Tire balancing beads

[roscoe]

While looking at the web site that had the DIY soda blaster (thanks Rick, I love stuff like that) I saw a page about balancing your wheel and tire assembly with small weighted beads that you put inside the tire. It lead me to another web site where they sell beads small enough to pour into a valve stem, so that you can use this technique with inner tubes as well as tubless wheels. The site was full, as you would expect, of testimonials all of which said it was the best thing since sliced bread. Anybody out there done this? Supposedly the free rolling beads go to the light side of the wheel and there-by balance it when in motion. All I know is that my laundry doesn't distribute itself that way and my washer sometimes takes a hike. Why would the beads end up on the light side? Come on all you physics geeks. I know quite a bit about dynamic balancing, but I can't figure this one out.

 

[RAC68]

Hi Jon,

Way back in about 1968 or 9, I was struggling to find the answer to what I thought was a tire imbalance (back then I had no idea what the Healey secrete was). After a number of unsuccessful on-car balancing attempts, I came across and purchased a led shot filled ring that mounted on the wheel rim and was supposed to dynamically balance the running gear. As you mentioned, the wheel’s vibration was to distribute the beads to where required to attain smooth balanced rotation and, because the beads were retained within a wheel rim mounted ring, the balance would not be disturbed by wheel bounce or changes in direction.

Although mounted with great hope, my shake at between 55MPH and 60MPH never disappeared. As a result of still having the shake, I assumed they were ineffective and I had lost my $20.

Did they work? I am not sure since it was many many years later that I found the vibration was scuttle shake and not wheel related.

I know my comments probably didn’t help, however, it was nice to review this experience.

All the best,
Ray 64BJ8P1 Original Owner

 

[57_BN4]

Wellll... everything will rotate, or at least try to rotate around it's centre of mass which is the point where all mass is equally distributed about.

Vibration occurs when the centre of mass and the centre of rotation aren't the same.

If you can imagine something that is heavier on one side, that heavy part doesn't need to be as far from the centre of mass to achieve the same equality as the lighter side, which needs to be further away to make up the difference. Hence why the mobile mass will tend to migrate to the furthest away part which happens to also be the lighter side.

The beads make a funny hushing sound when driving slowly, before they have enough inertia to fly outwards all the way around the wheel. I do wonder what they do to the life of an inner tube.

This method is also useful to balance a stubborn driveshaft that is perfect on the balance machine yet still vibrates on the car. Pump a heap of thick grease in the hollow driveshaft tube and it will eventually migrate to the right place and balance it.

Andy.

 

[RAC68]

Andy,

I assume from your comments that you are using the bead balancing method. Other than a “hushing sound” at slow speeds, how does it work at mid and high speeds? I am aware of the bead method being used on some large in-place machinery, but wonder how it would work on a car where bumps and directional change could displace the shot in the tire’s tube.

Thanks for the drive shaft balancing idea… hadn’t heard or thought of that solution before.
All the best,
Ray 64BJ8P1

 

[57_BN4]

Hi Ray,

Some years ago I used one of those emergency hairspray tyre repair cans to try and fix a slow leak and thought nothing of it. Months later I kept hearing this odd swishing noise coming from the back of the car when stopping. I took it to a tyre shop (to fix the slow leak) and the guy removed the tyre and showed me about two cupfuls of marbles rolling around in there which had formed when the gunge I squirted in there congealed together.

The tyre guy explained about the balancing beads thing and said that I could leave the marbles in there but I didn't really see the point. The car in question was a 1975 Austin Mini so I don't think I'd have ever noticed whether the wheel was more or less balanced as it was such a noisy rattly old thing anyway.

Coming to think of it now, using a tyre balancing machine on a wheel with stuff inside it would be difficult as the balance would change all the time.

Andy.