Approx how many miles do you get on a set of bearings?

[profdant139]

I have a very small trailer -- 2500 lb, fully loaded. I get my bearings repacked and inspected every year. (Probably could do it myself, but I want some professional eyes on the hardware.)

I tow around 10,000 miles a year. We don't go much over 62 mph. We do a lot of very rough road travel -- on rocky forest roads --at very low speeds.

I had around 70,000 miles on my bearings. The mechanic did the annual inspection and said that the bearings were shot -- he showed them to me, and they were. So I got them replaced. Not cheap, but gotta do it. (This is the same mechanic who has taken care of my family's vehicles for 28 years -- honest as the day is long. Often tries to talk me out of needless repairs -- "those brakes have plenty of life left in them -- wait till next year on the brake job.")

My question is this -- assuming proper maintenance, roughly how many miles does a set of bearings usually last? Is the number lower on a single axle unit?
Should I replace them every 50,000 miles? I don't mind spending money for safety, but I don't want to spend money for no good reason.

Your advice and experiences will be greatly appreciated!

[Huntindog]

profdant139 wrote:
Huntingdog, this is one of those "woulda-shoulda-coulda" situations. Next time, I will know better. I am hoping that this thread serves as a wake-up call to anyone who has to replace the bearings.

That is what this forum is all about.
I will add one more thing in regards to shock loading.
IMO, the best thing to do is increase the axle size to get bigger bearings... I do not think this is your solution though. You appear to have more axle than you should need. and you are getting decent service from your bearings. Still, if you had some extra $$ and wanted to make it more bulletproof... It is an option.

Many TTs a built with axles that are barely legal. Those are the ones that can greatly benefit from an axle upgrade.

[profdant139]

Huntingdog, this is one of those "woulda-shoulda-coulda" situations. Next time, I will know better. I am hoping that this thread serves as a wake-up call to anyone who has to replace the bearings.

[Huntindog]

profdant139 wrote:
I have since learned that one can specify Timken -- who knew? Next time, that is what I will do.

Last I looked, Timken hade USA made bearings, and China made bearings. Your Choice. The was a large price difference

[profdant139]

I have since learned that one can specify Timken -- who knew? Next time, that is what I will do.

[Huntindog]

K-9 HANDLER wrote:

Huntindog wrote:

K-9 HANDLER wrote:
It may have been mentioned but bearing preload also plays a factor in service life. Obviously too loose or too tight is not good.
Had a farm wagon running gear from the 40s with original bearings up till last year. It was a gravity bin wagon which got drug around behind a corn picker for decades. Not alot of miles but hard off road service.

Bearing preload is a term sort of like doing an axle flip.... What it says is NOT what it means.
Axle bearings are NOT preloaded. They are adjusted to have a specified amount of FREE PLAY.
When they heat up expansion takes up the free play, so that the bearings operate at zero clearance.

The specified setup clearance can be set with a dial indicator, or by following the EXACT procedure in the axle manual.

Thanks for setting me straight. Timken does discuss "preload" (axial interference) in their manual for setting their tapered roller bearings.
https://www.timken.com/wp-content/uploads/2016/10/5556_Bearing-Setting-Brochure-1.pdf

Timken discusses setup of tapered roller bearings for various applications. One could get the wrong idea, by only reading part of it.
The following excerpt is IMO the most concise explanation of two different ways to set up bearings for two very different applications.

Timken on bearing setup wrote:
Generally, the ideal operating bearing setting is near- zero to
maximize bearing life. Most bearings are set with a cold setting
of end play at assembly. This comes as close as possible to the
desired near-zero setting when the unit reaches its stabilized
operating temperature.
Some applications are set with cold preload to increase
rigidity and axial positioning of highly stressed parts that
would otherwise be dramatically affected by excessive
deflection and misalignment.

The part talking about cold preload.... I have never seen this apply to a wheel bearing application.

I have seen it when rebuilding differentials. The gears are setup using roller bearings. But in this application, there is so much force that the differential housing actually stretches/deflects a little in use. If no preload is set at installation, then the bearings would be too loose.

[tomman58]

I have my bearings checked and greased as per Jayco's recommendation 12 months or 12 thousand miles. It isn't a big thing with me as after a year of trailering I put 12 to 15 thousand on my trailer. The dealer looks at all the important part and inspects brakes and many other things. For a few bucks I get told whats what and what is looking to fail.

[K-9_HANDLER]

Huntindog wrote:

K-9 HANDLER wrote:
It may have been mentioned but bearing preload also plays a factor in service life. Obviously too loose or too tight is not good.
Had a farm wagon running gear from the 40s with original bearings up till last year. It was a gravity bin wagon which got drug around behind a corn picker for decades. Not alot of miles but hard off road service.

