Trailer bearings - hub full of grease or not?

[Seppo BNE]

Wondering what the consensus is (if any!) on trailer bearings and packing the hub full of grease.
Heard 2 completely different opinions from guys who work on trailers : RWC guys and professional trailer repair guys....

1) Pack the housing full of grease - water has nowhere to fit in, so less corrosion.

2) Just pack the bearings - don't bother with excess grease.

Both kindof make sense, but, what do you do?

Another thing was that bearing buddies were supposed to become illegal sometime?
Due to excess grease being pumped through and flinging out onto discs and reducing braking effectiveness.
- VMR (forget which ones) were apparently getting rid of them due to that?

Seppo...

[Marchy001]

I'm 6 months into a trial on my used and abused Chinese bearings (18 months old at start of trail). Outboard gear oil and wheel bearing grease mixed to a custard like consistency. Dust cap stuck on with retaining compound as with the inner seal insert. Filled void between the bearings with the goo before fitting outer bearing and filled dust cap prior to fitting. Bearings packed with grease as per normal.

Average hub temp at port servo car park with standard grease 48-55 deg c. Average hub temp with weird concoction 35-40 deg c. Measured with IR thermometer.

It's messy if you get the mix too thin and also rather messy when disassembling but so far I'm pretty happy with the trial.

To be honest didn't think it would work but so far so good.

[Out-Station]

Pack the bearings with standard bearing grease. Use standard caps and marine seals, use Loctite 515 when you press the steel marine seal into the hub, same on the cap. Put the hub onto the axle with the rear bearing in it, before you put the front bearing onto the axle use an oil syringe to put about 15ml of heavy gear oil into the hub whilst you hold it level to stop it running out. Put the front bearing etc and cap (sealed with 515). Works a treat, oil and grease forms a slurry in the hub and works back into the bearing continually. Works for me anyway.

Scott

[Smithy]

When I had my Stabi I put Durahubs on. I thought they went well as did my pro mate who had them on his cat. The clear glass allowed you to maintain a visual inspection of the oil.

[Rip it up]

Another plus one for the dura hubs. There is a reason semi trailers run oil filled hubs.

But the rear seal area must be installed perfectly. Speedy sleeves and adhesives must be used.


Damo's dodgy boat building repair shop.

[ShaneC]

Problem is if a seal fails on a dura hub the whole thing heats up and flogs out before you know it has even happened. I have changed more bearings than any human should ever have to in a lifetime on the side of the road but since I built my new trailer with 3 tonne bearings its been good. I have come to believe that too much grease is not enough. A mate of mine who does 1770 a couple of times a month with a big boat on average has not touched a bearing in five years using the same theory.

[scottar]

I subscribe to the full of grease means no room for water theory. I have never had an issue touch wood.

[Crunchy]

Always found bearing buddies very good just don't over pump, only enough to have the plate wobble, not enough to drive it out to the edge of the buddie or you do risk the back seal.

[Seppo BNE]

Thanks for the replies so far.. I hadn't heard of thinning the grease with oil.. Nor durahubs, will check them out!..

After 6 or so trips on a new set of bearings done at roadworthy, one of the rear bearings was already full of milky grease after the service.
The inner slipring? on the hub that rubs on the rubber was the wrong size and was spinning freely in the hub, where it's normally solid in place.
I had a spare hub set ready to swap over and just did that. It got me wondering though on the rear seal as well.
I greased it up and put it together, but it looks like it's free to spin on either the hub side and the axle side.
It looks like it's designed to have the seal fixed and the rub strips on the hub side rubbing. (Is this right?).
Adhesives were mentioned above?.. do you glue the seal to the axle with something to stop it spinning?

[Marchy001]

Yeah I stick the rubber to the axle too. Any oil resistant sticky stuff that I find laying around the toy box gets the job. Hardest part is sticking stuff and working with oil/grease at the same time. If possible I let the the rubber seal sit glued for a few hours before reassembly.

[gazza2006au]

Good topic this one

i've never encountered a bearing failure and i have towed very long distances one trip took almost 24 hours of pretty much non stop driving in NSW

i have always thought the theory of filling the hub with grease would under G force feed the bearings grease especially on highways doing 110kph the centrifugal force would push the grease to the outer hub than feed it into the bearings as needed by pressure but the rear seal and front caps would lock in the excess grease from pushing out

make sense?

i always fill the hub haha ;D

[aussiebasser]

Had the Stratos 9 years now. 3 sets of tyres. Still running the original bearings. Bearing Buddies, don't overfill.

[ozscott]

Bearing Buddies with Timkin or similar good quality bearings and you cant go far wrong.

Cheers

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[tunaticer]

Drill and tap the hub between the bearings and fit a stainless grease nipple.

[gofishin]

I use Durahubs, or their equivalent, but hubs not filled with oil, just grease. They also allow me to easily prime the grease nipple, tapped into the stub axle. Best part is the clear window gives a nice quick visual indication of what's going on inside.
Cheers
PS. There is a 2" Durahub on the side of the road heading north at the Anzac Ave exit - if anyone wants it. Might have a dent in it though, as it hit the concrete wall hard I am told :) .

[Feral]

My opinion is it is just a waste of grease.
Marine seals, just pack the bearings as normal. Check the temperatures regularly after a long run, if you don't have to, don't back the hubs under cold water whilst still warm, that is the most likely time you will get water in the hubs. (Regardless of whether they are full of something or not, as the contents (be it air oil or grease) will tend to shrink as it cools creating a small vacuum).

[Scalem]

Always found bearing buddies very good just don't over pump, only enough to have the plate wobble, not enough to drive it out to the edge of the buddie or you do risk the back seal.

You and Aussiebasher have it right, that's what I do, six years since my Dunbier was new, lazy hubs ( 1st to go in water ) are still original set, had to replace front rotors due to rust so they are newer, about 4 years now. I Touch hubs after long drive and Luke warm temp tells me they are still good, I take the bearing buddies off every 6 months or so to inspect, grease is not milky so back on they go without disturbing or blowing dust onto the grease. All good!

Scalem


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[FNQCairns]

I dont use any of the trendy stuff, used BB for a while and they where ok. over 30 odd years of boating reasonably often I have not had a failure and i have done all my bearings myself, surgical cleanliness is the go when fitting, I pack full most of the void full of grease and use a lot of time filling the bearing before fitting and also pack the region between the rear seal and rear bearing till chokers and keep a reasonably thick finger smear of grease at the back of the hub/seal where it meets the axle to ward away potential rusty areas spreading inside the lip of the seal as that has caught me out before as I had to change the axle or potentially not get my 6 years out of the new bearings.

Oh on packing hubs, if a bearing starts to go and this heats the hub past normal op temp, poorly packed hubs have less than 1/10th the watery now leaking/oily grease running around (literally) to keep a level of lubrication happening...the oil in the grease was used up hundreds of km ago in the dryer packed hubs and the bearing has been running metal on metal with only the clay filler component of the grease ever since...guess which one will probably make it home.....on average if tested.

[Fed]

Here's my take for what it's worth...

All seals leak, it's impossible to get a perfect seal on a moving part.
The best defense against water is to have the hub completely full.
The only way to completely fill a hub is with bearing buddys.
If the seal isn't weeping then the hub is not full.

My before and after bearing maintenance which took 30 Seconds with a rag.

110873

110874


Now here's a picture from a guy who reckoned he had a perfect seal and also used bearing buddys.

110875

My response was, "Your hubs are not yet full".
He still doesn't believe it... *shrug*

[BAR UP]

I pack mine full and use bearing buddies. My other practice is I replace my bearings every xmas so I know when I did them. 99% of the time they are perfect when I change them. I then recycle the 12 month old bearings into my box trailer and bike trailer. Pretty good turn around and get good useage out of them.

[littlejim]

I used to go through bearings after a couple of outings. Always the bigger inner bearing. Despite bearing buddies. However bearing buddies make the perfect hub cap.
Then I started packing the inner seal (ribs) with grease as well as packing the bearings.
The bearings last for years now.
I usually try to clean and repack them once a year but doesn't always get done. (You can see how things are working if you have a shoofty every now and then.)

[Seppo BNE]

Thanks for the replies!! - will keep on top of the bearing buddies with grease and see how things work over time :)

The finish on one axle flange was pretty poor so might end up tidying that one up next time it's off for checking.
Will also repack the hubs full of grease - more the merrier I reckon! :)

Durahubs/oil hubs maybe coming when I slowdown spending on the boat itself!! :) :)

[Fed]

If you're running the old moving seal type then fit speedi sleeves to it.
http://www.skf.com/au/products/seals/industrial-seals/power-transmission-seals/wear-sleeves/skf-speedi-sleeve/index.html

[Scalem]

So if I can ask a stupid question. How do you know if the hub is completely "Full of Grease"???
If you travel that close to the line, one more pump of the grease gun and oops, that's too much now as the grease has popped the inner seal and you may as well start again. Bearing buddies have springs to compensate for the increase and decrease of internal pressure caused by temperature fluctuation. If the hub is too full of grease there will be little room for the spring tension on the backing plate to perform to the way it is designed. I think of it as a shock absorber, the internal design is to cushion impact. Too much grease will inhibit the cushioning of the positive ( when hub warms up while travelling) and negative ( sudden cooling off as the hub enters the water) pressures. When I pack hubs and bearings I probably half fill the hub with grease, no more, so that the air in the hub will help with expansion and contraction as the BB is designed to do.

