Rear Brake Trouble

[rags]

as the drum rotates it will contact your shoes in low spot of the elliptical rotation.

i think that this would cause a severe brake pulsation. the shoes can move with the drum side to side with the hold down springs, but not up/down as the shoes are anchored that way by the pin at the top.

 

[Big_John]

UPDATE:
So I decided to test the "bent axle" theory for my own entertainment. The rear end is currently sitting on jack stands. I started the car, let it warm up, and threw it into gear. Then I positioned myself under the wheel well (dangerous, I know) and carefully observed the axle flanges. Driver side had an observable amount of movement, which doesn't seem normal to me. Passenger side was a bit better, but the same type of movement. I can't describe the movement, almost like an elliptical movement rather than the normal circular movement. I also noticed that on both sides, whenever I torque the drums down, it's as if the adjustment gets tighter. Could it be the drum centering itself to the bent flange? Not sure. Ordered new e brake cables even though they seemed to be working. I'm already there, so why not? Anyways, I wanted your guys' opinions before I go spending more money. Thanks all.

Are you looking at the tire? Or the hub?

While any wobble in the hub would be amplified greatly by the time it gets out to the tire tread, if it's that bad, you would feel it.

Time to buy a cheap dial indicator and stand. Harbor Fright will have a cheap version that will work just fine for this. First thing is to check the endplay in the axle. Then check the run out of the axle flange at the center hub.

Yea, it's not a good dial indicator (my favorite is the Brown & Sharpe/Tesa) but it will do this job.

Clamping Dial Indicator

 

[USSMOPAR]

Fire this mechanic - the good mechanic would have immediately replaced
the return springs. How is it i am the only person to point this out while the rest are wallowing in verbage and making rocket science?. Did the mechanic check the end play on the axles? There could be a bad wheel bearing....Back to brakes 101 - The springs pull the shoes back when the brakes are released...bad springs...shoes drag.
A real clutch/brake relining company will have the shoe arcing equipment.
Rochester Clutch n Brake is one company many have had great success with.

 

[70NewY’ER]

Axle housing looks to be in good shape. It’s weird because I haven’t noticed any pedal pulsation while driving. Drum didn’t appear to be contacting the backing plate from what I could see. The wheel bearings are a little over a year old. They’re the Mopar Performance “green” style bearings. They aren’t making any alarming noises from what I can tell, and the heat didn’t seem to be coming from them. I took the drums off on both sides so I could observe the hub itself. I think I’ll get the cheap Harbor Freight dial indicator and test each side. I’ll also get some fresher hardware just in case.

 

[Big_John]

The wheel bearings are a little over a year old. They’re the Mopar Performance “green” style bearings.

And did your "mechanic" install those?

Bet the axle got bent during the remove/install.

 

[rags]

Fire this mechanic - the good mechanic would have immediately replaced
the return springs.

I noticed that both of the wheel cylinders were acting as if they were slightly applied while trying to put the springs back on

the springs are returning the wheel cylinders. i've seen broken return springs caught inside the bottoms of brake shoes without any overheating issues.

 

[rags]

question i have to ask: when did you first notice this problem? if it were caused by a failure in a repair process it would have been noticeable directly after the repair. bad part or workmanship wouldn't surprise me at all, but you would know immediately. i watched a guy bend an axle by beating a brake drum off, but there was no question about it. he did the brakes, put the new drum on, spun it by hand and did an "oh ****".

 

[70NewY’ER]

And did your "mechanic" install those?

Bet the axle got bent during the remove/install.

If there is an issue with the axles, that’s what I’m betting my money on. I feel like there are few who care when working on these cars unfortunately…

 

[70NewY’ER]

question i have to ask: when did you first notice this problem? if it were caused by a failure in a repair process it would have been noticeable directly after the repair. bad part or workmanship wouldn't surprise me at all, but you would know immediately. i watched a guy bend an axle by beating a brake drum off, but there was no question about it. he did the brakes, put the new drum on, spun it by hand and did an "oh ****".

I actually started to notice after the mechanic installed all of the new parts. This was an older mechanic who I usually only go to for inspections. I brought it back to him after I noticed. He told me that they were adjusted a little tight. He backed off on the adjustment, still hot. He told me to drive the car around to wear in the shoes. That’s when I decided to get a second opinion from the current guy. And here we are lol

 

[rkrochen]

I actually started to notice after the mechanic installed all of the new parts. This was an older mechanic who I usually only go to for inspections. I brought it back to him after I noticed. He told me that they were adjusted a little tight. He backed off on the adjustment, still hot. He told me to drive the car around to wear in the shoes. That’s when I decided to get a second opinion from the current guy. And here we are lol

Again have you researched what temps are normal???? If you are seeing 300deg F that is normal. Here is an article in regards to this.


Hot Topic
What are the normal Operating Temperatures for Dexter Axle Components and Assemblies? This is a question that we have asked Dexter to help address due to the volume of questions we receive in Airstream Customer Support on this topic. We are contacted by owners that indicaThe function of brakes is to convert the kinetic and potential energy of the vehicle to heat generated by the rubbing friction of the brake linings against the brake drum or rotor. Normal operating temperatures for most drum brakes range from 150 degrees F. to 400 degrees F. Temperatures can exceed 600 degrees F. during certain stopping conditions although the braking effectiveness is considerably reduced at these elevated temperatures. Temperatures above approximately 650 degrees F. may damage brake components and brake drums. Disk brakes may operate up to about 1600 degrees F. without damage. Most people fi nd 150 degrees F. too hot to touch comfortably. Do not touch brake drums or brake components immediately after stopping the vehicle. Severe burns may occur.
Bearings: Tapered roller bearings can withstand considerable temperature without damage. The bearing lubricant generally cannot. Temperatures in excess of about 200 degrees F. (measured at the outside of the hub.) may indicate a bearing or bearing lubrication problem. Temperatures in the range of 140 degrees F. to 175 degrees F. are considered normal. Use extreme caution when attempting to determine hub temperature. Normal bearing operation temperatures may cause the hub to be too hot to touch comfortably. The above

 

[rags]

from 150 degrees F.

that's the exact temp. that i would expect to see with moderate braking on a full size car. why is he seeing 300 degrees or just a plain overheating issue repeatedly with just the rears (or now just the right rear if i read correctly) but not the front. the front brakes work harder than the rears to stop the car. shouldn't the fronts be as hot or hotter than the rears?