Bearing preload is a term sort of like doing an axle flip.... What it says is NOT what it means.
Axle bearings are NOT preloaded. They are adjusted to have a specified amount of FREE PLAY.
When they heat up expansion takes up the free play, so that the bearings operate at zero clearance.

The specified setup clearance can be set with a dial indicator, or by following the EXACT procedure in the axle manual.

Thanks for setting me straight. Timken does discuss "preload" (axial interference) in their manual for setting their tapered roller bearings.
https://www.timken.com/wp-content/uploads/2016/10/5556_Bearing-Setting-Brochure-1.pdf

[Huntindog]

K-9 HANDLER wrote:
It may have been mentioned but bearing preload also plays a factor in service life. Obviously too loose or too tight is not good.
Had a farm wagon running gear from the 40s with original bearings up till last year. It was a gravity bin wagon which got drug around behind a corn picker for decades. Not alot of miles but hard off road service.

Bearing preload is a term sort of like doing an axle flip.... What it says is NOT what it means.
Axle bearings are NOT preloaded. They are adjusted to have a specified amount of FREE PLAY.
When they heat up expansion takes up the free play, so that the bearings operate at zero clearance.

The specified setup clearance can be set with a dial indicator, or by following the EXACT procedure in the axle manual.

[K-9_HANDLER]

It may have been mentioned but bearing preload also plays a factor in service life. Obviously too loose or too tight is not good.
Had a farm wagon running gear from the 40s with original bearings up till last year. It was a gravity bin wagon which got drug around behind a corn picker for decades. Not alot of miles but hard off road service.

[colliehauler]

profdant139 wrote:
oldwizard, my mechanic said this was unusual, too, and he is a very experienced trailer guy. I have to chalk it up to rough conditions, I guess. The wheels are 14 inch -- as big as I have room for -- and I am running Goodyear Endurance, fully inflated.

But the trailer bounces a lot on very rough freeways -- no way to prevent it -- and that is going to lead to "shock loading" of the bearings.

You could lower the tire pressure were the tire gives a softer ride as long as it's at or above recommended tire pressure.

[profdant139]

oldwizard, my mechanic said this was unusual, too, and he is a very experienced trailer guy. I have to chalk it up to rough conditions, I guess. The wheels are 14 inch -- as big as I have room for -- and I am running Goodyear Endurance, fully inflated.

But the trailer bounces a lot on very rough freeways -- no way to prevent it -- and that is going to lead to "shock loading" of the bearings.

[theoldwizard1]

profdant139 wrote:
I have a very small trailer -- 2500 lb, fully loaded. I get my bearings repacked and inspected every year. (Probably could do it myself, but I want some professional eyes on the hardware.)
.
.
.
I had around 70,000 miles on my bearings. The mechanic did the annual inspection and said that the bearings were shot -- he showed them to me, and they were. So I got them replaced. Not cheap, but gotta do it.

This seems unusual, especially if you have them serviced annually !

Trailer bearings are usually pretty cheap. Less than $30 (some less than $20) for inner and outer bearing and grease seals on etrailer.com.

[JIMNLIN]

Too many variables to say how long bearing will last.

I would add to other issues is a 2500 lb trailer is small and has small diameter tires/wheels = high rpm tire speed at 60-65 mph vs 16"/17.5" much taller tires.

All my single axle trailers were harder on bearings than multi axle trailers were. Brakes can boil the hubs so a 2500 tandem axle has more brakes making for a cooler hub. Then speed and driving style and how aggressive are the brakes set up can overheat hubs. And taller tires roll ride easier over those cracks/potholes/RR crossing/etc.

[profdant139]

Based on what I am reading here, I am going with rough roads. Not only do we tow on rocky forest roads, but we tow on California freeways, in very poor repair. Potholes and cracked pavement and mismatched expansion joints. "Shock loading," indeed.

Since there is no way to avoid this (without moving out of state!), I will just have to be vigilant and proactive.

[colliehauler]

Huntindog wrote:
If you ever look at a bearing diagnosis chart, you will see pictures of bearings that are on their way to failure... The interesting thing is just how many different causes are listed.
Everything from Improper setup, lubrication, overloading, shock loading (rough roads). and others I cannot recall at the moment. At any rate, such a chart and its pics can determine pretty much what went wrong. Not all of the causes are attributable to improper setup or lubrication.

I doubt it would be much help though after a failure has occurred.

As for the expense, IF you got some american made bearings, it is justified. The chinese ones are really cheap.... I am not going to get into the quality aspect, other than to say it appears to be inconsistent. Many bad reports, and some good ones.

Spot on.