Servicing wheel bearings

Submitted: Monday, Apr 07, 2008 at 20:01
ThreadID: 56415 Views:3102 Replies:12 FollowUps:8
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I had my camper van serviced a few weeks ago and have not used it since then. Today I started to get it ready for a trip and noticed that the cap was missing from one of the axles. There was gobs of blue grease over the nut and end of axle. I went back to the company (without the van) and asked for a replacement. It occurred to me that they were servicing the bearings by simply packing the dust cap with grease. They denied this and say that they do it properly by removing the hub, cleaning, repacking etc etc AND they fill the cap with grease to help with heat dispersion. When I got home I fitted the two new caps without the extra grease. (and some difficulty due to a nasty lip on the new caps). What do the experts think?

Kingo
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Reply By: DIO - Monday, Apr 07, 2008 at 20:09

Monday, Apr 07, 2008 at 20:09
M'mmm that's interesting. I was always taught that the cap was in fact a dust/moisture cap designed to keep foreign matter out - not to hold a reserve of grease.
AnswerID: 297256

Reply By: Member - shane (SA) - Monday, Apr 07, 2008 at 20:20

Monday, Apr 07, 2008 at 20:20
i think i would check that the bearings were indeed repacked, i don't know of any mechanic these days that packs the dust caps with grease. from what i understand this was an old practise when the quality of the grease left something to be desired, as the grease heated up it would draw the reserve in from the cap. the washes nowadays is to big to let grease in/past it and today's grease will no flow anyway.
AnswerID: 297259

Reply By: splits - Monday, Apr 07, 2008 at 20:26

Monday, Apr 07, 2008 at 20:26
After working for a few car dealers years ago and servicing countless wheel bearings, I have found that the caps that don't have grease in them, or nuts that have been washed clean during servicing and have not had more grease smeared on them, usually have plenty of rust the next time you take them off.

The same applies to the surface area inside the hub between the bearings. I have seen many with rust in there as well.

Brian
AnswerID: 297260

Reply By: Dave B (NSW) - Monday, Apr 07, 2008 at 20:39

Monday, Apr 07, 2008 at 20:39
Not sure I agree with the heat dispersion argument.

As has been stated, the washers are pretty big now so the possibility of heat getting transfered across that very small opening around the washer would be pretty slim I reckon.

It's just a waste of grease as far as I am concerned.

I use Moreys Red on my bearings and they run really cool, and the Red sticks like that stuff to a blanket.

Dave
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AnswerID: 297268

Reply By: Member - Phil G (SA) - Monday, Apr 07, 2008 at 21:14

Monday, Apr 07, 2008 at 21:14
If I can just relay what my knowledgeable FIL said to me years ago.

Trailer bearings usually rust out with time because of water or condensation getting in. Easiest way to stop water or air getting in is to pack it full of grease.

Cars are different. The hubs get very hot because of the brakes are used every day, and this tends to keep the water out, so they don't often rust. Also car bearings don't sit around for months waiting for the next trip.
AnswerID: 297277

Follow Up By: Member - Kingsley N (SA) - Monday, Apr 07, 2008 at 21:22

Monday, Apr 07, 2008 at 21:22
Thanks fellas. A few different opinions seem to prevail.

Phil, your argument seems logical. I just have to trust that they actually did what they claim to have done.

As I said to the caravan service manager, if my Dad had seen me doing that to the old FJ, (after he had taught me to do it properly) I would have lost my driving rights for weeks!

Kingo.

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Follow Up By: Angler - Monday, Apr 07, 2008 at 21:25

Monday, Apr 07, 2008 at 21:25
Phil,

This is particularly important with boat trailers, My old dad always put plenty of grease in the available space, he always said grease was much cheaper than a failure on the track.

Pooley
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Reply By: Member - David P (VIC) - Monday, Apr 07, 2008 at 21:29

Monday, Apr 07, 2008 at 21:29
years ago I read a technical article relating to the repacking of wheel bearings,and I remember it said that if you over-pack the cavity it would actually cause overheating causing the grease to flow away from the bearing causing bearing failure.....silverback
AnswerID: 297281

Follow Up By: Ozboc - Monday, Apr 07, 2008 at 21:58

Monday, Apr 07, 2008 at 21:58
not with todays Greases , some claim to have any heat / no liquid properties - , meaning your bearings will be glowing white before the grease liquifys (if at all ) then disperses - i have not seen this as yet - but have to presume truth in advertising.

as for packing the dust cover - it may be a waste of grease , but who will honestly be stingy enough to say that 30 mls of grease is an unexceptable waste of grease ? also , if this space is occupied with grease , it makes water and dirt ingress into this area a lot harder than if it was not packed with grease.... when you correctly pack bearings using the palm of your hand to force grease into the races - you will probably waste the same amount of grease that would be in the dust cap anyway ....

