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Aside from cost RB 1-pc solid piston eliminates 2 components - The puck and the set screw.
Benefit of fewer parts:
Less chance to break down or fall apart.
Can transmit brake torque direct and more effectively - One part (Piston only) vs. 3 parts (Piston + Screw + Puck)
Uniform heat for one material (SS) vs. 3 materials with different heat coefficient (Aluminum piston, steel screw, & titanium puck)
Vented piston helps to quicken brake release
Result is a better performed caliper with less parts to care and maintain - Figure a 991 with 6/4 piston calipers you have a total of 20 pistons which means you can save 40 components with RB pistons over OE or other aftermarket solution.
The hollow stainless piston has about the same thermal resistance as the titanium puck plus stock aluminum piston. The stainless piston will expand at a different rate than the aluminum caliper which does create a greater leakage risk past the piston seals (a main advantage of the stock aluminum pistons, which then required a thermal spacer to reduce heat conduction into the fluid through the highly conductive aluminum).
IMO the titanium pistons would be a no-brainer IF they could be installed without removing the caliper and disassembling the pistons and they were more reasonably priced. But since they require full disassembly to hold the aluminum piston while removing the center bolt holding the puck in place, R&R labor is actually higher for the pucks than the full stainless pistons.
Tough call.
Thank you for that!
Yeah, seems like there's no clear winner unless you throw price out the window. In that case, the titanium pucks might be better to simply reduce the possible risk of a fluid leak? Any indication about how likely that is to happen?
The other ideal solution is to replace the entire caliper with a better design, like the RB one? Cost notwithstanding.
Aside from cost RB 1-pc solid piston eliminates 2 components - The puck and the set screw.
Benefit of fewer parts:
Less chance to break down or fall apart.
Can transmit brake torque direct and more effectively - One part (Piston only) vs. 3 parts (Piston + Screw + Puck)
Uniform heat for one material (SS) vs. 3 materials with different heat coefficient (Aluminum piston, steel screw, & titanium puck)
Vented piston helps to quicken brake release
Result is a better performed caliper with less parts to care and maintain - Figure a 991 with 6/4 piston calipers you have a total of 20 pistons which means you can save 40 components with RB pistons over OE or other aftermarket solution.
What is the risk of a fluid leak? Is that a real risk or theoretical?
What is the risk of a fluid leak? Is that a real risk or theoretical?
It's strictly theoretical.
The seal is made of EPDM with a temperature limit of 300F- Same as our standard (black) boots. So we know the fluid would hardly operate exceeding that temperature or the seal would have failed.
At 300F literately there is no difference in thermal expansion between stainless steel and aluminum. By fact stainless steel is a material that's far more stable in volumetric change (along with the temperature change) than aluminum, so in essence stainless steel is a more ideal material than aluminum even at "elevated' temperature that can "significantly" change the volume (expansion).
The piston barrel and caliper cylinder never be in contact each other, rather they are separated by the oil seal seated in the cylinder groove and this is how our pistons are made of:
Machined from stainless steel stock bar with thin wall cut process to optimize the weight and strength
Very tight tolerance (0.025mm or 1/1,000")
Chrome plated for a hard surface (RC 60)
Polish to mirror like finish
Tight piston tolerance translates into longer seal life (less fatigue due to less stretch), and more efficient brake performance (quick brake response and release). Our calipers have no "knock back" issue, nor had to incorporate a spring behind the piston to help release like other aftermarket calipers. RB calipers have been running since earlier 2000 for 10-15 years+ (WRX, NSX, RX7, RX8) before needing rebuild.
It's strictly theoretical.
The seal is made of EPDM with a temperature limit of 300F- Same as our standard (black) boots. So we know the fluid would hardly operate exceeding that temperature or the seal would have failed.
At 300F literately there is no difference in thermal expansion between stainless steel and aluminum. By fact stainless steel is a material that's far more stable in volumetric change (along with the temperature change) than aluminum, so in essence stainless steel is a more ideal material than aluminum even at "elevated' temperature that can "significantly" change the volume (expansion).
