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As old as it is, that car still probably has both antilock brakes and a proportioning valve.
And there is the problem. Most likely the proportioning valve is stuck and not allowing the fluid to go to all wheels evenly. Assuming it has a Hydraulic Control Block, I'd replace the entire unit. It can't be much money.
Had a proportioning valve totally lock up on a 74 F100. New pads, new front rotors, hard pedal, and zero brakes.
Keep in mind it wa working before we replaced the calipers. Not working properly, but it did stop effectively and the pedal did nto go to the floor (there was pressure).
1 - I believe in that car the master cylinder is split into 2 lines, that go crossways (so LF and RR on one and RF and LR on the other), so yes, if you introduced air into the line upstream somehow on a front, the opposite corner rear may need a bleed.
2 - As noted, may need a tool to bleed the ABS if air is somehow in there (or as already mentioned potentially bleed the MC), and also as noted, make sure the calipers are on the correct sides.
3 - If the "new" calipers are re-manufactured ones (and they almost always are), I've found the failure rate of those out of the box to be higher than I'd like. It's possible one of the "new" calipers is leaking, although if you aren't noticing brake fluid leaking, then the amount is probably small enough, that it wouldn't cause a completely to-the-floor pedal. That would result in some noticeable fluid loss.
If all is installed correctly I would bleed the system again but
Leave the bleed screws open
Run a clear plastic hose from the bleed screw to a bottle filled part way with clean brake fluid.
Make sure the hose tip is submerged IN the fluid.
Pump brakes until you see only clean fluid coming out.
Sometimes when people do brakes they squeeze the caliper pushing the fluid back in the line. There is a bunch of old fluid rust and trash behind that caliper and it’s going back in the lines.
If you push the caliper in open the bleed valve and let that stuff drain out in a bottle
If all is installed correctly I would bleed the system again but
Leave the bleed screws open
Run a clear plastic hose from the bleed screw to a bottle filled part way with clean brake fluid.
Make sure the hose tip is submerged IN the fluid.
Pump brakes until you see only clean fluid coming out.
Sometimes when people do brakes they squeeze the caliper pushing the fluid back in the line. There is a bunch of old fluid rust and trash behind that caliper and it’s going back in the lines.
If you push the caliper in open the bleed valve and let that stuff drain out in a bottle
This is what a bleed kit is. A small clear plastic bottle with a magnet on it, a hose and a nipple designed to seat in the bleeder valve. You can collect the parts and make one yourself, but for $7 - $10 it is worth buying one made for the purpose. the small bottle with a magnet to hold it in place is very onvenient.
We actually pumped the brakes until the bottle was getting full, closed the valve and dumped the fluid back into the master - four of five times per side to make certain all the air was out.
Still have not been able to get to the rear bleeder valve (where you cannot use a hose because the car is made so there is no clearance. I did discover my 8mm wrench is missing and you cannot get a socket in there, so I have to stop and buy a wrench. Then we can try bleeding the read brakes and see what happens.
I do not think the master has blown seals, because on the front brakes, the fluid continued to come out forcefully and the front brakes actually work, there is pressure there, just not enough. The car will stop, but not quickly and the pedal is super soft. The rear wheel does not appear to be stopping. It keeps turning when the fronts lock up. the car does not pull to the side when braking like it did before, so it seems both of the new calipers are functioning as they should.
The design of the rear brakes is stupid stupid stupid. (typical of Chrysler). You cannot get to the bleeder valve with anything but an open end wrench. There is no room to get a socket or a bleeder hose on it. Cannot even get a box end wrench on it. It is probably going to have to sit for a week before we can get to it.
CJ, with you being in rust country and having to use an open end wrench on this, a couple of thoughts:
1 If you have never heard of Kroil penetrating oil, it's the best I know of and many experienced mechanics agree. Get some Kroil and put on that bleed valve, ideally a couple of days before you work on this. Possibly second best is PB Blaster, you can get that at Wally World if no one seems to have Kroil. Or you can mail-order Kroil from Eastwood.
2 Maybe you can get a tubing or flare nut wrench on the valve? That would be better than a regular open end.
3 If the valve is stuck, don't force it. Tapping on it with a small hammer, preferably a brass hammer, may help. It may be possible and probably is to dismount the caliper and then get a socket on it. Tapping on the wrench may also help. Tap, don't pound.
