Centramatics for Vintage?

[TomW]

Originally Posted by TomW

... Is InlandRV’s product too small to be effective? I don’t know – Gotta think about this one.

After analyzing a still from a training video from Centramatic, a photo from InlandRV’s web site, and photos of the original Centramatics I bought & returned several years ago, more conclusions have been drawn about the effectiveness of the dynamic wheel balancers offered by both Centramatic & InlandRV.

While I know my analysis would have more validity with either design prints or sacrificial wheel balancers, the former was not available, and the entire topic is not important enough to purchase & butcher perfectly good balancers just to reverse engineer performance. Please accept that errors may have occurred. This is nothing but a paper exercise.

To understand what a reasonable goal was, I went out to my Airstream, and found the wheel with the most balancing weight attached to it, and sat down to figure out if the performance of InlandRV’s dynamic wheel balancer would make the weights unnecessary.

The worst-case wheel had 4 ounces (113 gram) of lead on the front side, AND 3.75 ounces (106 g) of weight on the back side (at the same location) for a total of 219 grams balancing weight mounted eight inches away from the hub’s centerline.

InlandRV’s product, with its reduced size would need to position 350.4 grams of weight at the same location to provide the same balancing result.

While I got a kick out of this entire self-imposed task, I know most people could care less about the technique & actual number crunching. I will spare you except for one image:

My analysis (as I said is not based on reliable data) indicates InlandRV’s product can only accommodate 214.5g of imbalance. This is 61.2% of the goal.

It was only fair at this point to analyze what Centramatic sells for 15 inch wheels. As the diameter of their product is 2-1/2 inches larger than InlandRV’s product, a more favorable result was expected.

Centramatic needed to provide 292 g of balancing weight on its six-inch radius to provide the same end goal. My error-prone analysis yielded only 271 grams. While better, it would only be 92.8% effective on the same wheel.

In conclusion, either balancer should be capable of correcting for imbalance in the cast-iron hub. But it appears to be prudent to balance the wheel/tire combination before depending on either product to make your Airstream’s ride more smooth.

Oh, and the perfect balancer would have measured ~13 inches in diameter.

Tom

[Action]

Originally Posted by TomW

Tom

With all of that said, this tire is a great example of one that should be taken off the road, based on the cracks in the side wall, no matter how in balance or out of balance it may be.

On a seperate note not knowing anything about a Centramatic other than it's picture in this thread, I would be concerned about it's design restricting air flow for brake drum cooling. Many parts of the country this wouldn't be an issue. In AZ it gets a lil hot. But just to let you know it's a dry heat.

>>>>>>>>Action

[DPeakMD]

Originally Posted by TomW

...While I got a kick out of this entire self-imposed task, I know most people could care less about the technique & actual number crunching. I will spare you except for one image:

...
Tom

Hey, Tom, is that an HP 41C(V/X) ? That brings back memories! Sweet post!

[TomW]

Originally Posted by Action

With all of that said, this tire is a great example of one that should be taken off the road, based on the cracks in the side wall...

Dave,

See post one of this thread:

http://www.airforums.com/forums/f465...ean-63758.html

Tom

[TomW]

Originally Posted by DPeakMD

Hey, Tom, is that an HP 41C(V/X) ? That brings back memories! Sweet post!

You're looking at a 41CX with a Math I pack, Machine Design Pack, and an HP-41 Advantage pack.

I just can't part with it - It still has the Mohr's Circle program I input key by key back in college.

Tom

[Action]

Thanks Tom. I have posted on that thread as well. So hope you get the new rubber soon. And yes I noticed the wood only side as well.

BTW I have a HP12C that I use daily. (I am in the mortgage biz) Most snicker because they consider it a dinosaur, and it works for me.

>>>>>>>>>Action

[Wabbiteer]

A large weight requirement is the heavy spots of the tire carcass and the wheel aligning, so... often when large weights are called for a considerate mechanic will pull the schrader valve from the stem, break the bead and rotate the tire 120° or 180° and finish the balance.

[Inland RV Center, In]

A counter balance weight 180 degrees from the heavy spot, still leaves a part of the circle untouched.

Each weight, the heavy spot or counter balance, effects only 150 degrees of the circle.

The best lead weight counter balances, is using 2 weights, 120 degrees away from the heavy spot. That then, provides an overlap that in turn provides a good balance for about 10,000 miles, as per Snap On.

We can balance the running gear to better than 1/10 of an ounce. But, that old Snap On equipment, is no longer made.

The Centramatics balances the complete circle, as shown in their video. That balancing system, also extends the mileage life of the tires, be it on a car, truck or trailer.

Andy

[ROBERTSUNRUS]

Hi, since we all know that the tire/wheel combination can be balanced, and they still should be done. But the big un-known is the un-balanced brake drums, so we have Centramatics to take care of them. I have Centramatics on my trailer and my tires/wheels are machine balanced.

[Airstreamer67]

TomW, I love your mathematical and scientific approach to tire balancing.

I tried to put Centramatics on my 67 Overlander a few years ago, but ran into the same problems as the original poster. They would not fit the factory wheels.

As an alternative, I put DynaBeads in my tires, and they get the job done with flying colors. The DynaBead organization has a recommended amount of beads to provide the amount of balancing needed for a particular tire size, but one can increase or decrease the amount as might be desirable.

The advantages of DynaBeads include the fact that they are very economical, they last as long as you want them to (you can even reuse them if you want to go to the trouble of doing so), and, Ta Da, the biggie, they provide compensating weight balancing on the very edges of the TIRES, not the much smaller wheel rims. So, any amount of weight from the DynaBeads provides a magnified balancing effect compared with the Centramatics. I'm sure you would have a field day figuring the differential.

The disadvantage of the DynaBeads is that it is recommended the owner use a special filtered valve stem/core, which theoretically prevents the beads from discharging out the valve when checking air pressure. However, the valve stem/core from DynaBeads is very cheap, and I have found using a regular valve stem/core actually works very well. I found this out when, ironically, I had one valve with the special filtered stem/core that stuck open. After fiddling with it, I finally replaced it with a regular non-filtered stem/core, and it's been working flawlessly ever since, with no observed discharge of beads upon checking air, using my PressurePro tire monitor, etc.

So, I would recommend DynaBeads for consideration.