Brake issues again

[high n mighty]

I have had a very spongy pedal for a long time and no rear brakes.
I have pulled the rear out of the hilux and after clamping the rear brakes off thought it would be interesting to see if I got a pedal back considering that everyone I speak to says that its to do with my handbrake and other rear parts etc.

I still had a spongy pedal??? I have a new master cylinder new pads and the system has been bled numerous times??

WTF??

[JBE]

In my case, the proportining (or load sensing) valve was the problem which I haven't thought off. But this was on a GQ.

Cheers
Joachim

[high n mighty]

Ok to elaborate. these probs started after havin my engine rebuilt by a mob that turned out to be dodgy. The brakes where fine before the rebuild and the lift that is on it was on it then.

I have gone to great lenghs to find the prob but no-one has the right answer or atleast the one that works. One mechanic was able to get them back but I lost them again the first time I took it offroad.

[turbo gu]

have you tried clamping off each corner until you have a pedal. that way you can elimnate front calipers as a problem. check if all the lines are tight near the engine,possible they have left a line slight loose thats allowing air into the system

[Daisy]

spongy pedal ...

Let me tell you what happened with my GQ yesterday..

Spongy pedal after bleeding numerous times.. i gave up and rang a brake guy to come over.

he repeated procedure i did.. still spongy...

started the car.. and blocked BOTH lines.. front and rear

Pedal slowly went to floor meant master cyl was rooted...

Replaced that.

Pedal still spongy.. went half way to floor that time..

blocked off rear brakes, still the same.

Reversed procedure.. blocked the front brakes..

Turned out to be a siezed calliper..

- causes spongy brakes as they dont clamp properly.

So.. probalby in your case.. the rear callipers are shot.. (or are they drum?)

If they are shot.. buy yourself a seal kit from a brake shop for each calliper anywhere between 15 - 25 dollars per side and use an a/c to blow the pistons out and give it a good clean and buff and put the new seals on with plenty of grease and stick it back on.

Hopefully the answer mate.

TOM

[high n mighty]

Now I'm gettin somwhere, thanks guys I will see what happens while blocking the fronts independantly also. I figured it could only be in the calipers cause they are the only old part of the system.

If they have had it I shall get a seal kit then I guess, keep ya's posted

[dumbdunce]

Now I'm gettin somwhere, thanks guys I will see what happens while blocking the fronts independantly also. I figured it could only be in the calipers cause they are the only old part of the system.

first rule of fixing stuff - NEVER assume that a new part is good! - although 99% of the time new parts work perfectly, there are times when they don't, and it's possible even for a brand new master cylinder to have a fault.

did you bleed the new master cylinder itself, by cracking the lines on it and pumping some fluid through? sometimes you get bubbles stuck in the master cyl that never come out with regular bleeding.

are all the soft lines in good condition? when they get old they can stretch and induce some softness to the pedal feel.

[Roctoy]

try removing the anti squeal shims from the front calipers, the thin pieces of tin that sit between the callipers and the pads.
I had the sam problem about 3 months ago and that's what was causing it.
they were bowed just enough to give a spongy pedal.
Cheers Chris

[dave]

I had a simlar prob, bleed brakes would get pedel back 2 days later no brakes. replaced master cylinder, replaced rear wheel cylinerds and linings ,checked front calipers were working ect.
Replaced the preportining valve problem fixed.

[MYTTUF]

Had a similiar prob with the 80 after replacing pads and checking calipers and ended up belleding the proportioning valve and it was sorted.
Also if you just put in pads without maching the discs am I correct in thinking the pads will need to be bedded in before the work perfectly?

[dumbdunce]

Also if you just put in pads without maching the discs am I correct in thinking the pads will need to be bedded in before the work perfectly?

depends on the condition of the discs to start with, if the are good and flat then it shouldn't make much difference, and even if they are pretty rotten there should still be fairly good pedal, just pathetic braking performance until the pads bed in.

[high n mighty]

I will check all the system again next week, thanks for the help again people

To re-cap, while the master cylinder was replaced so was the pads, shoes and wheel cylinders and the front rotors machined, all this was done by a brake mechanic(great result eh).

So after two mechs an a brake specialist, this is why I will do it myself this time. All the suggestions seem to be very valid so I guess I have a slow process sorting it out