spongy brakes

[johnA]

hello gents iv'e been helping a friend bleed the front brakes on his zx9 and after bleeding until there are no bubbles left the lever still pulls back to the bars its got braided hoses and six pot calipers and no visible leaks or weeping from anywhere. any ideas what could be wrong.
many thanks in advance john

[Pigford]

IF all the hydraulic system is good (m/c working correctly, etc) then it could be either warped discs or dodgy piston seals returning the pistons back too far?

The warped disc is something I had once .... they were dished slightly, enuff to push the pistons back further than the m/c travel could take-up!

[johnA]

thanks very much for your reply mate will check that and let you know when the bike is stationary you can pump the lever as many times as you like and it pulls back to the bars every time.

[Pigford]

Sounds nmore like a bad m/cylinder?

[z1bman]

has it got two or three hoses? if its got two hoses connected to the master cylinder its air trapped at the banjo fitting if that's what you have change the banjo bolt for one with a bleed nipple fitted

[ADRIAN H]

has it got two or three hoses? if its got two hoses connected to the master cylinder its air trapped at the banjo fitting if that's what you have change the banjo bolt for one with a bleed nipple fitted

Good tip, didn't know you could get them.

[z1bman]

http://www.ebay.co.uk/itm/HEL-Stainless ... SwpONZPv~y

[johnA]

its got 2 hoses one to each caliper direct from the master cylinder.

[z1bman]

you will need a double banjo like what i have posted

[johny brando]

hello gents iv'e been helping a friend bleed the front brakes on his zx9 and after bleeding until there are no bubbles left the lever still pulls back to the bars its got braided hoses and six pot calipers and no visible leaks or weeping from anywhere. any ideas what could be wrong.
many thanks in advance john

Assuming the brake was Ok before you started the exercise ????? Well ' Personally' I'd firstly invert your Master Cylinder so the outlets @ 12 o'clock & bleed that first in that position, then ensuring the caliper bleed nipples are truly @ 12 o'clock ....also I'd release the mounting on the brake splitter if he has one & try to invert that so if possible so the caliber supply hoses are @ 12 o'clock again & hold that position whilst bleeding the callipers again. OR "back bleed the system "from each caliber bleed point using a small tube to a large volume syringe filled with brake fluid & one caliper at a time -force all the oil in the system back up into the Master Cylinder ( removing the additional oil volume in the Master Cylinder by another syringe as it then fills up) . Also once you get the best pressure you can put a cable tie on the F-brake lever to hold the system pressurised for 24 hours ..then release the cable tie ( this helps with micro bubbles in the system ) & if it's still no good ------Caliber rebuild kit of Ebay. I hope this might help you & Good luck . Johny B

[johnA]

thanks very much for your help gents.