will#224 Posted August 15, 2009 Report Share Posted August 15, 2009 I'm wondering, on recent brake calipers the pistons are hollow and some of the more expensive calipers pistons are drilled i guess to allow the gasses to escape. I have some tokicos from 1989. same stuff fitted to the zxr750, zzr1100, zxr400 and the likes. They are like new, infact the same calipers were for sale brand new on ebay recently. The pistons have a metallic insert which looks copper based? what is this? i'm guessing a heat sink of sorts? Any knowledgable folk please inform and if this leads on to a discussion about the best calipers as per the other disk discussion that'd be cool.... Link to comment Share on other sites More sharing options...
will#224 Posted August 16, 2009 Author Report Share Posted August 16, 2009 No one? Link to comment Share on other sites More sharing options...
2 smokes 4 ever Posted August 21, 2009 Report Share Posted August 21, 2009 All pistons are hollow, to save weight, and have been for 25+ years Some of the later ones the pistons are actually made of plastic or similar, again to save weight Any wieght saved in the caliper is unsprung weight and therefore needs to be as low as possible The closed end is fitted into the caliper first Some have a cap fitted over the open end, with what appears to cork or something in the middle - the purpose of these I do not know. Link to comment Share on other sites More sharing options...
gregtrx Posted August 21, 2009 Report Share Posted August 21, 2009 think the cork is just to stop crap building up. I got some gold spot calipers for my old trx, the pistons were lovely ally with a teflon coating, so much nicer than the rusty chrome on the original ones. Don't know how long they last. Titanium would be the material to use really, to minimise corrosion, or something like a nice chunk of nylon or similar that could withstand the fluid. Link to comment Share on other sites More sharing options...
dodgy_tom Posted August 21, 2009 Report Share Posted August 21, 2009 If they are the bits I think you mean then they are to do with heat dissipation, and also to prevent the pistons corroding to the pads. I always thought they were ceramic. Link to comment Share on other sites More sharing options...
will#224 Posted August 22, 2009 Author Report Share Posted August 22, 2009 If they are the bits I think you mean then they are to do with heat dissipation, and also to prevent the pistons corroding to the pads. I always thought they were ceramic. I think we are on the same page. They might be ceramic but i have a knackered piston from an old caliper and i rubbed it with emery cloth, a copper like material came away. Very soft. Link to comment Share on other sites More sharing options...
gregtrx Posted August 22, 2009 Report Share Posted August 22, 2009 Could that have been a build up of copper slip that some people like smearing all over the backs of brakes Link to comment Share on other sites More sharing options...
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