Rick Bell

I've recently had some brake issues that I've never heard of happening before in all my 50 years.




The 74 plymouth scamp was purchased by me, being a dummy and paying $4k for it. To get it running all it needed was the brakes bled.




Come to find out the booster was not working and it had some seals missing. But the front had reman calipers, new brake pads and was all set up as factory first.




I had to get an aftermarket booster to make the system work properly. No parts are available for this car.




The issue is that once I bled the brakes I took the car onto the highway and after ten miles or so the front steering started to shake. Then shake very badly until I pulled over.

Thought the wheels were coming off. I got the lug wrench out and tightened them.




Found the front wheels so hot you could fry an egg or three on them. What was happening? It appeared that perhaps the proportioning valve was not allowing the pressure to back off.




So, I did what anyone would do and purchased a new one. These are a factory for the disk to drum cars. Research told me everything is normal. 11-inch rotors. 1 inch thick. reman calipers, new pads.




I put the new proportioning valve on and I realized I could not get pressure out the front calipers in order to bleed them. I bench bled the Master while in the car. Tired it again. Could not get much fluid out the

calipers.




Took it to a brake shop. They said the same thing. Could not get the front to bleed. Perhaps a bad valve.




I decided to take it off and put my old valve on. But not before I removed the spring on the front inside the valve. Found out the brakes bled fine. So got back in and took it for a ten mile trip using the brake a few

times and running about 70. Just behind most of the cars.




On the way back the steering wheel got shaky and started to vibrate badly. I pulled over and found the lugs to be super tight, and the wheels on the front to be pretty hot. Probably wouldn't fry bacon as before, but hot enough

to slow cook a steak. Remember this is the old valve, but the spring tension removed on the front. Brakes bled fine and I got good flow through them even after the air came out.




What is happening? When I took the front brake line off at the master I found that the ten-mile road trip did very well. No shaking wheel. No getting hot. In fact the hubs were just mildly warm. It is the brakes that are causing all

hell to break loose in this car. No pun intended.




3 times I've tested after bleeding the brakes and all 3 times the car steering wheel has started to shake uncontrollably. Not as bad this last time with the valve spring off. But still does shake and vibrate. And wheels get HOT.




I changed the master cylinder. The calipers. The booster. And the brake pads are new so I have not replaced them. In fact, they are the only part of the brake system that I've not changed out.



The new proportioning valve didn't work at all. I've got to try and send it back. The old valve seemed to work. Yet if the front tires got hot then it must be not allowing fluid to backflow? Or release.

Now this old proportioning valve with the insides tweeked did better. It allowed me to bleed the brakes with no issues. But still is making the brakes or rotor hot like fire. And then causing a warped rotor or loose lugs???




I'm not sure why the wheel starts to jump around in my hand and feel just like I'm losing the front tires. Both of them. But only when they heat up. Not when they are cool. When starting out the brakes, everything runs smooth as silk.




Help!

OPlease oplease..
Rick Bell

RacerHog

Rick... Have you changed out the old brake hoses...
1-Might be acting like a one way check valve?
2- Reset the rod for the master cylinder to booster.. I think it my be to tight.. Take the master off pull the rod out and turn the stud screw in 2 turns and see if thats any better?
If you have headers on the car. Check to make sure one of the brake lines are not to close to the header. That will cause it to happen also.

Keep us posted..

Iowan

I like the break hose idea, they go bad from the inside.

Rick Bell

Hi.

Thanks for the advice for sure. Yep did the setting on the rod that comes out of the booster and into the master. It is got space. Just about an 1/8 of an inch to make sure it is not compromising the set up.

Again, I like the break line mention. However, all brake lines have run clear fluid through. I mean I've bled the brakes over 7 times now. Each wheel has a good stream coming out. When bleeding. And just looked. Headers are at least 3 to 4 inches from any of the lines.

Remember. My brakes now are working. Correctly. Now that I broke the spring in the old proportioning valve. Before that they were feeling exactly like they were hanging up on the front. Meaning still putting pressure on the pads. To make them get hot.

Guess what. The brakes are now doing great as far as I know. Just do not understand why my front wheels are getting so very hot after ten miles on the freeway.

Remember when I said I disconnected the brake line on front brakes and the car did fine? It kept a smooth roll, no steering issues. Just couldn't stop! Wheels stayed only slightly warm to the touch after ten miles. No heat.

