Trouble With Rear Brake On 280pro

[edgas250]

i have recently replaced the rear pads and tried to bleed the system,

when iwas in process of bleeding i wedged the pistons in as far as they would go, so there flush with the caliper, then fitted the pads put wheel on and all back togetherand bleed it,

now when im pumping the brake to get resistance the pistons are coming out so far but not far enough to put pressure on the pads,

im not kidding i must have pumped constantly for atleast 15minute!

anyone know what it could be??

Thanks

[peterb]

Hi there,

It could be that you are not getting enough travel to fully bleed the system. Try 2 things. Use a tool to wedge between one of the pads and the disc and try to get the other piston moving by actuating the brake pedal. If this doesn't work, take the brake pedal of, (it's worth doing anyway to use loctite on the pedal bolt clamp threads when you re-fit), you can now use a screwdriver to actuate the master cylinder which provides a far greater stroke than when using just the brake pedal. This should work. Incidentally, it's not necessary to bleed the brake system when replacing the pads.

Bye, PeterB.

[edgas250]

yeh i know that, the reason was it was low on fluid, so thought it wouldnt take long to bleed, as previous week i did the clutch and front brake,

4 days on and still no back brake!

so when you say take the pedal off, do you mean remove the complete unit and push screwdriver into the cylinder attached to the frame?

[no1]

1st make sure you have got a feed from the resevoir to master cylinder (no kinks)

Then make sure you have got a little bit of free play on pedal other wise the fluid from the resevoir gets cut off.

Then crack off the banjo bolt on the master cylinder push down the pedal then tighten bolt then release pedal repeate this a few times until you are happy with no air.

Then crack off banjo bolt on rear caliper push pedal down tighten bolt then release pedal do this until you are happy that there is no air.

Then do the same at the bleed nipple.

[cdn280]

so when you say take the pedal off, do you mean remove the complete unit and push screwdriver into the cylinder attached to the frame?

You can remove the pedal as mentioned, or you can remove the 2 bolts that hold the master cyl and pull it out of the way so the push rod from the pedal comes out. You can then put 1 bolt back in and use a philips scewdriver or small rod to push the piston much farther than you can with the pedal.

I always have to do it this way or as you said you can pump forever and not get any pressure.

[edgas250]

i tried this last night and no joy,

i was talking to a ktm enduro rider last night and he has mentioned that ktm's are prone to the seals in the cylinder going after pad changes due to pushing the pistons back into the caliper?

does this sound likely?

[peterb]

Hi there,

I've not heard of this happening on GG brakes. I have had success with using a syringe on the bleed nipple and forcing hydraulic oil from the caliper upwards. Can be a problem getting a syringe.

Bye, PeterB.

[edgas250]

i have ordered anew mastercylinder kit anyways as it was only

[edgas250]

just to let you know, i replaced the piston and spring in the MC blead the system and it works fine!