RacingBrake

RacingBrake caliper rebuilding application coverage is getting better and better for Porsche, as we get more inquiries and interests from Porsche community.

http://www.racingbrake.com/category-s/7185.htm

We have piston sizes from 28/30/33/34/36/38/40/42/44 to 46mm, with 30 & 32mm in height, so chances are we have all the size for your calipers but if you can't find your models/calipers just tell us and we will identify them for you.

RB pistons are machined from solid 304SS bar stock, with thin wall cut process to reduce the weight, having 6 vents to help brake release. The surface is of chrome plated to assure the smoothest movement for modulation and brake control, and for leak free service whether the calipers are under cold winter in your garage, or the hot summer on tracks.



RB's unique yet simple design Stainless Steel piston is all you need to replace a variety of OE type pistons:



The advantage of Stainless Steel piston over OE's aluminum:

1. Better thermal stability (less volumetric change as temperature changes)
2. Better strength & rigidity
3. No corrosion
4. Very lower thermal conductivity - Transmit on about 10% of the heat vs. aluminum, so you will not boil your brake fluid nor would need titanium shims or other cumbersome constructions like you see on different OE pistons.
5. One solid piece construction - Unlike OE's 2pc which the top (yellow) part is usually of "phenolic" - different material than aluminum so it can get cracked or separated due to the heat stress.

Regardless what type of OE caliper pistons you have:

Like this shaft/seal inside pistons from 996 Turbo



Or this type from 997 TT



Or this type from 997 GT2/3 (Phenolic top is separated from piston body):



They can be replaced with RB SS piston, seal and dust boot for a clean and less cumbersome set up, and bring your calipers to a new life.



Picture below shows SS pistons, Oil seal (in black), and Dust boots (blue) which is made of Teflon for high temperature track application. If you don't track you will only need standard (black) boots.

ROG100

This could be really useful to the 928 community as the caliper/piston rebuild kits from Brembo/Porsche are crazy expensive.
Do you have any experience with fitting your kits to 928 brakes? I see no reference to 928 on your site.
More detail and compatibility info. would be very useful.

Pfc. Parts

The first thing I noticed was your pistons don't seem to have the asymmetric shelf cut into the face? At least on my 85 S3, that's a necessary feature I believe.

Vilhuer

These are more for later four piston calipers than anything used before '86 MY. Also one thing to keep mind in is that there are several different versions of "S4" calipers. Not sure if these work with early versions.

GlenL

We like people who provide hard-to-find parts.

Seals are easy to find but do you provide the pistons for the single-piston, "fist" calipers?

RacingBrake

Noted 928 951 968 944S2 944 TURBO have different construction in piston due to the use of dust seal than dust boots, while seals are the same.

What components are you most looking to replace?

Pfc. Parts

I, for one, might be interested in pistons. Not sure if it's the seal that made the difference in piston face? I thought it had to do more with the way force was transferred between the piston and the pad? Do you recognize the "shelf" I was talking about? I'd take a picture but mine are back in the car now, I might be able to find a drawing from a rebuild kit that shows it. It's used to orient the piston when it's put back in the barrel of the caliper after a rebuild.

RacingBrake

We didn't notice the difference in piston configuration than later model calipers except they are straight (no groove to seat the boots bellow).

Please explain what's "Shelf" in your piston.

Pfc. Parts

I've attached a drawing that shows the position and purpose of the "shelf" in the 928 "fist" style single piston caliper. The shelf is used to orient the piston in the caliper bore during rebuild.

I made a "special tool" out of cardboard stock to assist in correctly locating and indexing that shelf as described in the WSM for a 1985 928 S3.

BTW, You can print this drawing and transfer it to heavy card stock, then cut it out with an X-acto knife and use it as an orientation tool during caliper re-assembly.

Regards,
Scott.

ammonman

Here's an image of the early caliper/piston. Notice the relief cut on the piston face.


Mike

Pfc. Parts

What he said

Thanks for the picture Mike!

RacingBrake

These are 928/944 calipers we know:





All pistons are 32mm in height and the caliper has internal dust seal w/o the provision for external dust boots like most modern calipers:



If these types of pistons and seal are what you are looking for I am sure we can make them available.

Hilton

Porsche changed the both the piston sizes and the type of dust seal used during manufacture of the calipers you show.

Look for Porsche technical bulletin 8907 (dated June 30 1989) for more information on the various combinations and differences in pistons/sealing rings.

Pfc. Parts

Great reference Hilton, thanks. The calipers pictured look like the early stock 4 piston design released with the S4? I'm not familiar with them myself.

So, how much membership money do you need to pay to get a custom tag under your screen name? I suppose I could figure out how to turn my location upside down, but Dr. Bob has the very cool "Tool Dropper" line I have to admit I envy (and unfortunately emulate...)