Trailer Bearings; How Hot is to Hot

[dicko1980]

Hi Guys,

I just replaced the bearing and seals on my 5m Dunbier Trailer and am a little concerned on how much heat buildup there was in the hubs after road testing at a 100km/h highway run. I jacked the axle up and checked the wheels for freeplay and drag, but they were fine. My concern is that I am shortly planning on towing my boat from Townsville to Karratha/Dampier, so I need to know that I won't be let down on the side of the highway. I haven't overpacked the hubs with grease and it was of a proper spec for the job. So how hot should hubs be to touch after doing a few km's at highway speed?

Cheers
Dicko1980

[FNQCairns]

Hi Dicko IMO too hot is when the oil in the grease which is contained in the base carrier separates so the grease starts to leak so to speak, the bearings are all metal so they can run at relatively high temperatures OK but not I guess preferable.

They might be simply bedding in and producing a little extra heat.

We were forever at every stop checking the temperature of bearings on a 2.5tonne + setup and they at high speed and a hot day got quite hot but not enough to melt the grease, it's hard to put a value on say 60-70deg? at times but didnt cause a failure.

Does your trailer have brakes? did you check straight after pulling up?

edit: If you are really worried pull them and check for discolouration, I always overpack, still yet to see a problem from it like people say happens, I suspect the problem with overpacking is actually the bearing or job not the quanity of grease.

cheers fnq

[INTIMIDATOR]

Hey Dicko
I'f you carn't touch em , that's tooooooooooo hot!
You carn't over pack them, thing's like bearing buddies keep them full so when you put your hot wheel's /bearing's ect under water at the ramp metal cool's and shrink's , so it suck's in the grease instead of water.
If you replaced your bearing's and seal's i hope you took the time to replace the cone's that the bearing's sit in inside your hub.This is not a nice job and sometime's the "she'll be wright mate" approch come's in play!
The only other thing that may heat them up is if you have done your castle nut up too tight,these little babbie's only need to be firm enough to stop the wheel from knocking when it's jacked up.EG quarter of a turn past finger tight.
Hope this help's as that's not a good feeling setting out and wondering if the wheel is about to fall off!!!
Cheer's Payney

[trueblue]

When doing up the axle nuts (Castelated nuts - with split pin slots) you should do them up until you can no longer feel freeplay when you rock the tyre sideways.

Then:

Back the nut off to the next slot in the nut for the pin. Wheel bearings will always overheat if they are too tight. There must be some slight freeplay in the bearing.

"Finger Tight" isn't a good way to measure tightness of a nut. Routinely the nuts and axle threads are slightly damaged, and a little tight as a result. You must check freeplay by rocking the tyre sideways. Better to be slightly loose rather than tight.

Cheers

Mick

[dicko1980]

When doing the wheel bearings today on the trailer I was assisted by my brother who is a diesel fitter. The bearing were not tensioned to tight as we have checked freeplay and hub drag. It just seemed a little surprising that the hubs were a little hot. It was a hot today in Townsville and and the hubs didn't seem any hotter than the tyres.

[trueblue]

Should be fine then

[Angla]

I'd go with the fine thing too.

They will get hot to touch but not hot enough to burn with a short touch. It's a judgement thing.

Chris

[Black_Rat]

If you place the back of your hand on the hubs and can hold it for a couple of seconds it should be fine. I have a Dunbier trailer for a 5.4m boat and when have checked after a run usually are only very warm to touch.

It's probably a silly question but did you physically force grease into the bearings ? ie: get your hands dirty and push the grease with your fingers inside the bearings ? I only ask because sometimes people will just coat them on the surface without pushing the grease in and this would lead to overheating.

[Noelm]

one thing that can 'trick" you is under rated or under inflated tyres, if they are too light for the job, they will get very hot and after a period of time, will heat up the hub assy as well, I once had a big boat with those 6.00X9 velox wheels, did a long trip once and the tyres got so hot, it melted the tube to tne tyre, I found the only way to run them was to inflate to about 50PSI to stop the flexing in the tyre wall, was not too bad after that.

