new brakes getting hot!!

[chev-obsession]

ok so i just recently swapped to front disc brakes....
i got new rotors, calipers, pads etc. we drove it down the road again today and the rotors were hot again, i touched th lugnuts and nearly burnt myself!!!!
The pedal rod is not a factor, so now im asuming that i have a bad master cylinder or proporting valve??? because when i put the pads back onto the rotor it would not turn freely, i had to use two hand to get it to move.
I never thought that this swap would be such a pain!

[dznucks]

i think thats normal.

their going to get hot as hell. Have you ever watched a night race, where you can see the rotors glowing when they are braking? brakes work by frictional force, friction produces heat.

My wheel have always been tough to spin. the pads have never "retracted" from the rotors. that little bit of force isn't anything to compared to the Hp of the engine. Once you over come that frictional force and get the truck rolling, momentum takes over and it become insignificant.

[LockDoc]

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Are both sides that hot or just one? Be sure and check both sides.

I don't think they should get that hot and I'm not sure you can compare a race vehicle to a street driven vehicle. Anyways, I would check to see if the master cylinder piston is not returning far enough to allow the fluid to return to the master cylinder, therefore keeping pressure on the calipers after you use the brakes the first time. I don't know what all you changed or what pieces you may have used from each brake system so it is really hard to diagnose this kind of problem. You might try opening a bleeder screw on one of the calipers after you have used the brakes to see if there is any residual pressure in the system.

LockDoc

[rlm316]

With the wheel off and after you have braked the truck and there is resistance to the wheel turning, open the bleeder screw on the caliper. See if there is a pressure escape from the bleeder and if that frees the resistance on the rotor. There should be no residual resistance on the rotor with the brakes not in use, so the tire should spin freely when the pedal is up.
Where all the components of the swap new?

[big_al_71]

I would rebleed the brakes and check the calipers pistons to make sure they are going in and out, just a thought...

[68gmsee]

Getting extremely hot is not normal. A little yes, but not hot enough to burn you. The rotor vibrations should make the pads back off from the rotor surface as tire rotates.

If they don't, check all of the components mentioned above and make sure that the pads move freely in and out. Sometimes you have to actually sandpaper the moving surfaces so they are smooth and use high heat grease for lubrication.

[chev-obsession]

when we drove it around it would pull to the right, but the drivers side rotor was the side that was schorging hot....

i replaced the rotors, calipers, pads, balljoints with new ones. i re used the old master cylinder, proptioning valve and brake booster.
im pretty sure that its not normal to be hot at all considering that i went no more than 2 miles. when i had the truck jacked up (before i test drove it), i could barely turn over the rotor by hand on the passenger side, and the drivers side was pretty tight too.

[LockDoc]

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If it had drum brakes on it before, you might get by with the master cylinder but the proportioning valve is different. You need a disk brake prop valve. I'm not saying that is the problem but I would put the correct one on it. Have you had a chance to check the front bleeders for residual pressure? You could have a bad flex hose too.

LockDoc

[cparman]

Originally Posted by chev-obsession

when we drove it around it would pull to the right, but the drivers side rotor was the side that was schorging hot....

i replaced the rotors, calipers, pads, balljoints with new ones. i re used the old master cylinder, proptioning valve and brake booster.
im pretty sure that its not normal to be hot at all considering that i went no more than 2 miles. when i had the truck jacked up (before i test drove it), i could barely turn over the rotor by hand on the passenger side, and the drivers side was pretty tight too.

Did it pull when you applied the brakes? If so the left caliper is hung up. recheck all of the parts, and ask the parts supplier for a left caliper

[lolife99]

You need a disc brake M/C and porportioning valve for sure. I would replace the bossster also. What about rubber brake hoses to the calipers? Are they new or used?

I just did this swap on my 69. But I'm running a manual disc brake master cylinder.

[chris71]

Originally Posted by lolife99

You need a disc brake M/C and porportioning valve for sure.

X2, if you have the original drum/drum mc and distribution block, then you are sending too much psi and not enough volume for those new disc brakes, you need the correct MC and prop valve for your brake combo.

if one side if getting really hot over the other side i doutb the MC or dist. block is causing this, i would double checkeverything that you did for that wheel, spindle nut on way too tight? pads installed incorectly?caliper not bolted down properly? etc.

it doesnt hurt to double and triple check things or just redo them altogether, ie take caliper off take pads off, reinstall caliper, reinstall pads, etc etc. i have seen a guy in a rush put a pad in backwards and in one night of driving he wore the rotor down on one side all the way to the fins

[chev-obsession]

ok i dont know if i clearified this by now, but i got parts off of a 71 suburban with power disc brakes. i took the brake booster master cylinder and proptoning off of the suburban. so the master cylinder and all of that is for disc brakes. and it only does it after i drive the truck around for about 2 miles.

sorry for the confusion

[68gmsee]

I had a similar thing happen on two of my vehicles.. First time on a van and then on my 69 Chevy drum brake.

On the van it turned out to be a bad piston/caliper. There was a badly rusted out area and the piston was binding and not retreating all the way.

On the 69 chevy it was the rear brakline rubber hose that was restricted so that only "pressurized" fluid was allowed to the brakes but only a slow trickle to pass back to the master cylinder.

Here's how I found out what was happening on the van. I jacked up the supected tire and cranked the truck. Had the wife step on the brakes while I was rotating it. As she released it I continued to rotate it and noticed it was still dragging. I then removed the tire and did the same thing. I could visually see that it was not releasing completely.

On the 69, I did the same thing but found out that by loosening the bleed valve the brake would release immediately.

Hope this helps.

[jim zag]

After you step on the brake pedal loosen the master cylinder nuts and pull the master away from the booster and see if the rotor turns easier.

[chev-obsession]

well that makes sense... and my rear brake hose does cut it pretty close...

is the 4-wheel drive rear hose the same as a 2-wheel drive for 71 or 72?