Overheating right rear brake

[Edward J.]

Re: Overheating right rear brake

Here's what I found yesterday.

The brake drum measures within spec, so it's not too large inside.
The wheel cylinder links appear to be extending out too far on the right rear, and can't retract back in. Given this, the brake pad stays applied and the drum warms up.

Currently it has ACDelco brand links and a Raybestos wheel cylinder.
Before I randomly purchase other links and/or wheel cylinders does anyone know of a proven wheel cylinder/link combination that works?
The left rear (and the front wheels) have the same brand combination yet work flawlessly.

Thanks.

PH

Pat are you sure that the e/brake cable is retracted Al the way, if the shoes are not resting on the pin at top,
try backing cable off all the way.I have seen this before. If the lever is not resting on shoe with e/brake off. You may have found the issue.

[Patrick H.]

Re: Overheating right rear brake

Ed,

At rest, it does appear to be on the upper pin. When I push the brake, the links extend but do not retract. I can push the shoes and therefore the links back in, and it happens again the next time.

[Patrick H.]

Re: Overheating right rear brake

Patrick, I had a similar problem. I replaced the wheel cylinder and polished the pins. I also noticed that my backing plate was not torqued all the way and it move when the brakes were applied.

Thanks Harry.
do you recall what brand of wheel cylinder you used?

[Edward J.]

Re: Overheating right rear brake

So the pistons are hanging up in bore. I within the last year brought ACDelco front wheel cylinders for the front of my 63 all was good, got them from Rock Auto. The rear ones on car are Napa. There a few years old. You could try Harry’s idea. Polishing the pistons or clean up the bore, if this is indeed the issue.

[Patrick H.]

Re: Overheating right rear brake

They seem to hang up, or almost overextend.
They definitely don't retract.

I may try some polishing and also a new wheel cylinder, especially if Harry has a brand suggestion.

[Richard M.]

Re: Overheating right rear brake

Ok I had a 61 pair of front wheel cylinders with a light internal spring on one, heavier internal spring in the other. That side dragged an pulled.

Maybe you have mismatched springs too. I'd pull both to compare. You may get a new cylinder with the same anomaly and still have problems.

Rich

[Harry S.]

Re: Overheating right rear brake

Thanks Harry.
do you recall what brand of wheel cylinder you used?

Believe it or not NAPA. I did take them apart and inspect them. They looked good. When I put them back together I put brake fluid on all the parts. The same fluid in the system DOT 4.

They work just as well as my other 63 with original rebuilt Delco wheel cylinders.

[Patrick H.]

Re: Overheating right rear brake

Believe it or not NAPA. I did take them apart and inspect them. They looked good. When I put them back together I put brake fluid on all the parts. The same fluid in the system DOT 4.

They work just as well as my other 63 with original rebuilt Delco wheel cylinders.

Thanks.
I'll have to inspect the one on the car, but will also pull out the one I removed from before and see how it looks.

[Patrick H.]

Re: Overheating right rear brake

Here's an update -

I ended up polishing the inside of the wheel cylinder on the right rear and reusing that wheel cylinder, as Rock Auto sent me all LEFT sided parts despite listing them as RIGHT. However, it made no difference.

By unhooking the emergency brake under the driver's seat I found that I could then drive the car and have no increase in heat of the right rear. However, having it hooked up results in 10-15 degree increase in right-sided temps. I have played around with the cables and amount of tension, and my theory is that the reproduction cable is stiffer than the original material, and doesn't slide as well inside the sheath. Due to the asymmetrical pull on the cable at the bracket the right side gets pulled a bit more and doesn't release as well.

Right now I have the emergency brake as "slightly usable" with no over heating, and that's how I will leave it for the owner.

[Gary R.]

Re: Overheating right rear brake

Interesting, I am building a set of 63 TA now and the owner told me he disconnected parking brake years ago, maybe the same thing happened?

[Duke W.]

Re: Overheating right rear brake

Lubricate the cable with Lok-Eze or equivalent... spherical graphite in a petroleum distillate emulsion. Graphic is an excellent lubricant to minimize friction in high load low speed applications like control cables.

It's best to remove the cable, hold it vertically and feed the emulsion down until it runs out the bottom. Then lay the cable flat and rotate it a couple of dozen turns to spread the graphic around. The petroleum distillate will evaporate with time.

Before you add the graphite, lay the cable flat and rotate it to get a baseline. After the graphite application it should rotate with noticeably less friction.

Cosworth Vega clutch cables have a habit of stiffening up due to their length, routing, and proximity to the exhaust header tubes. Some have even had the clutch cable support pull out of the the firewall.

Clutch cable lubrication with graphite became a normal maintenance procedure when I felt a noticeable increase in pedal effort... disconnect the cable at the pedal pin... remove the support from the firewall... pull the cable through the firewall, hold in the vertical position and let the emulsion run down between the cable and sheath for about ten seconds.

Duke

[Patrick H.]

Re: Overheating right rear brake

It's best to remove the cable, hold it vertically and feed the emulsion down until it runs out the bottom.

Duke

Yes, I know.
That's not happening. It's together, and the owner would really have to make it worthwhile to take it all apart again.
I tried looking up the cable lubrication tools but I can't see that any would easily fit, and I'd still have to take some of it apart.

[Richard M.]

Re: Overheating right rear brake

Here's an update -

I ended up polishing the inside of the wheel cylinder on the right rear and reusing that wheel cylinder, as Rock Auto sent me all LEFT sided parts despite listing them as RIGHT. However, it made no difference.

By unhooking the emergency brake under the driver's seat I found that I could then drive the car and have no increase in heat of the right rear. However, having it hooked up results in 10-15 degree increase in right-sided temps. I have played around with the cables and amount of tension, and my theory is that the reproduction cable is stiffer than the original material, and doesn't slide as well inside the sheath. Due to the asymmetrical pull on the cable at the bracket the right side gets pulled a bit more and doesn't release as well.

Right now I have the emergency brake as "slightly usable" with no over heating, and that's how I will leave it for the owner.

Glad you got it. Frank D. had cable issues too. Post #12.

[Patrick H.]

Re: Overheating right rear brake

Glad you got it. Frank D. had cable issues too. Post #12.

Yes, but these were new, not seized originals.
However, in both cases the cables caused overheating. It appears the overheating on the car here was not as severe, which is good.

I'm still meditating over whether or not to get them lubricated, or leave them alone.

[Richard M.]

Re: Overheating right rear brake

Yes his were old and tired, but I wanted to reference his experience as another idea for you then. Not exactly the same cause, but related.

He did end up with a new cable set from CC that was good and solved his problem.

I myself would feel relief by lubricating them for peace of mind.

Rich