Hi,

I've just finished overhauling both of my front calipers and after struggling with two stuck pistons fitted new seals and pads all round. I've put everything back together but even after bleeding the system with clean brake fluid, the brake leaver is very spongy, the breaks don't start to bite till the leaver is about halfway in. The pads are biting the discs and the piston all seem to be out equally and there is no air left in the lines. I've got braided lines and they seam like there in good nick.

Is the master cylinder the next thing to check/overhaul or is there something i am missing as the breaks didn't feel this spongy before!?

Cheers

Russ

yeah, check the M/C and get any trapped air out of it..
if you do an advanced search on 'NC30 front btake caliper' you should find something that helps

How many miles have you done since fitting the new pads?

they'll take about 200miles to bed in and until then youll find them spongey until the pad surface forms to the shape of the disc's,

in the mean time, cable tie arround the lever over night, bleed any excess air out the caliper the following day,
do that for a few days and you'll be right

og and BTW the BRAKES are spelt BRAKE not breaks

Cheers for the replies gents.

I've done a round 50ish miles i guess so i guess that has something to do with it. I'll Leave the lever bound up overnight and take it from there. Cheers also for pointing out my school boy error.

Rustyp81 wrote:Cheers for the replies gents.
I've done a round 50ish miles i guess so i guess that has something to do with it. I'll Leave the lever bound up overnight and take it from there. Cheers also for pointing out my school boy error.

Less of the GENTS its means different things in the biking world!

i have CBR6 calipers on my bike and for weeks they were cack when i fitted new discs and pads, but they back to shit hot again.

tieing the lever before MOTS is always a good thing

crack the banjo bolt on the MC and bleed that too. The MC banjo bolt is usually the high point of teh system so will collect air. Be careful to ensure you have enough fluid in the resevoir

skinnydog0_0 wrote:crack the banjo bolt on the MC and bleed that too. The MC banjo bolt is usually the high point of teh system so will collect air. Be careful to ensure you have enough fluid in the resevoir

Cheers mate, a combination of this and leaving the lever bound over night has pretty much restored pressure to the lever. I'll bind the lever again tonight and should have done near 200 miles by the end of the week so should be sorted by the weekend! :)

cheers

Russ

Make sure you bleed each side a couple of times after having the lever tied back, you still need to get as much of that air out as possible.

Something i tried recently, due to the same problem was to attach a clean hose to the drain nipples on the calipers, allow some fluid to fill the hose, then blow compressed air into the end to force the fluid back into the system but dont blow for too long or you'l get air in again, any bubbles trapped near the master cylinder are flushed up into the reservoir. Its a more active method of removing bubbles than just pumping with the lever.

MexicanGringo wrote:Something i tried recently, due to the same problem was to attach a clean hose to the drain nipples on the calipers, allow some fluid to fill the hose, then blow compressed air into the end to force the fluid back into the system but dont blow for too long or you'l get air in again, any bubbles trapped near the master cylinder are flushed up into the reservoir. Its a more active method of removing bubbles than just pumping with the lever.

I think you would need to be very careful doing this when the calipers have fluid and possibly air in, as you may blow the piston seals out of place.