Board logo

bleedin brakes
mad-butcher - 30/4/04 at 07:25 PM

in more senses than one bled the fronts no prob's but no joy with the rears. t peice is on top of dif plate well the 2 by 1 cross member . just can't seem to get the air lock over the highest point release the pedal and the fluid just runs back ...any ideas....
tony

Peteff - 30/4/04 at 07:37 PM

Undo the flexy at the rear and put it in a jar of fluid. Get someone to pump it for you till the bubbles stop. Take it out of the jar with your thumb over the end and reconnect it quick. Theory is it will suck fluid back in as pedal returns.

JoelP - 30/4/04 at 08:32 PM

i had never done brakes before yesterday, i bought an eazybleed kit which uses tyre pressure to push fluid thru, so you dont have to pump the pedal. just run round opening the nipples until the flow out has no bubbles in it! absolutely pisss easy, i got hard pedal feel first time!

britishtrident - 30/4/04 at 09:22 PM

quote:
Originally posted by mad-butcher
in more senses than one bled the fronts no prob's but no joy with the rears. t peice is on top of dif plate well the 2 by 1 cross member . just can't seem to get the air lock over the highest point release the pedal and the fluid just runs back ...any ideas....
tony



Nothing to do with not getting the airlock over the highest point --- the actual ammount of fluid in the pipe work is tiny compared to ammount of fluid displaced by a stroke of the mastercylinder.. So either something is wrong with your bleeding technique or the master cylnder or pipe unions.

Bleeding technique ---
(1) Don't release the pedal --- bring back quite slowly --- if you have Teeves (ATE) master cylinder bring back very very slowly as they are prone to drawing air past the mastercyilnder seals-- Teeves systems are best pressure bled with a posative pressure in the master cylinder resevoir.

(2) On last stroke hold the pedal down until the nipple is nipped up only then bring the pedal back slowly.

It is important the bleeding jar is held high and the bleed tube a good fit, also only unscrew the nipple just enough to give fluid flow.

It worst comes the worst and above fails try clamping the (rubber) flex hose just enough to put a restiction on the flow and bleed it again. --- the clamp acts like a one way valve.

Master cylinder --- In addition to a duff seal corrosion or damaged bore/crud at the end of the cylinder can cause the seal to allow air to be drawn in as the pedal returns.
Also make sure that the piston comes back far enough to uncover the recuperating port.. With balance bar system the pushrod may need pulled back manually.
I know is obvious but even a tiny pipe work leak will cause a spongey pedal.


[Edited on 30/4/04 by britishtrident]

DEAN C. - 30/4/04 at 09:43 PM

Any difficult brake bleeding problems just use an eazybleed!
Clutches can sometimes be the worst and I have never known the eazybleed not to shift any awkward air bubbles.
Remember if you mess about too much(especially with secondhand cylinders) you will more than likely knacker up the master cylinder seals.
Most mechanics I know have got one of these stashed somewhere for the awkward jobs.

Hellfire - 30/4/04 at 10:37 PM

We had a similar problem - the airlock was in the master cylinder. Disconnect the rear pipe from the cylinder and check it's getting this far first!

We disconnected then pressed the pedal - loads of bubbles came up into the res. as the cylinder filled up...

HTH

britishtrident - 1/5/04 at 06:31 AM

Re Eazy-bleed

A good way of bleeding (in fact just about the only DIY way of bleeding Teeves systems) BUT when using this or other presure bleeding equipment it is important to also pump the pedal at least a couple of strokes otherwise air can get trapped in the mastercylinder.

Bleeding tools that either pump the fluid the wrong way through the system from a nipple or use a vacum to suck it out a via nipple should be avoided.


One of the reasons I am very much against braided hoses was trouble I had bleeding a new system with them --- After a couple of hours I discovered the one end fittings hadn't been fully drilled through -- the resulting in a blind hole and no fluid getting through to one of the rear brakes.

bob - 1/5/04 at 08:43 AM

If you have rear disc/caliper set up this problem is common,calipers on sierra/granada are usually at 12 o-clock so indy set up leaves(nipple)highest point in wrong place meaning airlock.

I bled my rears off the hub but have since bought the eezibleed kit for pressure bleeding.