I need to buy a tyre for my spare wheel.
The shop asked whether I want to get it balanced or not.
I used to think that balancing is only applicable when they are actually fitted in axles.
Do I have to balance the spare wheel also?
If I balance the spare wheel now, do I not have to balance it when I need fit in the car at a later stage?
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It going to need balancing if you want to use it. Might as well do it now while is off the car.
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I've never had a wheel balanced on the axle, they always do it on a machine after fitting the tyre. Best to get it done or you might find the car driving like a pneumatic drill.
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>> I've never had a wheel balanced on the axle .........
Wheel balancing on the car was common in the 1960s and 1970s for cars with McPherson strut front suspension which at the time made the car very sensitive to out-of-balance wheels or brake discs and hubs. Vibration damping/prevention measures weren't very well understood. All manner of things contributed to vibration ~ even engine mounts for example. I had my 1967 Hillman Hunter wheels balanced that way. The idea was that all of the rotating parts directly or indirectly attached to the wheel were balanced as one unit. When the wheel was run up to speed without any balance weights the vibration was frightening. I thought the bonnet was going to fly off and the car fall off the stands.
Last edited by: L'escargot on Fri 19 Mar 10 at 13:36
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If you can balance it when fitted to an axle - good luck. That would be the ideal method but I have not seen it done for decades.
Most people have their , full sized,spare wheel balanced and thus ready to replace a punctured tyre without the further need to visit a garage. The assumption is that the drive shafts , hubs etc. are machined true by the manufacturer and do not need balancing.
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Ok, my assumption was wrong then :)
I'd get it balanced on spare wheel then.
:-)
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Showing me age now, i used to balance them on the car, i was pretty good at it too if i say so meself.
Then someone would take them off to change brakes or something without marking wheel and stud and they'd have to be done again.
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We used to balance them on the car, but as other posters have said, the other method seems to have taken over.
Anyone any idea why?
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i know a lad on the last day in his tyre job balanced all wheels on his head
the punters paid too
and it wasnt me before anyone asks.........
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>>Anyone any idea why?
A wheels-on balance, with only one sensor placed under the suspension can not give the same resolution when considering dynamic balance.
A wheel-off balancer will typically have two sensors spaced along the machine's axle, and the output from these two sensors can be combined mathematically* to first obtain the values of static and dynamic imbalance, and then to take these imbalance values and the geometry of the wheel to calculqate the two balance masses.
* Static imbalance is a rotating force, while dynamic imbalance is a rotating moment, and in general terms, these produce sensor outputs which (in broad terms) are in phase with each other for static imbalance, and mutually out of phase for dynamic imbalance.
A wheels-off balance using a single sensor can't perform this seperation between static and dynamic imbalance with the same degree of precision (if at all!). As each vibration happens once per revolution, they have the same forcing frequency, and so, it's not possible to filter out the two parts of the response in the frequency domain.
Dynamic imbalance tends to try to alternately steer and camber the wheel as it rotates, and this is a motion which is more stiffly resisted by the suspension components, where static imbalance tends to make the wheel hop, in the direction where the suspension is designed to be compliant. This means that the resonance caused by static imbalance is at lower frequency, and hence at lower speed that that caused by dynamic imbalance. Static imbalance is typically at about 30 - 40 mph, while dynamic imbalance usually begins nearer 70.
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NC, I had a feeling you wouldn't hold out on us for too long. Nice to see you here. G.
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Thanks for the welcome, as well as the email prodding me!
I should really be spending my spare time writing job applications, but, clearly I can't resist a wheel balancing question!
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...but, clearly I can't resist a wheel balancing question!...
NC,
I'd be inclined to leave that fact off the CV.
We know how interesting such things can be, but others are not quite so understanding. :)
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>> used to balance them on the car
>> Then someone would take them off (..) without marking wheel and
>> stud and they'd have to be done again.
Why? How were the wheels held on?
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>> Why? How were the wheels held on?
In the normal manner, ie 4 or 5 bolts/studs.
What I think he's referring to is that not only was the wheel balanced, but the hub and driveshafts were taken into account as well. If someone took the wheel off but failed to put it back on in exactly the same place, lining the wheel up with a marker point on the hub then it may well require balancing again.
Last edited by: VxFan on Fri 19 Mar 10 at 10:05
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Old Volvos have a little prong on the hub corresponding to a hole in the wheel, so it will only go back on in one position.
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>> What I think he's referring to is that not only was the wheel balanced but
>> the hub and driveshafts were taken into account as well.
Spot on, it did have draw backs too in that rotating tyres could mean having to rebalance, i used to balance both on and off the car, and as Vx says the effect inside the car of some judders not tyre related could be reduced by on car balance, probably in hndsight not always a good thing.
Just out of interest in those days Michelins usually required little if any correction, just span them up to check, where other makes could need a lot of weights to correct.
CP, istr Reno's being similar.
Last edited by: gordonbennet on Fri 19 Mar 10 at 11:49
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Does spare wheel require balancing? - Alastairw
