Hi all,
I have a 1986 GSXR750 running what I believe is a 1992 front wheel and discs. I've had these wheels on here for a while and have always had problems getting the brakes setup correctly. I'm running standard callipers with 1 mm offset spacer between the calliper and fork leg to centre them, however getting them to operate without binding has been a bit of a nightmare. I've checked the spacing across the front axle which is correct for the setup I'm running (standard 1986 speedo drive with a spacer to align) and a correct spacer on the non-speedo side.
I've also rebuilt the callipers with new pistons and seals, cleaned everything before setting up and bleeding the system again. The master cylinder is working correctly and don't believe I have an issue there. One possible problem could be the original callipers from the 1986 model were design to operate with a 4.5mm width disc, whereas the later models ran a 5mm width disc. The original 1986 callipers also ran a thicker pad at 8.7mm, whereas the later model ran a 8.5mm pads. I'm thinking the square seal in the calliper isn't getting enough piston travel distance to deform correctly and recess the piston. Any thoughts? The discs also look a bit worn so thinking about what to do next, maybe replace like for like discs and run the later callipers with an adapter?
Cheers,
Al