70 Cuda disc brakes very hot

[JohnnyMopar]

Yes these are Power brakes.  Good point, Thanks.

[ShelbyDogg]

His Lugnuts were so hot that you couldn't touch them.  Are you dealing with temps this high?

Rob

[Chryco Psycho]

Thanks Rob even though I knew the fix on Cudaguys car I still missed it here , I wasn`t thinking about a new master & the possible length difference

[ShelbyDogg]

I miss alot of things too.  But every once in a while I remember a thing or two.  I have a real bad problem with names though.

I hope it fixes JohnnyMopar's problem.  CudaGuy's car would start shaking a little on the highway. Bad things could happen if you drove for miles with your foot on the brakes.

Rob

[JohnnyMopar]

You can probably keep your finger on the lugnuts for a couple seconds before pulling them away!

Once I pull off the master cylinder, how long should the rod be on the power booster?  Are there any precautions I need to take when removing the master cylinder from the booster?

Thanks!

[ShelbyDogg]

No,
Just unbolt the 4 bolts, pull it away from the booster enough to get to the rod, then shorten it a little.  See if you can tell if the rod is depressing the piston when the Maset cylinder is pressed against the booster.

[JohnnyMopar]

I went out and pulled the master and saw that the rod that goes into the booster had the adjustable nut on it.  I made the rod has short as I could, I reduced the rod by about 4 thread lengths (about 1/8 of an inch).  Didn't start the car too late, I'll try tomorrow.

Thanks again!

[JohnnyMopar]

What a mystery!

After adjusting the rod of out the booster, there is no change in the amount the brakes are dragging.

I tried to pull out the brass fitting in the master to see if the rubber nipple was present, but I could get the brass fitting out.  I looked online and saw that the correct disc brake master has one larger reservoir in the back and a smaller one in the front, if looking at a top view of the master cylinder.  My MC has these two different sized reservoirs.

Any other ideas?  Could it be the two proportioning valves?  Thanks.

[ShelbyDogg]

The front brakes should be going to the LARGER of the 2 resevoirs on the mAster cylinder. You can confirm this by bleeding the front brakes and seeing which one lowers in fluid.  The larger one of the 2, should not have a RP valve in it.

If you drive the car, then immediately jack up the wheel, can you spin it by hand?  There should only be a slight drag and not feel like the brakes are stuck.  If they feel too tight, turn the wheel to the outside and reach in there with a wrench to open the bleeder screw to see if any pressure releases.   If it does and releases the brake, it could be a bad booster. Try it with the engine running too.

You need to find out if pressure is coming from the hydraulic side or if it is mechanically binding at the caliper.

Rob

[JohnnyMopar]

Thanks to everyone for the tips!

After pumping the brakes several times, I jacked the car up and noticed the wheel could be turned, but with quite a bit effort.  I opened the bleeder on the caliper and the brakes released and the wheel turned much easier (still some drag), but felt correct.

I then removed the Master Cylinder and took out both brass fittings.  Both ports had residual valves in them!  I have a correct Master Cylinder on order.  Hopefully this fixes the problem! 

[ShelbyDogg]

Just leave the valve out for the larger resevoir then reinstall the MC.  Make sure that the larger one is going to the front brakes.

[Chryco Psycho]

Make Sure the residual pressure valve is reinstalled int he rear brake side of the master If you decide to reuse the old one without it it can suck air into the wheel cylinders on drum brakes

[JohnnyMopar]

When removing the brass fittings with a drywall screw, I made the openings substantially larger.  I was thinking they may not seal well with the brake line?

$28 for a reman MC from Napa, can't go wrong.

Thanks.

[Chryco Psycho]