How Hot Do Your Trailer Bearings Run?

[fishingfever]

I have packed and replaced my boat trailer wheel bearings and races. I'm confident the bearings were full of wheel bearing grease. The spindle nut was tightened down, the wheel turned a couple of times, and backed off to the first notch the keeper would lock onto so it isn't overtightened. The trailer has disc brakes. I've never had hubs run this hot. I have a digital infrared thermometer so my readings are pretty accurate. After a 25 mile test drive one side read 150 degrees and the other 158. You couldn't hold your hand on them for an extended period of time. I took it to the man that usually does my tire work and he thought it may be due to the disc brakes. This is the first trailer I've owned with brakes so maybe they do run hotter. Do anyone elses bearings routinely run this warm? Thanks for any responses, I'm heading to Canada next week and I'm a little paranoid.

[perchjerker]

Originally Posted by fishingfever

I have packed and replaced my boat trailer wheel bearings and races. I'm confident the bearings were full of wheel bearing grease. The spindle nut was tightened down, the wheel turned a couple of times, and backed off to the first notch the keeper would lock onto so it isn't overtightened. The trailer has disc brakes. I've never had hubs run this hot. I have a digital infrared thermometer so my readings are pretty accurate. After a 25 mile test drive one side read 150 degrees and the other 158. You couldn't hold your hand on them for an extended period of time. I took it to the man that usually does my tire work and he thought it may be due to the disc brakes. This is the first trailer I've owned with brakes so maybe they do run hotter. Do anyone elses bearings routinely run this warm? Thanks for any responses, I'm heading to Canada next week and I'm a little paranoid.

its the disc brakes

they run hot

[Hot Runr Guy]

unlike drum brakes, which have springs to pull back the brake shoes, disc brakes rely on an ever-so-slight amount of rotor "wobble" to push the pads back. If your rotors are true, and the bearings are adjusted so that there is no free play in them, then there really is nothing to push the pads back, so they can drag ever so slightly.

I'd jack the wheels up, and see if there is any back and forth movement. If not, I'd pull the cotter pin and loosen up the nut 1 more notch.

HRG

[perchjerker]

Originally Posted by Hot Runr Guy

unlike drum brakes, which have springs to pull back the brake shoes, disc brakes rely on an ever-so-slight amount of rotor "wobble" to push the pads back. If your rotors are true, and the bearings are adjusted so that there is no free play in them, then there really is nothing to push the pads back, so they can drag ever so slightly.

I'd jack the wheels up, and see if there is any back and forth movement. If not, I'd pull the cotter pin and loosen up the nut 1 more notch.

HRG

the seal in the caliper bore is a square cut seal

that seal design pulls the piston back ever so slightly

thats why they have square cut seals. The seal twists and causes the piston to retract.

Thats why you dont see o rings in calipers. An o ring would just roll in the groove and not cause the piston to retract

the reason discs run hotter is they generate a lot more braking force than drums do. This is because the surface area of the piston is much greater than that of a wheel cylinders pistons.

Larger surface area=greater stopping power=more heat.

[fishingfever]

I appreciate the responses, and I believe the disc brakes make them warmer, but are your hubs so hot you can't keep your hands on them?

[mrwalleye5]

Depends how often and how abruptly I apply my truck brakes and engage the surge brakes on the trailer. I experimented one time just to see if it was infact the disc brakes by slowing down well before having to stop and basically coasting to a stop. The hubs on all wheels were then basically the same temperature.

[REW]

To check to see whether it is an issue with the brakes or hub, just pop off the wheel and pull the pads off of the brakes.

Then, take the trailer for a 20 mile drive and measure the temperature of the hubs. If the hubs are still hot, you have an issue with the bearings being too tight.

Now, go ahead and put the pads back on the trailer and take it for another run. Recheck the temperature.

If the temperature is up to the aforementioned 150-180 degrees, you have brakes that are causing the heating.

The pads should not cause the hubs and wheels to heat up to that degree. You might open the bleed valve to remove any possible braking effect from the surge brakes and test again. The removal of the bleed valve will remove any braking pressure from the pads, and any pressure that you have is from the caliper itself during the relaxed state.

If you still have excess heating under this condition, you might consider replacing the calipers. Basically, when there is no braking going on, the calipers and pads should back back out so that they are just lightly touching the rotors and should give you minimal heating.

REW

[REW]

From a trailer's owners manual:

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http://www.walleyecentral.com/forums/Image1.gif
Trailering
• Immediately after trailering, periodically check the wheel hubs for excessive heat by touching the nose of the hub. It is normal for the hub to be very hot under normal conditions, warmer than is comfortable to the hand. Wheel bearings on trailers with brakes generally run a bit warmer than trailers without brakes. A good way to check for excessive heat is to compare the heat of the trailer nose hub with that of the vehicle hub, the temperature should be about the same.

[4JawChuck]

If your really worried you can always go out for a 20 min hwy drive and put the vehicle in neutral and coast to a stop...then check the hubs.

Easy way to get peace of mind.

[perchjerker]

Originally Posted by REW

To check to see whether it is an issue with the brakes or hub, just pop off the wheel and pull the pads off of the brakes.

Then, take the trailer for a 20 mile drive and measure the temperature of the hubs. If the hubs are still hot, you have an issue with the bearings being too tight.

Now, go ahead and put the pads back on the trailer and take it for another run. Recheck the temperature.

If the temperature is up to the aforementioned 150-180 degrees, you have brakes that are causing the heating.

The pads should not cause the hubs and wheels to heat up to that degree. You might open the bleed valve to remove any possible braking effect from the surge brakes and test again. The removal of the bleed valve will remove any braking pressure from the pads, and any pressure that you have is from the caliper itself during the relaxed state.

If you still have excess heating under this condition, you might consider replacing the calipers. Basically, when there is no braking going on, the calipers and pads should back back out so that they are just lightly touching the rotors and should give you minimal heating.

REW

never do this!! never remove the pads and use the trailer!!!

If you pull the pads off you run the risk of the piston pushing out and contacting the rotor and destroying the caliper and rotor. Every brake apply will make the piston move, it will have nothing to stop against and keep moving unit its eventually hits the rotor.

If you really want to see if the brakes are causing this heat (which they are) is activate your reverse lockout and drive it and see how warm they get.

If you really want to know about the heat generated by the disc brakes, feel the front brakes of your tow vehicle after towing for a few miles.

they will be just as hot or hotter then the trailer's I can guarantee you that.