Path: utzoo!utgpu!alliant.com!UUCP Reply-To: british-cars@alliant.com Errors-To: british-cars-request@alliant.com Sender: british-cars-request@alliant.com Return-Path: Posted-Date: Sat, 3 Feb 90 10:03:49 PST Date: Sat, 3 Feb 90 13:03:49 EST From: robbp@pyrthoth.pyramid.com (Rob Pryor) Message-ID: <9002031803.AA22786@pyrthoth.pyramid.com> To: british-cars@alliant.com Subject: Re: Disc brakes Newsgroups: list.british-cars Distribution: ut Approved: devnull@gpu.utcs.toronto.edu >. . .I replaced the brake pads on my TR250. The old ones were almost >compeltely worn so I had to push the pistons back into the caliper body to >make room for the new pads. About 30 miles later. . .I pushed down on the >brake pedal and almost nothing happened. I . . .found out what had caused >the failure. The pistons had rusted and pitted up to, but not past, the >sealing gasket in between the caliper body and the piston. When I pushed >the pistons back into the body the seal was now resting on the pitted area >of the piston which didn't make a good oil seal, and the brake fluid >squirted out through the rust. I guess the piston boot can be expected to >keep out only *almost* all of the moisture. I had a similar problem with my Healey back a few years ago, only I found pitting both on the pistons and the caliper body, in the grove where there seal rests. As new calipers were $300 each, I succeeded in convincing myself that new pistons, at $50 each, would fix the problem. They didn't. Some calipers are 3-piece where the cylinder that holds the piston bolts on to the main caliper body. I believe Jag calipers are this way. The Healey has a second type of caliper which is 2-piece, split down the middle, with the piston cylinder cast into each half. The 3-piece style can be bored and sleaved at a reasonable price, but I couldn't find anybody who could do the Healey calipers. I know the manual warns against splitting the halves, but there has got to be a way to split, bore and sleave, and re-assemble them and have them work correctly. -- _____________ _____________ Robb Pryor, \____________\_____________/____________/ Pyramid Technology, \__________ __________/ Mountain View, CA 94039 \________ AUSTIN-HEALEY ________/ VOICE:(415) 335-8465 \___________________________/ USENET:robbp@pyramid.com