Scalem

[littlejim]

My inner bearing seals let water in.
Found it hard to believe they would not let air (compressed by bearing buddy or heat) out.
However I guess if you have jagged bits with perfect tolerances you might be lucky. I wasn't.

[scottar]

. When I pack hubs and bearings I probably half fill the hub with grease, no more, so that the air in the hub will help with expansion and contraction as the BB is designed to do.

Scalem

Only issue with that theory (and I don't know the answer) is which one has a greater volume change due to temperature fluctuation. I know air changes volume considerably - put a bit of hot water in a milk bottle, put the lid on and give it a shake - it blows up like a balloon and then sucks back down when it cools. Does anyone have any idea on the volume change with grease over a typical thermal range of a bearing???

[Scalem]

I doubt grease changes in volume as it increases in temp and even if it does it would not be more than air to help with the design of the BB which should keep a positive pressure inside the hub.

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[gofishin]

... Bearing buddies have springs to compensate for the increase and decrease of internal pressure caused by temperature fluctuation... And therein is the way they are designed to work Brian.

Any 'pressure', whether +ve or -ve, arises from a change in density of the grease due to temperature changes, and hence the volume 'it wants' to occupy within the hub. Air compresses easily, grease does not - hence (too much grease) popping off inner seals.

The BB/hub is recommended to be charged with grease so that the spring is compressed by half; no more, no less. This then allows the spring to compensate for density/volume changes with the grease, (+ve and -ve), compressing or retracting the spring as required.

'If' I only wanted to half fill my hubs, I would use dust caps (but that's just my opinion). Done this in the past, but then moved on to B/B's, where I used them as above (full hubs, 1/2 spring deflection - wouldn't use them any other way)... but moved on again and would use neither of above again (unless I had to).

If you're happy with how you do it, and more importantly it works well, that's all that matters so just go fishing/boating and enjoy it :) .

Cheers
Brendon
PS. Next meeting is the 2nd Monday (12th Oct), due to public hol, and there is gear/tackle for sale, so bring $'s if you are coming :)

[gofishin]

I doubt grease changes in volume as it increases in temp and even if it does it would not be more than air to help with the design of the BB which should keep a positive pressure inside the hub.

Sent from my HTC_0P6B6 using Tapatalk see previous post (and yes I am a slow thumb typer, so you replied while I was typing :) ). If you have air in the hub, BB will probably not keep a +ve pressure. It is not designed to seal air, only grease and (hopefully) water. The spring (when used properly) gives it a small +ve pressure due to spring force.
Cheers

[scottar]

So assuming that grease won't change or has a minimal change in volume due to temperature in comparison to air, if you don't want your hubs to suck water past the seals when you dunk them after warming them up ( None of us would sit at the ramp long enough to let them cool properly when we are cracking our necks to get going) then to me it makes sense to fill the hub as best possible with grease through whichever means you choose - manual packing or bearing buddies as against only greasing the bearings and leaving a large volume of air that will contract on cooling and create a suction - sound theory????

[Scalem]

Good thought but notice I said I half fill the hub with grease not totally. Most hubs or BB will lose a small percentage of grease during normal use so topping up via the grease nipple is a good practice occasionally but you need some reserve space for grease. If you pump more in when it's already full, thats when you start popping inner seals and dust caps and can actually lose bearing buddies if they have not been a tight fit.

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[Fed]

So if I can ask a stupid question. How do you know if the hub is completely "Full of Grease"???
Scalem I pump the BB up then spin the wheel until the BB relaxes, then repeat MANY times until grease starts to weep from the rear seal.
I guess there could be bubbles of air still inside that will come out sooner or later but I think it's pretty much all grease.
I got 10 years out of my last bearings before I scrapped the trailer and they still felt perfect, my current trailer is on about 5 years and so far so good.
Other than a little grease pump up maybe twice a year I never give them a thought, same as car wheel bearings they seem to last forever.

Edit: Hard to pop marine seals when they rest against a 45mm square axle and my non genuine BBs have a bleed off hole in the side to limit compression.
I'd like to get genuine BBs but if it ain't broke......