But connect them back up and my wheels get super hot, the dang steering wheel starts moving back and forth like a tire is out of balance,, then if I keep going down the highway, eventually the steering wheels starts to shudder madly in my hands while I try to
keep it steady. If I let go of the wheel it drives straight. Just that it dances back and forth in front of me uncontrollably. Never seen or felt anything like this in the past 50 years!

Thanks for the feedback.

The only thing that didn't get changed on the brakes in front was the pads themselves. They looked and measured out to be exactly what they were supposed to be. Also they are brand new. And again when they ride against the wheel with no pressure on them;
the car stays steady and does not shake or shudder.

I want to put my go pro on the fender so I can see what the tires are doing at 70 when all this chaos starts with my steering wheel. This car I sit to low in it to stick my head out the window and look at the drivers wheel.

So what do you think? Do the go pro? Or Replace rotors, bearings, and pads? Makes little sense that these are causing the issue, however. I've never heard of a warped rotor. In my life. Never heard of bad pads. And when I drive it without the brakes in front the wheels run true and straight down the road and are hardly warm when I get back.

I don't know. I'm just frustrated as heck about it. Ready to give this pos away to someone that is tougher than me. LOL

Iowan

You have replaced the hoses with new? This is important because if the hoses are not new they can pass fluid under pressure one way but will not let it flow back.
How about the master that you replaced did you get one for dist/drum set up?

RacerHog

(Guess what. The brakes are now doing great as far as I know. Just do not understand why my front wheels are getting so very hot after ten miles on the freeway)
Dont forget. The front pads are supposed to drag slightly all the time..... The Brake System has a Residual Valve to hole the calipers brake pad against the brake rotor. Unlike the old brake drum systems. this keeps brake pedal travel down to a minimum.

At this point. If all the steering linkage is known good. Shocks are good, and so on.... I would check the brake rotors and have them cut to make sure these are true and go from that point.
One other thing.... Dose the car Coast ok after you drive it a few miles?

Rick Bell

HI.

Thank you for the advice.

The answer is no I didn't change hoses. Didn't think about it. But that would or could cause an issue if it won't travel back. Not sure how or why it wouldn't tavel one way and not the other. So maybe it could be. Thank you.

I've had two master cylinders for it. One came on the car which was new, the other I bought new. And when bench bleeding they both appear to work. And the only MC available for that car is the factory known MC which is for disk/drum. brakes.

I will definitely consider your comment here and take heed.

Thank you so much for coming up with something new I've not considered.

Rick

Rick Bell

Hi again.

About the rotors. Just to make sure they are not an issue, along with the pads. I've ordered new drilled/slotted rotors and new pads. Calipers have already been changed to the required remans I was told to get to make sure the old calipers were not a problem. But good call. Just because I've never heard of bad rotors that would cause overheating. Does not mean that these are not causing an issue.

As far as the coasting. Man, when the wheels heat up it will still coast. But again the steering is shaking so bad when they are hot that all I want to do is get it off the road.

So yes the wheels still turn with light friction as a disk will put on rotors. But again it could be more friction than it could be applying more friction than apparent.

Because it does not get hot for a good 10 miles of fast travel like in the 70 to 75 range on the freeway. I could drive it around all day at low speed and the brakes would have time to cool off between read lights and going slow. I think.

Thanks again for your patience and your help.

Rick

Ps. I will be putting on the new rotors and pads today. I will also look into the hoses for the front. I really never thought a hose could pressure one way and not the other. But if they are doing that it would make perfect sense.

I did find out in testing that the issue is still there, even after taking the spring out of the proportioning valve operation. And even with some air in the lines, the brakes work and also still overheat in the front. So not the proportioning valve. Possibly the brand new one I bought probably was bad sense me and the mechanic both tried to bleed the front and they would not bleed. Perhaps the valve is not working correctly. And it is just trying to add more drama to my situation.

Coronet 500

The hoses could do this, odd they would fail on both sides at the same time but for the cost I would replace them.

I did a quick search and found the same problem on a B Body and it came down to proven poor operation of an aftermarket metering valve or possibly master cylinder. They were still debating it at the end of the thread I found. I will search on For A Bodies only Forum and I would suggest you do the same.

Coronet 500

Check this one out. He found his problem.

https://www.forabodiesonly.com/mopar...en-hot.307987/