Brake bleeding problem.

[Lucius]

I've just been trying to bleed my rear brake but nothing seems to work. I've just installed new rear sets after a stack, that moves the master cylinder from horizontal to vertical. I can think of three problems that may be causing it:

1. Master cylinder seal broken. The push rod was bent in the stack so maybe caused damage to seal. Also when push rod was removed brake fluid dripped out of the master cylinder.

2. Air bubble in top of master cylinder. With the master cylinder in the vertical position it places the banjo bolt at the top. Although i don't think it's this, cause I tried bleeding them holding the master cylinder horizontal.

3. New push rod to short. The new rear set kit came with a new shorter push rod. I thought that maybe the push rod might not be long enough to push the piston all the way to the end of its stroke. Although i don't think it’s this either as when i tried to bleed the brake holding the master cylinder horizontal i also tried to use the original pushrod to ensure the piston was going to the end of its stroke.

Any ideas guys? If it's the seal in the master cylinder can you get them replaced?

[drew74]

get a 10ml syringe with a bit of pipe the same dia as brake bleeder nipple and attach to syringe, draw up 10ml of fluid attach to brake nipple, crack it and inject it, then lock again, just make sure your mas cyl is low to start....

[Lucius]

Is that what they call "reverse bleed"? That's the only thing I haven't tried. I thought of it but need to get my hands on a syringe.
Cheers.

[emrys74]

if your near Kelmscott you can have mine if not super cheap have them for $10

[Lucius]

Thanks for the offer mate, just bought one on fleebay...

[Veefore]

10cc syringe? My local chemist has them for about $5.

[Paraletic]

if you have removed the brake line you may need to also bleed the master cylinder first.

[Marty_Blade_11]

On my old Ducati the breather valve was on the top so I had to take the caliper off and turn it upside down to bleed the rear brakes. Or the other way around. I still had to take it off to bleed it.


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[Lucius]

if you have removed the brake line you may need to also bleed the master cylinder first.

Yeah, the whole system's been stripped. The 100ml syringe i bought was $1 on ebay. Once it arrives I'm going to try a reverse bleed with the syringe and see what happens. The bleed nipple is at the lowest point on the rear caliper.