ZCP Caliper Rebuild Pistons and Seals, Questions

[Estoril]

Opinion:

I can't imagine pulling calipers and not replacing seals and boots. The cosmetic exterior of a caliper doesn't matter at all. (If it were me - I'd powder coat it - but you are past that now). I know that front seals and boots are available because I just ordered a spare set after replacing mine 2 weeks ago.

I personally wouldn't fool with larger rotors. There is nothing to gain since you didn't mention solving a problem.

[George Hill]

I wanted to piggy back on this as I didn't see another thread about rebuilding ZCP calipers...

Part numbers (Per Caliper):

• Front
  • BMW
    • Piston Seal Kit - 34-11-1-157-037
    • Guide Pin - 34-11-1-157-041 x2
    • Guide Boot Kit - 34-21-6-869-617
    • Bleeder Screw - 34-11-6-758-107
    • Bleeder Screw Cap - 34-11-1-153-198
  • ATE
    • Piston Seal Kit - 250037
    • Guide Pin - 990049 x2
    • Guide Boot Kit - 260009
    • Bleeder Screw - 390337
    • Bleeder Screw Cap - N/A
• Rear
  • BMW
    • Piston Seal Kit - 34-21-6-753-682
    • Guide Pin - 34-11-1-157-041 x2
    • Guide Boot Kit - 34-21-6-869-617
    • Bleeder Screw - 34-11-6-758-107
    • Bleeder Screw Cap - 34-11-1-153-198
  • ATE
    • Piston Seal Kit - N/A
    • Guide Pin - 990049 x2
    • Guide Boot Kit - 260009
    • Bleeder Screw - 390337
    • Bleeder Screw Cap - N/A

My question is pistons. It looks like there are a lot of options for front pistons:

• BimmerWorld - 100.34.530.0043
• Rageitparts.com

But what about the rear? The 46mm piston seems not listed in many places. I did find Frenkit offers one, P464802, has anyone used these? What about other vendors?


Frenkit also sells rebuild kits of varying levels of "completeness." Generally I stick to Genuine or ATE parts here, but certainly will consider other options.

• Front Kit
• Rear Kit

[PSUEng]

George Hill check out BiggRed Brakes from UK. They have pistons listed (look under E85 Z4 application.). I used their seal kit in the rear but not the pistons. Seal fitment was good but haven’t installed the calipers yet. I’m not sure on the pistons but the seals were sourced from Spain when I purchased.