Rear caliper problem (Audi 80, B4) - Page 5

BIGGYIN · 22-06-12, 06:22 AM

Quote:

Originally Posted by Greavesy

Also when the pedal is pushed you can hear a woosh in the engine bay.

When I was bleeding mine,this happened.Thought a seal had gone.
I reverted back to the manual way(Fast jabs,then slow jabs of the peddle.) and more air came out.Used alot of fluid,but there much have been an air lock somewhere?
Peddle is not 100% the way it felt before I started,but the brakes are spot on.

Just keep trying.

Greavesy · 22-06-12, 09:27 AM

really loosing the care to get this done atm, was supposd to be going to Scarbrough in it today but thats not going to happen, going in my mates S4 now instead.

Greavesy · 26-06-12, 07:16 AM

Right, it's a been a few days since I touch the 80, has anyone got anymore suggestions for me to try before i have another go?

If I don't get it working this wk it's going to a garage.

urS6 · 26-06-12, 08:32 PM

I used to have problems getting a really firm pedal until I got a pressure bleeder. Gunsons Eezibleed is OK (£20), Sealey's pressure bleeder is much better (£60). Unless you get a good flow, it's possible that you have an air lock, particularly if you have dismantled the system and allowed significant amounts of air to get in. If you pump the pedal up and down 10 or 20 times, do you get pressure - if so, then there must be air in the system.

I have heard of people damaging the master cylinder when bleeding the brakes, by pushing the piston further than it's ever gone before and tearing it's rubber seal on a rough bit of the cylinder, so it's possible that in the act of bleeding the brakes the old-fashioned way (by pumping the pedal synchronized to opening and closing the bleed nipple), you damaged the master cylinder. In that case, you'll never get any pressure.

Buy or borrow a pressure bleeder and put another litre of fluid in before giving up.

8690q · 26-06-12, 09:10 PM

ABS unit ?

I had one working caliper on the front, assumed caliper seized. Did all the usual checks, found nothing wrong with caliper. I got another ABS unit from the scrappies, fitted it, bled the brakes and enjoyed two fully working front brakes again.... which was nice.

Are you getting sufficient fluid out of the bleed nipple on the problem caliper when trying to bleed it ? Even with me standing on the brake pedal with all my weight and the bleed nipple open no fluid came out of my problem caliper.

Greavesy · 27-06-12, 02:00 PM

8690q I've resolved the issue with the calliper now, that problem was that the level of the back for the handbreak wasnt fully returning so the piston just moved out and then returned.

urS6, I've managed to find a mate with a pressure bleeder so I'll give that a try.
Just wondering if it would be worthwhile replacing the master cylinder before using more brake fluid, just incase?

urS6 · 27-06-12, 06:49 PM

Quote:

Originally Posted by Greavesy

Just wondering if it would be worthwhile replacing the master cylinder before using more brake fluid, just incase?

If it's on the original master cylinder, then it's probably a good idea - 18 years of brake fluid which may not have been changed often enough is likely to have inflicted a fair amount of corrosion on the cylinder and the seals are probably pretty mushy as well.

Take care when bleeding the conventional way, not to press the brake pedal too far - lots of 75% presses is correct, not a few 120% presses. This is certainly true of old master cylinders where you don't want the seals contacting corroded bits of the cylinder - just the nice smoothly-polished bits.

Greavesy · 28-06-12, 07:28 AM

right, i'll get one ordered.

Greavesy · 03-07-12, 07:21 AM

Please check out my new thread.

http://www.classic-audi.co.uk/forum/...ad.php?t=23308

Greavesy · 20-07-12, 10:52 AM

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

22-06-12, 09:27 AM	#42
Greavesy Grown up member Join Date: Apr 2012 Posts: 159	really loosing the care to get this done atm, was supposd to be going to Scarbrough in it today but thats not going to happen, going in my mates S4 now instead.

26-06-12, 07:16 AM	#43
Greavesy Grown up member Join Date: Apr 2012 Posts: 159	Right, it's a been a few days since I touch the 80, has anyone got anymore suggestions for me to try before i have another go? If I don't get it working this wk it's going to a garage.

26-06-12, 08:32 PM	#44
urS6 Grown up member Join Date: May 2010 Location: Worcestershire Posts: 115	I used to have problems getting a really firm pedal until I got a pressure bleeder. Gunsons Eezibleed is OK (£20), Sealey's pressure bleeder is much better (£60). Unless you get a good flow, it's possible that you have an air lock, particularly if you have dismantled the system and allowed significant amounts of air to get in. If you pump the pedal up and down 10 or 20 times, do you get pressure - if so, then there must be air in the system. I have heard of people damaging the master cylinder when bleeding the brakes, by pushing the piston further than it's ever gone before and tearing it's rubber seal on a rough bit of the cylinder, so it's possible that in the act of bleeding the brakes the old-fashioned way (by pumping the pedal synchronized to opening and closing the bleed nipple), you damaged the master cylinder. In that case, you'll never get any pressure. Buy or borrow a pressure bleeder and put another litre of fluid in before giving up.

26-06-12, 09:10 PM	#45
8690q Grown up member Classic Audi Club Member Join Date: Jun 2009 Location: Coalsnaughton Posts: 190	ABS unit ? I had one working caliper on the front, assumed caliper seized. Did all the usual checks, found nothing wrong with caliper. I got another ABS unit from the scrappies, fitted it, bled the brakes and enjoyed two fully working front brakes again.... which was nice. Are you getting sufficient fluid out of the bleed nipple on the problem caliper when trying to bleed it ? Even with me standing on the brake pedal with all my weight and the bleed nipple open no fluid came out of my problem caliper.

27-06-12, 02:00 PM	#46
Greavesy Grown up member Join Date: Apr 2012 Posts: 159	8690q I've resolved the issue with the calliper now, that problem was that the level of the back for the handbreak wasnt fully returning so the piston just moved out and then returned. urS6, I've managed to find a mate with a pressure bleeder so I'll give that a try. Just wondering if it would be worthwhile replacing the master cylinder before using more brake fluid, just incase?

28-06-12, 07:28 AM	#48
Greavesy Grown up member Join Date: Apr 2012 Posts: 159	right, i'll get one ordered.

03-07-12, 07:21 AM	#49
Greavesy Grown up member Join Date: Apr 2012 Posts: 159	Please check out my new thread. http://www.classic-audi.co.uk/forum/...ad.php?t=23308

20-07-12, 10:52 AM	#50
Greavesy Grown up member Join Date: Apr 2012 Posts: 159	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