Trailer bearings - sealed or open ?

electrosys

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I'm currently renovating a dinghy trailer and have just turned my attention to the hubs and bearings. The existing bearings are open deep-seat ball-bearings (not tapered roller), and one inner bearing felt a bit rough - until I removed it, and now it feels alright (typical ...).

The inner of the two bearings relies on a plasticky seal which is fitted to the hub to keep the muck out, which looks a tad worn, but I dunno where to get a replacement.
In order to improve the sealing, I was thinking of fitting a sealed inner bearing and removing one of it's rubber seals, leaving the other in place to complement the existing worn seal.

And then I thought - hang on - why not fit sealed bearings (fully intact) instead of open bearings anyway ?

So - thought I'd sound out your opinions re: sealed vs. open trailer wheel bearings. (not planning on immersing the trailer, and pumping grease into the hub on a regular basis etc.)
 

Neil

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Google trailer parts and you'll find that hub/bearings complete are little more than sourcing bearings alone.

Except if you take the bearing No.s to a bearings supplier, you get will get them for a fraction of the price a trailer parts supplier will charge.

I looked into stainless bearings (I dunk the trailer hubs each trip). I needed to order 500 sets in my size..........
 

electrosys

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Except if you take the bearing No.s to a bearings supplier, you get will get them for a fraction of the price a trailer parts supplier will charge.
That's quite true - but there's more to it than that: the hub package deals invariably contain dubious quality Chinese bearings - I much prefer to use SKF or Timken, even if they are expensive. I find with bearings, you tend to get what you pay for.
I looked into stainless bearings (I dunk the trailer hubs each trip). I needed to order 500 sets in my size..........
What size do you need ? If I see your size on my meanderings, I'll PM you.
 

Lakesailor

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(not planning on immersing the trailer, and pumping grease into the hub on a regular basis etc.)
So cheap bearings will not be any problem then. Boat trailers don't knock up a load of miles.

I found that bearings for a 4 wheel trailer I had were £11 each set for cheap ones (which lasted at least 3 years and were still good when I sold it) or £90 a set from a Barrow-in-Furness supplier ("We supply nuclear submarine bearings so you won't get better than that")

Your choice of course.

Too much grease can cause problems as well. Particularly failed grease seals. When you assemble bearings you should put just enough in to fill the cages.
 

Neil

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I haven't had my new trailer bearings out yet, but I think the hub is exactly the same as my old trailer: a 203 mm Hub (part No. ISBR061), with 4 x M12 wheel bolts on a PCD of 139.7 mm.

Bearings to fit are :
Inner, Part No.s 67048L and 67010 for the bearing and cup, respectively
Outer, Part No's 44649 and 44610 for the bearing and cup.

These No.s are universal and can be bought at any bearing supplier. When I last bought bearings, Indespension UK quoted £45 stg for a bearing set for one wheel. Bearing King in the UK quoted 22 stg for the two bearings - for their high quality range. The same with their 'budget' range worked out at £10.00 stg for the pair....... Given that the life of even the best bearing is limited when it's dunked in sea water, there's probably no harm in going cheap and replacing regularly.....

The Superhub seal (ISHU045) is extra - I haven't seen this from a general supplier yet, but from the bearing size: Dimensions - d (inside diameter) 31.750mm Dimensions - D (outside diameter) 59.131mm. Anyone knowing of a non-trailer parts supplier that does this seal might let me know - its £12 stg each from Indespension.
 

electrosys

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Too much grease can cause problems as well. Particularly failed grease seals. When you assemble bearings you should put just enough in to fill the cages.
Using Ebay as a source, Timken 6205's can be sourced for around a fiver each, or a 'no-name' brand - presumably from China - for a little over a pound each. This morning whilst washing out the remaining grease from the old bearings, I reflected on the precision with which bearings are made - micron machining tolerances using the finest steel etc., and wondered how anyone can make such precision items for a quid each ? And of course, that pound includes profit margins, storage and transport ... I reckon a fiver for a quality bearing is a bargain, anything less is absurd.

