Caliper pistons
 

Did a caliper overhaul, and whilst my calipers are all now perfectly clean and the new seals are in, a few of the pistons have scratches on the business side of things. What's recommended here- new pistons? I think the previous owner of the calipers tried getting them out with a pair of pliers :mad:

I can take a few pictures tomorrow if need be.

Re: Caliper pistons
 

work out, once the calipers are on the bike how far out the pistons come, are the marks under the seals or above them?

if above then dont worrey, if below then it may be problematic, also depends on the direction of travel of the scratches and how deep. if they are lengthwise of the piston then oil could seep past, if circular then its less of an issue. If not raised then mabey some nail varish could be used to smooth off the dips. Get the idea.

If they have been working fine till now, then dont worrey too much.

Re: Caliper pistons
 

there are all sorts of marks, done particularly deep but still. I think they're going to be below the dust seal on most pistons. There's a guy on eBay who machines pistons up, a lot cheaper than the 112 quid Suzuki want for the 4 pot calipers. 220 quid to do both calipers!!

Re: Caliper pistons
 

It's a judgement call, pics would be good.

Re: Caliper pistons
 

I'll get some pics as soon as I'm home Chris.

The calipers were mucky and some pistons seized. And they came off a bike that was on the road!

Re: Caliper pistons
 

Yeah it happens, put some rubber grease on calipers and behind seals when you fit them.

Re: Caliper pistons
 

Yup I've changed all the seals and used plenty of rubber grease. I'll pull the pistons out of the finished caliper and take a photo of them too.

Re: Caliper pistons
 

Also I'd advise flushing a bit of fluid through to remove any excess grease. It doesn't do any harm floating around in there (turns fluid red) but I can't really see it doing it any good.

Re: Caliper pistons
 

http://img84.imageshack.us/img84/7446/img0083tj7.th.jpghttp://img84.imageshack.us/images/thpix.gif


The scratches are higher up than i thought. That's pretty typical of 4 pistons over 2 calipers. The same side, incidentally.

Re: Caliper pistons
 

Doesn't look too bad to me, if it's a sharp edge then you need to break that with very fine wet and dry. Surface finish is more important than perfect tolerances on rubber seals.