Wee Willy Posted July 16, 2010 Report Share Posted July 16, 2010 Has anyone any bright idea on how to move a stuck piston in a Girling calliper? Just spent 3 hours fighting it.... Calliper is otherwise OK so don't want to junk it......have tried all the usuals, such as levers, hammers, g-clamps etc....is there any penetrating oil type substance one can safely use on brake calliper pistons, for instance? Quote Link to post Share on other sites
Norman D Posted July 16, 2010 Report Share Posted July 16, 2010 Any penetrating oil will do as you are going to renew the seals anyway, then connect to a master cylinder put a g clamp on the good piston to stop it emerging and build up pressure, if you dont have a loose m/c fit back on car and press pedal.without fitting brake pad to stuck side,if this doesnt work you will need heat and hammers but if it stuck this much it probably needs scrapping or resleeving. Quote Link to post Share on other sites
Malcolm Tatton Posted July 16, 2010 Report Share Posted July 16, 2010 Presumably the pistons are scrap anyway and you will replace them when you rebuild the caliper. If so then one way is to tack weld a bar accross the top of the piston and use it to lever the pistons free. I had a similar problem, took the caliper to a company who rebuild bus and truck calipers and they got both pistons out fairly easily using that method. My efforts using hydraulic pressure had failed and I was impressed with way they got mine free! Malcolm T Quote Link to post Share on other sites
stuart Posted July 16, 2010 Report Share Posted July 16, 2010 Presumably the pistons are scrap anyway and you will replace them when you rebuild the caliper. If so then one way is to tack weld a bar accross the top of the piston and use it to lever the pistons free. I had a similar problem, took the caliper to a company who rebuild bus and truck calipers and they got both pistons out fairly easily using that method. My efforts using hydraulic pressure had failed and I was impressed with way they got mine free! Malcolm T Spot on Malcolm thats usually the favorite way if all else fails and replace with stainless pistons. Stuart Quote Link to post Share on other sites
John390 Posted July 16, 2010 Report Share Posted July 16, 2010 Compressed air? Just don't get your fingers in the way! Cheers John Quote Link to post Share on other sites
stuart Posted July 16, 2010 Report Share Posted July 16, 2010 Compressed air? Just don't get your fingers in the way! Cheers John I have got an adaptor made up for airline to brake fitting but sometimes 150psi just aint enough Stuart. Quote Link to post Share on other sites
Alec Pringle Posted July 16, 2010 Report Share Posted July 16, 2010 Hi Bill, as described, tack a lever on - you need to be able to rotate the piston to free it . . . . I do have some penetrating stuff that usually works for calipers, lethal and NLS on H&S grounds. Also spare calipers, and if you need one in a desperate hurry on temporary loan I'll meet you at a halfway point. Cheers, Alec Quote Link to post Share on other sites
Wee Willy Posted July 17, 2010 Author Report Share Posted July 17, 2010 Thanks for the suggestions chaps....will try again today although have no access to compressed air or welding....don't want to replace an otherwise good original with a lesser repro part but looks as if I may have to.... Quote Link to post Share on other sites
RogerH Posted July 17, 2010 Report Share Posted July 17, 2010 Hi Bill, if it is stuck then it is almost certainly rusty. If it is rusty then the surface will be damaged and it will not seal. The repro stainless pistons are good. However they don't stop the caliper rusting and can still cause the piston to seize (although much ess likely). Roger Quote Link to post Share on other sites
Andy Moltu Posted July 17, 2010 Report Share Posted July 17, 2010 Wedge the moving piston in so it can't blow out & relieve the pressure & try an airline to blow out the stuck piston (put a rag to stop it going flying when it comes free) If you've access to a hydraulic pump you could to the same with that if it will give more pressure than the air compressor. Quote Link to post Share on other sites
ianc Posted July 17, 2010 Report Share Posted July 17, 2010 You have available, free of charge, a press capable of applying over half a ton to the piston. This press is your TR itself! Disconnect the caliper from the upright, place it beneath the chassis member (the flexible hose should be long enough to permit this) with a substantial piece of steel between the pistons. Support the protruding ends of the piece of steel on blocks, then lower the car so that its weight pushes the piston into the caliper. By alternately using the master cylinder to push the piston out a little, then the weight of the car to push it in, it should free the stuck piston. Clearly, you must prevent the free piston from popping out of the caliper! Make sure that you have axle stands or timber blocks in place in case anything slips whilst you are doing this! My disc-braked TR2 and 4VC had a stuck piston when I bought them in the 1960s, and this method worked in both cases. Ian Cornish Quote Link to post Share on other sites
Dick Posted July 17, 2010 Report Share Posted July 17, 2010 I have removed stuck pistons in the past by screwing a grease nipple into the flexy hose hole...restraining the free piston with a G clamp and using a good grease gun pumping grease in until the piston moves.......lots of pressure with a grease gun. Dick. Quote Link to post Share on other sites
Don Elliott Posted July 17, 2010 Report Share Posted July 17, 2010 At 80,250 miles from new, I replaced the seals on the front disc brake calipers in my 1958 TR3A. I kept the original pistons but I changed all the rubber in the system and switched to silicone (DOT 5) fluid. The oily nature of the silicone brake fluid lubricates the seals, bores, pistons, etc. and I have had no issues with jamming (or anything else for that matter) since 1990, having driven another 104,000 miles. Quote Link to post Share on other sites
Wee Willy Posted July 17, 2010 Author Report Share Posted July 17, 2010 Pleased to report that a combination of penetrating oil, a 5 foot lever and 10 pound hammer and a new seal kit have now got my brakes working...thanks for all your suggestions....However, latest woe concerns clutch hydraulics....see new posting....BIll P Quote Link to post Share on other sites
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