Trailer bearings

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IJL

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I have a boat trailer of considerable age but have replaced the hubs bearings and brakes and all works well as long as a repack the bearing regularly. If I don’t take the time the bearings rapidly get rough and need replacing. This is with fresh water use I assume salt water will wipe them out even faster.

I was curious if more modern sealed bearings on boat trailers are any better, do they need such regular attention?
 
IJL said:
I have a boat trailer of considerable age but have replaced the hubs bearings and brakes and all works well as long as a repack the bearing regularly. If I don’t take the time the bearings rapidly get rough and need replacing. This is with fresh water use I assume salt water will wipe them out even faster.

I was curious if more modern sealed bearings on boat trailers are any better, do they need such regular attention?
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The problem is a oil ( grease ) seal only works one way, designed to stop oil getting out.

Now what happens is you get the brake drums hot, drive into cold water, hub cools, pressure in hub drops and sucks moisture in through seal, over time this becomes water, this then corrodes the bearing.

Going back to the 60's / 70's when I was involved with trailer suspension design we made water protected axles for boat trailers, these had two oil seals back to back, so stopping grease getting out and water getting in. We also fitted a dust guard to protect the outer seal, and O ring to grease cap to stop water ingress that way.

You can, or you used to be able to, get a single seal with back to sealing faces, fitting these will help, then fit self-amalgating tape ( or Google Self-Fusing tape ) and seal the joint between hub cap and hub. This should help bearing life.

Do not over fill bearing cavity with grease, this will not lubricate bearing, but will increase running temperature. The inner race should be fitted into the outer, then grease pushed through the gap between inner and outer race till it appears on the other side. This is the only grease that needs to be used, all other grease does nothing.

Brian
 
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Worth searching for "bearing savers". These are just spring-loaded plungers that attempt to maintain a positive pressure inside the bearing cavity at all times. Never tried them myself but some people reckon they work well. For me, there are two choices:

(a) fit the cheapest "no-name" eBay bearings I can find and replace them annually (just treat them as disposable) or
(b) Go for a really well-known quality make like Timken or NSK and take care of them, stripping a re-greasing several times a season.

I'm only towing a 100kg dingy though, with simple, unbraked hubs, and I can get a set of cheap bearings for £8 (yes, that's both sides)! I don't any more, but when I used to trail longer distances, I'd keep a spare set of bearings in the car, and a pair of hubs with the new outer races already pressed into them. You don't need many tools and it's not much longer than changing a wheel if you get a puncture.
 
In NZ (and Australia) there are commonly available Boat trailer Hubs and stubs sets for people (pros and amateurs) constructing boat trailers.
These have a better lip seal that has bi-directional seals and the replacement kits includes a replaceable thin steel component like a "speedi-sleeve" that is pressed in and the seal runs on.
Also widely available are "bearing buddies" that replace the dust caps and maintain a positive lubricant pressure. (or do they just compensate for the suction caused by temperature difference when you submerge hot bearings? I admit i not quite sure.)
I have a trailer- sailor on a non braked trailer. I submerge the wheels completely to launch and retrieve. It takes me 20- 30 mins after i arrive at the launch ramp to rig and prepare so the bearings are probably cooled down a lot. I don't have bearing buddies, but should probably buy them. Even so i expect to replace both wheel bearing sets a maximum of once a season.
They cost 15 pounds for a kit that contains the two tapered bearings plus the seal and the speedi-sleeve, and it takes me about 25 mins to do so its not a big deal.
Cheers
 
The "sealed roller bearings" are standard car wheel bearings and not sealed against water, but instead have dust seals at each end. Personally I don't like sealed bearings because if they have been in the hubs for a while then you will need big tools to get the hub nut off and then a hydraulic press to get the bearing out of the hub.

As Avocet says, if you can get bearing savers to fit then go for it, they keep the grease under slight pressure helping to keep the water out.

Pete
 
Pete7 said:
The "sealed roller bearings" are standard car wheel bearings and not sealed against water, but instead have dust seals at each end. Personally I don't like sealed bearings because if they have been in the hubs for a while then you will need big tools to get the hub nut off and then a hydraulic press to get the bearing out of the hub.

As Avocet says, if you can get bearing savers to fit then go for it, they keep the grease under slight pressure helping to keep the water out.

Pete
Click to expand...

Filling hubs with grease causes bearing failure due to high temperature running.

Brian
 
Can't say that is my experience, lack of maintenance particularly over the winter with water inside the bearings is normally the cause and identified by rumbling bearings that can be heard when towing or if ingored when the wheel falls off. Excess heat tends to be badly adjusted brakes or over tight bearings.

Back to the original question, with taper bearings they can be changed at the road side with a jack, hammer and large screwdriver if necessary so worth carrying at least one spare set and some split pins and grease.
 
Pete7 said:
Can't say that is my experience, lack of maintenance particularly over the winter with water inside the bearings is normally the cause and identified by rumbling bearings that can be heard when towing or if ingored when the wheel falls off. Excess heat tends to be badly adjusted brakes or over tight bearings.

Back to the original question, with taper bearings they can be changed at the road side with a jack, hammer and large screwdriver if necessary so worth carrying at least one spare set and some split pins and grease.
Click to expand...

But if you use the correct parts, you don't get all the failures.

Brian
 
More like checking them regularly, not only the bearings but the seal at the back and the stub axle surface it runs on, any corrosion there and your new seal is toast in a few miles. If in doubt change them, which is much easier than sitting on the side of the motorway on a Sunday afternoon with the wheel missing.

The dive club boat trailer was always a worry due to lack of maintenance, we even got to the point of doing a demonstration of how to change a wheel bearing during the lunch break on boat handling courses.

Pete
 
Thanks for the feedback, I have a trailer sailer so the trailer is a key part of the package, at the minute i'm resigned to changing the bearings before going on the road but its a bit of a faff. I'm looking to change boats next year and wondered if more modern kit would require a smaller tool box. It sounds like bearings are always going to need attention which makes boats that can be launched without immersing the hubs very attractive.
 
Durahubs are good, many sealed systems either suffer from people injecting too much grease and blowing the seals (they seem designed to work with +ve pressure in the hub or the suction when a hot bearing is immersed in cold water sucks water in. The Durahubs look like the best solution, but not sure of any companies have taken them on over here yet.
 
Avocet said:
I think I'm missing something here? What do you mean by "correct parts"? Good quality ones?
Click to expand...

If you fit twin lip seals that will stop water ingress through the seal, taping the grease cap will stop water ingress that way. In the 60's - 70's I worked for Rubery Owen we supplied most of the boat trailer axles, except for washing out the brakes there was little to do, bearing failure was not common.

Ebay have twin lip seals http://www.ebay.co.uk/itm/21x35x7mm-2-Pack-Rotary-Shaft-Oil-Seal-R23-TC-Double-Lip-With-Garter-Spring-/161090659986?pt=LH_DefaultDomain_3&hash=item2581c06692

Brian
 
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