The piston barrel and caliper cylinder never be in contact each other, rather they are separated by the oil seal seated in the cylinder groove and this is how our pistons are made of:
Machined from stainless steel stock bar with thin wall cut process to optimize the weight and strength
Very tight tolerance (0.025mm or 1/1,000")
Chrome plated for a hard surface (RC 60)
Polish to mirror like finish
Tight piston tolerance translates into longer seal life (less fatigue due to less stretch), and more efficient brake performance (quick brake response and release). Our calipers have no "knock back" issue, nor had to incorporate a spring behind the piston to help release like other aftermarket calipers. RB calipers have been running since earlier 2000 for 10-15 years+ (WRX, NSX, RX7, RX8) before needing rebuild.
A better brake system/components by design.
Thank you.
And just to be clear I’m asking about your replacement pistons in the OEM caliper and not your own caliper design (which does look nice!).
And just to be clear I’m asking about your replacement pistons in the OEM caliper and not your own caliper design (which does look nice!).
Yes, it's a design and construction comparison on piston between OEM/Brembo and RB.
Our calipers use internal dust seal rather than external dust boots.
The internal dust seal not only keeps dust out but also act as a back up (secondary) seal in case of oil seal failure. In our test stand we run pressure test with only dust seal (no oil seal) @600 psi, it drops ~10% of pressure in every 5 minutes or 30+ minutes until the system pressure is complete exhausted, more than enough time for a driver to coast to a safe place w/o instant loss on brake.
Back of the envelope, the gap between the stainless piston and aluminum caliper walls would open up by about 0.001” when transitioning from room temperature to 300F. So I agree that this is not a major concern. But for that same reason the risk of any deal life issues due to aluminum cyclic “stretch” of the seals would be low as well (overall movements due to temperature are low). Wear seams like it would certainly be dominated by the sliding of the pistons in and out of the bore, and due to cyclic pressure from the brake fluid.
Originally Posted by RacingBrake
It's strictly theoretical.
The seal is made of EPDM with a temperature limit of 300F- Same as our standard (black) boots. So we know the fluid would hardly operate exceeding that temperature or the seal would have failed.
At 300F literately there is no difference in thermal expansion between stainless steel and aluminum. By fact stainless steel is a material that's far more stable in volumetric change (along with the temperature change) than aluminum, so in essence stainless steel is a more ideal material than aluminum even at "elevated' temperature that can "significantly" change the volume (expansion).
The piston barrel and caliper cylinder never be in contact each other, rather they are separated by the oil seal seated in the cylinder groove and this is how our pistons are made of:
Machined from stainless steel stock bar with thin wall cut process to optimize the weight and strength
Very tight tolerance (0.025mm or 1/1,000")
Chrome plated for a hard surface (RC 60)
Polish to mirror like finish
Tight piston tolerance translates into longer seal life (less fatigue due to less stretch), and more efficient brake performance (quick brake response and release). Our calipers have no "knock back" issue, nor had to incorporate a spring behind the piston to help release like other aftermarket calipers. RB calipers have been running since earlier 2000 for 10-15 years+ (WRX, NSX, RX7, RX8) before needing rebuild.
Yeah, seems like there's no clear winner unless you throw price out the window. In that case, the titanium pucks might be better to simply reduce the possible risk of a fluid leak? Any indication about how likely that is to happen?
The other ideal solution is to replace the entire caliper with a better design, like the RB one? Cost notwithstanding.
I would not replace the caliper, which would start impacting pad availability as well as brake bias. I would keep it OEM as much as possible.
Note that the .2 calipers have a revised piston design that appears to be less prone to cracking (rounded corners).
FWIW, my stainless steel RB pistons and seals held up fine for over a year of active driving (about 13-14 track days). Not a very long time yet, but I drive rather hard.
FWIW, my stainless steel RB pistons and seals held up fine for over a year of active driving (about 13-14 track days). Not a very long time yet, but I drive rather hard.
That's my GTR Caliper with the Puck chilling out. I just ordered the kit from RacingBrake. This has been some of the most thorough and quickest response I've had from a company.
I am hoping to have this done by the weekend so I can send it at NJMP Monday & Tuesday. Will post feedback.
Question for RB or anyone that's familiar with their replacement piston kit for OEM. The RB website and pictures posted here show a hi temp silicone based dust cover (I'm assuming) that's an option with their kit. The website page warns that these parts should not come in contact with brake fluid or they will be damaged. I'm ignorant when it comes to rebuilding calipers but my first thoughts after reading that: is that realistic from an install standpoint and what happens if one of your pistons starts leaking fluid. I would think that any parts in the system would be (should be) resistant to brake fluid?
04-30-2019, 05:38 PM