This business of too much grease is interesting - which reminds me, my motivation for posting was to discuss the engineering merits (or otherwise) of fitting sealed bearings instead of open, rather than becoming overly pre-occupied with the economics of bearing replacement ...

My current hubs have 2 x open bearings separated by a sleeve, which is a slide-fit onto the axle. The sleeve effectively forms the inside of a cavity, with the hub itself forming the outside of that cavity, with the bearings forming it's two ends. Even if the open bearings are pre-packed with just a modest amount of grease, it is expected that the user will, in due course, fill that cavity with a grease gun using a nipple which is fitted into the hub - the cavity holding something like 1/2 a golf ball's volume of grease. So in practice, there's no way of limiting the amount of grease deployed. Could this then be a case for using sealed bearings ? Indeed, this brings me to my central question - why are sealed bearings not used on lightweight trailer wheel hubs in preference to open, as such bearings are supposed to be maintenance-free ? I sense there may be a good reason, but as yet I don't know it.

Neil - I'l keep a weather eye out ...
 

rotrax

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Hi, IMHO it will depend on the use you give your trailer. If, like me, you immerse the wheels and then pull it out and park it, use cheap bearings.If however you are prudent and careful and immediatly hose them of in fresh water and then dismantle and regrease them use top quality ones that will last for years. Some time ago I had a Johnson 3.5 outboard. It had gone in the sea and the bearing under the flywheel and ignition had rusted out. When running it sounded like someone dragging a gas stove up a cobbled street. I pulled it in pieces and enquired the price of a Johnson spare part. £48.00 plus VAT! It had a tiny roll pin to hold it in position so the outer race did not rotate. I found a Honda 125 motorcycle wheel bearing in stock of the same dimension, double shielded.I removed one seal, used Locktite and put it back together. Still working perfectly five years on.The bearing used can be found anywhere in the UK for under £6.00 retail.I probably paid half that. I am a fan of the homespun philosophy that says an engineer is a man who can make for a shilling what anyone can get for a quid! Whatever route you go, Good Luck.
 

Neil

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Could this then be a case for using sealed bearings ? Indeed, this brings me to my central question - why are sealed bearings not used on lightweight trailer wheel hubs in preference to open, as such bearings are supposed to be maintenance-free ? I sense there may be a good reason, but as yet I don't know it.
..

I'm not familiar with your particular set up, but the perceived wisdom of sealed bearings (and I don't know this for a fact) is that you can't keep the water from getting in, but that the seals stop it getting out again, to their detriment.

I know of posters who pump in grease through the bearing saver nipples after every trip, but I find that the grease (and I've used a few brands) gets very runny after a decent trip and then runs down the backplate.
 

electrosys

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Well, I don't intend dunking the trailer and had finally decided to fit Timken sealed bearings - until I read:
http://www.electronicsweekly.com/bl...ms/2007/04/bogus-bearings-look-more-real.html

So it seems there are genuine Timken (SKF, ZKF etc) bearings, and then there are Ebay 'Timken' bearings - and it's almost impossible to tell 'em apart by eye. Added to which, many reputable bearing manufacturers are having their products made in China, India and elsewhere, so the country of manufacture isn't necessarily a useful guide to quality.

So - sod it - I've ordered a 10-pack of China's finest (sealed) and will carry a spare set in the glove compartment, and see how they go.

Thanks for all your words of wisdom.
 

davey

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Sealed Bearings vs Non Sealed

Re boat trailers and bearings. A common dodge is to have a cup of tea before launching the boat. There are two good reasons for this, #1 is that it allows the hubs to cool, #2 is that it refreshes the driver ready for the task ahead. Next dodge is to pump a few shots of grease into each hub before dunking the trailer. If one employs "Bearing Buddies" (tm) or lookalike products a spring loaded plunger will maintain a positive pressure in the hub. With trailers that use classic Mini hubs there are other dodges, #1 is to carry a spare hub complete with new studs and wheel nuts. This is extremely affordable and can save one hundreds of pounds or even the complete outfit. ( boats and trailers are often stolen whilst their owners are away trying to get a wheel bearing - pikeys with crane-equipped lorries) Dodge #2 is to use threadlocking compound on the wheel nuts. This is most important on the left hand side of the trailer because "precession" will attempt to undo the nuts. ("Precession" is the reason why bicycle pedals have opposite handed threads). If slightly longer wheel studs are used the nuts can be double-nutted using a Nyloc nut on the top. "Sealed" bearings are not a good idea for boat trailers as once water gets in it will never get out. Stainless steel bearings are also highly suspect as their load carrying capacity is inferior to that of traditional bearings.

