the parts stores have it here where I live so I can go check.

I have one, I'll try to sneak off and measure it. I think its just a few MM wider than the UrS version.

Thanks. I still want to keep the original carrier to prevent having to buy any extra parts for the conversion. But I am curious as to how much extra clearance they are giving the 22mm rotors. If I had to guess... I'd say it's close to 25mm.

The stock carriers cleared but these fit better and I owned them, I'll try and find my spare to measure

Ok, more measurements for documentation... I measured the distance from where the face of the wheel hub back to where the face of my carrier bracket bolts on to the knuckle and came up with roughly 52.5mm. This will be the base measurement of what the adapter plates are built from. That way if there are variance from year to year (which I don't think there are) then all I would have to do is get your measurement and mill down the difference or make the plate thicker.

Here is the super scientific cardboard template that I gave the machine shop. You can see how flat and simple it is. No extra spacers needed.

I found a B5S4 carrier and it was 26mm wide at the machined opening to clear the rotor.

26mm.... hum my guestimate was off by 1mm Not bad. Thanks.

Happy to contribute

Here it is... Final product...

C3/C4 caliper, carrier, and pads

2010/11 S4 330mm x22mm (1mm turned off of each side and now 330x20) I didn't want to buy B5 carriers...

My adapters

2 bolts

[youtube]https://m.youtube.com/watch?feature=youtu.be&v=Sz4qYzA7ijE[/youtube]

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Dude rad. I dig it.

Very nice! My 300mm rotors looks small in an 18" wheel