Rear Caliper Scoring

[Michaelb]

Never been real happy with the rear brakes on the XR400. Seems to lock-up and stop okay on the dirt, but not much stopping power on the road (I put this down to the Knobbys).

Anyway, thought I would do the piston and seals and discovered some slight scoring in the piston sleeve. Piston and seals seemed okay - any views about whether the scoring is likely to be impacting the brake function and is it bad enough to replace? Sorry the pics aren't real clear, but the scoring can be seen and felt. Cheers.

[fuelpumP]

[fuelpumP]

don't put your finger while cleaning piston. I heard this while searching how to renew my rear brake pads. I still don't know which nut will be removed just to replace new pads. there was a url error soryy for that. I ll work on it to relink later. I don't want to renew the fluid only pads. cheers

[jasonbc]

If the piston moved in and out freely then i wouldn't think it would cause any issue, did you see any fluid leaking past the seals? if not don't worry about it

[borris]

I would not worry. I would check your rotor thickness though. I just checked mine and found the rear is 3mm and the fronts are 1.6mm service limits are 4mm and 2.5mm respectively. I can actually flex the disk. A thin disk gets hot and loses breaking effectiveness very quickly. When they get thing they can also crack.

I have gone for stainless wavy disks this time rather than OEM. Bringing them over from the US means I am basically getting both for the price of a single disk in the UK even allowing shipping and taxes.

[Michaelb]

Thanks for the responses. Couldn't see any leakage and wasn't using any fluid, so will just put in new seals and polish up the piston.

Borris - I also bought a new wavy disc for the rear($80 from a dealer in melbourne) and am looking forward to testing it out.

Cheers.