Brakes overheated, could the bearing be the cause

ScottnSherrie wrote:

wa8yxm wrote:

There is another issue.. This one bit me on a car

The brake hose is a multi-layer thing, SOMETIMES the inner layer can fail in such a way it becomes a one-way valve. Allowing brake fluid to enter the cylinder and engage the brakes, but not allowing it to return to the master cylinder and tank thereon. OF course sitting in your drive waiting for you to get to it.. It leaks back.

Someone else posted the same thing. My plan is to service all the brakes with a good cleaning and greasing the parts that need greased (doubt they have ever been serviced) and replacing the hoses at each caliper. Once that is done it will be time for a test drive and measure the heat off all the discs every few miles. I have an IR temperature gun that makes that easy.

If they are still overheating, I'll replace the caliper.

If you want to try the service route, make sure you exercise the caliper while it is disconnected, to the full throw. Get some air and lubricant under the exterior dust seal of the caliper piston, too. IMO, you've pretty much described a sticking brake caliper.

"The Manual" may be directed more to "Remove and Replace" than to "Theory and Understanding." This is some kind of Chevy/Workhorse/P3x-something, right? If so, it has "full floating" rear axles.
Full-Floating Axles use wheel bearings that are lubed by the rear axle lube. That's right, From the Differential. So if a Manual says to Repack the Bearings after a brake job that required pulling the bearings apart (some of the drum rear braked vehicles are like that, our 1983 E350 was), what you are actually doing is protecting the bearings from failure while the rear axle lube works its way out there. The grease you packed will be washed away.
Those bearings need to be adjusted. "Set Up" like front wheel bearings. The difference you'll see is that the spindle is hollow for the full float drive half axle to slip through. And the bearings themselves will be very large. There are also grease seals like front wheel bearings have.
Since its the rear axle lube that lubes the wheel bearings, it's essential that the rear axle lube be ***FULL*** and not contaminated with water, etc. If it isn't full, the lube will not slosh out to the wheel bearings on turns and that's how it gets out there!
My bottom line here is this. With the coach level side to side, check the differential oil lube. Make sure the level is at spec (may need a Manual), and stick a piece of clean white cloth in there. See how it looks. If the lube is full and clean, I'd be much less suspicious of a bad bearing.

wa8yxm wrote:

There is another issue.. This one bit me on a car

The brake hose is a multi-layer thing, SOMETIMES the inner layer can fail in such a way it becomes a one-way valve. Allowing brake fluid to enter the cylinder and engage the brakes, but not allowing it to return to the master cylinder and tank thereon. OF course sitting in your drive waiting for you to get to it.. It leaks back.

Someone else posted the same thing. My plan is to service all the brakes with a good cleaning and greasing the parts that need greased (doubt they have ever been serviced) and replacing the hoses at each caliper. Once that is done it will be time for a test drive and measure the heat off all the discs every few miles. I have an IR temperature gun that makes that easy.

If they are still overheating, I'll replace the caliper.

It can't be the parking brake. My rig has a drive line parking brake.

The brake is engaged unless it is receiving hydraulic pressure from the hydraulic brake booster pump. This occurs with engine running and shifter out of Park.

There are no cables to any of the wheel brakes.

Bearing heat can be transferred to the rotor but if the bearing is that hot.. You are quite likely going to know it and you are quite likely now seized up.

Bosch brakes used on Workhorse and some other chassis units are noted for stiction.. In this case moisture builds up in the caliper piston.. Causing it to "Swell" a bit and size in the caliper chamber, this makes the brakes drag and overheat big time.

The heat drives the moisture out of the piston, As it cools it returns to normal size and ...... Once again works.

There are many fixes.. Bosch came out with a new piston and workhorse (Among others) issued a recall.

This same brake however, Has been used on commercial trucks, with no issues, for many years... WHY no problems with trucks.. normal operation generates enough heat to drive the moisture out before it becomes a problem is MY Theory.. You are welcome to come up with an alternate theory.. I won't argue.

I drive my motor home at least 60 miles every two weeks in the summer, 20 2 out of 3 in the winter and have not had that problem.


There is another issue.. This one bit me on a car

The brake hose is a multi-layer thing, SOMETIMES the inner layer can fail in such a way it becomes a one-way valve. Allowing brake fluid to enter the cylinder and engage the brakes, but not allowing it to return to the master cylinder and tank thereon. OF course sitting in your drive waiting for you to get to it.. It leaks back.

One of the most common problems is the parking brake. They are cable and the cable rust ect. Also they should never be set when parking long term as they will rust in place and not release. I think I would check into the parking brake cables for rust. Many can just be lubed and worked a number of times to free them up. But also could be the bearing,ect as others said. But if its a one time thing and you do set the parking brake every time you park I will lean to the parking brake cables.

Deleted double post

I never seen where you had a brake heating problem before.
But disc brakes always drag a little because there are no springs pulling the pads away from the discs like in a drum brake. This has always been a problem w/ disc brakes, sometimes causing squealing, squeaking, but in most cases causing no problems at all.

FYI, a disc brake caliper is,,,,,,or should be free floating on the pins, meaning that it is always allowed to center itself over the rotor, so that the pressure on each pad is always equal, also that the brake drag is also always equal. If one pad is worn more than the other, it will likely mean that the caliper is not floating freely, and will require cleaning and possibly some lubrication. (check shop manual) A caliper that doesn't float freely can also cause more brake drag, causing minor heating, especially if a front wheel bearing is not adjusted properly.......being too loose will cause the caliper to constantly move back and forth, possibly causing more dragging.....more heat.

If a wheel bearing was ever bad enuff to cause a brake problem, I would think you would feel it and hear it while driving.

Yes a bad bearing can cause the hub to get extremely hot and that will transfer into the rotor/drum. If you have the hubs off already, I would go ahead and grease or replace the bearings.

ScottnSherrie wrote:
Last summer I drove about 20 miles to a a campground. The left rear got so hot it boiled the brake fluid (temporarily lost the brakes) and they were smoking. Drove home by stopping every few miles for it too cool off. Checked the disc temp at each stop with an IR temp gun. It got over 400 degrees by time I got home.

I'm thinking of just cleaning and greasing slides on the caliper (they've been neglected) and replacing the break hose.

Probably just the parking brake.