Leaking piston seal
 

Leaking piston seal, I think...

Stripped and rebuilt the binding front breaks on my pointy and on bleeding I discover I'm losing fluid from the caliper. Does this indicate a knackered piston seal or could it be something else?

If it's the seal, is it potentially saveable or is it a goner for sure?

If I need seals, where do I get 'em other than a dealer?

So many questions...

Re: Leaking piston seal
 

Sounds like the seals knackered, they're not that expensive though, I know wemoto sells them.

I'd also check why the seal went, wait for someone who's done more SV brakes to say for sure but if the piston is scored then that could knacker the seal, also any crap there when you've pushed it back could have damaged it.

If the fluid is coming from the inside of the caliper then it's bound to be the seals, if it's on the outside then possibly an unseated bleed nipple or banjo washer?

Re: Leaking piston seal
 

If it is the seals, I just got them for my curvy. From the dealer they were just over £20 for the four dust seals and 4 piston seals. So they are not too expensive. I don't think wemoto was any cheaper to be honest when I looked.

Re: Leaking piston seal
 

7 quid per piston from wemoto so the dealer it is, whoda thunk it?

Thanks troops.

Re: Leaking piston seal
 

I'd get a big can of brake cleaner too and be really careful checking for anything that could possibly have caused damage, no point fitting new seals for them to get knackered too.

Re: Leaking piston seal
 

Wise words mate. That I do have and the seals are coming from Wemoto because Mickey Oates wanted 30 quid for 2...

Re: Leaking piston seal
 

You'll be needing some red rubber grease for when you put it back together. Some car parts shops sell it in little sachets. Give the grooves the seals sit in a good clean out to remove corrosion and then apply a decent amount of grease to each seal and groove before refitting the seals - try to make sure there's not too much excess on the fluid side.

Re: Leaking piston seal
 

Gotcha. What am I using there apart from the brake cleaner? Is scotchbrite OK or too abrasive?

Re: Leaking piston seal
 

If you are careful you can chip away with something like a small screwdriver etc but take care as its alluminium and the corrosion build up can be tough.

I found that these Dremel type tools are pretty good. You can often get a nylon stiff brush head that looks a little like a miniature chimney sweep brush head. Perfect for cleaning out the grooves.

After you've cleaned them and before you fit the seals make sure that the piston sliding surfaces are free from damage (e.g. plier marks from where they may have been dragged out of the calipers :rolleyes:) and that they slide freely in and out. If they are at all stiff then further cleaning is needed, particularly to the thin raised section of the bore that sits between the dust seal groove and piston seal groove.

If you have one then a dentist type mirror can be really useful to see inside the seal grooves to check for corrosion build up. Its usually white and can be difficult to see.

Mike

Re: Leaking piston seal
 

Bloody hell, is there no end to things I haven't got in my tool kit?

But top tips, hadn't thought about the raised section between the seals for example, thanks mate.