VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Rear wheel overheating

Today I was driving my 1939 for a longer drive in the countryside. After 45 mins drive I heard a high frequent whistling sound, like a small bird. I stopped the car and felt some smell and I found the rear left side wheel hub was very hot, I could hardly touch it. I waited some minutes to let it cool down. I drove slowly 5 more minutes to my destination.Then I realised the brake pedal was lover than normal, and I had to pump it a couple of times. Then I parked the car for many hours..

On my return in the evening, the brake pedal movement was Ok. No more «bird sound», and no overheating. I stopped the car several times to check the temperature of the wheel. On my last check at home, I found a minor heating again. Something is wrong in there.
I have to check out this and solve it. What is the most likely reason, the wheel bearing overheating or some brake failure?

It may be a rear wheel brake cylinder sticking , or broken return spring for the shoes.
I cannot see it being a rear wheel bearing issue , as the rear axle bearing is lubricated from the differential oil.

I would place the rear axle on stands with the wheels free to turn, have someone depress the brake pedal, and turn the wheels by hand to see how long it takes to have the brakes release the drum again. If you cannot turn the wheel reasonably quickly, the shoes are not returning to normal position away from the drums.

The brake shoes also have a rubbing block area, that may have worn away, and the shoes are getting stuck on these worn areas.

It could be many things but if I don't use my 39 for an extended period of time the wheel cylinders will start to lock up from moisture contaminated brake fluid. After replacing the wheel cylinders I have been trying to drive it at least every two weeks and it seems to have helped.

I think you will need to remove the wheel and drum and inspect the wheel cylinder. Of course if it is gunked up all of them will need rebuilding.

Dave

I agree with the above suggestions,

Sometimes a brake HOSE will collapse inside and allow fluid to travel toward the cylinder (when under pressure) but not let it return or allow it to return very slowly. It sort of acts as an unwanted check valve.
Since the rear axle has only one hose, it could cause the problem on both wheels or perhaps the adjustment of the individual rear wheels would allow the problem to occur on one side only.

Mike

Problem solved.
Today I removed the brake drum. I found a small brake fluid lekage, but more important, the wheel brake cylinder was stuck in one direction, so all force went to one side. And a little surprisely, it was full of rust.

So the only solution is to change the rear brake cylinders. Lucky I am, I already have a pair of spares.

Thanks for letting us know your diagnosis. Your plan to install new cylinders is right on target.

The rust you saw is the result of the design of these cylinders with the "over the cylinder" adjuster. They do not seal the end of the cylinder like the rubber boots on later designs. So that area is exposed to air and moisture.

There is a trick some of us use to minimize/reduce the chance of rust. We remove the adjuster from the end of the cylinder and put a coating of brake paste or grease on the exposed bore between the end of the piston and the adjuster. I also put a thin coat on the shoulder on the end of the cylinder where the adjuster turns. Plus I lubricate the adjuster threads with it. I use CRC Brake and Caliper grease.

I would look to the drum and shoes being too tight. Back off the adjuster (counter clock when looking at the wheel cylinder from front to back or back to front until the wheel moves freely. Then go in the other direction until the wheel locks up an will not turn with arm pressure on the circumference of the tire. Then back off 4-5 clicks. That adjustment may clear the problem.

Also check the parking brake tightness.

Good luck with it.

Charlie