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Brake Caliper Rebuild - stainless pistons vs. aluminum?

Old 01-04-2018, 02:51 PM
  #46  
RacingBrake
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Matching caliper cylinder and piston diameter is subject to mfg tolerance on either parts. Our pistons are precisely ground before receiving chrome plating and final polishing, so their tolerance should be highly accountable.
Expansion rate on stainless steel (RB pistons) is less than 1/2 of aluminum (OE pistons), so a tighter tolerance on SS pistons is warranted.

Source: https://en.wikipedia.org/wiki/Thermal_expansion



The piston movement of a brake pedal's "Apply & Release" is acting upon the pressure seal. So in theory the tighter the tolerance between metal parts (piston & cylinder), the quicker of the action and longer life of the seal will be although the tolerance difference effect here may be negligible.
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Old 07-07-2018, 10:31 AM
  #47  
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I rebuilt my 996 GT3 calipers with RB stainless steel pistons and there seals and boots, its a dedicated track car and now with 3k track miles and a year later and they're still looking great! No more pucks and those pistons look awesome - very pleased with the quality of the product. I just bought a spare set of calipers and plan to rebuild these with the same.



RB Stainless pistons and rebuilt kit :-)
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Old 07-07-2018, 10:46 AM
  #48  
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Originally Posted by hollmatt View Post
I rebuilt my 996 GT3 calipers with RB stainless steel pistons and there seals and boots, its a dedicated track car and now with 3k track miles and a year later and they're still looking great! No more pucks and those pistons look awesome - very pleased with the quality of the product. I just bought a spare set of calipers and plan to rebuild these with the same.



RB Stainless pistons and rebuilt kit :-)
Very nice! Did you use the silicone boots or are those standard boots?
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Old 07-07-2018, 05:23 PM
  #49  
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I used the standard RB ones on this set and they have lasted well. For my next set i'm going with the High Temp ones as i use the Permatex grease rather than brake fluid anyway when i'm installing seals etc..
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Old 07-07-2018, 06:39 PM
  #50  
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Originally Posted by hollmatt View Post
I used the standard RB ones on this set and they have lasted well. For my next set i'm going with the High Temp ones as i use the Permatex grease rather than brake fluid anyway when i'm installing seals etc..
I used brake fluid to assemble and despite my best efforts I must have gotten some on the new silicone boots... Which subsequently dissolved after a couple track days. My fault.
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Old 07-08-2018, 03:46 PM
  #51  
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Originally Posted by RacingBrake View Post
Front 42/44mm:
http://www.racingbrake.com/RB-Calipe...-p/st-40bs.htm

Rear 28mm:
http://www.racingbrake.com/RB-Calipe...-p/st-41bs.htm

Blue boots are available as option (over standard black boot)

p.s.
Stoptech caliper components are 100% interchangeable with Brembo.
Do you have the boots for the porsche 928 s4 calipers (964T calipers) ? i just did a pad change while installing my new Racingbrake.com rotor rings (after 3 full seaons by the way ) and two of the rings basically fell out when pistons were compressed. i was able to just put them back, but i dont think they are doing much now. does the new one just snap or press fit into place?

thanks!

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Old 07-13-2018, 04:18 PM
  #52  
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Unfortunately the old Porsche calipers had different construction than the modern ones, so both the pistons and dust boots are not the same except the oil seals.

Due to low demand on those old applications so they are not being made available.

https://www.racingbrake.com/category-s/7552.htm
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Old 09-18-2018, 11:25 PM
  #53  
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Default Rebuild with RB pistons and High Temp Boots

Just finished this rebuild with the RB pistons and High Temp Boots - plan to use install these over the winter - love the fit and quality of this product

996 GT3 fronts

996 GT3 rears
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Old 09-19-2018, 04:53 PM
  #54  
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I'll add a quick note to anybody considering these -

If you have to repair/rebuild your caliper, once you have these pistons - make sure you buy genuine Brembo seals, or the seals sold by RB.

I must've nicked or damaged one of the seals when I rebuilt them this winter (finstalling the RB kit) and found one of the pistons seeping after the first track event I put on the car. I thought I'd save a few bucks, as a local auto parts place could get me a generic piston seal in time to make a weekend (made by Centric)... vs overnighting the official Brembo seal or waiting for a replacement seal direct from RB. The generic seals didn't fit. Too thick! Had to scramble and found a local Porsche Indy shop that had an official Brembo caliper rebuild kit in stock. Had to eat the cost BUT the Brembo seal fit like a champ.

In other words - don't skimp. This is otherwise a super nice kit.

Last edited by Hacked 987; 09-20-2018 at 08:17 PM.
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Old 09-19-2018, 10:37 PM
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Any real advantage to the RacingBrake pistons over the StopTech replacements? I figure StopTech is obviously a bigger company that will be around for a while in the event there is an issue or replacement parts will be needed in the future.

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Old 09-19-2018, 11:21 PM
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OP:, I'm not going to read all 55 posts to see what others said, but as an engineer will say this. SS pistons have a substantially lower thermal conductivity than most any aluminum alloy. If you are concerned with brake fade, SS pistons are better. SS pistons are much harder than aluminum, so if not done well designed, there may be an increased risk of cylinder wall scoring with SS pistons. Ideally the pistons' O-ring design prevents any contact of SS pistons with aluminum cylinder walls.
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Old 09-20-2018, 12:04 AM
  #57  
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We hope to be entering the piston business soon...


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Old 09-20-2018, 01:14 AM
  #58  
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Originally Posted by 09RedGTS View Post
OP:, I'm not going to read all 55 posts to see what others said, but as an engineer will say this. SS pistons have a substantially lower thermal conductivity than most any aluminum alloy. If you are concerned with brake fade, SS pistons are better. SS pistons are much harder than aluminum, so if not done well designed, there may be an increased risk of cylinder wall scoring with SS pistons. Ideally the pistons' O-ring design prevents any contact of SS pistons with aluminum cylinder walls.
But one must take into account the ceramic insulating later Porsche puts between the pad and the aluminum disc, vs. the SS being in direct contact with the pad with these replacement pistons...
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Old 09-20-2018, 01:15 AM
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Originally Posted by Ohio Performance View Post
We hope to be entering the piston business soon...

Did you guys consider doming the pistons in the opposite direction to increase the stiffness / reduce the compressibility of the piston structure with brake pressure? AP Racing advertises this as a feature on their caliper piston designs. Just curious if others have considered something similar.

Last edited by Mech33; 09-20-2018 at 02:02 AM.
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Old 09-20-2018, 02:39 PM
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Originally Posted by 09RedGTS View Post
SS pistons are much harder than aluminum, so if not done well designed, there may be an increased risk of cylinder wall scoring with SS pistons.
Is this the main reason (in addition to CTE) why brake caliper manufacturers don't use SS pistons?
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