[dicko1980]

The bearings were packed with grease by hand the proper way, which is very messy. As for the tyres, they are the original tyres that came with the trailer. Thanks Dunbier for supplying two tyre of different tread patterns and brand name. The tyres are chinese rubbish that will be replaced with light truck tyres before I leave. The tyres are also going to be inflated with Nitrogen, so they run cooler.

Thanks for the help guys

Dicko1980:D

[Noelm]

light truck tyres the ONLY way to go, dunno about the Nitrogen thing though, but I guess "why not" going to be hard to reinflate tyres further 'down the track" though, not a lot of Nitrogen compressors at servos that I have noticed!

[Roughasguts]

Good question, Bearing are to hot at 177deg C or 350 deg F that's when the special purpose greace fails designed by timken.
Timken say bearing should not exceed 300 deg F or 150 Deg F for precission bearings.
Don't seem to be much info on it, but double the ambient temp for the bearings seems to be the sweet spot.
Of course the braked bearings will run hotter, by maybe 50% or more.

[Juzo]

too hot is when you hear a big BANG, and your bearing buddy gets fired off across the road followed by the mess that was your bearings..................at least that's how I found it :)

[Roughasguts]

Now that's another thing bearing buddies, Timken don't seem to recomend heaps of grease under presure, and no where to go.
(guess thats bearing buddies under pressure, filling a void so no air then no water)

I use bearing buddies but don't do long distances, wonder if there not recomended by timken. Wondering do Timken make a product similar to bearing buddies.

[Y-Not]

My bearing buddies 'leak' grease if I try to force too much into them this has been the way since I got them and was told by the trailer people that this is how they should be. They said some of the cheaper imatations dont Leak this excess grease but they didnt seem to think that was a real issue anyways.

[ozbee]

mate your bearings are fine your living in the tropics not like brisbane they have a heat wave and all you see is pictures of them at the beach. try standing in sand up here in middle summer be blistered in ten seconds. see what im getting at most tyre failure up here is from heat build up from the road. have done the trip to darwin a few times from townsville towing my boat only thing to be aware of after a trip usually the outer tread will start to come away the heat hardens the rubber so really doesnt matter whether you use a cheap chinese or better trye tried both much same results bin them after 24 months. leave a few barra have a great trip also i used bearing buddies the inner seal is desgined to stop rubbish getting into the hub grease will push out with very little pressure. one fill one round trip . good guide remember open highway speed pee on hubs at pee stops steams fine crackling noise beware . good fishing.

[Luc]

Even after a long trip, my trailer bearings have never been too hot for me as to be unable to confortably hold my hand on the hub.

I use bearing buddies and have had no problems.

Luc

[Roughasguts]

Hi ozbee, always wondered after marking your hubs at rest breaks, does that stop the dogs from marking there territory.

If it works I know what i'm doing this weekend with a carton of beer.
Might stop them crapping on what use to be me front lawn.

[toolman2810]

Me thinks any hot is too hot, if you can feel your bearing cap is hottet then ambient temperature. Then I don't think they will last too long

[Roughasguts]

Don't think thats right there Toolman.
Any bearing or friction surface will build up heat more than ambient temp.
Also any heat from brakes, tyres, will sinc into the bearing eventually.

[ozbee]

good point roughasgouts maybe vb to keep vic dogs away xxxx for qlds . a little information from a old fitter whos greased a few bearings in his time from babies to ones that weigh more than your boat and dreams. grease has mainly two properties one is to hold oil for lubrication second is bascially soap to hold it in suspension otherwise it would all run out. have you noticed that wheel bearings seem to get to a certain temp then stay the same day or night running this is not by accident a lot of science and money is spent by oil compaines developing greases for a wide range of enviroments .eg bearings on conveyors running inside furances. this is where the soap compenent is so important goal is as the bearing face heats up the grease absorbs heat and that soap becomes less vicous this allows fresh grease and oil to fall into the bearing surface as the hotter oil and grease flow out it will re solidify so in fact you create a venturi affect moving oil though the bearing alas best lubrication as it goes round and round . more grease is not better a bearing housing should contain one third grease two third air this is the recommened. do bearing buddies help not really only that we drive in dirty dusty conditions as most bearings fail from dirt getting in usually through back hub seals so if u keep pushing grease through slows the time for dust to reach the bearings.