Maintaining your wheel bearings is an article subject matter which has been covered since the beginning of time; and I don’t want to re-invent the wheel, so to speak, but it seems many boaters don’t take note of the top-tip for reliable towing – even though it’s still the number one killer of a happy family at holiday time.
For part 1 of this article, we’re going to recap on how to change and maintain your bearings, as well as get a bit scientific – for those that tend to read engineering and applied sciences matter in their evenings.
Winter time is here and many boaters are putting their boats to rest for the ‘closed’ season. But, whether you’re storing your craft come summer time again, the importance of maintaining and looking after your trailer’s wheel bearings can’t be stressed enough. Over the Christmas holiday (which feels like a lifetime ago!), I travelled to my getaway spot to spend some quality time with my craft. It was something I’d counted down since about 360 days prior, as I imagine every other traveller had done too. I was barely out of my home town before the roadside began being intermittently littered by cars with trailers – and it’s never good when you see the trailer with only one wheel on. I stopped to help the first few tyre-less travellers, but tireless I was not by the time I reached the fourth one.
Naturally, I only really stop for boaters because I don’t have much in common with say, horse riders, but when speaking to these road-side stricken drivers, there were two things in common. First, all of them had underestimated the importance of looking after their wheel bearings. Number two was the sheer disappointment on the face of the family. I’m sure we could do a quick count as to who wants either of those, let alone both, and we could all guess how many readers will raise their hands. So then, why do we let it happen for lack of a quick, cheap solution?
Trailer maintenance may be a bit of a messy job, but all you need is 45 minutes and the right tools and you’ll save yourself so much hassle in the future. But, if you can’t imagine waking up on a weekend and thinking ‘today I need to check those trailer bearings’, then simply get it done by someone reputable; Honda Marine Somerset West, for example, charges around R600 per hub and it’s worth every cent to have it done for you professionally.
The science
According to V. Elliott, Machine Design, it is estimated that up to 50% of all the energy used in the world is consumed in overcoming friction. A lubricant (the most important property of which is viscosity) is a substance used in the attempt of achieving the goal of minimising friction. He continued by tabulating that at room temperature (20°C), air has a viscosity mPa.s of 0.018. Water has 1.000 mPa.s; and to give you an idea, honey is rated at 1 500 mPa.s.
When it comes to wheel bearings, Burquip is interested in Mineral Oil Greases which comprise mineral oil and a cationic ‘soap’ which is usually Lithium based and is designed to hold the oil as a sponge of positive cations. For those that aren’t following me; it means that as the temperature or pressure is increased, the oil leaves the sponge to perform lubrication on the surface in which it is in contact with; and returns to the sponge when the pressure or temperature is decreased. However, grease has a finite life-period, determined by the service conditions/intervals – and is why abrasive substances (such as salt or sand) must not contaminate the grease.
Designed to deliver high performance, modern greases have EP additives (Extra Pressure) which are used to improve the ability of the grease to reduce friction under high loads – like the loads present for wheel bearings.
The basis
If the above brings back bad memories of school and the reason you dropped science class, fear not. All you have to know is that a good greasing is what will keep your wheel bearings turning smoothly by reducing the friction between surfaces. However, a word of caution: not all greases were created equal! NEVER mix your greases! It’s an inexpensive part of the process so rather don’t even mix grease from the same manufacturer. Greases aren’t always compatible and it may drastically shorten the expected life of the bearing.
How to
Skill level required: Competent DIY’er or confident with hand work. Trailer manufacturer Burquip walked us through replacing wheels bearings – but simply checking, maintaining and replacing is the same process. We used a trailer which had the most common wheel bearings for boat trailers. Burquip also limited themselves to tools you would have at home – some are specially formed, but you should be able to find a substitute in your garage…
