WHEEL-BALANCE WOES
Kleingeld Conradie takes life seriously. This may be because he is an elder of the Gereformeerde Kerk, or it may be because he’s a banker. Most people think it is because his wife is one of those people who cannot tolerate any of the niceties of being alive, such as having children, enjoying the outdoors, listening to good music, or even something really important like taking the occasional alcoholic beverage. To make matters worse, Kleingeld usually wears a dark suit.
His daily transport, a 2007 Ford Fiesta, is pristine and gets washed every week. It has been very reliable but lately developed a vibration through the steering wheel. It starts at about 90 km/h but settles when he goes faster. He had taken the car to three different tyre dealers to get the wheels balanced but was always disappointed. The last dealer used an on-car balancer, but it made only a slight difference. He eventually brought the car to us so that Syd could take a look at other possible causes.
Syd examined the car for play in the steering box, suspension joints or the wheel bearings, but could not find sufficient variation to set any warning signals ringing.
I was eventually dragged into a discussion on what to do next and decided to ask advice from my friend Ziggie. He runs a tyre shop in the nearest large town and offered to take the car under his wing.
Kleingeld agreed to take his car to Ziggie’s tyre shop and we sat back and waited for the result.
Ziggie phoned me that afternoon with the news that the car was fixed. His balancing machine operator had simply balanced the front wheels correctly to a close tolerance.
When I asked why the other tyre dealers could not do it, he explained that there are a number of possible reasons. The way the vibration appeared and disappeared showed that the wheel was dynamically unbalanced. This needs more precise measurement to cure than static unbalance, which simply gets bigger as the speed increases. Some tyre dealers employ untrained operators who tend to be lax when it comes to feeding important information like the hub-to-machine distance into the machine, or who are careless in placing the balance masses in the correct places. It’s also true that very few machines are regularly calibrated and the rough handling that they usually receive tends to reduce their accuracy.
A GREASY BUSINESS
Our town is not as backward as you may think. We have a breakdown service. The vehicle consists of an ancient bakkie fitted with one of those quickly removable frameworks that turn it into a recovery vehicle. The service is operated by Voetstoots Venter, who also runs a second-hand car lot. The gossip around town is that he has never sold a car with a roadworthy certificate. It is further claimed that none of the cars would ever pass a roadworthy test and some could not even get to the test grounds under their own steam. This predicament doesn’t seem to bother him. He’s always cheerful and friendly.
The other day he brought me an old Isuzu bakkie with a seized front wheel. The owner, a farmer who does a lot of his own maintenance, came with him. He was not in the mood for small talk and lost no time in telling me that he’s just replaced the wheel bearings. He was convinced that the fault must lie with the cheap Chinese units that he only purchased because the counter-hand insisted that they’re as good as OE bearings.
As soon as Hennie saw the leaks around the dust cap, as well as the amount of grease inside, the mystery was solved. There was far too much grease in the hub and this had caused overheating. Hennie looked at the other front wheel and found that it was also overfull and would soon have seized.
He started Japie on the repairs and explained to the farmer that, when repacking wheel bearings, the grease should not occupy more than about 40 per cent of the free space. The grease should circulate as the wheel rotates and, if there is no free space, this can’t happen. This will cause overheating, the grease will soften and leak out, and the bearings will seize. There should initially not be any grease in the dust cap, but some will eventually find its way there.
A JUMPING SPARK PLUG
Our workshop may have only one trainee, but we have a very good training system. Every lunch and teatime, Japie gets the benefit of learning from three experienced mechanics. The other day, the subject of swearing came up. Syd maintained that it’s useful because colourful words often help to clear the brain when a problem appears to be insoluble. Hennie agreed, citing the fact that many mechanics believe in the power of four-letter words.
Japie then said that he feels sorry for preachers because they’re not allowed to swear, so they can’t have much of a swearing vocabulary. I disagreed with the last statement because, in my youth, I once didn’t tighten a spark plug sufficiently and, when I started the engine, it jumped out and made a dent in the closed bonnet. The car’s owner, an Anglican priest, subsequently displayed a purple-language vocabulary that would have surprised even a sailor.