wheel bearings maintenance

[Carol H]

Originally Posted by Raz

That's what you get for going to the dark side.

I thought I went to the VERY Shiny side!

[kcburro]

I am usually a very light user. About 200 miles monthly, not in winter. New axle, upped tires to 14" in late 2014. Just finished first long trip, 1400 to Black Hills. Maybe it's time for a repack?

The cap on the hub on drivers side has disappeared, grease all dirty. Picked up a cap from local trailer service that supplied the Dexter axle. "That'll fit." It didn't. Looks like it should, it is just a hair big, literally. but even a whack with rubber mallet didn't do it. Is there a trick I'm missing?

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[Raz]

Originally Posted by Carol H

I thought I went to the VERY Shiny side!

Touche'

[Raz]

Originally Posted by kcburro

I am usually a very light user. About 200 miles monthly, not in winter. New axle, upped tires to 14" in late 2014. Just finished first long trip, 1400 to Black Hills. Maybe it's time for a repack?

The cap on the hub on drivers side has disappeared, grease all dirty. Picked up a cap from local trailer service that supplied the Dexter axle. "That'll fit." It didn't. Looks like it should, it is just a hair big, literally. but even a whack with rubber mallet didn't do it. Is there a trick I'm missing?

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I use a small piece of 2" PVC pipe to drive mine in. It fits on the lip. That avoids dents. Might be worth taking the other side off and compare to check the size.

[Paul O.]

Originally Posted by Raz

I use a small piece of 2" PVC pipe to drive mine in. It fits on the lip. That avoids dents. Might be worth taking the other side off and compare to check the size.

That is an ideal way to mount them. They are spin formed out of thin sheet metal and are actually designed to be "a hair too big", as kc described it, so that they go on tight (a heavy press fit). When seated, their thin wall conforms to the diameter of the thick wall steel hub.

[Joe Romas]

Anyone ever heard of "fretting"?
I've seen the beginnings of it on SIX sets of bearings on my 17' Casita.
See photo #1
Fretting | NSK

While searching for a thread that shows and explains it I found many references to it on many different brands of travel trailers including Air Stream.

Don't bother about setting up free play or greasing, I've been over it all.

Joe

[redbarron55]

Sometimes with roller or tapered roller bearings that have too much grease the rollers won't roll but get bound in the cage and slide.
If a motor that has an axial drive (no belts) has a roller bearing in the output end this will result since the bearing has no load to make the bearing rollers turn.
In this case the proper bearing would be a ball bearing instead.
We have to make certain that the motors we install have the proper bearings for the application or this might result.
Often the cage makes a high pitches screeching noise when this has progressed.
The trailer bearings will always be loaded, however and this should not be an issue.
It is possible that the bearings are over greased and the grease did not clear on initial use and the rollers did not initially turn.
A bearing should not be packed more than approximately 1/3 full to allow the grease to be pushed from the races and not have this problem.
Over forty years I have seem almost as many problems from over greasing than under greasing.
However you pays your money and takes your pick.
Since you said not to give advice as the worrying about preload etc, I won't

The other reason for fretting is the trailer or bearing during shipment or if it is mounted in a high vibration and the bearing sits in one spot while shaking.
This can be brinelling or false brinelling.
Here is a link to the SKF PDF in this subject.
http://www.skf.com/binary/86-62751/R...estigation.pdf

This is a good reason to maintain bearings, but an important thing is to clean and inspect the bearings even when replacing to detect any sign of distress.
This is a major part of my work in preventative maintenance and in determining the cause of any failure or incipient failure.

[charlsara]

It is nice to hear from an actual expert on this subject. It is amazing to me how many opinions we hear on this subject.

An interesting thing happened were I work. We have some 6 wheel drive concrete trucks. Most commercial trucks have wheel bearings that run in oil. This one has greased bearings on the steer axle. The manual says to repack the bearings every year or 12,000 miles. It is an all day job to do so. We made a decision to run them until one failed. That was several years ago. We are still running them.

I had a Suzuki Samurai that after 27 years I got around to rebuilding the front end. The bearings had never been touched. They looked fine but I replaced them because I didn't want to tear it down again.

Just to be safe I repack my trailer bearing every three years. They have never looked like they needed it.

Just my two cents worth . If you like to repack wheel bearings every six months go for it. 👍


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[Roy in TO]

Originally Posted by redbarron55

Here is a link to the SKF PDF in this subject.

