The saga continues. . . (B4 Audi 80)

[Greavesy]

Evening all,

Right then, if you've read my other thread (Here:http://www.classic-audi.co.uk/forum/...ad.php?t=23141)
you will already be aware of the nightmare I'm having with my brakes.

I've managed to borrow a pressure bleeder from a friend that uses air pressure from a spare wheel to pressurise the system.

I've re-bled they system tonight and got TONNES of air out (YAY!) BUT. . . the pedal still goes all the way to the floor, the pedal judders (WTF?!), if I pump the pedal it seems to pressurise up but if I leave it a second or two I can then re-push the pedal to the floor (BOO!)

HOWEVER, with the peda pushed half way down all the calipers lock the discs up.

Anyone got anymore idea's before I take a can of petrol and a match to the 80?

cheers,

Andy

[keithyboy]

Have you changed the master cyclinder?

[Greavesy]

no. I was hoping it wouldnt be knackered but I'm starting to think it is.

I'd have thought if the master cylinder was knackered the pedal wouldnt come back up?

[keithyboy]

Originally Posted by Greavesy

no. I was hoping it wouldnt be knackered but I'm starting to think it is.

I'd have thought if the master cylinder was knackered the pedal wouldnt come back up?

If there is air in the system the pedal will pump up and stay firm as long as you keep your foot on the pedal because you've compressed all the air in there. When you take your foot off, it goes soft again.

If the master cylinder is goosed it might pump up but I suspect that if you pump it up then keep your foot on the pedal it will sink back to the floor as the fluid bypasses the seals.

[Greavesy]

Originally Posted by keithyboy

If there is air in the system the pedal will pump up and stay firm as long as you keep your foot on the pedal because you've compressed all the air in there. When you take your foot off, it goes soft again.

If the master cylinder is goosed it might pump up but I suspect that if you pump it up then keep your foot on the pedal it will sink back to the floor as the fluid bypasses the seals.

I will try this tonight.
Air couldnt be being sucked back into the system through the bleed nipples could it?

[Ben]

Originally Posted by Greavesy

the pedal judders (WTF?!)

Like when the ABS kicks in? If yours has ABS then there could be an airlock in the pump.

http://www.ross-tech.com/vag-com/cars/absbleeding.html

[keithyboy]

Originally Posted by Greavesy

I will try this tonight.
Air couldnt be being sucked back into the system through the bleed nipples could it?

Doubt it to be honest. If there is air going in, they would weep a bit of fluid. If it's enough to make the pedal disappear completely, it would be quite a big leak. Is the fluid level dropping?

[Greavesy]

fluid level isnt moving

I dont know if anyone I know has Vagcom.

[Greavesy]

Update for everyone.

I gave up with this and took it into a garage while I was on Holiday.
Turns out I had a big air lock in the system and also I'd kinda fitted the rear calipers the wrong way round (as in, left on right, right on left) didn't really think that would have been possible as everything still fitted correctly.


Cheers,

Andy

[keithyboy]

Originally Posted by Greavesy

Update for everyone.

I gave up with this and took it into a garage while I was on Holiday.
Turns out I had a big air lock in the system and also I'd kinda fitted the rear calipers the wrong way round (as in, left on right, right on left) didn't really think that would have been possible as everything still fitted correctly.


Cheers,

Andy

Glad you got it sorted. Getting all the air out of abs systems can be a bit of a bastard sometimes. I would have thought putting the calipers on the wrong sides was impossible too.