Wheel Balancer Accuracy and Repeatability

[gregs]

I have a question for those of you that have a name brand commercial balancer or work with one. How accurate and repeatable is your machine? Lets say you balanced a tire&wheel and reached 00 - 00 and without moving it on the spindle it comes back to 00 - 00 after a couple more tries. But if you loosen the wheel and turn it a 1/3 to a 1/2 on the spindle and rebalance it again do you always get 00-00 again? Or if you take it off the machine completely and put it back on will you get 00-00 again?

 

[yellowbox]

Yes you should
Fix aflat will give false readings every time though

 

[gregs]

Nothing inside, but used tire on a used wheel.

 

[yellowbox]

Could be a busted cord in tire

 

[gregs]

Going to do a little more testing with a couple of different tire/wheels.

 

[chris142]

Just spin it. Put on weight and put it on the car. Dont be like the guy that put 9 weights inside my jeep wheels. He would spin,add weight,spin again,add weight etc

 

[txvwnut]

If it is properly calibrated you should get a zero reading after reclocking the wheel and spinning it. If is not properly calibrated then it will read the imbalance of the machine assembly and give that number as a needed correction.

 

[gregs]

If it is properly calibrated you should get a zero reading after reclocking the wheel and spinning it. If is not properly calibrated then it will read the imbalance of the machine assembly and give that number as a needed correction.

So its a cheap chinese balancer I bought used and fixed a few problems it had (pickup board for the weight location) and various other loose hardware and connections. I had a really good steel wheel to use for the calibration along with the 3.50 oz weight. The thing is whenever I do the calibration and spin it afterwards it never asks for 3.50 oz at 180 degrees. Its usually 3.25 oz or slightly less. The manual states something like "3.50 oz or close to it" I tried changing the offset amount "A" to see if that would have any effect since the rim diameter and width is fixed. It only made a noticeable difference if I went a fair amount higher or lower, anything somewhat close and it stayed the same.

Also when I spin the wheel after calibrating it shows it needing weight on the the inside of the wheel, usually around .5-.75 oz. Which is also similar to the weight it asks for if I reclock a tire/wheel also usually asking for it on the inside.

Are you saying that the machine could possibly have an imbalance within it? And the amount it asks for if I reclock it is that?

 

[dscheidt]

if your wheel is lug centered, it's entirely possible the hole in middle isn't really centered. that will change how it gets read. So will a bad mounting cone, whether the wheel is concentric to the center bore or not (or adapter plate, if you're using one, same problem. )

 

[KSJeff]

Is it bolted down? My Mayflower balancer would be all over the place when it wasn't bolted down.

 

[rlitman]

If it is properly calibrated you should get a zero reading after reclocking the wheel and spinning it. If is not properly calibrated then it will read the imbalance of the machine assembly and give that number as a needed correction.

Um, to put it simply: no. Balancers don't work like that. Calibration determines the quantity of weight the balancer recommends to correct imbalance, but does NOT have anything to do with determining when a wheel is balanced 00-00.

...The thing is whenever I do the calibration and spin it afterwards it never asks for 3.50 oz at 180 degrees. Its usually 3.25 oz or slightly less...

So you're throwing on 3.5oz of weight imbalance, and it's reading that off by 1/4oz? That's about as good as can be expected calibration wise. As for the balance shifting when you rotate the wheel on the hub, it could be a lot of things, but it isn't a calibration issue.

 

[gregs]

Is it bolted down? My Mayflower balancer would be all over the place when it wasn't bolted down.

No its not bolted down. I have considered it as a possible solution but the manual clearly states it does not have to be bolted down. It doesnt move around when operating. I did slide some 1/4" rubber matting pieces under the 3 points it sits on to possibly dampen any harmonics. Dont know if it actually does anything.

 

[gregs]

if your wheel is lug centered, it's entirely possible the hole in middle isn't really centered. that will change how it gets read. So will a bad mounting cone, whether the wheel is concentric to the center bore or not (or adapter plate, if you're using one, same problem. )

The wheel I use for the calibration is a newish oem Ford steel wheel. It was the spare from a vehicle that never got used. It runs pretty true for a steel wheel. The wheels I am working on now are steel white spoke trailer wheels, and they look to run fairly true as well.

 

[gregs]

So you're throwing on 3.5oz of weight imbalance, and it's reading that off by 1/4oz? That's about as good as can be expected calibration wise. As for the balance shifting when you rotate the wheel on the hub, it could be a lot of things, but it isn't a calibration issue.

Thats kinda what I figured in regards to the calibration. I figured if the manual said approximately 3.5 oz when you spin it after calibrating, that it would be close enough. I mean your swinging a 3.5 oz of weight around in one position so the balancer can locate it relative to a position.

 

[rlitman]

Thats kinda what I figured in regards to the calibration. I figured if the manual said approximately 3.5 oz when you spin it after calibrating, that it would be close enough. I mean your swinging a 3.5 oz of weight around in one position so the balancer can locate it relative to a position.

Stupid question here, but is your calibration weight even 3.5oz? Most of my weights are off a bit one way or the other, because weights today are too often based in metric units (grams), with either 25g or 30g weights being labeled 1oz (which is really around 28g). 82.5g is about 2.9oz, and 105g is about 3.7oz. But 1/2oz here or there is really the best most balancers can reach repeatedly. They may read to 1/4oz, but that doesn't mean they can hit that level of precision repeatedly.

 

[gregs]

Stupid question here, but is your calibration weight even 3.5oz? Most of my weights are off a bit one way or the other, because weights today are too often based in metric units (grams), with either 25g or 30g weights being labeled 1oz (which is really around 28g). 82.5g is about 2.9oz, and 105g is about 3.7oz. But 1/2oz here or there is really the best most balancers can reach repeatedly. They may read to 1/4oz, but that doesn't mean they can hit that level of precision repeatedly.

I am fairly sure it is. When I worked on it before I remember weighing it to verify. But can double check again.

When I spin it after calibrating it and get a small weight on the inside and the larger but not 3.5 oz on the outside, I figured that was do to it trying to dynamically balance it?

I sorta put it in the category of it being close enough for a cheap chinese balancer. I wonder how accurate they are compared to a newer "real" commercial balancer. I am guessing the technology it has is probably from the early 80's.

 

[KSJeff]

I wonder how accurate they are compared to a newer "real" commercial balancer. I am guessing the technology it has is probably from the early 80's.

The last two that I mounted and balanced were checked by Discount Tire and unchanged so mine was good on that particular set. They were aluminum rims and summit 225/55R17s. I did the backs and when he blew the front I had him go up there. They balanced the new ones and checked the back ones.

 

[rlitman]

I am fairly sure it is. When I worked on it before I remember weighing it to verify. But can double check again.

When I spin it after calibrating it and get a small weight on the inside and the larger but not 3.5 oz on the outside, I figured that was do to it trying to dynamically balance it?

I sorta put it in the category of it being close enough for a cheap chinese balancer. I wonder how accurate they are compared to a newer "real" commercial balancer. I am guessing the technology it has is probably from the early 80's.

I would guess that a large enough static imbalance could be misread by the force sensors, and that's what's throwing it off. Try setting it to static balance mode and see what it says.

The technology hasn't changed much since the '80's, with two exceptions. Some newer balancers can split weight recommendations to hide them behind spokes (still based on the same mechanisms though), and road force balancing is an entirely different thing.

 

[gregs]

I put one of the tire/wheels off my Suburban on it. Newer tires, aluminum wheel. They are due to be balanced. Checked the existing balance and it wanted weight added. But it looked like I had lost the inside weight at some point.

Took the weights off and spun it up. Added the weight it called for and spun it again. It wanted another.5 oz on the inside so I added that and got 00-00. Spun it a few more times and still 00-00. The majority of weight is on the outside, opposite the TPMS like it was before.

Then I clocked it about a 1/3 of a turn and it called for .75 on the inside and .5 on the outside. I didn’t change anything and put it back on the burb.

So could the spindle be out of balance? It runs true and I checked it and the bearings before. What about the handles / wings on the cup nut? I can see it not be in the same place after you clock it. Any tire shop would just do what I did and as long as they qot 00-00 it would be good to go. They are not going to be clocking to check it again.

 

[rlitman]

I put one of the tire/wheels off my Suburban on it. Newer tires, aluminum wheel. They are due to be balanced. Checked the existing balance and it wanted weight added. But it looked like I had lost the inside weight at some point.

Took the weights off and spun it up. Added the weight it called for and spun it again. It wanted another.5 oz on the inside so I added that and got 00-00. Spun it a few more times and still 00-00. The majority of weight is on the outside, opposite the TPMS like it was before.

Then I clocked it about a 1/3 of a turn and it called for .75 on the inside and .5 on the outside. I didn’t change anything and put it back on the burb.

So could the spindle be out of balance? It runs true and I checked it and the bearings before. What about the handles / wings on the cup nut? I can see it not be in the same place after you clock it. Any tire shop would just do what I did and as long as they qot 00-00 it would be good to go. They are not going to be clocking to check it again.

I get this a lot on my Jeep's LT tires. Hardly ever on my car tires. What I've found on my own wheels is that the heavy offset weight makes the tire want to tilt left on the cone while you tighten the nut, and if the tire isn't pretty close to vertical when it reaches the balancer hub, it ends up binding up a little bit off-center. The cone can only move it so much. If I force the wheel upright with my left arm as I tighten the nut with my right, this issue usually goes away for me.

 

[gregs]

I get this a lot on my Jeep's LT tires. Hardly ever on my car tires. What I've found on my own wheels is that the heavy offset weight makes the tire want to tilt left on the cone while you tighten the nut, and if the tire isn't pretty close to vertical when it reaches the balancer hub, it ends up binding up a little bit off-center. The cone can only move it so much. If I force the wheel upright with my left arm as I tighten the nut with my right, this issue usually goes away for me.

The issue seems more prevalent on larger truck tires verses car tires also. I have encountered something similar when getting them on the spindle. I have thought about adding a little grease to the cone to see if it would help centering it in the wheel. I also thought of using a HF moving dolly and add some type of simple lift to it to make it easier to load and unload the tire on the machine.

 

[rlitman]

... have thought about adding a little grease to the cone to see if it would help centering it in the wheel...

It probably would, but it would also attract all kinds of dirt. I'm also not sure if the sticking is on the cone or the hub face (probably both). Never took it that far. Ever since I started holding the tire up by hand (and yeah, it's a royal pain), it stopped happening to me.

Let us know what you find. What you're seeing is very real, and it's come up in other threads before, with no good solutions that I'm aware of. I do suspect it's a common cause of imbalance, but since it's usually limited to about 15g, it sneaks past most people's radar.

 

[gregs]

It probably would, but it would also attract all kinds of dirt. I'm also not sure if the sticking is on the cone or the hub face (probably both). Never took it that far. Ever since I started holding the tire up by hand (and yeah, it's a royal pain), it stopped happening to me.

Let us know what you find. What you're seeing is very real, and it's come up in other threads before, with no good solutions that I'm aware of. I do suspect it's a common cause of imbalance, but since it's usually limited to about 15g, it sneaks past most people's radar.

Do you have your machine bolted to the floor? KSjeff mentioned it making a difference for his Mayflower unit. Mine does not shake or move that I can see or feel, but I was wondering maybe the cabinet has more flex with the bigger wheels causing the force sensors to be less accurate since the are attached to the inside of the cabinet. Just a thought.

 

[rlitman]

No. Mine's a Snap On hand-spin that sits on the floor on three points. It doesn't move at all, and no bolts needed, but bolting down a hand-spin balancer is usually pointless. That's more of a thing for a powered spin machine.

 

[gregs]

I have worked out some issues going back to doing a better job of getting the wheel centered and running true. I cleaned up the cones and added some lube, cleaned up the wheel centers and backs and made sure I was lifting the wheel and getting it positioned correctly. I also blew out the position sensor and checked all the connections.

I think I also figured out that just loosening, turning the spindle, and retightening it doesn't necessarily keep the wheel centered back on the spindle that well. I found repeatability improved if I loosened it a lot, turned the spindle 90 degrees and then lifted and tightened it back up.

When I see wheels that are balanced at a tire shop they typically spin them once, add weight and I guess spin them again to verify and there done. Weights are in one spot on the outside plane and one spot on the inside plane.

Whenever I spin them on my machine, the first spin gives a weight inside and out, I add the weight, then when I spin them again it typically calls out for additional weight. Its usually on the inside and will ask for .25 to .75 additional. If the original weight was at 12 o'clock position, the additional weight is usually somewhere between 12-4 or 12-8. If I add the weight it usually comes back 00-00 balanced. My manual says it can take up to 3 spins to perform a balance.

If I read online it basically says that having weights in two different locations on the same plane is not correctly balanced. I did find some information on how to move the weights to solve that problem and did spend some time doing that, but theres no way a tire shop is going to take the time to do that. So far I have just been working with the 17" tire/wheels off my Suburban and some 15" trailer tire/wheels that are typical white spoke trailer wheels and used 235/75-15 AT's. The manual says max diameter for the machine is 31.5" and both of these are around 30.5", so its near the max if that makes a difference.

Any thoughts on the machine calling for additional weight and having weights on two different locations on the same plane? I feel like I have have solved some issues and trying to figure out if the rest is just the machine? Or if I should be looking at something else?

 

[39CAMC]

I have worked out some issues going back to doing a better job of getting the wheel centered and running true. I cleaned up the cones and added some lube, cleaned up the wheel centers and backs and made sure I was lifting the wheel and getting it positioned correctly. I also blew out the position sensor and checked all the connections.

I think I also figured out that just loosening, turning the spindle, and retightening it doesn't necessarily keep the wheel centered back on the spindle that well. I found repeatability improved if I loosened it a lot, turned the spindle 90 degrees and then lifted and tightened it back up.

When I see wheels that are balanced at a tire shop they typically spin them once, add weight and I guess spin them again to verify and there done. Weights are in one spot on the outside plane and one spot on the inside plane.

Whenever I spin them on my machine, the first spin gives a weight inside and out, I add the weight, then when I spin them again it typically calls out for additional weight. Its usually on the inside and will ask for .25 to .75 additional. If the original weight was at 12 o'clock position, the additional weight is usually somewhere between 12-4 or 12-8. If I add the weight it usually comes back 00-00 balanced. My manual says it can take up to 3 spins to perform a balance.

If I read online it basically says that having weights in two different locations on the same plane is not correctly balanced. I did find some information on how to move the weights to solve that problem and did spend some time doing that, but theres no way a tire shop is going to take the time to do that. So far I have just been working with the 17" tire/wheels off my Suburban and some 15" trailer tire/wheels that are typical white spoke trailer wheels and used 235/75-15 AT's. The manual says max diameter for the machine is 31.5" and both of these are around 30.5", so its near the max if that makes a difference.

Any thoughts on the machine calling for additional weight and having weights on two different locations on the same plane? I feel like I have have solved some issues and trying to figure out if the rest is just the machine? Or if I should be looking at something else?

Since I read your original post, when I think of it, I have been loosening the collar, moving the wheel and re-spinning a few assemblies when balancing on my Hunter at work. I have had one of them out of about a dozen ask for different weights and only .25oz.

The typical procedure is to spin once, get a reading and add weight and then do a "checkspin" On that machine (a 2 year old Hunter RoadForce Elite) the check spin rarely asks for a weight change but it does happen. Of course, it spins the wheel to where the weights go, holds it, and puts a laser red line where to put the weight. It also has a camera to read the wheel profile so it knows pretty exactly where each plane is.

I have a Snap On Hand spin machine in my trailer that we use at the track. Conditions aren't nearly as nice as in the shop, I am usually doing it in the trailer which may bounce or move. Temps can vary quite a bit as well. Also, it is not nearly as precise as to where you put the weights and on this balancer, it is less than 50% that the first spin gets it to zero.

As far as weights on more than one place on a single plane....on a purely technical basis if you get it balanced to zero it is good. Zero is zero.

However, it is fundamentally sloppy. There are people here who judge a 140lb truck tire/wheel assembly with 2oz of weight as junk and poorly balanced - I work in the real world and am not nearly that picky (2-3oz per plane is my personal limit) but the overall goal is to achieve balance with as little weight as possible. More weight is ugly and adds more failure points in the future. Especially with stick on weights, a .25oz slice seems to be much more likely to fall off than a longer piece.

My personal procedure - (FYI I work almost exclusively with stick on weights) if the original weight was at 12 and it asks for more weight between 10-2, I add it next to the original stack. If it asks for more between 8-4, I remove the amount it asks for from the original stack and do a checkspin.

If the checkspin is still not zero, I see if the above will work again, but if not, or the additional weight is in the 90 degree dead zone (8-10 and 2-4) I usually remove the weight on that plane altogether and start over.

If my weight changes don't "make sense" on the checkspin (e.g. I added .50oz and it changes 1oz in a random location) I tend to pull all the weights, reseat the wheel on the balancer and start over.

Overall, judging by the weights I scrape off and the vibration complaints I fix from other shops, not many tire shops spend anywhere near the time or thought that you or I do towards balancing.

HTH,

DaveW

 

[gregs]

So far all of my "testing" has been to test the machine and test my ability to use it. Since the machine was used when I got it and it had a problem its hard to tell if it's the machine or me that is causing the repeatability problems.

But the whole thing that got me to this point was issues I had with tire shops over the years. So spending a little more time per wheel doesn't bother me, but just want to make sure I am doing things correctly.

 

[djbmw]

Bolt it to the floor... or something very heavy.

For aluminium and mag rims, make sure to back-cone ( the cone is on the spindle, then the rim, then your large cup and nut). For steel rims you can front-cone (rim goes on the spindle, then cone, then slip washer and nut) ... but back coning is generally the preferred method.

On my machine I also have to use my brain and interpret what the machine wants. For example, if it calls for 0.5 opposite of where weights already are, i will REMOVE 0.5 from the existing weights and not add any new weight.

 

[rlitman]

...Any thoughts on the machine calling for additional weight and having weights on two different locations on the same plane? I feel like I have have solved some issues and trying to figure out if the rest is just the machine? Or if I should be looking at something else?

Could be your calibration is a little off. Could be you dialed in numbers for diameter, width or offset that are a little off. But as small as you're getting, it could also just be pushing the limits of the sensors.

My old machine only has one diameter measurement, and when I'm doing clip on weights for the inner circle and stick on for the outer, that single number gets me close, but it isn't perfect. Rim width should be the width between the two weight circles. With clip on weights, you'll want to check with calipers, but with stick ons, a tape measure will get you closer. Offset should be to the inner weight circle, which is inboard when the inside gets stick on weights. These differences of maybe half an inch will add up to the kind of errors you're describing.

 

[gregs]

Could be your calibration is a little off. Could be you dialed in numbers for diameter, width or offset that are a little off. But as small as you're getting, it could also just be pushing the limits of the sensors.

My old machine only has one diameter measurement, and when I'm doing clip on weights for the inner circle and stick on for the outer, that single number gets me close, but it isn't perfect. Rim width should be the width between the two weight circles. With clip on weights, you'll want to check with calipers, but with stick ons, a tape measure will get you closer. Offset should be to the inner weight circle, which is inboard when the inside gets stick on weights. These differences of maybe half an inch will add up to the kind of errors you're describing.

Thats what I am seeing. I have played around with changing the offset number to see how it affects the outcome. Still playing around with the Aluminum options when using stick on weights. The wheels I have that require stick on weights only use them for the outside plane and use hammer on ones for the inside. I guess it deducts for the offset of that ringed area behind the spokes? Is there some kind of industry standard for the distance from the outside edge of the wheel to the area behind the spokes designed to have the weights attached?

If I can commit to a place to put it, I am considering bolting it to the floor to see if that changes anything even though the manual says its not required.