Wheel Bearing OR Brake Failure?

[davideh]

In the last year we have had two wheel bearing failures on our Flagstaff Classic Super Light 5th Wheel Trailer (2007). Our tow vehicle is a 2007 Toyota Tundra four wheel drive (5.7 liter engine) with a Pullrite SuperGlide hitch. Wheels are pulled, inspected and the bearing repacked once a year.

Both times the failure occurred on the curbside, but was different wheels. Heavy smoke was observed and the wheel was hot. Luckily there was no fire and neither the wheel or tire were damaged. The bearings and brakes were trashed.

The repairs involved replacing the brakes, brake hub, and bearing. In both cases the spindle was cleaned, the spindle groves cleared and new parts installed.

The first failure was called a bearing failure although I did not question the techs for details. But the technician repairing the second failure said it was a brake failure. The tech's reasoning was that the insulation was chafed at the opening into the hub, shorted the hot wire causing the brakes to engage, over heat then fail the brakes and damage the bearing.

I saw the damaged parts in the second failure and the brakes were totally destroyed, but the bearing would still rotate (badly).

My questions:
1. Is the wire chafing a possible cause and have others observed this problem?
2. Are wheel bearing failures common and what are the typical causes (besides lack of grease and overloaded)?
3. What additional inspections / maintenance might stop these failures?

Davideh

[doughere]

Just get a new mechanic. His explanations leave me wondering if he knows what he's doing.

Over 35 or so years I've never had a bearing or brake failure(gobs of tires, plenty of other minor disasters, but no bearing or brakes). Having two failures is WAY past normal.

Doug

[Learjet]

for the folks that don't believe, I to got some grease on a pad once and it was never the same, even after much cleaning...it was GRABBY.

It is true!

[eHoefler]

In actuality, oil or grease in the brakes can and does cause a brake to heat up and on occasion, cause a wheel to lock up. With the intense heat of braking and the brake dust, the oil/grease will turn into a tar and cause the brakes to grab and stick to the drum. Eventually causing the wheel lock up and/or catch fire.

[ScottG]

Hybridhunter wrote:
The above post makes no sense at all, for many reasons, but anyhow.....
I concur with the above posters; find a new mechanic, quickly.

I assume that was directed at me;
When one of my brakes got saturated with grease it was running at nearly 200 degrees while the others were around 110. The only problem was the grease and once it was removed (in a NAPA parking lot) the wheel returned to a normal temp for the remainder of the trip.
Just because you don't understand or have experience with something doesn't mean it isn't true.

[Hybridhunter]

The above post makes no sense at all, for many reasons, but anyhow.....
I concur with the above posters; find a new mechanic, quickly.

[ScottG]

fj12ryder wrote:

ScottG wrote:
(snip)
Or, some one is utilizing the EZ lube system and loading up the brake shoes with grease which makes them run increasingly hot .

Would you please explain that statement? You may cause a grease leakage by improper greasing of an EZ Lube system, but how will "loading up the brake shoes with grease" make them run hot?

If anything it will keep them cool by reducing friction when you try to use them. 🙂

I've actually experienced this. If a bunch of grease gets on the shoes it causes a lot of drag and even though it's grease, it gets hot.
The odd thing is the brakes still grab good when they have grease on them. I'm sure it's not as good as being clean but they do grab hard.

[chuggs]

davideh wrote:


My questions:
1. Is the wire chafing a possible cause and have others observed this problem?
2. Are wheel bearing failures common and what are the typical causes (besides lack of grease and overloaded)?
3. What additional inspections / maintenance might stop these failures?

Davideh

1. No...wire shorting would cause less braking...depending on your controller...you will get a fault message. Is it possible that your breakaway switch has been accidentally pulled?/ or faulty?

2. Not with regular maintenance.

3. If the breakaway system hasn't been active for some reason...I really cannot offer much. You say it's been on the curb side both time...has it been the same axle?

If it's only been one spindle...then that would draw my attention next.

Personally, I would start by picking a pet axle...replace both brake assemblies, install new Timken bearing cones and races as a pair, new quality double lipped grease seal...remove ALL the old grease. Get NEW grease and pack those bearing FULL of grease with a packing tool... Dexter axle has a list of recommended grease... I believe AL-KO just recommends a NGLI #2 with Lithium based soaps...and a minimum drop point of 400 degrees F. Don't mix greases...pick one of the recommended greases and stick with it. Follow the mfg. instructions for proper sequence for tightening the axle nut. Adjust the brakes following the mfg. instructions. Now...when you start towing...make a stop occasionally. Go back and put your hand on the axle hub...are they all running cool...do you have a hot one? Is it your pet axle or the other one? You have to figure out how to pinpoint the location of the problem...if there is one.

Do your axles become submerged at all?

I'm kinda at a loss...because carefully serviced axle hubs, done on an annual basis, that don't get submerged in water --- have NEVER been a problem that I know of. If someone puts in cheap bearings...or under-rated bearings...over tighten or under tighten the axle nut...you can start to have problem...but you're looking at catastrophic problems.

[fj12ryder]

ScottG wrote:
(snip)
Or, some one is utilizing the EZ lube system and loading up the brake shoes with grease which makes them run increasingly hot .

Would you please explain that statement? You may cause a grease leakage by improper greasing of an EZ Lube system, but how will "loading up the brake shoes with grease" make them run hot?

If anything it will keep them cool by reducing friction when you try to use them. 🙂

[Jayco254]

That wire shouldn't be hot until the brakes are applied either at the tow vehicles petal or the breakaway switch, which you might want to check.

[ScottG]

The brake guy doesn't know what he's talking about . If the hot wire shorts to ground then it most assuredly WILL NOT engage the brakes.

My guess is whom ever is servicing your bearings is not setting them up right - few really know how to do it right even though they do it all the time. Most adjust them way too loose and that makes heat.

Or, some one is utilizing the EZ lube system and loading up the brake shoes with grease which makes them run increasingly hot .

[coolbreeze01]

Sounds more like tech failure than equipment failure. Good luck finding a competent shop.

[powderman426]

kaydeejay wrote:
Might want to ask your tech about that "Hot" wire!
There is no such thing at the hub until the brakes are applied, at which point you WANT them to work.
Rest of the time the wires are either ground or zero volts. Nothing to short there.
So I'm calling B.S. on his explanation!

If it WAS an overheated brake that caused the problem, then it was due to mis-adjustment (too tight) causing them to bind.

Agreed. It could also be from not leaving enough play in the bearing.

[kaydeejay]

Might want to ask your tech about that "Hot" wire!
There is no such thing at the hub until the brakes are applied, at which point you WANT them to work.
Rest of the time the wires are either ground or zero volts. Nothing to short there.
So I'm calling B.S. on his explanation!

If it WAS an overheated brake that caused the problem, then it was due to mis-adjustment (too tight) causing them to bind.