Is all wheel balacing the same?
Are certain machine more accurate? Is on car better than off car?
or at the end of the day does it not make any difference?
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Hi Simon,
If you can find somewhere that does it, on-car balancing is better as it'll counter any problems to do with the drive train as well as out of balance wheels.
Otherwise, some machines can be better than others, generally newer machines are the best bet, but in my case with a Peugeot 306, the 'cyclone' wheels are notoriously difficult to balance because an adaptor is needed as there's no centre hole to mount them to the machine, and this adaptor does nothing to help the accuracy of the balancing.
Hope that helps...
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on-car balancing is better....
But if you get them balanced on the car, and have to remove a wheel for whatever reason, rememeber to fit the wheel back exactly in the same place on the hub. Marking the hub with a small dot of white paint in line with the valve stem will help.
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In my opinion better off car.though it isnt fool proof in some respects depends on the person doing the balance as to accuracy unless you have drive train issue see no need for it.
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I know someone who had a whining diff on a SAAB after on-car balancing, so I have always avoided. There are two main types of off car balancing, static and dynamic... I'm not sure what the difference is, but I think dynamic is to do with having weight on the inside and outside rim instead of just one (usually the out side) and both outside and inside can have the weight in a different positiona around the circumference. For a better description, best you use a search engine!
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I am prodding the grey matter here and it tells me that car wheels will tend to balance correctly at only one speed because centrifugal force varies as the square of the speed (I think).
So if a wheel is out of balance due to excess rubber weight on the outside of the tread say weight W1, and you balance the wheel by placing a led weight W2 diametrically opposite, and make it a bit heavier than W1 because it has to be on the wheel rim, the wheel will show balance statically like a pair of scales.
Now spin the wheel and W1 will go faster (larger radius) than W2. The centrifugal force due to each weight will build up as the speed increases and each weight will try to pull the wheel in its own radial direction.
If the two forces were equal there would be no problem, as long as the balance weight did not fly off.
But because W1 has a larger radius it travels faster than W2, and so its pull will dominate, and when the speed gets high enough, the out of balance pulls will result in vibration felt through the wheel shaft.
Thus wheels should be balanced at the sort of speed they will be used at. For instance 70 mph.
Over to the mechanics for an audit.
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After once watching on car wheel balancing with the drive shaft dropped to an acute angle this put me off the idea for good.
There must surely be a possibility of drive shaft joint damage unless they have now found a different way of doing it.
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the drive shaft dropped to an acute angle.... There must surely be a possibility of drive shaft joint damage....
How will the acute angle cause damage? It is a universal joint which is designed to be twisted into all different acute angles - one of which is when you turn the wheels to go around corners or roundabouts.
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DD,
Some FWD cars that I've worked on in the past definitely did not like the wheels turned when the suspension was hanging right down, i.e. with car jacked up.
Likewise the rear drive shafts on my Triumph, when driven by the engine with car jacked up and blocked. They turn OK but you can tell that it's not a good thing to do by the noise and roughness.
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The last time I had a wheel balanced on the car, quite a long while ago, the fitter had to spin and brake the wheel several times and I was left with very noticeable wear on the tyre where the machine had engaged with it.
In any case, any out-of-balance in the drive shaft, brake disc, etc. will be at a relatively small radius and shouldn't be noticeable. If it is, then something is definitely wrong and needs correcting at source.
Also, I understand that the dampers have to be in top condition for wheels to be balanced on the car.
Like Alvin, I'm staying with off-car balancing.
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An interesting survey to do (perhaps across our members) would be weight of lead used on wheel versus make of tyre on wheel!
One wheel with a lot of lead does not prove it is the tyre (the wheel fixings might be out) but a make requiring consistently larger weights would raise the question.
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Worthy of note, is that LandRover now balance wheels at the factory with a machine which first bed's the tyre onto the rim, by simulating driving with a load on the tyre, with braking forces. They claim that there's no point balancing a wheel when the tyre has just been fitted, because once it's driven in anger it may settle in differently. Maybe it would be best to return to the garage a few days after having the tyres fitted and have them balanced then instead of at first.
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it's funny that you should mention this sooty,
last time i needed new tyres, i found a little place 60 miles up the coast that had a good one-time offer on a set of uniroyals, so i trogged up there to grab a set. when i arrived they were very busy, but managed to squeeze me in, they fitted the tyres, and put then straight back on the car, i asked about balancing and they told me to come back next week and they would do them. i thought (at the time) that i was being fobbed off, and had then done next day at our local fitters. what i took (at the time) to be cutting corners was probably forward thinking and maybe the "correct" way to do the job?.
billy.
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This would explain the judder I get on my private driveway when going between 80-90. KPH, of course.
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