Dyna Beads

[deeman]

What is the science ...or just another scam?

[Evan]

It is a case of flawed physics. The beads will distribute themselves along the most out of round portion of the tire which will cause the tire and wheel to be even more out of balance. Fortunately, the actual product is too lightweight to have much effect so the problem it causes isn't very noticable.

[macona]

I have seen balancers like that on some equipment. I want to say centrifuges where they may not be evenly balanced.

[Evan]

Imagine an elliptical tire with the centre of rotation at the crossing point of the major and minor axes. Throw in some beads of anything and rotate the tire. The beads will all collect at the point furthest from the centre of rotation which will increase the imbalance. It cannot work. The entire concept defies logic.

[TGTool]

How about lighter than air beads that displace the air on that side and restore the balance?

[Arcane]

The purpose of the beads isn't to balance your tires...it's to transfer the money in your pocket to the seller's pocket.

[sid pileski]

Deeman- Well, I'll let you know. A friend of mine swears by them. He has 2 Gold Wings and a BMW R900 that he uses them in.
I just changed the tires on my Sportster and I put them in.
So, we'll see.

Sid

[toyjeep73]

Deeman- Well, I'll let you know. A friend of mine swears by them. He has 2 Gold Wings and a BMW R900 that he uses them in.
I just changed the tires on my Sportster and I put them in.
So, we'll see.

Sid

I know a lot of people that use them in offroad tires -- i.e. 36"+ Swampers that don't balance well. They seem to believe in them. They are big in the heavy hauler industry as well (so I have heard).

The cheap guys in teh Jeep club just through some golf balls in the tires.

[J Harp]

What about the tubular rings containing steel balls sold for keeping truck wheels in balance? I never could see how they could work, but some people swore by them. I also believe they were used on some automatic washers.

[Evan]

Believing they work isn't the same as knowing they work.

[dfw5914]

http://www.practicalmachinist.com/vb/general/ot-wheel-balancing-beads-192084/

Read post #18

[Evan]

Note this small caveat in his explanation:

Note that this depends on the tire being round - if it is out of round (or, in the real case if the axle is not at the geometric center of the circle) then the wheel will not balance as we define the term.

If the tire were round and centered it would be balanced. Out of balance is caused by out of round or off centre or both. The density of the materials used in the tire doesn't change appreciably from one part to another so that isn't the problem. It is precisely because tires may be out of round that racers shave the tread to make tires round.

If the tire isn't round or it is not centered then putting anything inside the tire is going to increase the imbalance as it will migrate to the largest radius inside the tire. That in turn will make matters worse and increase the tendency to concentrate movable materials at the worst point.

If it worked tires would come with "self balancing" materials instead of using wheel weights.

At any rate, it is easy to test. Can anybody find independently supervised test results from a dynamic wheel balancer?

[Mcruff]

I have been using dyna beads in my motorcycle tires now for about a year and a half (4500 miles or so). Balanced fine with them even at high speeds of 110+mph. I have a friend that has been using them for around 4 years and 3 sets of tires. I know quite a few guys that use them and have been for years with no ill effects at all and tons of mileage on them. If you want to see how they work go to youtube and type in dyna beads, you will see exactly how well they work.

If the tire were round and centered it would be balanced. Out of balance is caused by out of round or off centre or both.

Not necesarily true, I work in injection molding and I can tell you that the density of plastics and rubber can vary depending on the shot and how the cavity is filled. The part will still come out round but can have a heavy side quite easily that is caused from over packing from injection nozzle opening and closing out of sync from normal process.

[CCWKen]

They work great for antique car tires/wheels where there's little historic interest or location to hang modern weights on the wheels. Of course, the use is in vehicles that seldom exceed 50mph. I wouldn't use them in a modern car tire. In fact, I don't think it's recommended or they have a limitation on speed. They do have a place and they DO work. Just be sure it's the correct application.

[Evan]

They do have a place and they DO work. Just be sure it's the correct application.

Got any proof anywhere? Not testimony or anecdotes, but actual scientific testing reported by an impartial observer.