Brakes nightmare.....

[geeman]

Hi all, i havnt posted on here in a long time but have been getting along well. The car is close enough to finished, just a few odd jobs to sort out. One thing that really has got me stumped though is the brakes. I just cant seem to get them to work well. I have bled and re bled many times, and even bought a pressurised bleeding kit which made the bleeding process much quicker. However, i cant seem to get the brakes to stop at all. Pressure only builds after around 30+ pumps of the pedal, and from what i have seen there dont seem to be any leaks. I did have to reflare one connection, but that was it, i havnt seen any other leaks, but yet no pressure builds. Any suggestions?

I dont imagine the master cylinder has any issues, as it worked well when it came out of the donor, but i may be wrong. Im using the standard rear sierra drums as well.

Thanks

[JakeH]

mechanic speak...

seems to me like you have quite a bad pocket of air somewhere, seen this before and it can be a bugger to fix.

have you tryed bleeding the brakes from the furthest from the master cylinder first then next furthest and so on? (furthest being the longest run of brake pipe) this may cure your problem. if not im stumped!

EDIT: you could also try opening all the bleed nipples at once and leaving it to drip through for a bit, just be sure the reservoir is full all the time

hope this helps

Cheers

Jake

[geeman]

Originally Posted by JakeH

mechanic speak...

seems to me like you have quite a bad pocket of air somewhere, seen this before and it can be a bugger to fix.

have you tryed bleeding the brakes from the furthest from the master cylinder first then next furthest and so on? (furthest being the longest run of brake pipe) this may cure your problem. if not im stumped!

EDIT: you could also try opening all the bleed nipples at once and leaving it to drip through for a bit, just be sure the reservoir is full all the time

hope this helps

Cheers

Jake

Hi, yep, have always bled in the logical ordar, furthest away first. Im happy to try anything that may get it to work at the moment.

I have now got through my first 4 litre can of fluid but Ill keep giving it a go and see what happens. One thing i notinced is when using the prussurised bleeding kit(20psi) once i finish bleeding but without having removed the kit, the brakes work relatively well and only take around 2-3 pumps of the pedal to get firm, however this would be expectd as it is pressurising it to 20psi.

Thanks.

[js1uk]

Sounds like the fluid is getting past the master cylinder plunger seals, so when you are pressing the pedal, it is not moving the brakes.

[mark]

Sound like master cylinder to me, quite a few m/c failures have arisen after they have been stripped from the donor and left dry for several months

[geeman]

Originally Posted by mark

Sound like master cylinder to me, quite a few m/c failures have arisen after they have been stripped from the donor and left dry for several months

I guess ill look around for a cheap master cylinder as it may well be the case its gone bad then, however i just noticed that when i pump the brakes for some time, i realised fluid was seeping out of the top of the resevoir, even when the lid is on as tight as i could get it. Any indications as to what the problem may be?

Thanks

[leroybrown911]

At risk of sounding stupid, have you got drum brakes on rear? Do you have some pedal? just not very good brakes?

If so the self adjusters may be worth a look. I have had similar issues on VWs. After fitting new pads, shoes and discs and bled the system, I had no pedal due to one self adjuster not moving as it should.

I am not familiar with Sierra drum brakes, however they are probably similar.

If this is the case, move the self adjuster manually with the drum off the car. Adjust it up so the drum fits just nicely over the shoes and then replace drum.

[flyerncle]

As above,remove the lip from the drum and click them up manually,clamp off the hoses and try it and also make sure the brake light switch is not vertical as this may give you a pocket of air.

It does sound like the seal may have gone bad with the fluid moving back and forth in the tank.

[geeman]

OK, after another day of trying to get the brakes to work i still havnt had much success. Firstly i tried what was suggested, and fistly, after moving the adjusters, for some reason,after a few pumps of the pedal it became reasonably stiff and only took about 2-3 pumps to fully lock the brakes. At this point i thought if i bleed them agan, i should end up with working brakes, so i went ahead and bled them, and a few air bubbles came out, however, now the brakes are back to what the were earlier, and the pedal can be pumped many many times before it gives much resistance at all.

I also angled the brake ligt sensor so its sideways, but that didnt seem to do anything. IM not sure tis the master cylinder that has a problem,a s at one point the brakes were reasonably stiff, however i may just buy another one to see if it helps as this is really becoming very frustrating.

[flyerncle]

Make sure the teeth on the ratchet's are ok and not slipping as they will return under spring pressure.

I have repaired them with a thread file many times.