Originally Posted by d15b7
i never replace the dust boots on my race cars when i rebuild the calipers; they burn right up after a day on track. also, the piston to caliper bore clearance is definitely the loosest when everything is cold; typically i'll see some weepage after being parked for a week on the wheel and thats when i know that the seals definitely need to be replaced. if i take the car out on track with the weepy seals they stop weeping as soon as the brakes get hot and are ok for the rest of the day (one time arrived at the track for a race and at that point saw the weepage and raced it anyway, so that's how i know). typically i can spot the weepage before a race weekend during the nut and bolt and go ahead and rebuild BEFORE the race! so, seal to piston clearance is definitely the biggest when cold and closes up when hot
Dust boot serves the purpose to prevent dust/water from going inside pistons thus can prolong the life of caliper seal and pistons (=caliper life)
RB blue boots are specially made of Silicon material (vs. standard boots of EPDM) for track applications, it can resist temperature up to 450 deg F (vs. EPDM 300 F), which is usually above most track applications so they will never got burnt our like standard boots. (Reminder: Must avoid contacting brake fluid during installation)
RB stainless steel pistons are machined from stainless steel bar stocks for high strength and rigidity under the heat. Its bores are featured with thin wall cut to reduce the weight gain over aluminum pistons.
The outer surface receives a very fine grinding before chrome plating and final lapping finish to maintain an ultra smooth mirror like surface with a tolerance of .0015", and a very hard surface that is highly resistant to corrosion and abrasion. Also added to the brake pad backing plate contact circular surface is the vent cut, which not only can reduce the heat transfer to the caliper but also help in brake release.
None of these feature can a conventional OE aluminum piston, nor expensive Titanium piston offer.
A lot of "details" is working into our caliper rebuild components to ensure your Porsche calipers can be rebuilt with only 3 simple components; Piston, Seal, Boot, no matter how OE calipers constructions are. And after rebuild you'll know why your OE calipers can not only perform better, but also last a lot longer.
We are shipping OE caliper rebuilt kits daily (most are track customers) for many years and yet to see any customer that needs to "rebuild" their calipers after rebuilding with RB components.
Illustration to RB SS Pistons: