Centramatic Dynamic Wheel Balancers

[Lynn]

Hmmm. One of the downsides to centramatics or beads is that it's really only accomplishing a "static" balance.

Unless I'm mistaken 'static balance' refers to the old bubble balancers where the tire/wheel combination is balanced without rotating, and 'dynamic balance' refers to the newer machines that spin the tire/wheel combination to evaluate its balance.

So, since the beads are distributing themselves around the wheel while you are going down the road, how is it only a 'static' balance? Seems to me it's a continuous dynamic balance. And fans argue that to be one of the biggest benefits.

 

[1stDeuce]

You're partially mistaken... Just spinning it on a machine does not mean it's a "dynamic" balance. If you tell the machine to do a static balance, it does EXACTLY the same thing as a bubble balance, which is to balance the tire radially only.

A true dynamic balance MUST be done by spinning the tire on a machine, but accounts for variation in weight distribution around the tire by using different amounts of weight at different places on the front and back of the wheel. Dynamic balance can also offset slight tire or wheel wobble as mounted. The dynamic balance makes the tire spin true and smooth, whereas if you had a tire that was balanced statically, but had a heavy sidewall in one place, the tire would want to wobble slightly as it spun.

Sorry, but if you tell the tire shop you only want weights on the inside of your wheels, you're getting a static balance. You may as well buy a $20 bubble balancer and do it yourself.

Generally, it's not a problem for bigger heavier tires on heavy vehicles, but small cars do much better with dynamic balancing, as do any vehicles prone to DW.
I usually split the difference and put half the weight on the inside and half on the outside when I bubble balance... That way I'm not throwing off the dynamic balance any by putting weight only on the inside. No DW on my jeep yet!!

 

[Lynn]

1stDeuce, thanks for the technical explanation.

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I'm a high school physics teacher, and got hung up on the terminology. As I'm sure you know, static = non-moving and dynamic = moving (oversimplification).
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Ever since the topic of the balancing beads came up on this forum I have wondered about the physics of it. A simple analysis leads me to believe that if you have a rotating off-balance torrid, the heaviest spot will be pulled away from the center of rotation, and the beads will do the same, thus the beads will compound the problem.
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One explanation I've read talks about how, at high rpms, the torrid will start to rotate around its center of mass rather then around geometric center, making the lightest point of the circumference move away from the center of rotation, and the beads will distribute as advertised. For this to happen, though, the suspension must have enough play for the axle to scribe a circle in addition to rotating. I'm not sure I believe that will happen. I doubt that the axle is going to move far enough to allow change of the center of rotation.
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Also, the above change of rotation will only happen above a certain critical rpm. Above that rpm the beads should help balance, below they would hinder. That's not an issue as long as the critical rpm is below, say, 50mph. Right? At low speeds balance isn't an issue.
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I think this is one of those situations where there are too many, dare I say dynamics?, involved for me to hope to do a proper theoretical analysis.
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I have a headache...

 

[pappawheely]

I found this on their website. I'm not a physics teacher, all I know is that my truck rides real smooth and my tires are happy.

Edit: I can't seem to post the video? http://centramatic.com/Page.aspx?page=Video%20How%20Centramatic%20Balancers%20Work

 

[Wh1t3nukle]

So are you all mounted and running with these?

 

[pappawheely]

So are you all mounted and running with these?

Yes, I have a couple of thousand miles on them. You can feel the difference on the pavement. I have not installed new shocks yet, running on an ancient set of Rancho 9000's and my tire wear has been perfect. I put them on my trailer too.

 

[hangdog]

I agree with pappawheely on centramatics making a difference. Mine are mounted behind Michelin XDS2 245/70/19.5 tires. The ride is not perfect but way better than not having them at all. I found an article talking about the bastard tire on another forum. Apparently, there's more to mounting a 19.5 tire than just adding weights.


Wow. I never thought I'd see the day when a guy named Julio could take me to school on how to mount a truck tire. Boy was I wrong!

Everyone knows I bought a brand new Hino from Hadley Wrecker/Rush trucks this summer. What you may not know is I have been fighting a bouncing tire syndrome in the front end of the truck since I picked the truck up. After 14,000 miles and 4 tire shops I have finally found out what the problem was.

First, some background.

The truck was not ready when I arrived so Rush was forced to hire a mobile truck to install my new Alcoa aluminum rims on my truck just before I left with it. This is where the problem started. Improper installation procedures.

TDS Tires in Denver and specifically, a young man named Julio is the one that was finally able to diagnose what the issue was and help me to correct it.

19.5" tires are a bastard size to begin with. How they are mounted to the rims and how that rim is mounted to the truck is more important than any other tire size available. They really are too small to be a truck tire and too big to be a car tire. Hence, the 'bastard' designation.

When he lifted the truck to take the tire off, he gave it a spin and immediately knew what was wrong. The tire was not mounted to the rim properly causing the bead to be off center.

Rules of thumb.

You must make sure you use enough lubricant on the bead before you initially air the tire up. A dry install or an install with just water will cause problems. This is so important that Ryder trucks mandates a special lubricant to be used on all their tire mountings.
A 19.5" rim and tire should not be initially aired up with the tire in an upright position. You should lay the tire and rim flat on a level surface so there is no downforce applied that would cause the bead to not seat properly.
Tire machines and 19'5" rims are not matched well at all. Even with the adapters, you need to spend a little time spinning the rim on the machine to MAKE SURE it is running true. I watched him go through this process and with each rim, it took several adjustments and almost 5 minutes per tire to get the rim to run true. Once this is completed, you need to once again spin the tire and see if the bead is properly seated (see the picture below)
If everything is ok, you can then proceed with the balancing process.
There is something else I learned and I had never heard this before. There is a big difference between brand name and non brand name tires. This difference has everything to do with the quality and roundness of the tire. Brand name tires have a small yellow dot on them near the bead on the tire. This dot is considered the light side of the tire and should be aligned with the valve stem on the tire!

I never heard of such a thing but it's true!

He made a believer out of me! Spinning the tire on the machine, i could see how it was perfectly round. I was amazed. he then proceeded to spin the tire to balance it. The new tire and new rim balanced at ZERO WITH NO WEIGHTS! I don't think I have ever seen a tire that didn't need weights before.

Once the tires were balanced, he pulled another secret out of his pocket. He showed me a tool he uses to assure the tire is centered on the hub of the truck further ensuring a smooth running installation. It's a little tool called a "Tru-Balance". These are stud covers that are installed on three of the studs to center the rim on the studs. You should never rely on the centering devices of the hubs themselves as everything is machined from the stud positions. Besides the fact that you can install the tire off centered by not using this tool, tightening the lug nuts down on an aluminum rim in an off center position can (and actuall did) damage the lug holes in the rim. He recommends each truck carry this tool so if roadside repair is needed, you have the tool to make sure they center the tire when they reinstall it. I am buying one for each of my trucks to be carried in the toolbox.

The following are some pictures to help explain what I learned. I also have a video of the old tire spinning on the machine showing how out of round it was even though it was balanced perfectly.

Looking at this picture, you can see the bead strip. This is a line on the tire right near the tire seat. This line should be exactly the same distance from the edge of the rim all the way around the tire. If it's not, the bead is not seated correctly.





The following is the alignment tool for properly mounting the tires. Especially important on aluminum rims.















Got took to school! This truck drives like a dream now!

 

[chilliwak]

I found this on their website. I'm not a physics teacher, all I know is that my truck rides real smooth and my tires are happy.

Edit: I can't seem to post the video? http://centramatic.com/Page.aspx?page=Video%20How%20Centramatic%20Balancers%20Work

Thanks for posting that Papa. It shows how the whole thing works... I was always curious when I hear that people put sand inside their tires. I am thinking that would wear the tire from ther inside out....:smiley_drive:

 

[Wainiha]

I don't see any pics hanqdog.

 

[pappawheely]

Thanks for posting that Papa. It shows how the whole thing works... I was always curious when I hear that people put sand inside their tires. I am thinking that would wear the tire from ther inside out....:smiley_drive:

I've never done it but have heard that the loose BB's can do damage to your rims too.

 

[redthies]

Redthies, are you running real (expensive) tire balancing beads, or airsoft or regular BB's? I'm about to try heavy airsoft BB's in my tires just for fun. Balance is good w/o weights, but I do get just a little shake at 65mph.
I like the idea of centramatics, but I'm too cheap to buy them.

Sorry for the delay in responding... I am running semi-expensive actual balance beads. I think they are ceramic coated steel?

 

[wADVr]

I ran 8 oz of air soft bbs in each of my 33"s for several years. Tires always ran smooth and wore very evenly. I always worried I would loose bbs when I blew a bead but never did. I blew the beads on these multiple times even once in a creek and did not loose any bbs. The sound of the bbs bouncing off the aluminum rim when coming to a stop took some getting used to as it sounds similar to metal on metal brakes. I haven't ran this route for a few years but will likely go back when I convert to bead lock rims, someday.

 

[Belltownbikes]

Pappawheelie, why did you decide to use these balancers in the first place? I have a quigley Ford van which has intermmittent steering wackiness - every now and again it just doesn't want to go straight, or it doesn't want to come back to center after a turn. All of the steering components seem tight. If the problem was continuous, it would be easier to figure. Anyway, I am beginning to think that the problem might be balance related - every now and then everything lines up just right down there to create this wackiness. Was thinking that these centramatics might help. Any advice? Thanks. B

 

[Mobryan]

Pappawheelie, why did you decide to use these balancers in the first place? I have a quigley Ford van which has intermmittent steering wackiness - every now and again it just doesn't want to go straight, or it doesn't want to come back to center after a turn. All of the steering components seem tight. If the problem was continuous, it would be easier to figure. Anyway, I am beginning to think that the problem might be balance related - every now and then everything lines up just right down there to create this wackiness. Was thinking that these centramatics might help. Any advice? Thanks. B

If that conversion has leaf springs up front, double check the u-bolts holding the axle to the springs. I had a similar situation not too long ago and the culprit was a stretched ubolt, causing the spring centering pin to shear. The whole axle assembly was shifting front and back on the leafspring when I cornered, putting everything askew and creating the symptoms you describe. Unfortunately, I wasn't able to pinpoint it until after I drove up on the sidewalk and almost killed a bronze buffalo :Wow1:


Matt

 

[pappawheely]

Pappawheelie, why did you decide to use these balancers in the first place? I have a quigley Ford van which has intermmittent steering wackiness - every now and again it just doesn't want to go straight, or it doesn't want to come back to center after a turn. All of the steering components seem tight. If the problem was continuous, it would be easier to figure. Anyway, I am beginning to think that the problem might be balance related - every now and then everything lines up just right down there to create this wackiness. Was thinking that these centramatics might help. Any advice? Thanks. B

I have spent years driving in remote areas on big tires. Big tires don't always balance well. It's common when you are driving through sand, water etc to lose wheel weights throwing everything out of balance and tires are expensive. When I was scouting photo locations for Vegas to Reno a couple years ago I drove 3K miles in one week. That would kill an out of balance tire. I planned to run beadlocks in case I had to repair a tire in the field. Once you break the bead, the balance would be off with conventional weights. The Centramatics are durable and worry-free; two things I like when spending time far off the beaten track. When I am on the pavement my truck rides very smooth. It feels good and helps with wear and tear and maybe gas mileage. I could use any help I can get in that dept. :sombrero: