Bearings heating up after change.

[reelfishin]

Re: Bearings heating up after change.

I don't think it's so much a matter of "How tight" as to just not have any excess play. A properly adjusted bearing which is properly lubed will gain only minimal heat during normal operation. I just came back from 90 mile run with my one trailer, the bearing caps feel no warmer than the rest of the trailer. The only heat noticeable to the touch is in the tires themselves after a 70 mph ride for three hours or so.
The bearings have no looseness detectable. I normally just tighten the bearings to hand tight, or the point where all play is out, then go to the most accessible position on the castle nut. If it's closer to the last one, I turn it back, if it's closer to the next opening, I tighten it slightly.
You can also vary the adjustment a bit by swapping the castle nut as a different nut often gives you a better option for the cotter pin. I keep a box of old nuts for this reason.

The damage from looseness comes from impact and the lack of load distribution, especially on a heavily loaded trailer run on rough roads.
Regardless of what various manufacturers say, whether it's for their own protection or to simplify instruction, the method I've been using for so many years has worked fine.

Bearings don't generally get tighter with heat, everything expands together, including the hub and bearing bore. This is the reason for so much preload on both rear axles and differential bearings. The lack of preload there will create catastrophic failure in short time.

 

[CatTwentyTwo]

Re: Bearings heating up after change.

I took an auto repair class at our local community college in the early 70's and this is how the instructor told us to do it. After packing the bearing with grease, he used a 12" Crescent wrench to tighten the nut and then spun the wheel a few times. He then backed the nut off until loose and with the handle of the wrench at about 2:00, he just let the weight of the handle tighten the nut. Hardly scientific, but I have never had a problem with our cars or trucks doing it that way. Our boat trailer and travel trailer came with the castle nuts with 6 slots for the cotter pin. It always seemed like the nut would be to tight or way to loose. I purchased the nuts with 12 slots and they make it a lot easier to get a good setting.

 

[xxxflhrci]

Re: Bearings heating up after change.

After reading this thread, you guys have me afraid to pull anything out of my driveway for fear of catastrophic bearing failure. I don't have the vast experiece of some here. I only have been towing trailers for about 20 years. I have a 1974 camper, 1976 boat trailer converted into a utility trailer, and a 1985 boat trailer. The first two still have the original bearings. The boat trailer had the original ones until a year or two ago. I blew out the bearings in a hub due to my own ignorance. I went to blasting on the wheel with a pressure washer to knock off some loose paint. I figured the Bearing Buddies and their protectors would keep the water out. Wrong. I washed all the grease out and had a failure in about 30 miles. Anyway, I always just greased 'em, tightend the nut snug, and backed a bit makeng sure the hub didn't rattle back and forth endways. I figure my attempt at doing the right thing probably would keep me off the side road with troubles. I'd guess most of the guys on the side of the road broken down are the ones that never grease the bearings at all. In the event, if my attempts to do right are wrong, I always carry a spare set of bearings just in case.

 

[reelfishin]

Re: Bearings heating up after change.

..... I'd guess most of the guys on the side of the road broken down are the ones that never grease the bearings at all. In the event, if my attempts to do right are wrong, I always carry a spare set of bearings just in case.

