Spin-balancing isn't working... will Road Force?

[mrsilv04]

Originally Posted By: SF0059
Tell them. Did you buy the tire from them? If that is the case and Road Force doesn't take care of the issue get them to warranty the tire.


Yep. Tires came from them. If the Road Force machine isn't able to clear up the issue, they'll be putting on a new tire.

 

[stephen9666]

Originally Posted By: mrsilv04
Originally Posted By: Quattro Pete
Originally Posted By: mrsilv04
Last night, I very discretely marked the position of the stem on each of the tires, to see if they end up re-positioning any of the tires on the rim, with the Road Force balancing.

What you're talking about is match mounting in order to reduce the amount of balancing weights needed. It's different from road force balancing that can detect tire irregularities by applying 1200 lbs of pressure to simulate the weight of the vehicle on the tire as it rolls down the road. A tire can be perfectly balanced, yet cause vibration, and that's when you resort to road force balancing to figure out what's going on.


Well, they're calling it Road Force balancing. Their website mentions that they can Road Force balance tires.

I was under the impression that a Road Force machine can tell the operator how much to move a tire on the rim as well, to help improve things.


You're actually both sort of correct. When both match-mounting to reduce the weights needed and reducing road force variations there are situations where dismounting the tire and repositioning it on the rim can improve things.

With match mounting for weights, you're trying to match light/heavy spots on the tire and rim to reduce the amount of weight needed. That could necessitate moving the tire on the rim, although almost no shop ever takes the time to do that after the tire is mounted.

When optimizing RF numbers, I think you're trying to match high/low spots on the tire and wheel. Or, at least that's one of the things you're trying to accomplish. That can also require dismounting the tire.

Anyway, here's a video (not a fancy one) of someone using the RF machine. He measures the tire and gets 24 lbs. It shows him where to mark the rim and tire. He then dismounts the tire, lines up the marks and the RF number is reduced by half to 12 lbs.

 

[DuckRyder]

Many Hunter GSP balancers have the ability to "OEM Match". When this process is used the balancer measures the runout and balance of the bare wheel, then the tire is mounted and measured, the system then uses the road force, balance and runout measurements to calculate the best match. The system will estimate the amount of improvement possible and have the operator mark the wheel and tire to turn the tire on the wheel.

http://www.gsp9700.com/intro/index.htm

I've seen this process result in reductions of more than half the road force. It is a time consuming process though and much like alignments many operators will not try to reduce the road force if the machine deems it "acceptable". I think this acceptable number is programable, but 18lbs for passenger car tires and 25lbs for light truck tires are numbers I've seen more than once.

Some of the newest ones even have the ability to detect the "pull" in the tire and direct the tech where to mount each assembly on the vehicle.

http://www.gsp9700.com/how/index.htm

My shop always does this for me, and they always try to reduce the road force to the minimum possible. They are friends though, so I could be getting special treatment.

 

[millerbl00]

The balance machine must be calibrated once in awhile. If not its not accurate. Most shops don't calibrate their machines. I have noticed a big difference in the quailty of balance on the shops that do.

At one point Ford required way less than 25lbs of road force on there truck which was very diffcult.

 

[geeman789]

Originally Posted By: Chris142
What's with 4oz of weight? Way too much unless your running 40 inch tires.you either have a bad tire or bent rim


Any decent tire tech would have broken the assembly down, rotated the tire, and balanced it again to see if it reduced the amount of weight..

That much weight can be a sign of something as simple as random tolerance stacking, as in the heavy spot on the tire ended up at the heavy spot on the wheel... or a sign of a defective tire , or bent wheel.

If you re-position the tire, and confirm the wheel is true, and it STILL takes a lot of weight, you start looking at the tire. And if THAT tire vibrates... you may have a defective tire.

 

[Hohn]

Originally Posted By: Astro14
I would go back to square one.

What's the wheel runout? Has it been "curbed"? Replace the wheel...

Is there tread separation in the tire? Replace the tire...

