Wheel bearings

Submitted: Sunday, May 27, 2012 at 17:05
ThreadID: 95840 Views:2471 Replies:7 FollowUps:4
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Hi,

Just after some quick advice.

I had my camper serviced on Friday, they checked bearings and commented that they were perfect and did not need repacking with grease as current grease was ok.

I took it away for the night last night and on the way home today I stopped for fuel at a servo and thought I would check the hubs for heat, I found drivers side stone cold and passenger side warm ( not hot) it has electric brakes which they serviced as well.

Is slight heat ok, should both be cold or both be warm, not just one? Should I go back to get that bearing rechecked or not worry as it is normal?

David
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Reply By: okane - Sunday, May 27, 2012 at 17:28

Sunday, May 27, 2012 at 17:28
Hi David

G'day, There is something wrong, either one brake is not working or one wheel bearing is too tight. To check what is operational turn the brake controller to zero and take camper for a run. Check wheel bearings for heat. With the brakes one is still warm, it could mean one wheel bearing may be too tight or other bearing too loose. Jack up wheel and check there is no play in the wheels. If not the problem, the electric brake system may need adjusting. Good Luck
AnswerID: 486908

Follow Up By: David16 - Sunday, May 27, 2012 at 17:38

Sunday, May 27, 2012 at 17:38
Thanks Okane,

I felt the brake cover and it was cold so I don't think the heat was transferring from the brakes, the heat was on the small domed bearing cover.

I might run it back to 4x4 place that did the service so they can check it as they did say they slightly adjusted the bearings, as it was a camper I would say junior did the job! Maybe just a bit tight?
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Reply By: Member - Serendipity(WA) - Sunday, May 27, 2012 at 18:18

Sunday, May 27, 2012 at 18:18
When servicing bearings the preload is not an exact science and one may have a slight more preload than the other which might mean one runs a bit warmer.

I generally will check my tyres and bearings after about half an hour of running or 50kms. If they are too hot to touch I have an issue. If they are warm that is ok as to expected with friction.

Also if your camper is loaded with a water tank on one side and a bit heavier that side it may cause that side to warm up a bit more. I had an issue where a trailer was loaded on side and it sat a couple of inches out that way due to the leaf springs being compressed more one side and moving the axle back a bit.

Warm is Ok but too hot to touch is an issue. Trailers with little use can go years without service. It only is an issue if you have done water crossings or lots of dust.

Serendipity


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AnswerID: 486916

Follow Up By: David16 - Sunday, May 27, 2012 at 18:39

Sunday, May 27, 2012 at 18:39
Thanks Serendipity,

When I checked it it was after about 50 km, yes the passenger side was only warm, not hot, the drivers side was cold. The camper does have water tank but it was empty, it does have the kitchen and fridge on that side so that may be the factor as you suggested.
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Reply By: Michael ( Moss Vale NSW) - Sunday, May 27, 2012 at 20:16

Sunday, May 27, 2012 at 20:16
I had the same thing with my old off road trailer axle and now a new alko electric brake axle, still does the same only the opposite side. I asked my cousin who owns a caravan repair and service centre, he said he encounters the same problem with many vans and trailers. He cant offer any explanation as he treats all the axle service the same. Running a little warm is ok.. The drivers side on my trailer now is stone cold and the passenger side is only warm.. Michael

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Follow Up By: Axle - Sunday, May 27, 2012 at 20:55

Sunday, May 27, 2012 at 20:55
Mike ...Dunno about wheel Bearings!, But .That explanation reminds of a old married couple in bed .....lol.



Cheers Axle.
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Follow Up By: Michael ( Moss Vale NSW) - Monday, May 28, 2012 at 06:42

Monday, May 28, 2012 at 06:42
You are probably right Axle!! LOL!! Michael
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Reply By: Smiley Bill - Monday, May 28, 2012 at 09:25

Monday, May 28, 2012 at 09:25
Hi David16,

Warm should be fine. Extra weight on the passenger side of the trailer can have a effect on the temperature of bearings as well as the camber of the road.

SB
AnswerID: 486974

Reply By: trains - Monday, May 28, 2012 at 10:34

Monday, May 28, 2012 at 10:34
From my background as a mechanic, I have seen alot of discussion, and missunderstanding regarding wheel bearings in both trailers and caravans.

As they often sit for prolonged periods of use, and are used occasionally, time can go by and the owner forgets that its been quite a few years since they were last looked at.
Worst case, the grease has dried out, and you only have the wax paste with little oil, or lubricating properties in it.
Or its been subject to water and has rusted.

Ok, normal wheel bearing service in a car is around 20 to 40 000 depending on the make, but is often neglected,a nd thus full bearing replacement was often the only way forward.

So you can begin to see that some trailers are way over serviced to their car that tows them, and can be neglected.
Often the cause of failure.

So if the grease is still fresh, free of contamininates and good for use lets move onto the adjustment of them.

Most often, it was taught to wind up the nut tight to "seat" the bearings, ie make sure any grease that was cusioning the bearings when first packed and assembled was not going to give you a false feeling of tightness.
And then back off, spin hub, and then nip up to either minimal slop to the first nut flat to allow for the split pin, or some said to tighten up and preload the bearing to the next flat for the split pin.
Some trailers have only the nut and its 6 sided, so there is quite a range between each flat of the nut to enable the split pin to secure the nut.
In some cases, its far better to have some movement in the bearing, than tighten up further to the next flat and overtighten the bearing with too much preload.

Just this can give different hub bearing temps.

Also slight brake drag can give differing temps, as well as previously mentioned weights.

Some bearings have a locking collar for the split pin that fits over the nut, enabling more accurate setting of the nut.

Some bearings are designed for a certain amount of preload, where as others are ok with some slight movement.

Ideally, just tight enough to take out any movement, with minimal preload is the best rule of thumb for most if you dont have the specific specs available to you for your make and model.

Ok, now for how much heat is too much.

Bearings will get warm/ hot, its just a fact that they will.
What is normal operating temp?
Rule of thumb, is that if its too hot to touch for more than 5 seconds, its near or over 50degC.
Up to that is pretty much ok, Thats pretty much the hottest you want it to get, and to some, that feels too hot, if its radiating heat, and burns you as soon as you touch it, its too hot.

yeah, real scientific I know, but you will get warm to hot bearings, and there designed to run warm.

Hope this helps clear up some grey areas of wheel bearings :).

Trains

Ps, remember that front wheel bearings in cars often operate at much higher temps due to the heat soak from the disc rotor, or drum.

Thus in the early days when disc brakes arrived, high temp wheel bearing grease was required, pretty much all wheel bearing grease is high temp rated now, at least in the auto scene.



AnswerID: 486978

Reply By: MEMBER - Darian, SA - Monday, May 28, 2012 at 11:04

Monday, May 28, 2012 at 11:04
Hub temperatures commonly vary in my experience - if you have a hot hub centre with a much cooler outer drum, then you know it is bearing, not brake. It is easy enough to pop the cap off, take the pin out (replace with a new one is a good idea) and back off the castle nut - half a flat even can make a cool change to the bearing).

As for bearing servicing - it takes time and is a bit messy - you might need to tell them you want it done next time (and with new seals)...... :-o).
AnswerID: 486982

Reply By: David16 - Monday, May 28, 2012 at 17:22

Monday, May 28, 2012 at 17:22
Thanks for the feedback everyone,

David
AnswerID: 487013

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