4 You don't want a cheap wrench here. Once you wring off or round off the bleed valve you have made the eventual fix a lot more complicated and expensive. Pawn shops sometimes have Snap-On, Matco, etc. wrenches at about half new retail.
Good luck. Your post and previous posts make me think that bleeding the rear brakes should fix your problem.
If you can't get the bleed valves loose, you may want to take this to your "go to" mechanic, just bleeding the rear brakes should not break the bank.
Dumping fluid that has been through the system back into the master cylinder is generally frowned on, bad form. But of course if it's all clean new fluid you can get away with it, but don't tell anybody that I said it was OK.
This is what a bleed kit is. A small clear plastic bottle with a magnet on it, a hose and a nipple designed to seat in the bleeder valve. You can collect the parts and make one yourself, but for $7 - $10 it is worth buying one made for the purpose. the small bottle with a magnet to hold it in place is very onvenient.
We actually pumped the brakes until the bottle was getting full, closed the valve and dumped the fluid back into the master - four of five times per side to make certain all the air was out.
Still have not been able to get to the rear bleeder valve (where you cannot use a hose because the car is made so there is no clearance. I did discover my 8mm wrench is missing and you cannot get a socket in there, so I have to stop and buy a wrench. Then we can try bleeding the read brakes and see what happens.
I do not think the master has blown seals, because on the front brakes, the fluid continued to come out forcefully and the front brakes actually work, there is pressure there, just not enough. The car will stop, but not quickly and the pedal is super soft. The rear wheel does not appear to be stopping. It keeps turning when the fronts lock up. the car does not pull to the side when braking like it did before, so it seems both of the new calipers are functioning as they should.
The design of the rear brakes is stupid stupid stupid. (typical of Chrysler). You cannot get to the bleeder valve with anything but an open end wrench. There is no room to get a socket or a bleeder hose on it. Cannot even get a box end wrench on it. It is probably going to have to sit for a week before we can get to it.
Hey this is gonna sound lame but check the vacuum hose going to the brake booster. Sometimes the rubber grommet leaks. It sounds like you blew a seal in the booster/plunger/master. Even if the ABS module was bad your brakes would work you just wouldn’t have antilock.
Do the brakes get hard if you pump them with the key off?
What happens if you pump them, hold the pedal down and turn the car on?
You checked all the lines none are crimped?
You used new washers at the calipers banjo fittings?
The calipers were installed correctly?
If your rear brakes aren’t working either the master took a poop or the proportioning valve is jacked. But I never had a PV go bad.
If the MC is good no leaks I would check for a leak somewhere or air entering the system because that’s what it sounds like to me. Don’t discount having a bad caliper out of the box. If it has a tiny pinhole or if you reused the old banjo washers that could be the issue
Hey this is gonna sound lame but check the vacuum hose going to the brake booster. Sometimes the rubber grommet leaks. It sounds like you blew a seal in the booster/plunger/master. Even if the ABS module was bad your brakes would work you just wouldn’t have antilock.
Do the brakes get hard if you pump them with the key off?
What happens if you pump them, hold the pedal down and turn the car on?
You checked all the lines none are crimped?
You used new washers at the calipers banjo fittings?
The calipers were installed correctly?
If your rear brakes aren’t working either the master took a poop or the proportioning valve is jacked. But I never had a PV go bad.
If the MC is good no leaks I would check for a leak somewhere or air entering the system because that’s what it sounds like to me. Don’t discount having a bad caliper out of the box. If it has a tiny pinhole or if you reused the old banjo washers that could be the issue
Remember he said he has not bled the rear brakes. I think it's possible some air got in when he changed the calipers. I don't know exactly how this system is plumbed, but I think in at least some systems opening up the system in front can get air in back.
You do bring up a good list of stuff to check though.
Being that it is a 23 year old car in MI., the rubber lines might be clogged. I had a similar problem were peddle pressure would push the pads but because the lines were clogged, pads would not return. Interior of rubber lines deteriorate causing what looks like cholesterol in an artery to the point where you can't get a tooth pick in the line. It's happened to me twice on two old cars.
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