UK Caliper piston seal damage

ok I think I know the answer here but I'm wondering if the picture of the seal damage below would cause fluid to pass the seal.

The dents left in the rubber seal were full of metal swarf and there was some in the recess on the caliper itself when the seal was removed.

My thinking is if I clean up the groove/recess and fit a new seal I should have no further problems? (need to inspect the other seals too)

Are they stock Pistons?

If the seal was damaged that badly I would think it is possible to weap/leak past yes.

Do you have any idea where the contaminants have come from or got into the system I was thinking maybe the coating of the piston/Pistons may have flaked off ripping the seal.

Pull the 4 callipers off and split them remove all the Pistons and look for damage if not clean up and reassemble with a new deal kit it's not an expensive job as long as your Pistons are in good condition.

If there`s any damage to the chrome it`ll need a new piston and obviously seals, you don`t have to split the calipers to remove the pistons, you`ll struggle to get the actual caliper replacement seal anyway.

Doesn't Chris Wilson do the seals ?

Yes, Chris wilson does all the seals you need.

I bought a full set the other month

Doesn't Chris Wilson do the seals ?

Yes

Sorry I should of said these were the freshly refurbished calipers I recently bought on here so all the seals and Pistons were brand new. The issue is some metal fragments in the seal recess left over from the refurb, I put an airline on where the brake hose goes and as I raised the pressure the piston started bubbling as air/brake fluid escaped.

I will try a clean up, new seal and the air line again and see if all holds on the bench. It's always the same, the quick job you never expect to give you hassle er does!

I doubt they would have leaked, but it's far from ideal. The seals seal on the top and bottom, not the back edge. Pressurising calipers with air is possibly dangerous, if a piston pops out it's like a missile. They should be tested using hydraulic pressure, like they test air and gas bottles.

As Chris says a test with an airline isn't right. Air is, obviously, thinner than brake fluid so it's far more likely to pass a rubber seal than actual fluid is.

If there's no equipment for testing them simply use the brake line on the car to test them. Stick a block of wood between the pistons, fit the brake line, bleed the brake then press for all you're worth. If you're testing on the Supra remember to do it with the car started so that you get the brake boosting effect etc. That should quite quickly show if the fluid is passing the seals.

Ok I'll scrap the retest with the airline. They failed the on the car test before they went anywhere near an airline, when I went to bleed them! Fluid was pissing out? I used the airline to remove the suspected leaking piston to try and see what the cause was, found the shrapnel and seal damage so just trying to see if that was all that was causing the problem?

I've never experienced a piston fluid leak before, the piston and bore look mint so unless they got the tolerances wrong on the refurb I can't see past the seal damage but is it a definite red herring?

If it was only leaking from the one piston maybe try cleaning the offending bore etc up and fit a new seal and see if that cures it.

Don't fit the dust seal just try what Scott said with a block of wood and see if it stops the leak then go from there.

Ok I'll scrap the retest with the airline. They failed the on the car test before they went anywhere near an airline, when I went to bleed them! Fluid was pissing out? I used the airline to remove the suspected leaking piston to try and see what the cause was, found the shrapnel and seal damage so just trying to see if that was all that was causing the problem?

 

I've never experienced a piston fluid leak before, the piston and bore look mint so unless they got the tolerances wrong on the refurb I can't see past the seal damage but is it a definite red herring?

That really doesn't sound good at all.

Personally I would give it a good clean out, get a fresh pair of seals and see how it goes from there.

Sorry reading back I hadn't made it clear. Frustrating day, took off some uk's (that do need a good refresh) fitting these refurbed ones should have been easy, but I experienced the leak, had to go back to j specs I had lying around!

And cheers guys, will do just that, I had a rebuild kit waiting to do the originals so have the bits. The recent refurbed ones I purchased to make it all much easier Ie I could fit them and then take my time with the refurb of my originals.....kinda back fired!

Just a one word of warning, I refurbed a set of UK calipers and thoroughly washed them out using brake

cleaner and an airline.

Spraying the brake cleaner into the caliper where the banjo fits and spraying it the other way where the fluid

enters the piston chamber.

I repeated this process until i'd used a whole large tin of brake cleaner spray on four calipers.

I decided to take one apart and found that there was debris stuck where the two halves bolt together, right where

the two square section seals fit. The seals locate on a shallow counter bore, I've arrowed this in light blue

It might be wise to take this caliper apart to have a look as long as you can get the seals from CW still

It might be wise to take this caliper apart to have a look as long as you can get the seals from CW still

Yes, I can still supply these and recommend splitting UK calipers for piston and seal work.