Rear Brake Trouble

[70NewY’ER]

Hello everyone. I haven’t been updating in a while from being too busy. I’ve been working/ having work done on the Newport since my last post. I swapped out a lot of parts (both axle shafts, wheel cylinders, and even the rear passenger backing plate), and had the brakes adjusted a few times. The problem still lingers on. I just recently disconnected the parking brake cables to see if they were hanging up. Still hot. Temp maxed out at ~500 degrees F on the pass. rear, and ~300 on the driver rear. Fronts averaged 160. I’m going to start fresh on the rear adjustment and I will use the original drums (both were recently cut). With Carlisle coming up, I’m going to work as hard as I can to get this squared away. Any feedback would be appreciated. Thanks!!

 

[rags]

have you considered getting a set of brake pressure gauges? that'll be the absolute end of all the guess work.

 

[Boydsdodge]

have you considered getting a set of brake pressure gauges? that'll be the absolute end of all the guess work.

I need to get a set, I keep forgetting to do a search on a set.

 

[rags]

search on a set.

i did. amazon has a cheapie set but the gauges don't read high enough. for the price it might be worth getting for the fittings and hoses then add a set of real gauge heads. the gauges will tell the story here and put an end to the bullshit.

 

[70NewY’ER]

have you considered getting a set of brake pressure gauges? that'll be the absolute end of all the guess work.

I haven’t tried that. What would I look for when using the gauge? High pressure on one of the wheels?

 

[rags]

What would I look for

lower pressure to the front, higher pressure to the rear, pressure applying to the rear and not releasing. they tell the story. just get a set that'll read 1500 psi. the rear brakes are working harder than the fronts. why?

 

[70NewY’ER]

lower pressure to the front, higher pressure to the rear, pressure applying to the rear and not releasing. they tell the story. just get a set that'll read 1500 psi. the rear brakes are working harder than the fronts. why?

Ok. Would harbor freight have something like that? I don’t know if it will arrive on time if I got it online. Thank you for the tip!!

 

[rags]

harbor freight

not looking good. it's not a common tool but yours is not a common problem. like the infrared gun that your using, the gauges would put some numbers to it so that you can see what the system is actually doing. something went wrong with that original brake repair. it looks like you've re-replaced every last part. the workmanship was the issue. it's not easy for someone who doesn't know all the tricks to undo. hate to say, but the more work that's being done and the more parts that are being replaced increases the chance of compounding the original problem. the parts today are so horrible. be very careful in what you do.

 

[Vinny]

I haven’t tried that. What would I look for when using the gauge? High pressure on one of the wheels?

Did you replace the flexible hose for the rear brakes?

 

[rkrochen]

Have you considered swapping rear wheel cylinders from side to side to see if the problem follows the cylinder.

 

[70NewY’ER]

Did you replace the flexible hose for the rear brakes?

I replaced that sucker 2 or 3 times haha

 

[70NewY’ER]

Have you considered swapping rear wheel cylinders from side to side to see if the problem follows the cylinder.

I have not. I just had new wheel cylinders installed about a week ago. I have a feeling what rags is saying could be true. The more parts I throw at it, the more variables I’m introducing into the equation. It’s a shame that newer parts are so bad now.

 

[70NewY’ER]

This is an older picture and all of the hardware has been changed. I circled the shoe retaining nail and spring. Seems like the nail is too long and the spring can’t really keep enough tension against the shoe, allowing for some movement in the shoe. Could this lead to some sort of drag on the drum??

 

[rkrochen]

This is an older picture and all of the hardware has been changed. I circled the shoe retaining nail and spring. Seems like the nail is too long and the spring can’t really keep enough tension against the shoe, allowing for some movement in the shoe. Could this lead to some sort of drag on the drum??
View attachment 603722

That shoe looks like it isn’t bonded properly near the top.

 

[70NewY’ER]

That shoe looks like it isn’t bonded properly near the top.

Hmm I didn’t notice that before…

 

[Just Carbs]

The Chrysler service manual says something about that.
It says to stack an additional disk on the nail against the plate if the spring doesn't provide enough force to keep the shoe flat on the backing plate.
It also says to use their special lubricant on the shoe to plate contact area.

And I can see where the de-bonded shoe can cause spongy shoe syndrome. And drag.

 

[70NewY’ER]

The Chrysler service manual says something about that.
It says to stack an additional disk on the nail against the plate if the spring doesn't provide enough force to keep the shoe flat on the backing plate.
It also says to use their special lubricant on the shoe to plate contact area.

And I can see where the de-bonded shoe can cause spongy shoe syndrome. And drag.

I used a palm sander to take off excess material at the top of the shoes. Didn’t really make a difference unfortunately… but I guess it still could expand off the metal under high temps.

 

[Just Carbs]

My concern would be that it will compress flat under braking and protrude and drag when the brake is let off. Is it solid or springy?

 

[rkrochen]

As a note to this poorly bonded shoes are a hazard. There have been cases where they physically peel off during braking with bad results. That is the reason some people prefer riveted shoes. If this was my car I wouldn’t use these shoes.

 

[70NewY’ER]

My concern would be that it will compress flat under braking and protrude and drag when the brake is let off. Is it solid or springy?

The pedal seems pretty solid. I mashed on it a few times and it felt good. I did order a new set of shoes because I’m afraid the others might be glazed. I’ll try to true them up to the drums the best I can.