I picked up a free boat and trailer today which had been sitting over 40 years. Pumped up the tires, gave the bearings a shot of grease, hung a tag on it and headed home. It made it about half way when I heard the jingling sound of a loose hub. Not having a spare and not really being too worried about a rusty trailer, I continued along, just a little slower than normal. The bearings had disintegrated and left the hub spinning on nothing but races, the bearing buddy had fallen off and was gone, and the grease had splattered all up the side of the boat. I continued on another 15 or so miles and took all back roads. It made it home without losing the wheel. The castle nut and cotter pin prevented the hub from coming off. There was enough grease in there which prevented it from turning blue. When I got back, I spun off the nut, pulled the wheel and hub and the bearing races came right off. I popped in a set of use bearings for now so I can move it around but it somehow survived. I think if it had tossed the wheel, I'd have just left pulled my tag and left it wherever it died, I had nothing but my time and gas in it at that point and had already pulled the motor and electronics out and put those in my truck. The boat hull is the only value that was left. The trailer was badly bent and rusted out, and the tires were so badly cracked I could see cords showing between the cracks. The only other choice would have been to drag it home without the trailer or with only one wheel. There was no way I was paying a tow truck to haul a junk boat trailer home. A patrol car came along after a bit and followed me most of the way back keeping traffic away in case the wheel blew off in traffic. The wheel actually stayed on better while moving, when I stopped it flopped way over to the outside. The spindle showed no damage, but not that it matters, the middle of the axle is rusted more than half way through. The bearing gave out on a hard turn, around a traffic circle at about 30 mph, at least that's when I first heard it over the radio and wind noise.
It could have been going bad even soon into the ride but it didn't start squealing and rattling till after about 15 miles at about 50 mph.

 

[j_martin]

Re: Bearings heating up after change.

To pre-load a bearing, the bearing has to have a finish smooth enough, and be in a carrier machined accurate enough so that it doesn't overload in small areas and spall. I doubt there is any boat trailer hub that could take any but the lightest of pre-load, and to be safe, should have a thou of free play.

A thousanth or 2 of freeplay, with the film strength of anything you would put in a wheel bearing for lube, isn't going to experience any measurable amount of impact damage.

I'm not a trailer expert, but I do work with bearings. We have some tapered roller bearings that we pre-load to tons, and can turn them with your fingers. A boat wheel similarly pre-loaded would lock up immediately.

I would be comfortable with anything from a slightly noticable free-play to a foot-pound of "pre-load".

BTW, if you look at a new cotter key, you'll notice that one leg is longer than the other. Cut the short one off with a side cutter so that it just protrudes through the spindle and interferes with the castle nut, put the cotter key in the axle with the long side facing you, and bend it over the end of the axle. You will never have any interference problem, it will hold as well as any other way, and it will come out easily.

That's the way the "old timer" taught me to do it back in the 60's sometime.

hope it helps
John

 

[ron7000]

Re: Bearings heating up after change.

I think the trailer, auto, and bearing manufacturers know what they are talking about.

check this out. http://www.tiedown.com/abearing.html

on the left see "wheel hub kit instructions" which is here
http://www.tiedown.com/pdf/a125.pdf
which says: #7 Wheel should turn smoothly with no end play or wobble.

now read the bearing service TSB which is here
http://www.tiedown.com/pdf/c808.pdf
which says: objective: target is 0.001"-0.005" of endplay between spindle and hub.


what is your definition of endplay?
and what is it's relation to bearing preload?

 

[Nandy]

Re: Bearings heating up after change.

Wow, this is getting interesting. Maybe a thread on "how to install bearings" needs to be started.

 

[reelfishin]

Re: Bearings heating up after change.

Without the wheel installed, you will not likely 'feel' .001" to .005" of end play, but you may feel some wheel wobble with the wheel installed on the upper end of that spec. I would assume a lot of this has to do with the lower grade of bearings available lately. Even the last Timken lot I had were imported.
I've had lots of trouble with some of the lower end bearings lately, mostly with them just being soft. I had one race bend while removing it with a punch. The older bearings were much harder and were more likely to chip than bend or dent.
This would make not having any excessive free play most important, but it also makes installation procedures more critical. A softer bearing surface or race will not tolerate any significant preload any more than it can take impact without 'denting' by the rollers. It goes back to the old way of putting it, "Not tight, but not loose". They want zero clearance but not any preload or tension applied.
A problem arises when the adjustment relies on a castle nut, one slot or space can be more than .005" of end play worth of adjustment. I normally just swap out the nut or add a shim or washer to change the setting.

Attention should also be paid to the rear bearing seating area on the spindle as it can exhibit wear from movement if run with excess end play over time. A sign of wear here is a bearing that won't tighten far enough or rubbing of the grease seal on the next level of the axle or back flange.