My bike passed its mot today, but the tester said my brakes where binding, not enough to fail but they where not sliding back as they should.
Now i completely stripped the calipers, cleaned them , and rebuilt them ala jacksons lair ,new sliding pins where required, new seals and pin rubbers, pads etc, re greased them and they slid easily, refitted them, fitted braided lines, bled them and they bind

the discs and the wheel look straight and not warped by eye

any thoughts or clues why this is occuring

BigDonk wrote:My bike passed its mot today, but the tester said my brakes where binding, not enough to fail but they where not sliding back as they should.
Now i completely stripped the calipers, cleaned them , and rebuilt them ala jacksons lair ,new sliding pins where required, new seals and pin rubbers, pads etc, re greased them and they slid easily, refitted them, fitted braided lines, bled them and they bind

the discs and the wheel look straight and not warped by eye

any thoughts or clues why this is occuring

Hmm.

1. Have you bedded the pads in properly? Do some firm positivie braking for a few days when road permits from around 30mph to 0.

2. Is the brake fluid over-full? Too much fluid might not allow the pads to return off.

3. What greases did you use on the slider pins?

4. Were there any rubbers you didn't change?


Theres only 3 things I can think of atm that could cause binding.

1. new pads being overly thick and needing to bed-in / wear down.
2. stuck piston causing binding
3. stuck slider causing binding

How do the brakes actually feel?

Well you might be right on the brake pads being new
took the steed out for a wee ridette, and gave the front brakes a good fair few hard brakes
brake lever was normal, however came to a t junction, brake lever had all but no play
at all, front disc was scorchio, pulled over let it cool and tootled home,
bike straight in the garage up on the stands, wheel spins but with some friction resistance
rain stopped any further play, but will propably out on it to night weather permitting for another test

BigDonk wrote:Well you might be right on the brake pads being new
took the steed out for a wee ridette, and gave the front brakes a good fair few hard brakes
brake lever was normal, however came to a t junction, brake lever had all but no play
at all, front disc was scorchio, pulled over let it cool and tootled home,
bike straight in the garage up on the stands, wheel spins but with some friction resistance
rain stopped any further play, but will propably out on it to night weather permitting for another test

How full is the fluid in the brake resevoir... take a little out.

As the fluid gets hot it expands slightly and if the resevoir is full it will put the brake on for you...

will check that out, thinking back It probably is rather full as I had to take some out, as when after I had bled the brakes and tried to insert the condomesque rubber seal, I had a mad rush for a rag as it started to overflow.
which now I think thats why is so big and extends into the resevoir to take up any fluid expansion, and to save on brake fluid, seems like I got that wrong.( hugh sigh shrugs shoulders)