brake trouble

[tattoo]

hiya...

after a nice run to the coast on the way back i lost the front brakes completely....the lever came right back to the grip when i went to brake,after nursing it home i checked all the hoses,banjo bolts and the resovoir for signs of leaks,bursts or corrosion and found nothing wrong...i did hower fit new pads yesturday but it all went as it should of and the brakes felt good....i have tried rebleeding them and did get some air out of them then nothing,no air or fluid...does this sound lke the master cylinder has failed???? any advice would be fantastic

andi

[Kev L]

That would be my guess mate. Quick call to Wemoto for new seals.
Best of luck

[AMCQ46]

Only time I have had a "lever back to the bar" moment was when the pads got pushed back by a big tank slapper [not on the storm, but on my old race bike], then after a major brown triouser moment once I pumped the lever so the pads went back into position, all was OK.

Given that you have just changed the pads, this would be my #1 potential root cause. Is there a chance that one of the pads was not sitting correctly? How many miles / brake operations had taken place before teh problem.

AMQ

edit,
one other thought, is that it is very easy to damage the M/C seals when you are bleading the brakes. with no pressure you move the seal through the full travel, but in all the rest of operation the last part of the movement is never used, so a lot of crap can gather there and that is what might damage the seal when you start to use all travel.

But, given that the pressure came back and stayed once you pumped it, it may not be damage, but might have been contamination causing the seal to leak.

[oldbikeman]

A bit scary this one .Could have had a sticking piston which suddenly was n't .Service your callipers and replace Master cylinder seals.Got to have faith.

[tattoo]

update.

i spent the night taking the lines off(goodridge stainless) and fitting new sealing washers to all the banjo bolts and a mate told me to test the master by pushing my finger over the master outlet and pulling the lever to feel if theres pressure there....
i have pressure at the master and fluid down the lines to the banjo bolts on the calipers and when i operate the lever i have clear air free fluid from the bleed nipples but no piston movement...i've done everything i could think of except splitting the calipers.....a mate suggested it could be air locked in the calipers and the fluid i'm getting is going in thro the banjo and straight out the bleed nipples...is this possible and how do i rectify this without splitting the calipers....

AMQ....i'd done about 100miles after changeing the pads and it was mot'd that morning,the brakes felt better than they had felt in ages before they failed..thanks for the advice...

andi.

[sirch345]

Just a quick suggestion. You could try removing the handlebar and angling it so that you bring the banjo bolt lower than the master cylinder for bleeding. Air can get trapped there as it's sit higher when it's on the bike.

Chris.

[oldbikeman]

Like I said It's very common to get a sticking piston and the brake will still work ,now if it suddenly frees off the lever will come back to the bar.

[tattoo]

surprisingly it turned out to be two sticky pistons(small piston on both sides) and faulty sealing washers..i bought another set of washers from the honda dealers and they sealed straight away,as for the calipers,it's the first time i've had to split a caliper to get the pistons out and tbh reading the manual 2 or 3 times was a great help but on the first attempt the lever had very little movement and the brakes were binding when i'd put them back together so i restripped them and started again taking care to lube everything well with clean fluid,after bleeding up again the lever came good and they stopped binding.

thanks for the great advice lads,much appreciated

andi.

[sirch345]

Well done Oldbikeman, it would appear you were spot-on with the sticking piston theory

Glad to hear you found out what the problem was Andi, at least that explains what was happening. That should give you back some confidence in your front brake now When dealing with brakes you can't be to careful

Chris.

[oldbikeman]

I check my callipers every three months just to see that the pistons all push back easily.After a wet ride and being stood a few days is a big cause.Regular maintenance is vital on modern brakes as they do not use big rubber boots like old stuff.