I doubt that balancing is going to do anything...and you've already proven that it's this wheel/tire combo that is the problem...


With cast wheels, it's not uncommon to get porosity in some of the spokes. That can cause a 'light' spoke that will require a lot of weight offsetting it.

For a persistent balance problem, I would look at Equal/Counteract beads.

 

[CapriRacer]

Originally Posted By: mrsilv04
I've picked up a nasty vibration....


I think we'd all like an update, Mr. Silva (or is that Mr. Silver?) I know it's only been 2 days, but inquiring minds and all that!

Some thoughts:

I got the sense that this problem developed suddenly and was not related to any event, such as the purchase of tires or a brake changeout. If so, then some possibilities are eliminated and some are now possible.

Assuming the above is true, then I wonder if one of the tires has developed a separation. It's a little late in the season for this to develop (in Illinois), but it is still possible. It would be helpful if we knew how old the tires are (age and miles).

Second, I am aware that these kind of trucks are kind of sensitive to vibrations. I don't understand all that is going on, but I have heard that the center bearing isn't well supported and tends to vibrate, producing a vibration that feels very similar to an unbalanced tire. Further, reducing the vibrational characteristics of the tires helps the overall vibration of the truck. Ergo, you can "solve" this problem by getting round and well balanced tires, but the real problem is the bearing itself.

 

[mrsilv04]

Update...

I spoke to my mechanic, before I went back for the Road Force balancing session, to make sure that some sort of a mechanical issue wasn't being overlooked.

Last question, first. Center bearing was replaced 6,000 miles ago. Not because of an issue with vibration, but because the bearing itself was 'dry', and was dying a slow, painful death. The U-joints were checked at that time as well, and they were fine.

I was also told by the tire shop that my rear brakes could be suspect, but I re-did those myself (new pads and rotors), just a little over 12,000 miles ago.

The Road Force machine declared all 4 tires were good. The marks that I put on the tires show that two of the tires had been moved to a different "position" on the rim. One had been moved 180 degrees, and the other had been moved 90 degrees. Both tires/wheels that were moved are now on the rear axle.

The one tire that had 4 ounces of weight stacked up on it in one spot, is now down to less than half that. Quite honestly, the idiot who piled all of those weight on (this would be the same idiot who got all [censored] with me on Monday night), should have spun the tire on the rim, and then tried again. That's just a case of sheer laziness.

The other tire that had been shifted had less weight on it as well.

I was able to get it up to 70 for just a few miles, and was able to tell that the vibration at that speed seems to have been significantly reduced.

I hope to take it out this weekend, and drive several miles (at various speeds) on a recently paved highway to really get a good feel for how things are now. That's why I had delayed in posting an update.

 

[CapriRacer]

Originally Posted By: mrsilv04
Update......


Thanks for that. A question and a thought.

How old were the tires?

Just so you know, the 4 oz of weight would not cause a vibration, but might be a symptom of something amiss - and while rotating the tire reduced the amount of weight, that reduction would NOT be an indication that the problem was balance. I'm leaning toward "out of round" and rotating the tire on the rim made for a more round assembly.

 

[geeman789]

Originally Posted By: mrsilv04
Update...

The Road Force machine declared all 4 tires were good. The marks that I put on the tires show that two of the tires had been moved to a different "position" on the rim. One had been moved 180 degrees, and the other had been moved 90 degrees. Both tires/wheels that were moved are now on the rear axle.

The one tire that had 4 ounces of weight stacked up on it in one spot, is now down to less than half that. Quite honestly, the idiot who piled all of those weight on (this would be the same idiot who got all [censored] with me on Monday night), should have spun the tire on the rim, and then tried again. That's just a case of sheer laziness.



You probably had a tire with slightly higher road force variance mounted on a wheel with slightly higher runout... put those together wrong, as in the extra stiff spot on the tire matched to the extra high spot on the wheel, and vibration is likely...!

The fact that one tire was rotated 180 degree seems to support that scenario...

Was the first tire tech at the same shop as the road force balancing machine...?