One of the more common failures that occurs on 4WD’s, camper trailers and caravans is having a wheel come off, and it can happen at high speed, when you are going around a corner and when you are least expecting it. There’s a number of reasons for why wheels come off, but more often than not it comes down to people not taking the time to torque their wheel nuts up, or using incorrect settings.
If you don’t know what I’m talking about, every single stud that your wheel attaches to will have a recommended torque rating, and if you exceed it, or don’t do it evenly, or tighten it less than its meant to be you can have a pretty serious issue on your hands.
The most common issue is people over tightening their wheel nuts, and this is incredibly easy to do with the number of cordless (and pneumatic) rattle guns on the market today, and those who use these have the ability to overtighten your wheel nuts in a split second.
What happens when you over tighten wheel nuts?
As mentioned above, your wheel studs should be tightened to a recommended torque setting. If you do them up beyond this, you start to stretch the stud, which wrecks the stud, and can make it easier for wheel nuts to work their way loose.
On top of this, you fatigue the studs and it becomes significantly weaker than it should be. A huge number of people have suffered from wheel studs shearing off within a few hundred kilometres of visiting a mechanic or tyre shop, because they’ve weakened the studs and made them a ticking time bomb.
When you have a tyre puncture and require a metre long breaker bar to undo your wheel nuts, you know they’ve been rattled up far too tight and are likely damaged. Most wheel nuts should be easy to undo with a 500mm breaker bar. If its not, have a think about who tightened your wheel nuts up last!
What happens if you under tighten, or unevenly tighten wheel nuts?
On the flip side of the coin, if you don’t tighten your wheel nuts up properly, you risk the nuts working their way loose, and damaging the studs, wheel and also having it come off. Once the nuts start to loosen, you end up with the wheel chewing the stud out, and the stud chewing the wheel out, often resulting in them both being bin jobs.
If you do them up unevenly you can have the same issue, with the wheel either not sitting on properly, or the nuts coming loose.
Corrugations and wheel nuts
If you take your 4WD off road, you should be regularly checking the tension of your wheel nuts. Guaranteed after a few hundred kilometres of corrugations (sometimes less) you will find wheel nuts that are not as tight as they should be. I’ve experienced this on our 80 Series Land Cruiser, Reconn R2 Hybrid Camper and our Isuzu Dmax, and sometimes the amount of movement you find is considerable.
Replacing wheel studs
On most vehicles and trailers, its actually pretty easy to replace the wheel studs. On trailers you’ll have to remove the nut tensioning the wheel bearings, but as long as you are familiar with how to tension it you should have no issues.
Cars can be easy (if they have drum brakes), or more difficult depending on how much access you have before having to strip things apart further.
Its important that you get the right wheel studs too, as they are not all the same and it can actually be quite hard to get the right ones for your trailer if the hubs are not commonly used in Australia.
A number of months ago we were rolling into Marble Bar when we came across an older 4WD on the side of the road with a great big gouge in the bitumen. He’d lost his rear left (which is the most common to come off!), when a couple of his wheel nuts had come loose, and then the studs had either snapped or worked there way inside.
This resulted in the wheel departing the vehicle, and ploughing into town at a rate of knots. 2 people looked for several hours and were unable to find the wheel, whilst we played with the wheel studs.
We managed to get 4 of the 6 studs usable again, and stole one wheel nut from the remaining wheels, and got him mobile again with the intention to take it easy and get it sorted urgently. No one had parts, and a tow truck would have been difficult to get, but it does happen and more often than you might imagine.
Torque your wheel nuts up
The take away from this post then, is to spend some time finding out what the torque should be for your vehicle and trailer, and getting a torque wrench that you can use to check them. If you never leave the bitumen this becomes much less important in terms of them coming loose, but its still a good idea to know they aren’t too tight.
A good tyre shop or mechanical workshop will have a torque wrench for the final tension, or they’ll have adapters for their impact guns that set the torque to a reasonable level.