Lurbie

iTrader: (3)

I have the stock disc/drum setup. I flushed the brake fluid today primarily as a maintenance task, but hoping it might give me a little more braking power. When I went to drive it the braking was very weak. So bad the brake light came on and I didn't make it out of the driveway because it was so hard to stop at low speeds. So I jacked it back up, bled the fronts (because it felt like the fronts weren't grabbing) and the pedal was better but the brake light was still on. I decided to try to bleed the backs again and I got fluid out but when my son was applying the brakes I could still turn the drums by hand. He also said the pedal was not going down when I opened the rear bleeders. Applying the parking brake will stop the drum, but applying just the pedal won't. So, with bleeders closed, I had him pump the brakes while I tapped on the side of the combination/proportioning valve with a small hammer. Doing this will get the light to turn off briefly. When the light went out, he held the pedal and I verified the drums wouldn't turn. He could let go, apply the pedal again and the brake light comes back on and I can turn the drums by hand again. How did this go so bad just from flushing the brake fluid? I sucked the old fluid out of the reservoir and wiped it all out before filling it with new and beginning to bleed, but I wonder if I got some debris in the valve and now it's sticking?? I can't find a replacement combination valve from 1A, AZ, Advance, RockAuto, etc. but it looks like I may be able to disassemble it so that's my next task. Any other thoughts on why the valve is acting like this? Any thoughts on where I can get a replacement if disassembling, cleaning and reassembling doesn't fix it?
I had one last car show at work next Thursday, but it looks like I might miss it if I can't fix these brakes.

Tibo

iTrader: (15)

Did you bench bleed the master cylinder after you did that? If not then that's what needs to be done. On these cars with the front of the master cylinder pointed up you could have easily gotten a bubble at the front of the cylinder that will never come out without properly bench bleeding the master cylinder.

Lurbie

iTrader: (3)

Now I knew I was going to miss something I shouldn't have, I didn't think of that because I never pulled the reservoir off or touched the pedal while I was wiping it out. It makes sense and goes along with what was happening. After I pulled the spring out of the front of the combination valve wiped off the piston and put it back together, I bled the combination valve and went back to the back axle. I bled the right rear easily, the left rear had large air bursts with each pedal apply. It was stopping the drums so I let it rest and went to the fronts. Had a solid pedal so I took it for a short drive before it got dark. It barely wants to lock up now, but it stops. So I've still get more to bleed before I try to take it anywhere.

gta_knight

i think i might have to do this myself. i fitted a new master cylinder and booster to mine earlier this year and the brakes felt pretty good but ive been having a problem with one of the rear calipers so decided to replace both which ive done this week. even after bleeding both the rears with my vacuum bleeder the pedal is still super spongy. i think i let all the brake fluid come out, but i thought i would just pull all the air through by filling it up and bleeding it as usual ?

Tibo

iTrader: (15)

Anytime you put on a new master cylinder or let the reservoir run dry you have to bench bleed it with the ports exactly horizontal. If there is a tilt you can still have air trapped at the top, which is why you simply cannot just bolt the master cylinder in place and get all the air out.

gta_knight

Yeah I bench bled it originally and the brakes were pretty good. It's just from fitting these new calipers the fluid level got really low and I didn't realise. I think there was a pool of fluid still in the bore but I can't be sure. If just bled the rears again and the pedal feels better but I don't think it's as firm as it was.

The fluid in the rear part which goes to the front brakes didn't go down obviously so bleeding them won't make any difference will it ? If I can find the little bleed plugs I can just whip the master cylinder off and bench bleed it again

Tibo

iTrader: (15)

I just used a straight length of hard tubing with the appropriate fitting and flare and screw that into the master cylinder. The line is bent 90* and I have a clear tube squeezed on the end that goes into the master cylinder reservoir.

gta_knight

I don't suppose you know what size fittings they are ? Having trouble getting them here in the uk.

Tibo

iTrader: (15)

They should come up in a search of these boards but according to the AutoZone website they are Primary M11x1.5 , Secondary M12x1.0. (http://www.autozone.com/brakes-and-t.../719427_0_3508)