Another thing to think about is that providing you have a good seal in your cover - then once the grease heats up - it will expand , thus forcing its way into your bearings where an air pocket may be present , almost acting like the mechanical greasers you see on machinery with a preloaded spring and adjustable dispenser.

some machinery ( inc some new machinery ) still use a simple dust cap that you pack with grease and screw on to "inject" grease into bearings .... i have not seen these bearing produce excessing heat ? and this is going into a machine worth about $150 k ( one of the cheapest machines by far i have to maintain)

everyone will have a theory - greasing is not brain surgery --- having more grease than less will not create excessive heat - its a lack of lubrication that will produce heat ... grease often if in doubt - look for tell tale signs such as grease that goes off colour in a very short time ........

Boc
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Follow Up By: Member - David P (VIC) - Monday, Apr 07, 2008 at 22:40

Monday, Apr 07, 2008 at 22:40
check out TBF TECH - repacking wheel bearings....silverback
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FollowupID: 563313

Follow Up By: Member - Phil G (SA) - Monday, Apr 07, 2008 at 22:50

Monday, Apr 07, 2008 at 22:50
David,
I think the technical article is true of vehicle bearings, but doesn't matter on trailer bearings because they don't get as hot.
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Follow Up By: Member - David P (VIC) - Monday, Apr 07, 2008 at 23:08

Monday, Apr 07, 2008 at 23:08
yea, guess not. i used to think if 5oz was recomended 10 must be better.....silverback
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Reply By: Member - Graham H (QLD) - Tuesday, Apr 08, 2008 at 07:46

Tuesday, Apr 08, 2008 at 07:46
Why not filick a wheel off and have a look at the bearings. Will soon know if they were done properly and then u can rest easy.
Will only take half an hour and then you will know how to do it next time they need repacking.
AnswerID: 297321

Reply By: Dunaruna - Tuesday, Apr 08, 2008 at 08:24

Tuesday, Apr 08, 2008 at 08:24
If the cap is filled with grease, the grease is compressed when the cap is tapped on. An increase in temp can pop them off.

No grease in cap. The guy servicing your bearings is misguided.

AnswerID: 297329

Reply By: obee - Tuesday, Apr 08, 2008 at 08:58

Tuesday, Apr 08, 2008 at 08:58
this reminds me of caps with a grease nipple added. You used to see them on boat trailers and they came with a theory attached. I dont want to get into a discussion however.

I just check the trailer bearings every year and do whats neccessary. I have seen too many trailers on the side of the road with wheel off.

Owen
AnswerID: 297338

Reply By: Gronk - Tuesday, Apr 08, 2008 at 09:57

Tuesday, Apr 08, 2008 at 09:57
Trailer bearings don't get as hot as the car ?????

My last two have........electric brakes ...going down a long mountain pass...sure do get hot !!

Latest one....disc brakes....still get hot when asked to do some work !!!!

Sure you can pack the dust cover if it makes you feel good, but as said, it can't make its way to the bearing..
If you are worried about moisture getting in, I would be more worried about the rear seal..
AnswerID: 297347

Reply By: MEMBER - Darian (SA) - Tuesday, Apr 08, 2008 at 17:44

Tuesday, Apr 08, 2008 at 17:44
My Campomatic has the big HD hubs with the big bearing caps (as you can see I can't recall the size - but they are bigger :-o)....I always pack the caps with grease when servicing - even if that isn't done, every metal surface in there should have a good coating of grease on it, because as the others have said, moisture will get sucked in on water crossings and then it gets on with it's dastardly corrosion - on a 3 month trip, I had a bit of minor cap corrosion when I got home - and they had been full at the start - when I do fill them, the caps often let a bit of grease seep out over the first few days - can be a little unsightly (easy to wipe off) but I know they are full - and they haven't been heating up while running. Works for me............. I carry spare caps, seals, bearings, nuts and grease as well. It may be industry practice not to fill caps, but hey.... I didn't know that :-o).
AnswerID: 297397

Reply By: Member - Roscoe ET (QLD) - Tuesday, Apr 08, 2008 at 18:49

Tuesday, Apr 08, 2008 at 18:49
Have a look at this site: http://www.rverscorner.com/bearing1.html
AnswerID: 297410

Follow Up By: Member - Kingsley N (SA) - Tuesday, Apr 08, 2008 at 22:27

Tuesday, Apr 08, 2008 at 22:27
Thanks Roscoe,

That's just how my dad taught me to do it!

I can accept some of the advice above with reference to putting some grease inside the cap to prevent moisture getting in. The new caps were very difficult to drive home. In fact I used my Dremel to smooth the outer surface before they would fit.

Kingo
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FollowupID: 563480

Follow Up By: Member - Roscoe ET (QLD) - Wednesday, Apr 09, 2008 at 13:56

Wednesday, Apr 09, 2008 at 13:56
Kingsley,
That's how I was taught as well by my father-in-law who was a mechanic. You're right about those caps they can be a challenge!!
as a matter of interest I use Nulon Xtremel tacky stuff and seems to really stick to the rollers
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FollowupID: 563549

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