Passenger rear drum getting hot

[Zymurgy]

This issue got worse by the end of last year, and believe it has been on going for a few years.

For example today was a cool day, I took it out for a short drive maybe 8 miles. When I got back to the shop the front discs where 115F back, left drum 80, right drum 200.

I removed the emergency brake cable, no different. At least when it is cold the wheel spins freely. I have not yet jacked it up hot to see if it moves freely.

Can it simply be a bad wheel cylinder, there is no leaking. I replaced it 6 years ago.

I did a 73 disc brake conversion a couple years ago but pretty sure this has been going on for years before that. If the wheel gets to 350F it makes the car vibrate that used to be after 50 miles now it is closer to 15.

 

[Pete Kaczmarski]

Can it simply be a bad wheel cylinder, there is no leaking. I replaced it 6 years ago

Did you replace the shoes on the side where it leaked? my '62 300 was fine and looked clean but after driving a short distance the brake fluid came up from the brake shoes and the brake would lock up. We used brake clean and even burned them off with a torch but the brake fluid wicks into the shoe and comes out when applying the brakes.

 

[Davea Lux]

A stuck wheel cylinder could be causing this problem, but unless it is sticking only some of the time it is probably not the cause. The wheel spins freely when cold, as the brakes and drum warm up the drum will expand and move farther away from the shoes. So the wheel should still spin freely with everything warm. You probably do not have a bad adjuster as the wheel spins freely when cold. You need to jack the car up, remove the drum and check your rear axle for excessive end play or excessive movement when the hub is shaken. I suspect you have either a bad wheel bearing or one that is improperly adjusted. If the bearing is too loose it will cause the bottom of the shoes to rub on the drum and overheat the drum. It will only do this with weight on the axle. Check this and report back.

Dave

 

[Zymurgy]

I did a complete overhaul 6 years ago new lines, shoes and wheel cylinder. It sat for 32 years no actual leaking. It does not lock up when stopping.

I have an aftermarket adjustable proportional value to the rear drum installed when I did the disc conversion 2 years ago.

 

[Zymurgy]

A stuck wheel cylinder could be causing this problem, but unless it is sticking only some of the time it is probably not the cause. The wheel spins freely when cold, as the brakes and drum warm up the drum will expand and move farther away from the shoes. So the wheel should still spin freely with everything warm. You probably do not have a bad adjuster as the wheel spins freely when cold. You need to jack the car up, remove the drum and check your rear axle for excessive end play or excessive movement when the hub is shaken. I suspect you have either a bad wheel bearing or one that is improperly adjusted. If the bearing is too loose it will cause the bottom of the shoes to rub on the drum and overheat the drum. It will only do this with weight on the axle. Check this and report back.

Dave

I replaced the rear bearings last year. I thought this might be the problem. That side was bad and I did get rid of the bearing noise, but not this heat and eventual vibration

 

[Pete Kaczmarski]

Look for uneven wear on the hot shoes. Sometimes the wrong shoes are given and/or problems with the brake hardware.

 

[Davea Lux]

If the wheel bearing is improperly adjusted, the bottom of the shoes will show abnormal wear.

Dave

 

[Zymurgy]

They look pretty even but there isn't a lot of milage left this is only about 12,000 miles.

 

[thrashingcows]

I was going to suggest the rear drums dragging due to a bad prop valve....but since you have an adjustable unit I don't see that being the problem. You did grease the new bearings on that side? They don't get splash lubed from the diff oil. How much end play do you have on the axles... I go unit I can just "feel" movement, but can't actually "see" it moving.

What about the brake shoes themselves....are they on the correct side? Maybe remove the hard line from the junction block, and the wheel cylinder and blow it out in both directions, perhaps there is a piece of crud in the line that is acting like a check valve?

 

[Davea Lux]

It looks like you have the brake shoes on backwards from the photo. The shoe with the longer lining goes to the rear of the car. The primary and secondary lining on the shoes are made of different material. Note that these appear to have the short lined shoe to the rear of the car. When they are on backwards the brakes will chatter and overheat.

