Difference between SC and Carrera Rear Calipers

[rs6er]

Several years ago, when I was having my brakes done, the wrench told me that my original SC calipers were frozen and he sold me a set of used Carrera rear calipers. They were gold in color. I've been doing a lot of reading on the forum and it seems the Carreras used wider rotors than the SC did. I am finding that I am going to have to replace these 2 rear calipers because I can't get the bleeders out without breaking them (already did break one of them.) Should I replace these with Carrera calipers again due to my existing rotor thickness or should I replace them with SC calipers. My rotors and pads are in good shape.

[Todd Simpson]

John-You are correct that the Carrera rotors are wider but there is an additional difference.

The Carrera calipers used 42mm pistons compared to the 38mm pistons in SC calipers. This shifts the brake bias significantly to the rear. In normal use this means the rears do more of the work but raises the risk of rear lockup in a panic stop. Porsche compensated for this by using a proportioning valve in the rear starting in '84 with the introduction of the larger pistons.

So..if your wrench put Carrera rears on and didn't add the valve you've got too much rear brake. You should use this opportunity to put things back to either all SC or all Carrera, meaning rotors, calipers and PV. , (or in the case of SC, no PV.)

For reference, Carrera *front* rotors and calipers are a nice upgrade for SC's and can be bolted up with no other changes in the system. The bias remains the same with a nice upgrade in thermal capacity.

[rs6er]

Thanks Todd. That's pretty much what I thought, but I didn't realize about the rear bias. In retrospect, I have had this lockup problem once or twice. This guy has a very good reputation and I was considering him for my rebuild, but no longer. I also think he tightened the bleeders too tight which has led me to this problem in the first place.