Note that the police are usually extremely eager to radio for a tow truck. The reason is that they typically charge £50 or £100 just for radioing for the truck! (not many people know this) Just recovering one to a lay-by a couple of hundred yards away will often end up costing over £200.

PS In the UK it is fairly easy to get double lip "agricultural" grease seals to suit classic Mini hubs. Just take the hub or the old seal to an industrial bearing stockist such as Wyko or BSL-Brammer (both firms are excellent and my only connection is as a highly satisfied customer) The outer lip keeps the dirt and weather outside and the inner lip keeps the grease in.
 
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gus

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Alternative thinking

Why do so many boaters think that it is necessary to immerse the trailer wheels? I have trailed and launched various boats without wetting the trailer at all. It all depends on having the right set up with greased rollers and a winch. I once launched and recovered an 16' Orkney Longliner from the canal bank which was 2' above the water level. With the right set up the boat will literally climb onto the first roller of the trailer and as soon as you have firm contact, the boat is under your control no matter what the waves are trying to do to upset your recovery. Your trailer is not just a method of transport but a vital component in the safe launch and recovery of your boat, whatever the challenges.
 

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While I remember, (and I think it's already been said, sort of), a "sealed" bearing is unlikely to help keep the water out. It's certainly worth leaving the hubs to cool for a while, and those bearing savers can help, but ultimately, I've never had a boat trailer bearing fail from simply "wearing out" - it's always water damage in the end.
 

Lakesailor

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Why do so many boaters think that it is necessary to immerse the trailer wheels?

Bilge keelers will normally have to be floated onto the trailer.
I had one which could only be floated on or off it's trailer.
My Seahawk has a lift keel but you couldn't winch that onto it's trailer. The keel protrudes through a stub keel.

My fin keeler had to have 5ft of water to float off the trailer.

I could winch my clinker dinghy onto the trailer from the lawn and so never needed to wet the wheels when recovering but would normally need to float it off when launching.

The only system that is foolproof is a launch trolley carried on the road trailer.
More expense. Just service the bearings and renew every year. Much cheaper. You have to look at the brakes anyway.


Trailer/trolley by RM Trailers

trolley_full.jpg
 
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Pete54

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For a dinghy trailer or something which is not deeply immersed my preference is to use spring loaded 'bearing savers'. These are extended bearing caps which are spring loaded. They keep some pressure on the bearing space once they have been 'pumped up' with grease. This tends to keep the water out. The grease willl still dis-colour but the bearings do last a lot longer.

I'll certainly second (or more) the cup of tea suggestion to give the bearings a chance to cool.

Most new trailers come with sealed bearings - the disappointment on my mates face when his new trailer bearing failed was priceless!! But not unexpected given his treatment of them.
 

electrosys

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This forum's playing havoc with my Deja Vu ....

For what it's worth, I eventually followed Lakesailor's advice (thanks), and bought a pack of 10 off Ebay. They turned out to be 'Zen' bearings (http://www.zen.biz/) - absolutely superbly made: and both sealed and stainless.
The stainless spec is given in their data sheets - far more capacity than any dinghy trailer would ever need ...
... and if you don't like sealed, the rubber seals can always be hoiked-out to open the bearing up.

The really amazing bit is that they cost me about a quid each - how anyone can produce such precision items so cheaply is beyond me.
And as I run a 'dry' trailer, I'm expecting these to live much longer than I will.
 

Avocet

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I'd be interested to hear how you get on. I've often wondered about stainless bearings but have worried about what they might do to the carbon steel stub axle and / or cast iron hubs into which they're pressed. Has anyone experienced corrosion of these as a result of being in electrical contact with each other?
 
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