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I'm in middle of changing pads, discs and flexible hoses, and found one of front callipers had a tear in the boot. Does this have to be replaced? If so is it necessary to renew the seal inside the piston cylinder? Should I be replacing all the piston seals/boots as a matter of course anyway (they are the originals on a MY91, and I've already discovered the side plates have lifted so have to replace those too).
Yes it has to be replaced. No need to change the ring seal, unless they come as a set.
About the other boots and seals...no need really. I did do it a few years ago. I had one torn boot just like you. The new parts come from Brembo. Porsche sells them with a markup. They are pricey. In my case they came as a set with new pistons. As I was changing them I found the original parts to be in good shape. So unless Roger can get you just the boots and seals at a reasonable price, I wouldn't bother for now.
Yes please that's good of you! Would be a nice option
You can buy the full kit for the front of the 928, which is the same as the one on the 996 Turbo - 36mm and 44mm for £55 from Bigg Red in the UK. You can get the kit from eBay
I just did this on my GTS racer. Very easy.
The inner seals will be shot after 25yrs inside the caliper. Trust me. I have taken apart a few...
You can buy the full kit for the front of the 928, which is the same as the one on the 996 Turbo - 36mm and 44mm for £55 from Bigg Red in the UK. You can get the kit from eBay
I just did this on my GTS racer. Very easy.
The inner seals will be shot after 25yrs inside the caliper. Trust me. I have taken apart a few...
Excellent thanks - yes it's 44/36 on fronts. Can imagine the piston seals are shot - caliper has a hard life! It's surprising they still function after all this time. Given how jammed the pads were between the p,ates it's surprising there was much braking action, but the pedal feel actually felt pretty good. Looking forward to the results of new hoses and rebuilt calipers.
Wow great prices! Their 36/44 kit is $44, but UK supplier charging $80. Rip-off Britain indeed
I think you have got your numbers wrong - Zeckhausen is the rip off! Their kit is $70 per caliper. Bigg Red is $80 for both calipers!!!! Moreover I bought it on eBay on Sunday night and I had it in my hands on Tuesday morning. No faffing about with the idiotic courier companies, paying them at least £15 admin fee before the parcel is delivered etc. Bigg Red also do the rears - £27 - same kit as for the Porsche Cayenne and Panamera with 28/30mm calipers. Also, I'd rather deal with a local outfit if something goes wrong...
What I am finding more daunting is the plate removal. Not got there yet, but I am dreading stripped bolts...
You will love the pedal feel with new seals. What I found on my race car was that the inner seals had left black gunge on the surface of the pistons, making them less than smooth and difficult to push in or out. I bet you find less than smooth pistons inside yours...
My mistake - I misread your post and can see the eBay shop with £55 price. That is terrific.
I order a lot of parts from US so it's often well worth the time/extra faff for the very big savings sometimes made, and always have excellent service and depth of 928 knowledge hard to find here. That said I enjoy getting odd parts from OPC too!
All the side plate dome screws on one caliper I have removed were like soft cheese. I have only tried to take off one plate. Ground down both screws with dremel and plate just popped off. Dremelled slot in none screw shaft and it just turned out, but I made mess of slot with other one so will have to drill/tap or find someone to weld nut on and get remains of shaft out. Chisel didn't work to get it moving so I think the grind/slot technique is good if you're more careful than me with the slots! The plates were lifting to point of jammed pads so will be another nice improvement to braking system when all sorted.
06-19-2016, 10:45 AM
Torn caliper piston boot
