Tyre Balancing

[John L]

Has anybody tried this product, is it really as good as predicted?

 

www.dynabeads.co.uk

 

John

[Andy Moltu]

Reptillian Lubricant I would suspect.

I would have thought that the beads would tend to move to the furthest point from the axis - which may not be the correct place as to balance the wheel/tyre.

[john.r.davies]

That ad., and product, is physics-illiterate and pure hokum! "Spin" as it were!

 

A heavy point on a tyre will tend to fly off more than a lighter point, slightly stretching the tyre at that point so that it is further from the centre. As the same forces are acting on these beads, loose inside the tyre, where do you think these beads will go? Yup! Straight to the bulge, making the imbalance worse.

 

John

[had17462]

These cones are very good they fit on your local shops tyre machine.

Nick

[mleadbeater]

Highly dubious to me, ceramic beads rolling/bouncing around inside your inner-tubes, how long before they abrade away the rubber and cause a leak?

 

Mike

[Peter Cobbold]

I think they might work, some of the time. If they didnt , they'd most likely make tyre imbalance worse and the company would have gone out of business years ago. Its not like 'snake oil' additives where we have no way of knowing if they work or not, tyre imbalance is staringly obvious. Stuff the beads in the tyre...drive off... it shakes worse...claim your cash back, trading standards etc. They presumably do something useful.

So, how might they work? My guess is:

For a wheel thats bouncing up and down or steering round a corner, or out of balance side to side I suspect they dont work.

But for a smoothly rotating, straight ahead wheel, that is shaking the steering wheel - typical of wheel imbalance - then we have:

a heavy spot on the assembly that rotates at a slightly greater radius: that's the wobble we fell at the wheel. At first sight it makes a tiny bulge where the beads might be expected to settle, making the out of balance worse! BUT that bulge is moving faster tangentially than the rest of the tyre. ( Note: the tyre need not distort: the 'bulge' is shorthand for the eccentric motion about a moving spigot). So for beads to settle into the 'bulge' from the bulk tyre they have to accelerate to keep up with the bulge. But the beads' speed is dictated by the bulk tyre, they cant go faster than that. So the bulge is kept bead-free.

Looking another way:

The centripetal force acting on each bead is (M.V^2)/r

Their velocity v can only be picked up by contact with the tyre and air drag, and is slower than the velocity at the radius of the bulge , very slighlty. But the formula needs the square of the velocity making small differences bigger. Their mass M - providing they dont clump - is fixed. So with M and V fixed an increase in r cannot be achieved and beads are unable to reach the bulge.** On the light side of the wheel the tangential speed is slower in the wobble so the speed the beads pick up from the bulk tyre is less than on the bulge side, further ensuring the beads cant get speed enough to fly out into the bulge.Indeed the beads are most likely to push against the tyre on the slowest moving arc, the light side, and so acting as a counterweight.

 

So: its due to the energy of the beads, picked up from bouncing off the walls and air drag, that keeps them away form the heavy arc, and focusses them on the light arc. The beads' average energy reflects the speed of the two 'sides' of the tyre that are neither too heavy nor too light .But that average centripetal energy is greater than in the light arc, so they congregate there.

 

I would not use the stuff. If the beads clump its useless, it wont work on a bumpy road or in hard cornering, and possibly make things worse. On a motorway maybe, at fixed speeds, they could work.

 

Peter

 

** Force= (MV^2)/r

So r = (M.V^2)/F

Hence a bigger radius of rotation in the bulge ( r) needs a bigger force to get beads out there, but M V and F are fixed.

 

Edit:

The first paragraphs of the Introduction relates to the problem of how the beads might work:

http://rsta.royalsocietypublishing.org/content/366/1866/705.full

So....its far from simple. But we are on the right track, sort of:

"" The principal idea behind the automatic dynamic balancing (ADB) is that the balancing balls are subjected to a driving force caused by an apparent centripetal force acting from the offset centre of mass to each ball.""

Edited October 4, 2014 by Peter Cobbold

[littlejim]

But of course when you are driving the tyre isn't round like in the lab.

The contact patch is flat.

Does that send the little balls to the bulge at the front and the bulge at the rear of the contact patch on a constant basis producing heat and friction?

Dunno. But doesn't appeal to me.

[Peter Cobbold]

Very good point !

This is getting complicated. If beads congregate in the light arc, opposite the heavy 'bulge' on the tyre, then as they enter the contact patch they will be accelerated inwards towards the hub. I have no idea why they dont loose contact when the contact patch rotates away from the beads. Maybe the centripetal force acting on them is enough to keep them pressing against the tyre even as they go through the contact patch?? If the beads loose contact their counterbalance effect is lost.

I dont know. It needs numbers - beyond me.

 

I was thinking we need a transparent tyre. A pop bottle will have to do, although we cant see the beads' distribution:

 

No contact patch in the bottle...back to square one..

 

Peter

Edited October 4, 2014 by Peter Cobbold

[Peter Cobbold]

Here's the best explanation I can find (its sort of the same as mine):

http://www.innovativebalancing.com/HowItWorks2.html

 

But the contact patch is not mentioned.

 

Peter

[littlejim]

Pete,

wouldn't water do the same job as the little ceramic balls?

certainly be cheaper if you wanted to see if there was any difference?

 

(The farmer's dodge of water in the tyre is for a lower C of G; don't think they go fast enough to spin it out round the tyrewall.)

[Peter Cobbold]

Guessing, again: the beads will be about 3 times as dense as water and wont splash into tiny droplets where the air motion will dominate their distribution.

And difficult to sell water in litttle bottles.

Peter

[TorontoTim]

I seem to remember something on "Tomorrow's World" many years ago where a circular "tube" was attached to the wheel of a car. The tube has several ball bearings (or similar) inside it and, as the wheel span round, the balls "dynamically" balanced the wheel.

 

I always thought it was a fantastic invention, but have no idea if it would actually work. Obviously, we've never seen it in production...have we?

[Graze]

?....

And difficult to sell water in litttle bottles.

Peter

Seems to work over here, water is dearer than fuel at about $2/litre in small bottles vs $1.40 / litre for fuel

 

Graze

[littlejim]

This thread has been worth it to gain this gem from Andymoltu "Reptillian Lubricant I would suspect."

 

PS: if you are going to try water in the tyres, use the stuff Graze mentioned, obviously far superior to tap water.

[xstoka]

Just to revive an old thread, Has anyone had any recent experience using dynabeads or similar?

 

I have wire wheels and need to replace all my tyres and inner tubes which will then need to be balanced so have been looking into using these instead of weights.

[monty]

Just to revive an old thread, Has anyone had any recent experience using dynabeads or similar?

 

I have wire wheels and need to replace all my tyres and inner tubes which will then need to be balanced so have been looking into using these instead of weights.

 

To get wire wheels or any centre lock wheels properly balanced you will need a good balancing machine with proper old type 'cones' to fit the hubs. Most modern day tyre fitters do not have them or are ignorant of their existence! The cones can be purchased as mentioned earlier or you need to find the appropriate tyre fitting outlet who have them such as Blockley tyres or Paul Harris classic tyres (as advertised in Traction). I have struggled with this situation for years & gave up with the usual tyre fitters & bought the cones! Still sometimes a problem as many machines are not designed for centre lock wheels & will not accept the cones correctly!

Cheers.

[stillp]

Just to revive an old thread, Has anyone had any recent experience using dynabeads or similar?

 

I have wire wheels and need to replace all my tyres and inner tubes which will then need to be balanced so have been looking into using these instead of weights.

I see you're in Leicester? Take them to Rugby Classics http://www.rugbyclassics.com/

They did mine last year, good job at a very reasonable price.

No connection, just a satisfied customer.

 

Pete

[monty]

I see you're in Leicester? Take them to Rugby Classics http://www.rugbyclassics.com/

They did mine last year, good job at a very reasonable price.

No connection, just a satisfied customer.

 

Pete

That is excellent Pete, that kind of info is exactly what members need. I wonder if a list could be compiled of the people who can successfully do good old fashioned wire wheel & centre lock balancing?

Perhaps forumites could post their recommendations?

[Ben Freer]

I had Geoffrey's wheels balanced locally by a firm who assured me that they could do wire wheels. Wobbles still there. When he went in for pre-RBRR therapy at Revington's last week I got them done again and Dan said that they were better if they hadn't fitted any weights! He re did them and lo and behold no wobble so as everyone else has said get them done by someone who really knows what they are doing/talking about! That means from a firm recommendation.

[xstoka]

Thanks for the suggestions, i know of Paul Harris but not heard of rugbyclassics.com so thanks for that.

 

I would like to hear if anyone has tried the dynobeads method yet? As it does intrigue me as to how it works and if it is as successful as normal tyre balancing.

[TriumphV8]

The only way to get a good result is to rebalance

the already properly on the machine balanced wheels

again at the car.

 

I found out, that a simple remove and refit can create an imbalance of 30 grams-

 

I have the Hofmann finishbalancer SD-10 in use and I am happy with ot.

 

Our benefit is that tire shops in these days get rid of this wonderful eguipment.

Modern cars with electronics at the wheels do not like that and 4 wheel cars

are difficult to handle. So they sell them at a good price.

 

Modern cars have the wheel additionally centered in the middle,

we have them centered only by the wheel nuts.

Also the wire wheels do not center precise although they should

due to the cone and I found out they imbalance simply by car

standing in the garage.

[Z320]

Hmmmm, you could buy them, use them, find out and report?

 

Ciao Marco

[ChrisR-4A]

Assuming you have the special cones which fit in the centre of the wire wheel at the rear and over the outside of the hub where the spinner usually goes at the front then there is one other thing to watch out for, that is to make sure the back flange on the ballancer spindle which is often spring loaded is not touching the rear of the wire wheel where the spoke nipples are.

If the wheel rests on this flange it will not run true as it is held off the centre taper cone, and to correct it spacers are needed between the back flange and the cone to provide a gap.

The machine at my local garage needs spacers totalling just over an inch long to achieve this, they are 40mm internal diameter same as cones.

Another point on Ballancing wire wheels is to have the machine set for the weights to be fixed to the inside flange of the wheel only and to use the modern stick on weights. They cannot be seen and since I started using them nearly 10 years ago I have never had a weight come off and only had to rebalance when fitting new tyres.

Edited September 12, 2018 by ChrisR-4A

[Lebro]

I have had good results in the past by backing off the front brake pads, slackening the wheel bearing a tad, & letting the wheel find it's own balance point. Then add weight to the top, & repeat until it will stay where ever you put it.

 

Bob.

[RogerH]

Hi Folks,

I get my wheels done locally in W.London. The proprietor is Balan Singh - a good chap.

 

Roger