Brake troubles

[Petemcc]

Having trouble bleeding the brakes on my hilux.

Specs

80 series master cylinder - New
surf V6 front callipers - rekitted
new rubber brake lines
Woodward rear proportioning valve
mr2 rear calipers - seem in good condition. not rekitted.

I bench bled the master then stuck it in the truck.
Rear lines were empty front probably not much better.

Front brakes do what they are meant to. Hold foot on pedal and then release bleed nipple and pedal moves to the floor. Got heaps of air out and now just fluid.

With the rear brakes, with pressure on the pedal it doesn't move when you open the bleed nipple and only a small amount of fluid comes out. I thought there might be a blockage in the proportioning valve so cracked the line up near the fire wall and it was the same. when you leave the line cracked and push on the pedal a small mount of fluid comes out initially and then the pedal goes hard but not the floor.

My guess is that I have air in the rear section of the master and that the front are well bled. Pushing on the pedal compresses the air in the rear section and the pedal goes hard as the front takes up the pressure. When the releasing the rear bleed screw the pedal doesn't move as the front section of the piston is under pressure.

Does this make sense?

Could there be another problem?

what do I do now short of getting someone to vacuum bleed it for me?

I have done all of this with the engine off.

Cheers,
Pete

[jonossiksilvia]

try with engine on. i had issues getting rears to bleed once and having engine had the difference. once i had plenty of fluid coming out all nipples i then went back to bleeding with engine off

[jonossiksilvia]

try opening the proportioning valve right open and see if that helps too

[juz]

Yea 2nd the proportioning valve, my cruiser was a prick but got better with valve cracked right open. Make sure your turning it the correct way too, as I think (don't quote me) but winding it in opens it, out closes it..?
Once your sorted those valves are good though.

[bob_or_jim]

Hi Pete, Jeremy here. Just had a thought, Ive always been told to bleed from the longest line/hose first (so rear left?). Cant really see how this would effect your situation but I guess its worth a try.

Another thing, does the master cylinder already have a proportional valve in it? I think some did, especially if there from a vehicle with discs all round.

Worth a thought.

Cheers

[Petemcc]

Yea we did start at the back I think (was a couple of weeks ago) and went round each wheel about 5 times.

My latest theory is that it might be pedal adjustment. Ie the pedal is not letting the rear cylinder (in the master) come all the way back. When you then push on the brakes the cylinder doesn't move very much before it touches the front cylinder and then just puts pressure on the front brakes as the volume of fluid between the two cylinders can't get any smaller.

will hopefully check tonight.

re proportioning valve, I'm not too sure, I suspect there is one in the master but I have the rear on in now so might just leave it. The rear of a hilux is lighter comparatively to a 80 series? The proportioning valve is not my problem a this stage anyway as I cracked a line before the valve and still had the same problems.

Cheers,
Pete

[slidenyo]

bleed nipple at the top of the resovoir on the caliper?
have seen rh on lh before caused no end of confusion and a bad bleed every time

[Petemcc]

bleed nipple at the top of the resovoir on the caliper?
have seen rh on lh before caused no end of confusion and a bad bleed every time

Good point. Pretty sure it's right but will check this.

Cheers,
Pete

[Petemcc]

bleed nipple at the top of the resovoir on the caliper?
have seen rh on lh before caused no end of confusion and a bad bleed every time

That'll do it!

how mine are


Photo from one of hosehustlers thread



Will swap them over and see how I go.

I think I'll still check the pedal travel.

[slidenyo]

sorted?

[Petemcc]

yea mate. swapped them over in about 15 min, quick bleed and it's feeling much better.

Still have a bit more bleeding to do on it but it stops now and pedal feels way better.

Thanks heaps

[slidenyo]

all good chap next time i'm down Cromwell seeing the aunty i'll have to look you up for some track info,
last time we did nevis, mt moka, and went up the river behind arrowtown