brake issues update disc/drum conversion

[Dominique Williams]

So took my car in to the shop today to figure out the grinding noise coming from the rear drums and had them adjusted. mechanic told me to drive it around today and let him know if the grinding noise continues and sure enough 5-10mins into my drive the loud grinding started back up again got home and the the drive side was smoking but the passenger side rear drum was not called him and told him the situation and he believes that it is one of three problems either the the master cylinder/proportioning valve is faulty either and its cause the rear brakes to build up pressure and not release it causing that sound to happen or the emergency parking brake is too tight and im lost now on what to do this is getting really frustrating

 

[rkrochen]

Not sure why the brakes would cause a grinding noise unless it’s metal on metal. Also not sure this mechanic knows what he is doing because emergency brake adjustment is not difficult to fix. The best thing to do is pull the wheel and drum off and take some pics. That should tell the story.
My gut feeling is that the wheel bearing is bad.

 

[Davea Lux]

In the first place, no reputable mechanic would put a car back on the road with a grinding noise coming from the rear brakes.
The proportioning valve regulates the relative pressure going to the rear brakes, it should not hold pressure once the brakes are released. It sounds like either you have a brake cable hanging up for the park brake or the travel rod adjustment for the master cylinder is set too long and the master cylinder is not releasing properly. You could also have a bad brake hose to the rear brakes that is not allowing fluid to return to the master cylinder properly.

Dave

 

[stubs300]

This is why you must learn how to fix your own vehicles. Good Luck

 

[CBODY67]

One side and not the other? Parking brake adjustments are usually equalized between the sides, typically, as both of the rear cables have a common "pull point".

Internal issues with the hoses can be a hidden issue! A section of the inner hose delaminates and becomes an internal one-way valve. Pressure flows though it just fine, but then trhe flap locks that interna;l pressure and will not allow it to release.

Getr that car in a place it can stay for a short while, with the rear wheels removed and on qulaity, stable jack stands. Remove the rear wheels, then the brake drums, and send us some pictures of what's there, please. It might not be pretty, but I also suspect your learning curve will start to increase.

Unfortunately, even "back then", just because a tech might work for a car dealership and claims to know about "old cars", doesn't mean they really do, by unfortunate observations over the years. As well-meaning as these people might be, trying to help you out, it's getting to the time where YOU browse thorugh the Chrysler MasterTech videos (www.mymopar.com) and learn about Chjrysler brake systems. Sure. some of the characters might be a bit rough, but look more at the information presented rather than the sound of rhe voices.

I suspect there should be one on the basic hydraulic system, from the earlier 1960s, then one on the 1970s disc/drum power system. Look at EVERYTHING and fully understand them! Then download a FSM (www.mymopar.com), even if it might be one model year away from your car, and digest that information, too.

I fully realize that this might be a good deal of work/investment, but when others might tend to lead one astray, where you're currently at is usually the result. Build YOUR knowledge base and many here can add to it. YOU need to get that car back to its glory and know how to do it. And THEN your "war stories" can be increased, but with a better-outcome ending.

Just some thoughts,
CBODY67

 

[1970FuryConv]

Since one side is smoking and the other is not, I agree with ruling out the proportioning valve and master cylinder, because both cause the same action at both rear brakes. Since only the driver side is smoking, driver side is either adjusted too tight or the parking brake cable is sticking, continuing to activate the brake even when the pedal is released.
2 Checks

1. Brake Adjustment: Jack up the rear of the car, trans in neutral. Spin the driver side rear tire by hand. If it spins easily with a light rubbing noise from the brake drum, your adjustment is probably OK. If it's hard to turn, you will need to remove the tire and brake drum and use a spoon/screw driver to narrow the brake adjuster. (Adjuster is the toothed circular part at the bottom of the picture. Turn the toothed/gear part to shorten the adjuster.) Reassemble and spin again. Continue adjusting until you get the condition originally described.
2. Parking Brake Cable: Assure parking brake is released. Remove tire and drum. Pull the cable end with pair of needle nose pliers. Cable should move. If not, stuck parking brake cable is probably the problem. In picture, parking brake cable is directly behind and above the lower brake spring.

I also agree that you need a new mechanic. His diagnosis is faulty.

 

[Big_John]

OK, first thing to do is list off what you have done for the disc conversion.

What master cylinder, proportioning valve and if this was a conversion using factory parts or some sort of aftermarket kit?

Do the rear brakes have self adjusters or manual adjusters?

You need to pull the drums and look at a couple things. Any signs of fluid leakage? Are the shoes properly oriented? (is the front shoe shorter than the rear?) Does everything else look right?

You really need to find a new mechanic. It's not the proportioning valve. Probably not emergency brake either. Generally speaking, drum brakes, with self adjusters, don't have to be adjusted except at initial install, so him wanting to do that is questionable to begin with.