Technical Bias Tire Balance

I wore out the rear tires on Plan II, so I got a new pair, now that they're back in stock. Coker Classic L78-15. I mounted the first one, and put it on the little bubble balancer. Hmmmm..... I guess it's traditional to have lots of weight, that's why I have all these huge weights that I took off old rims!

 

Wow!

 

Seems excessive.

 

makes me wonder if they're not out of round, I like spin balance, answers both questions

 

Try breaking the bead then rotating the tire 180`. Back in the day we used to do that all the time, it often worked.

 

I don't think these wheels are that far out of whack.

 

They are Cokers. They might not be round.

 

I would find the spot directly opposite where the bulk of the weights are. That should be the heaviest spot on the tire.

Put a piece of tape or a chalk mark there.

Break the beads and find the weld seam in the outer hoop. That should be the heaviest spot on the wheel.

Turn the tire so that the marked spot on the tire is directly opposite the welded seam.

Re-seat, and re-balance.

 

That's the most likely explanation.

I doubt I'm gonna get 8 ounces of correction from doing that.

 

Try my trick first.

Few wheels are zero-balanced. Tires certainly are not.

You may only need 4oz of correction. If they are 8oz out, and the heavy spots are just too close to each other, placing them opposite each other will certainly help.

 

I have seen wheels where the heavy spot is inexplicably NOT at the weld seam.

Since you have a bubble balancer, you can figure out where it is pretty quickly.

If you find a drastic imbalance in the wheel, and they have welded centers, look for a honkin' overlarge weld bead for the center.

I have seen that put a wheel way out.

 

Thanks, I'll play with it in the morning. I'll put the other wheel on the balancer before mounting the tire.

 

Thats alot.!! turn 180 , I figure you know that. true-ing and on the car strobe light balance is best. Trouble is finding someone who still does that. Some Big truck shops still do it You may have to send tires back.

 

I'm not sending them back, they're reproductions of lousy tires....they're not modern tires that are CNC mfd to be dead on.

 

Oh, boy!

 

Uh yeah, That was the way it was.
Only formal training I ever had was a seminar by B.F. Goodrich.
We spent the day with a bubble balancer learning to split the weights by straddling the heavy spot. Must use crayon.
We go about thirty degrees apart centering our crayon mark. Then pick weight sizes that allow us to place one half the amount on the front of the rim, and one half on the back, or inside rim.
This means that for each heavy spot, weights are placed in four positions.
The large weights shown were indeed common. Small ones were of course also often needed. They referred to this process as 'Dynamic Balancing'.

 

Look up "Snap-on WBK-2 " wheel balancer , one of the more confusing systems of the '60's

 

Just went through this. I finally found a great shop that was able to shave my new Cokers to round. First question he asked was where did the tires come from. When I said Coker, he said I'll see what I can do. He said they are the worst and he's called them numerous times about their tires being out of round or taking a shit ton of weight to balance. They don't seem to care.

My tires were absolutely out of round and the pile of rubber laying there was a testament. And it wasn't just in one spot.

I really hope Coker gets their act together because they pretty much have a monopoly on the vintage tire game.

 

At first, I was able to balance my tires also using my buddy's Snap-On spin balancer. They will balance even being out of round.

What would happen is at 50-55 mph, the front end would start bouncing like a basketball. Since my car is fenderless, I could watch it happen.

At first I thought it was the ruts in the road. Found a stretch of perfect, newly paved road and it did the same thing.

When I got to the shop, he asked what is happening. Even before I finished, he said at around 50-55 mph? I knew I found the right guy.

He chucked them up in the shaver and the proof was in the rubber.

After shaving, car runs smooth at all speeds. I did not bother doing the rears. It cost $50 a tire to have them shaved and I didn't want to spend even more on top of the price of the new tires.

 

There’s an article in this month’s Hot Rod magazine about tire shaving. Apparently, if you know someone that does it, you’re lucky.

 

Anyone in the tri-state area, I can't recommend K&T highly enough. Great folks.

Here is a link to their webpage.

http://www.ktvintagecars.com/

I kick myself for someone was selling a 711 Truer for $500. I regret not buying. Seems like I could have a nice little side gig going.

There real culprit here is Coker. They really need to get their act together. Either fix the molds or true the tires before they leave the factory. With the prices they charge, it is bordering on robbery that you need to spend another $200 to make their tires runnable.

 

I learned how to use a bubble balancer in high school auto shop, using 4 weights....but it's not really dynamic balancing, for that you need a spin balancer, which can detect where the weight needs to go on the front and on the back to balance it in both planes at once. When using a bubble balancer to static balance, dividing weights front and back helps, compared to putting all the weight on the front or the back. Using 4 weights instead of 2 lets you get them just right where they need to be, but using a little extra weight to do so.

It's just an old Chevy, it ain't gonna be perfect. And it's a good thing you didn't see the weights on the slicks, which are M&H.

 

I’ve never used loose beads to balance tires. Has anyone used them?????

 

I broke the bead on the one I had mounted, turned the tire 120 degrees to get the light spot on the tire aligned with the weld in the rim. Still took 8.5 ounces to balance it.

The other wheel took about the same weight also.

The old pair of tires didn't take that much weight, I guess quality is going downhill.

 

If you can remember back to the early 00's we had many discussions on balancing beads. Lots of talk in the archives

 

Ill have to pic that up. In never get that mag anymore, but I do have that same Tire Truer. Maybe it has some tips on using it since i have yet to use mine.

 

There is a reason every tire shop had a shaver when bias ply tires were the norm. It's funny how people now think it's some sort of anomaly or rip off to have to do it to bias ply tires today.
https://www.motortrend.com/how-to/tire-shaving-race-cars/

 

I would think that the first thing on any tire mounting would be to check if the tire runs true..........is round/concentric. As you mentioned, newer tires are not generally known to have that issue. Even if you get the tire "balanced" weight wise, the whole mass is going to be moving in an eccentric rather than concentric.
Then you have to consider that those excentrics will be happening on both wheels at the opposite end of a lever . Might not be as bad with an independent front end, but a guy with a straight axle will probably feel it more.

Has anyone actually talked to Coker and asked why this problem seems to be more prevalent lately? Is it that people talk more (on computers) and become more aware of a problem thats always been there........or is the product quality becoming less important?

To me the important thing here is safety.......would not want to lose you or any other rodder due to misguided loyalty.

 

I've always have had good results, it seems, with a bubble balancer with slicks. But I've always have used stick ons in those situations.