A forum for owners of Yamaha TTR250 trail and enduro bikes!

MotoNoob_92 · Member

Brake Rub - is it normal?

Cubber · Super Guru

Hi there, brake rub is quite normal when pads have been disturbed - AS LONG as all the accmulated crud has been wiped off the pistons and caliper areas where it gathers.

The pistons push the pads onto the disks and it's only the disk eccentricity which returns the pistons and pads off the disk.

If, however, there is dust and gunge that prevents the pistons returning then they will stick out and rub.

Also, the retaining pins of the pads can get rusty/dusty and need cleaning off also.

There are no return springs that return pads and pistons clear of the disk so "slight" rubbing is normal.

Martyyn

TTRfan · Super Guru

Martyn's advice is spot on biggrin

Before pushing pistons back into their caliper to fit new pads or whatever, it is important to make sure that the visible portions of the pistons are really clean. I usually give mine a good spray of WD40 to wash and rinse the area and then ease them back in - being careful not to get too much on the pads! It is possible otherwise that you can damage the dust seals.

I would suggest dropping out one of the wheels and pump the brake to make sure the pistons are moving out freely. Then clean the area around them again, spray some WD40 and make sure that they move easily by forcing the pads apart with a wide bladed screwdriver. If that stops the rubbing then repeat on the other wheel wink

MotoNoob_92 · Member

Awesome, thank you! I think the rear has a normal amount of rub, but the front seems excessive. I’ll clean off the pistons as you suggested and check the seals. Is there anything I could’ve damaged by forcing the piston back before cleaning it?

Cubber · Super Guru

Forcing a dirty piston back into the caliper without cleaning its skirt can damage the rubber seals in the caliper body.

That's why it's advisable to clean them before pushing them back in. wink

If they went back easily and you didn't have to FORCE them back in you will probably not damaged them too badly. doh

Martyn

MotoNoob_92 · Member

Yes, it was fairly smooth. I’ll clean and recheck. Thanks a bunch!

mossproof · Super Guru

Rubbing noise is fine, actually binding is not. As long as the wheel turns freely it's ok but if there is resistance felt when you spin the wheel, the piston is not returning enough and the brakes will heat up and become ineffective. A good clean of the pistons and sliders should do the job. (And ought to be done fairly regularly on a dirtbike anyway)