more advice on brake caliper.

[bill]

hello again, I have the nipples free now. how I managed to free may be helpful to someone, went around the metal surrounding the nipple with a falt nosed centre punch hit it quite hard, then cut the end off the nipple hit it quite hard with a hammer, then with a good socket eased them free and bingo.

next question, leaving the pistons in place is it ok to wash the caliper in petol making sure no petrol gets into the brake pipe openings, finally do the pistons have seals inside and will they come out without having to split the caliper?, hope these are not daft questions, just like to make sure before I do any more work.

once again thank you, and I do appreciate any help.

bill.

[Philm]

I would use a proprietary brake cleaner from Wurth or similar. There are seals within the caliper, to remove the pistons you can appy compressed air in the hose port (the bleed needs to be blocked) and blowing the piston out. If this fails then you will need to use hydraulic force, either a hydraulic jack/pump or reconnect to the car brake line and pump them out by applying the brakes but this is going to be messy.

[Richard Fridd]

i think the s2 calipers have the seals fitted to the bores not the pistons.the pistons can be pushed out by means of hydraulic pressure without splitting the calipers.try to ease them out equally as once one is out the other one cant have further pressure applied hydraulically.a suitable piece of wood between opposing pistons can stop the freer of the pair from shooting out whilst the other is still stuck in its bore.some advise that the caliper should not be split although i have done this in the past to access+clean the corroded bores without any apparent problem.richard

[bill]

hi, once more thank you for the replies, I have removed the dust covers and there is no sign of any leakage, the 4 pistons all seem free  as though they have been overhauled in the past. Do you think I should just renew the dust covers and leave well alone?

thank you.

bill.

[lancialulu]

Dont use petrol unless you clean with something else like brake cleaner as petrol will make seals expand and fail!!!

But to gently push out pistons with compressed airuse a block of wood inbetween. keep fingers out of the way.

Tim

[Jai Sharma]

Just to confirm Richard is right that on S2 callipers the seals are in the grooves on the calliper itself.

[fay66]

I always clean with methylated spirit, and use special rubber grease suitable for brake usage or clean brake fluid when re-assembling.
As everyone says, use a piece of wood between the pistons, as they can come out with considerable force when using air or hydraulic pressure, and you certainly don't want your fingers anywhere near

Brian
8227

[bill]

hi thanks to all, this is the good thing about being in a club the help and advise you get from the members.

one quick one, would hammerite be ok to paint the caliper?

thank you.

bill.

[lancialulu]

I think Hammerite wont last long. I painted some hubs and they reverted to rust after a year. If they arent really rusty just clean up with a wire brush.

Check the pistons havnt lost there polished surface though and Brian's advice of using rubber grease is a good one.

I rebuilt two front calipers on my coupe with just a new seals kit and the MOT man said he had not seen such a perfectly balanced front brake performance. Shame my other fulvia pulled to the right (air buble finally diagnosed).

By the way good luck with the frustrating challenge of bleeding the little blighters!

Tim

[Richard Fridd]

i agree some finishes wont keep the rust at bay for long.i have in the past used a stove enamel specialist with a good result.for this i stripped the calipers.

[Richard Fridd]

it was actually 'powder coating'that was applied to my callipers thinking back

[Peter W]

Frost supply paint in aerosol cans specifically for brake calipers.  Various colours.
www.frost.co.uk

Peter