I actually started to notice after the mechanic installed all of the new parts.

awesome. @Big_John thinks your problem is hydraulic. the problem started after the repairs were done. you've checked or replaced or re-replaced all the hydraulic parts associated with the rear brakes except one. the master cylinder. was the correct one installed, drum brake master vs disc, and was it installed correctly? picture of it and the line connections would go a long way here.

 

[70NewY’ER]

that's the exact temp. that i would expect to see with moderate braking on a full size car. why is he seeing 300 degrees or just a plain overheating issue repeatedly with just the rears (or now just the right rear if i read correctly) but not the front. the front brakes work harder than the rears to stop the car. shouldn't the fronts be as hot or hotter than the rears?

awesome. @Big_John thinks your problem is hydraulic. the problem started after the repairs were done. you've checked or replaced or re-replaced all the hydraulic parts associated with the rear brakes except one. the master cylinder. was the correct one installed, drum brake master vs disc, and was it installed correctly? picture of it and the line connections would go a long way here.

Here are some pictures I just took:

Forgot to mention… he replaced the lines going from the master to the block, said they were rusted to it.

 

[rags]

that's correct for drum brakes someone else will have to verify the connections. i don't have a similar car to compare.

 

[70NewY’ER]

And did your "mechanic" install those?

Bet the axle got bent during the remove/install.

So I tested the runout and the flange face on both sides. Runout on each side maxed out at approximately .020”. The flange faces on each side maxed out at about .015”. Are these numbers too high?

 

[luigi164]

I also noticed that on both sides, whenever I torque the drums down, it's as if the adjustment gets tighter.

Been following this post. As you said ^^^ this it reminded me I had the same problem. As it turned out the problem was that the shoes were a fraction to wide ánd probably the drums were not turned deep enough so as I tightend the bolts the wheel turned heavier. So I would say: messure the depth of the drums and the width of the shoes. I bought another brand shoes and solved the problem. Went from Raybestos to Wagner. The Wagner shoes were 1mm less wider.

 

[Big_John]

So I tested the runout and the flange face on both sides. Runout on each side maxed out at approximately .020”. The flange faces on each side maxed out at about .015”. Are these numbers too high?

Is that TIR? Total indicator reading? Which is double how much it's actually out.

I think that is too much. It seems to me that I've seen .010" TIR as being maximum. Although I really don't think this is your brake issue.

It might be time to source some better axles. It might even be cheaper to buy a used complete rear.

IMHO, and there are people that don't agree, but I'd go back to the regular bearings too. I can't see any advantage in a street car running those green bearings. The only advantage for you in a street car is you don't have to set the endplay.

 

[70NewY’ER]

Is that TIR? Total indicator reading? Which is double how much it's actually out.

I think that is too much. It seems to me that I've seen .010" TIR as being maximum. Although I really don't think this is your brake issue.

It might be time to source some better axles. It might even be cheaper to buy a used complete rear.

IMHO, and there are people that don't agree, but I'd go back to the regular bearings too. I can't see any advantage in a street car running those green bearings. The only advantage for you in a street car is you don't have to set the endplay.

I believe it is the TIR. It would’ve been nice if the mechanic told me what he measured. I’m going to install a new master, brake hardware in the rear, and rear e brake cables just to be safe.

 

[Vinny]

Hello all. I have a '68 Newport with drum brakes all around. 2 3/4" up front and 2 1/2" in the rear. I had the brakes redone about a year ago. New master, wheel cylinders, hoses, shoes, hardware, wheel bearings, etc. I noticed that whenever I would take the car out for a drive, the rear drums got wayyy too hot (about 300 degrees F. on both). So, I figured maybe the problem was related to the proportioning valve, so I found an NOS P.V. on Hiltop Auto Parts and replaced the old one. Brakes still got hot in the rear. After that I thought it could be the drums and shoes, so I replaced them. Shoes are from Powerstop, and the drums are from Raybestos. Still very hot. The wheel bearings don't seem to be getting hot either. The major heat is coming from the shoes and the drums. I thought of everything and can't seem to figure out the problem. Not even my local mechanic can figure it out. Could the master cylinder be absorbing some engine heat and causing problems? Bent axle and/or flange? I have the car registered for the upcoming Chryslers at Carlisle event and I'd like to get this sorted out before going. I'm not an expert so any help on the matter would be greatly appreciated. Thank you!!

My friend had the same problem with his Duster. Was the rear flexible brake hose changed? They clog, the pedal pressure allows fluid in, but slow to release, thus keeping the rear brakes applied. Keep us posted.

Vinny

 

[70NewY’ER]

My friend had the same problem with his Duster. Was the rear flexible brake hose changed? They clog, the pedal pressure allows fluid in, but slow to release, thus keeping the rear brakes applied. Keep us posted.

Vinny

Yessir. Replaced twice, to be exact. It had no affect on the brakes unfortunately…

 

[rags]

I’m going to install a new master

just verify that the fabricated lines are connected to the master cylinder properly. which chamber services which axle? i can't answer that question because i do not have direct knowledge of how that system is configured.