YACT: tire balancing

[rh71]

I got my wheels balanced (not aligned) because I had been getting a vibration in the steering wheel during acceleration, up to 40mph. The balance fixed the problem (which is awesome)... but I'm curious:

- How does balancing actually work - all I know is that they use a computer, but what are they actually adjusting ?

- Why is there a 1-inch silver clip on all 4 of my rims now ? I was also under the impression that they balance just the front 2 tires.

 

[SaturnX]

Taking a stab in the dark, from a physics perspective...

But basically they'll put the clips, which are actually weights, on both the ouside and inside of your rims to account for irregular mass distribution.

Since the rim is manufactured it isn't 100% exact in all regards, and same with the tires, once you put the tires on, mass distribution might be slightly off. Thus the need of the weight to correct the balance and put the centre of mass directly in the centre of the wheel (so as you mentioned, to eliminate vibrations)

That's the best I can come up with.

--Mark

 

[Confused]

When wheels and tyres are made, they're not perfectly round, and they're not perfectly balanced.

When they're not balanced, as they spin, they vibrate. Take a CD and place it on the tip of one of your fingers and spin it, you feel no vibrations. Now, tape something to one side and try again - you'll feel it vibrate! This is the basic principle. However, due to the speeds that a wheel rotates, and the weight of it, it needs very fine balancing.

To do this, they place the wheel on a machine. Most machines have multiple wheel profiles (you choose which looks closest to the wheel you have) and you can specify where to place the weights. You tell the machine the size of the wheel, and give it some measurements of the edges etc, and it then spins the wheel, and by registering the vibrations/force that goes through the machine, it can figure out where the weights need to be placed to balance it.

Those silver clips are the weights, and they have written on them how much they weigh (in grams)

They will have done all 4 wheels because it doesn't take that much longer to do, plus if there are vibrations coming from the rears, you'll be able to feel it on the fronts, so it makes more sense for you and them to do it once (while they have the car up in the air)

 

[loic2003]

The wheel is spun and a measurment is taken as to where the wheel is unbalanced and by how much.
A small counter-weight is placed on the rim to compensate. The wheel is re-spun to check it's ok.

Tyres and wheels are not formed completely perfectly when manufactured and only a tiny amount of inbalance can result it nasty vibrations which are dangerous, sap speed and wear out parts such as the wheel bearings quicker.

The silver clip is the previously mentioned counter-balance. You can ask to have the clip placed on the inside of the wheel so they aren't visible.

Balancing the front wheels is most important since you steer with them and usually have power going to them in smaller cars, but you should always get all four balanced, especially since most people rotate their tyres so they get even wear on the fronts and rears.

 

[rh71]

:thumbsup: good stuff.

 

[loic2003]

By 'rotating the tyres; I mean periodically swapping your front and rear tyres over. For example if you have a FWD car, the front wheels have the power going through them and the steering. Concequently, the fronts will wear out significantly faster than the rears - unless you're partial to handbrake turns - so it'd make sense to swap the rear tyres for the fronts so the whole set lasts that bit longer.

You swap the rear-left with the front right, and vice-versa...

 

[DainBramaged]

Originally posted by: loic2003
By 'rotating the tyres; I mean periodically swapping your front and rear tyres over. For example if you have a FWD car, the front wheels have the power going through them and the steering. Concequently, the fronts will wear out significantly faster than the rears - unless you're partial to handbrake turns - so it'd make sense to swap the rear tyres for the fronts so the whole set lasts that bit longer.

You swap the rear-left with the front right, and vice-versa...

Except with my tires you can't do that. There is a certain direction that the tread goes so I can only rotate drivers side front to drivers side rear and likewise with passenger side.

 

[loic2003]

maybe swap rear left with front left, etc? that'd keep the same rotation direction

 

[funboy6942]

Think of a unbalanced wheel as a load in the washer on one side in the spin cycle. It vibrates like a bitch and you cant seem to get your SO off the damn thing!
How do you usually fix it. Buy moving some of the clothes to make it more ballanced.

Same thing with a wheel. With the machine they use you put in wheel size and width and it checks for an unbalance on the inside an outside of the rim. It then tells you how much weight to put on on the OPPOSITE side from where the problem is (like the clothes). For most this will get rid of vibration. Some cars if your taken off road can pack snow or mud in the wheel giving you a hell of a shake which can be easily fixed.

Alot of people like to use the fix-a-flat sealant instead of getting the tire pluged or patched which can mess up the ballance. The reason being is the liquid from the can once it seals the tire the left over has no where to go so it flops all around the inside of the tire. A good way to know that its the fix a flat messing up your ride is it vibrates really bad then smothes out and vibrates and smothes out. But its never the same all the time. It can vibrate like mad for awhile then just dissapear slowly come back and dissapear and sometimes depending on how much is in there wont take much speed to make it act nuts. If you ever use the stuff OR feel the car you bought may have a tire with it in there it can never be properly ballanced without taking the tire off and removing the excess liquid. And do note to the tire guy who is working on your tire if you have used it or suspect it is in the tire for most of that stuff is flamable. If you have a steel rim they generally use a steel bar to remove the tire and at times can cause a spark. If he doesnt know and that happends the tire could explode taking off the persons head killing them or doing some real damage so make sure if you used it of feel it could be in there to to mention it.

Hope that gives you and a few insite

 

[rh71]

Originally posted by: loic2003
By 'rotating the tyres; I mean periodically swapping your front and rear tyres over. For example if you have a FWD car, the front wheels have the power going through them and the steering. Concequently, the fronts will wear out significantly faster than the rears - unless you're partial to handbrake turns - so it'd make sense to swap the rear tyres for the fronts so the whole set lasts that bit longer.

You swap the rear-left with the front right, and vice-versa...

I made the mistake of not rotating my new tires for a while and the front 2's treads were much more visibly worn than the rear 2 (it's RWD/4WD, so that's sorta surprising). At that time, I asked them to rotate the 2 fronts to rears. Now when I brought it in for a balance, it included a rotation in the price but I couldn't help but simply instruct them to leave it and they recommend my best 2 tires to remain in the front. I don't know if they at least swapped sides... didn't care about the tire wear too much at the time. So right now for me, it's a vicious cycle... guess I'm just trying to wear the good tires out evenly at this point.

Anyway, did they make the right call in having the best 2 tires in the front ?