Dave

 

[Zymurgy]

I was going to suggest the rear drums dragging due to a bad prop valve....but since you have an adjustable unit I don't see that being the problem. You did grease the new bearings on that side? They don't get splash lubed from the diff oil. How much end play do you have on the axles... I go unit I can just "feel" movement, but can't actually "see" it moving.

What about the brake shoes themselves....are they on the correct side? Maybe remove the hard line from the junction block, and the wheel cylinder and blow it out in both directions, perhaps there is a piece of crud in the line that is acting like a check valve?

I did pack my new bearings, the end play is definitely an issue. I need to revisit my thread on the bearings, I wasn't able to get them to move tighter and I know I had some suggestions. I don't think this is the source of my heat because I have too much end play on both sides and the other is fine.

I presume I have the correct shoes because they all line up and are wearing evenly I bought both sides in a set. These have been in the same location for 6 years.

 

[Zymurgy]

It looks like you have the brake shoes on backwards from the photo. The shoe with the longer lining goes to the rear of the car. The primary and secondary lining on the shoes are made of different material. Note that these appear to have the short lined shoe to the rear of the car. When they are on backwards the brakes will chatter and overheat.

Dave

I hope this is the issue, I have had them on wrong for 6 years and I have had this problem since day one, so it would make sense.

 

[Zymurgy]

Thank you thank you thank you!!! I have looked at the photos and they are definitely backwards.

I am in a much better mood now!

 

[68 4spd Fury]

You have enough suggestions, all good. I'll add look at the tee and lines going to the rear for clogs and the distribution block under the master for the same thing.

 

[The Goose]

It looks like you have the brake shoes on backwards from the photo. The shoe with the longer lining goes to the rear of the car. The primary and secondary lining on the shoes are made of different material. Note that these appear to have the short lined shoe to the rear of the car. When they are on backwards the brakes will chatter and overheat.

Dave

If you ever disappear I know what they’re gonna replace you with...

Good save.

 

[mr. fix it]

Just in case mike, you may want to consider replacing the rear brake shoes if the right side has been cooked badly...
Once they are cooked they will never grip properly again...

 

[mr. fix it]

If the wheel bearing is improperly adjusted, the bottom of the shoes will show abnormal wear.

Dave

Hi Dave @Davea Lux .
Can you explain how an maladjusted axle bearing will cause uneven wear at the bottom of the brake shoes?

 

[Davea Lux]

Hi Dave @Davea Lux .
Can you explain how an maladjusted axle bearing will cause uneven wear at the bottom of the brake shoes?

In very simple terms, the brake backing plate is fixed to the rear axle housing. If the bearing has excessive end play, the axle will ride high due in the housing by not being properly seated in the race. The weight of the vehicle pushes the axle up relative to the housing since the outer bearing race is not properly engaged and seated. This causes the brake drum attached to the end of the axle to push up against the bottom of the brake shoes, friction results and the whole thing heats up. Left uncorrected, the bottom part of the shoes will wear faster than the rest of the shoes.

Dave

 

[mr. fix it]

In very simple terms, the brake backing plate is fixed to the rear axle housing. If the bearing has excessive end play, the axle will ride high due in the housing by not being properly seated in the race. The weight of the vehicle pushes the axle up relative to the housing since the outer bearing race is not properly engaged and seated. This causes the brake drum attached to the end of the axle to push up against the bottom of the brake shoes, friction results and the whole thing heats up.

Dave

I never would have thought of that.

I've seen shoes that were like new onthe bottom and worn on the top because of a lack of proper adjustment but never this being a cause
Thanks.

 

[Davea Lux]

I never would have thought of that.

I've seen shoes that were like new onthe bottom and worn on the top because of a lack of proper adjustment but never this being a cause
Thanks.

They wear out on the top because the adjuster is not properly engaging the bottom of the shoes, so the top of the shoes does all the braking and wears out first.

Dave