I am trying to set the brakes up and am getting very little pressure to the rear brakes (discs), I have no problems with the front, I purchased a new seal kit for the master cylinder thinking this was the problem and fitted it but still have very little of a pedal to the rear. Has any one encountered this problem and how did you solve it??

Any help is appreciated as I am attending a track day next week and she is going like a dream but won't stop very well.

Is it sierra standard parts all round? is there a bias valve fitted anywhere? disc or drum back end? is it definately well bled. Bearing in mind that back brakes always brake less, how have you concluded they arent working right - poor road performance or no resistance when its jacked up with a mate holding the brakes?

It is a standard Sierra master cylinder, there is an adjustable bias valve which is fully opened to the rear and the rear are discs.
The system has been bled fully numerous times and when we are bleeding it we are getting no resistance to the back. It was taken out for a test run for the first time tonight the fronts where locking up well before the rears. We also only get a pedal when the brake pedal has travelled half way down.

Check for a leak at a pipe connection --- get some bod to pump the pedal really hard while you go round in joint on the rear system with an inspection lamp.

If you have discs on the rear are the nipples at the top -- if not unbolt the calipers to bleed it with the nipples above the inlet pipe. --- also make sure handbrake cable is slack when bleeding. Very important to only tension handbrake after self-adjuster have been run up.

Bias valve piston is pushed in for more presure to the rear.

If you have proper standard flexy brake hoses try clampling each in turn to trace the problem

If that dosen't work try using bleed nipples to block off the port(s) to rear brake at the mastercylinder -- that will prove if the master cylinder is OK.

When bleeding remember the brake pedal must be held down when the bled tube is removed and the nipple tightened.



[Edited on 30/10/05 by britishtrident]

my mate had a simiar prob on his westfeild,but he put the rear discs on and the bleed nipples were facing to the bootom of the caliper,SHOULD BE ON TOP.

simon

Thanks for the suggestions, It seems the problem is with the master cylinder, I took britishtridents advice and put bleed nipples on to the master cylinder outlet for the rear and tried bleeding from there and it appears that the fluid is not making it from the resevoir into the cylinder.

Looks like I need to get my hands on a new master cylinder.

I had a similar problem which we found out to be the fluid not being able go go uphill!!

Front brakes...no probs, rears..no chance.

Thw pipe for the rear brakes comes out of the MC and is clipped to the footwell. It then travels uphill in order to keep the light pressure switch away from the gearbox. it then travels downhill through the tunnel to the rear. we had to remove the connection to the pressure switch and pump some fluid up to the top, re join it and hey presto it works.

If you have a similar set-up then this may be why. If you need a pic of my set-up let me know.

had a similar problem till i used one of those guyson ? pressure bleed kits ..i now use it on all brake bleeding jobs no more down, open, close, up, oh what did you say
tony

Yea, found that out also, after 2 days of no luck went out and bought one of those pressure bleed kits and had the job done in 45 minutes.

You live and learn... Roll on 5th Dec for her initial outing on the track.

Its an air lock because the calipers are normally in a 12 o clock position on the sierra but are now at a 10 0 clock position,you need to pressure bleed the caliper or as snoopy has suggested unbolt the caliper and roll it round the disc to bleed.

Just in case somebody hasn'y seen a pressure bleeder
Rescued attachment pressure bleeder.JPG