Off topic humour,
As a kid I passed a SKF building everyday on the the way to grade school. One day I asked my Dad what SKF stood for. Knowing that Svenska Kullagerfabriken was a mouthful for a young one, my Dad replied Spoons, Knives and Forks. I spent a chunk of my life thinking they made cutlery before finally learning they made bearings.

[Borrego Dave]

Originally Posted by charlsara

It is nice to hear from an actual expert on this subject. It is amazing to me how many opinions we hear on this subject.

An interesting thing happened were I work. We have some 6 wheel drive concrete trucks. Most commercial trucks have wheel bearings that run in oil. This one has greased bearings on the steer axle. The manual says to repack the bearings every year or 12,000 miles. It is an all day job to do so. We made a decision to run them until one failed. That was several years ago. We are still running them.

Agree with you on opinions but do have to say a bearing or what ever that does break on a concrete truck makes a big mess. Don't think I would have voted for that test especially being on the steering axle. That's just another opinion .

[Paul O.]

Well, this has turned into a great engineering discussion. I just bookmarked the thread to come back to it. My experience with bearings in previous life was in disk drives and the sizes were from 60mm bore spindles to 3mm bore carriage/arm. In our case the cleanliness of parts, including bearings was paramount. Some videos on trailer bearing maintenance that I saw on Utube are a total turn-off, showing some guy taking the bearings out and laying them down on a dirty floor/ground. We should remember that the more the bearings are taken apart and reassembled, the higher the probability of failure caused by contamination. This needs to be done meticulously and in a clean place. To those who do not do it themselves, I would say, look for the shop with the best reputation, that you can trust.

[steelypip]

Originally Posted by Paul O.

We should remember that the more the bearings are taken apart and reassembled, the higher the probability of failure caused by contamination. This needs to be done meticulously and in a clean place.

Quoted for truth. The one set of wheel bearings I ever replaced for damage on anything was because of grit.

A little too much grease probably won't hurt. A little too little grease probably won't hurt. A piece of grit or dirt in the bearings will reliably result in badness and you will have to replace bearings and races.

My SOP for bearing repacking involves a roll of cheap paper towels. I use them to wipe dirt away before removing anything. I use them to wipe excess grease away. I use them to put the bearings on. After washing the bearings and races (I've used both brakleen and carburetor cleaner), I use a fresh paper towel to wipe the bearings dry and wipe the softened grease off, and then set them down on a clean paper towel until they're repacked and ready for installation.

Yes, I've also used nice, kitchen-grade paper towels for this, but as they're really single use, the cheapies work fine and are less waste.

I've never had any problem with contamination since I've started doing it this way. I suppose I picked up the idea from doing carburetor rebuilds on a few sheets of newspaper with a roll of paper towels handy for wiping and holding jets and small parts.

[charlsara]

Originally Posted by steelypip

Quoted for truth. The one set of wheel bearings I ever replaced for damage on anything was because of grit.

A little too much grease probably won't hurt. A little too little grease probably won't hurt. A piece of grit or dirt in the bearings will reliably result in badness and you will have to replace bearings and races.

My SOP for bearing repacking involves a roll of cheap paper towels. I use them to wipe dirt away before removing anything. I use them to wipe excess grease away. I use them to put the bearings on. After washing the bearings and races (I've used both brakleen and carburetor cleaner), I use a fresh paper towel to wipe the bearings dry and wipe the softened grease off, and then set them down on a clean paper towel until they're repacked and ready for installation.

Yes, I've also used nice, kitchen-grade paper towels for this, but as they're really single use, the cheapies work fine and are less waste.

I've never had any problem with contamination since I've started doing it this way. I suppose I picked up the idea from doing carburetor rebuilds on a few sheets of newspaper with a roll of paper towels handy for wiping and holding jets and small parts.

That is an excellent method. I do that myself. However I am prone to use Bounty!!

[redbarron55]

You might just want to keep a spare set or sets of bearings greased in a good baggy and when you feel the need install them. Clean and inspect the old ones and put them in the bag.
Carry the bag for a set of road spares.

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[Carol H]

Originally Posted by redbarron55

Carry the bag for a set of road spares.

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Good advise as a girlfriend found out when one of her trailers wheel bearings failed in a fairly low populated area you should not expect the local mechanics or shop to carry the bearings and seals you need.

She lost 2 days of her 4 day vacation waiting for UPS to de'v the right parts to where she broke down.