1100 GS Brake spongy ??

[ozrockrat]

OK it got to the stage where I had to double pull the front brake to get good pressure. Then I have done the following.

Replaced pads (others were at 1mm)
Bleed the brakes (Dot 5 ) could not get good pressure.
Flushed and re bleed using dot 4. No decent pressure.
Removed tank and bleed the ABS unit then the front calipers. No decent pressure.

Master cylinder does pump fluid OK while bleeding.
THere is a noise coming from the ABS unit (un powered)
Fluid level does not go down. Not losing fluid.

I have bleed brakes before (from bicycles to 240 tonne trucks) but now I am at a loss.

My thoughts
Bulging hose??
Master cylinder bypassing under pressure??

Any suggestions / experiences??

PS this is also posted on Advrider.

 

[hops]

could be

the hoses, if they are original rubber types they are most likely getting on a bit and could benefit from a set of braided types. 'Hel' do a set and Steptoe did have a contact. Try tying up the front lever so it is held on overnight. This sometimes helps otherwise check that you have bled the calipers and ABS module in the correct order.

 

[(RIP) Kaister]

heres a way to test if its the hoses - but only do it on rubber ones at your own peril.

using a proper pipe clamp or careully adjusted mole grips clamp the hose at various points.

you should feel the lever rock hard at all test points.

start at the top directly under the handlebars - if its spongy now its your m/c seals.

then just above the 2 to 1 splitter - spongy now - its the hose bulging

....then onto each hose etc etc.

you've either got air in the system or its your caliper seals swelled,gripping the pistons and pulling the pistons back too far on release.

 

[ozrockrat]

Thanks guys I will try out your recommendations tonight. From the replies here and on Advrider I think a new set of hoses and a master cylinder rebuild are a good idea even if the current problem is air. The bike has done 130,000 miles and is 10 years old .