brakes hot!!!!!help!!!!please!!!!!

[deedee]

I just put a loaded caliper set up front, new wheel cylinders in back w/ new shoes and a new brake booster with master cylinder. I drove the first 70 miles no problem then one day I went to a friends that was 20 miles away, when I got there the brakes were soooooo hot and the pedel was so hard to push. I waited for about an hour or more and the brakes worked fine( cooled off) when I pulled up at home the pedel was hard to push and they were hot again. every time I get in the car I don't go that far because it's getting worse. when they are hot the brakes work on their own. It's like I'm drivining around with my brakes on. It sucks. help!!!!!!

[Arne]

Which brakes get hot? Front or rear?

If it's the fronts, my first thought would be one or both front brake hoses breaking down internally. That allows fluid to go into the calipers, but restricts it from returning. The more you use them, the 'stucker' they get.

Test that by pumping the brakes several times with the engine running, then release the brakes and crack open the bleeder valve. If it spurts, that's the problem.

Could be a mis-adjusted power booster pushrod, too. That might be even more likely, actually.

[MikeW]

It's like I'm drivining around with my brakes on. It sucks. help!!!!!!

I'd say are are driving around with your brakes on and the heat is from the friction of constant contact even when the pedal is not pressed. While I'm sure others here will be able to provide you with advice on what you might be able to do yourself to fix this my advice would be to not try to drive like this until you're sure it's fixed. Working brakes are the most important thing on your car and if nothing else it may be the one thing to have an expert look at.

[deedee]

at first the rear was doing it (both) now just the driver side sometimes. the front is both all the time.

How do you fix the first problem Arne? I'm a do it your selfer.

[Arne]

If it's the hoses, you simply replace them with new and bleed the brakes.

But since you say that it affects both front and rear brakes, hoses don't seem too likely. I now think it is a mis-adjustment or mis-match between the power booster and the master cylinder. Might be something as simple as a pushrod length adjustment. You should adjust the pushrods as indicated in the factory manual for your year Z. Also make certain that the master cylinder and the power booster are both made for your year car.

[SteveJ]

My 2¢: I have to agree with Arne's last post. I have a sneaking suspicion that the pushrod length is wrong.

[deedee]

the push rod is the some as the orriginal. I measured the old one and the new on they're the same length but there was an adapter on the one that came out of my car. I put the adapter off the old on and put on the new one. because when I first drove it around the block (after the brakes were done) there wasn't enough braking power. that's when I put the adapter on. it makes the push rod about one inch longer. now I have too much breaking, problem.

[Arne]

Well, I'd have to say that we have identified the problem. From here, you'll need to compare all three parts - the master cylinder, pushrod and power booster - to the old ones you removed. One of them is wrong.

[kinfish]

Sounds like you lengthened the pushrod significantly which moves the piston in the master cylinder. This equates to having some degree of brake action without having your foot on brake pedal ........ eventually the impacted wheels will get hot. In free state, need to have that adjustable rod in brake booster provide small gap at interface with piston in master cylinder.

Hopefully you saved the old parts ...... this issue has a simple solution but requires some time and patience to get if fixed correct.

[jmortensen]

Yep, you guys pretty much got it. You need free play in the brake pedal. If the brake pedal can't fully relax it can close off the port the the master cylinder reservoir. When this happens the pressure can't release. When that happens everything is fine when the car is cold but the longer you drive the more heat you put into the fluid, which expands it which pushes the brakes on harder, which heats it up which expands it more etc.

Had that same problem with the clutch once but in that case as the fluid gets hot the clutch starts slipping. Adjust the rod so that you get 1/8 to 3/16" free play in the pedal before the pin that moves the master even starts to move, and shorten the piece between the master and the booster so that it isn't touching, and you should be fine.

[deedee]

I'm still getting hot brakes(the rims are hot to the touch.) when I adjust the push rod the feel in the peddle changes from hard to soft but the brakes still get hot when the peddle is soft. I'm wondering if AutoZone sold me pads that are too thick. No matter how much adjusting I still have hot brakes.when they get hot as I'm driving the car gets harder and harder to drive. They act like I'm drivining with the brakes on and they get stronger and stronger.

[Arne]

Which pushrod are you adjusting? There are two. One from the pedal to the power booster, and another one inside between the booster and the actual master cylinder. I'm betting there is a mis-match or mis-adjustment on the booster to master pushrod.