Cerbera AP brake calipers - learn from my mistake

[Flatplane8]

Just in case it helps someone else, I had my callipers vapour blasted to clean them up before painting. I left the pistons in, and the anodising was removed from the top part of them. They would still work ok, but I think over time the bare aluminium could corrode and lead to problems....





Now as well as new seals, I'll need new pistons

[darreni]

I thought the pistons were steel rather than aluminum?

[Basil Brush]

darreni said:

I thought the pistons were steel rather than aluminum?

The high temp versions of the CP5200 had stainless pistons but the standard ones are alloy.

[Supateg]

Stainless ones on eBay.. item No. 286035368193

[Flatplane8]

Supateg said:

Stainless ones on eBay.. item No. 286035368193

Thanks, seen those just asking the seller if they will fit as the depth of the pistons is slightly less.

[Basil Brush]

They measure the same depth as my replacement alloy AP ones but, as they do not have the skirt around the edge, they're effectively a few mm shorter so may be tight depending on disc width and pad thickness

[Supateg]

Just for information, years ago I found two part numbers for the CP5200 pistons, phoned up AP technical, the chap said the wrong pistons could exit the bores if the pads are past minimum friction material!

[Flatplane8]

Supateg said:

Just for information, years ago I found two part numbers for the CP5200 pistons, phoned up AP technical, the chap said the wrong pistons could exit the bores if the pads are past minimum friction material!

Yes, it’s only about 2mm but could make a difference. The eBay vendor has not responded so I at not risk it.

[Flatplane8]

Here are the part numbers from AP Racing, I spoke to their technical department this morning. I’ve ordered them from Raceparts who have been very helpful.

CP2290-50 CP2409-124 CP2260-66 Stock Code Description QTY Unit Price Total
PISTON-1.62x32.0ALU-SIB 4.00 Each 26.01 104.04
PISTON-1.50x32.0ALU-SIB 4.00 Each 22.35 89.40
PISTON-1.50x27.4ALU-SIB 4.00 Each 20.65 82.60
UPS24 UPS NEXT DAY 1.00 Each 8.50 8.50

Sorry about the formatting, the numbers I found listed elsewhere for the Cerbera didn’t seem quite right. These pistons are 32mm deep. I decided against the stainless ones as not deep enough.

[Flatplane8]

Basil Brush said:

They measure the same depth as my replacement alloy AP ones but, as they do not have the skirt around the edge, they're effectively a few mm shorter so may be tight depending on disc width and pad thickness

Thanks for making that point. I measured the discs, the thickness of the pad backing material and the depth of the seals. If the pads were accidentally run down to the backing plates then I think these stainless pistons could come past the seals. They looked good, but the genuine AP ones weren't much more expensive.

[Flatplane8]

Supateg said:

Stainless ones on eBay.. item No. 286035368193

Thanks, seen those just asking the seller if they will fit as the depth of the pistons is slightly less.