Brembo 4 piston caliper rear conversion??

[EuroxS4]

Hey guys So about a year ago or so i installed 17Z 6 piston brembo calipers on my b6 a4 avant. I recently found someone thats making brackets to fit 4 piston brembo rear calipers and wilwood MC4 parking brake caliper for the b6 a4 and s4 cars. The question is will I have enough master cylinder if I install the 4 piston rears on the car?? Has anyone done it?? The kit uses b8 s4 330mm rear rotors.

[BARRY]

i'm no expert but master cylinder size changes generally change the required pedal movement to apply a given pressure from caliper to pad and rotor. without knowing proper sizing of the factory master cylinder, the only way to know for certain is to put it all together and test. if all else fails the RS4 Master Cylinder would be a valid replacement (if it fits) as it is a factory multi piston front and rear braked vehicle.

[EuroxS4]

Looks like rs4 and s4 share the same master.


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[Matt Devo]

if all else fails the RS4 Master Cylinder would be a valid replacement (if it fits) as it is a factory multi piston front and rear braked vehicle.

the RS4 uses standard single-piston sliding rear calipers just like the A4/S4

[BARRY]

ah good to know. thanks!

[fR3ZNO]

There are online calculators you can use to punch in caliper and master cylinder bore diameters to see what kind of stroke change you'd get. Just basically uses Pascal's Law equation... short answer is you could probably get away with the A4 master, but I would hate the excessive pedal travel...

[EuroxS4]

There are online calculators you can use to punch in caliper and master cylinder bore diameters to see what kind of stroke change you'd get. Just basically uses Pascal's Law equation... short answer is you could probably get away with the A4 master, but I would hate the excessive pedal travel...

Exactly my point.Upgrade is not a upgrade if there isnt sufficient force behind it.Also I just noticed that the kit in question uses 22mm s4 rear rotors but the caliper is designed to take 28mm thick rotors so theres a airgap of 2.5mm per side on each caliper that will affect pedal travel also. I will see if this can be resolved and what Im gonna do.

[outsider6661]

https://www.audizine.com/forum/showt...30733-rear-bbk

The master won't be an issue, I ran this set up in the rear for a few years. The peddle had very minimal travel. The rears complemented the 18z in the front very well.

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[EuroxS4]

Yeah that setup will not fit under 17” wheels.


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[fR3ZNO]

Exactly my point.Upgrade is not a upgrade if there isnt sufficient force behind it.Also I just noticed that the kit in question uses 22mm s4 rear rotors but the caliper is designed to take 28mm thick rotors so theres a airgap of 2.5mm per side on each caliper that will affect pedal travel also. I will see if this can be resolved and what Im gonna do.

As far as I know, that gap would be taken up after a few pumps of the pedal. The pistons wouldn't have to advance and retract 2.5mm everytime you press the brake pedal. If that was the case, your pedal travel would change as your brake pads wore down. The piston advances and compensates, only retracting slightly when your foot is off the brake.



That's still not ideal though, once the pads are worn, it's likely the piston may become over extended.

Also, I ran B5 S4 fronts and B6 S4 rears, and even after bleeding my brakes dozens of times, I still had what I thought was excessive pedal travel. So I could never understand when people said their pedal travel "was fine" on even larger setups than mine.

[boostedutah]

Does that guy you know still have brackets? I've been looking for a while now and can't find anything

[EuroxS4]

Does that guy you know still have brackets? I've been looking for a while now and can't find anything

Sadly no, no longer made. I have no idea what happened. But they are no longer being made. If I have time I will see if I can copy and draw something up in cad. But with the current work load and ton of other projects, it's gonna be a while to be honest at best.

[86turbodsl]

That company no longer exists. The brackets shouldn't be too hard to design and make for a motivated individual. Shame too, those looked like good parts.

[b7_drizzy]

Sorry to revive this thread. Did you ever finish up those CAD drawings? And does anyone have actual pictures and measurements of the rear voshmods kit? I'm an undergrad mechanical engineering student and pretty familiar with how to create stuff in Solidworks but I have no idea what the brackets look like.