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Wednesday, June 1, 2011

Continuous Wheel Balancers

Centramatic's Continuous Wheel Balancers

Wheel Balancing, some background:

Wheel/tire combinations can be balanced in many different ways, including static and dynamic, on and off vehicle, as well and various types of permanent balancing systems.

Skipping on down...

After researching my options, I decided to give Centramatic's Continuous Wheel Balancing system a try. Long popular with over-the-road truckers, Centramatic has recently designed a balancer to fit popular light truck wheels, including 6-lug Toyotas. I phoned them up and ordered a set of:

P/N: 300-305; Model KP-12
Price $199.00/set of 4 plus $5 shipping

(in contrast the Sun Tech balancers are about $380/set)

A week later a box arrived from Centramatic with the four wheel balancers. Closer examination revealed a galvanized steel center disc to which was crimped a plastic "donut" full of heavy steel shot suspended in a synthetic oil. Kind of reminded me of one of the old hula-hoops with the pellets inside that made a "shoop-shoop" sound as it spun. Each unit weighs about 5 pounds, or so. The inner hub cutout is 4-1/4" dia. and easily fits over the stock hub, the outer diameter is 12-1/2", so you should check that your rims have enough clearance inside for the balancer to fit, the plastic donut projects about 1-1/8" at its maximum thickness. They fit inside both my Toyota factory 15x6 rims as well as my 15x10 custom rims (both steel). There was not a lot of extra room, though, so be sure to measure your rims before ordering.

UPDATE: Apparently Centramatic has decided to drop the 15" version of this product, except for police vehicles. What prompted this, I'm not sure, but it looks like Sun Tech is the only other option at this time.

Installation:

Installation is fairly straight forward, jack up the vehicle, remove the wheel, slide the balancer over the hub, plastic donut facing out, and re-install the wheel.

Simple enough in back, but on my '85 front solid axle, I found the brake caliper protruded beyond the face of the hub a bit. In the picture above, the red magnet is not quite flush with the hub mounting surface. I painted the protruding part of the caliper white and you can see it sticks out at least 1/4" beyond the hub face. Most wheels are dished away from the hub surface so this is not a problem, but the balancer disc extends straight out from the hub all the way to the inside of the rim.

I ground down the small raised section on the caliper to remove most of the interference. Even so, I found it necessary to add a 1/4" spacer (pictured) to gain enough breathing room between the balancer disk and the caliper. I have run these spacers with my 33x9.50 tires for over two years now without problem. There is enough extra length in the stock wheel studs to accommodate a 1/4" spacer and still have a few threads protruding beyond the lug nuts for safety. Users of 1/2" thick or thicker wheel spacers will have no clearance issues at all.

Note: If you are dead set against wheel spacers, best to check the caliper clearance on your truck *before* ordering this product, it may not be for you!

Here is the installed balancer and the somewhat tight clearance at the brake caliper (this is still with the 1/4" spacer installed). Actually there is more clearance than pictured above, since the balancer is somewhat dished inwards until the wheel is bolted down, flattening the dish and pulling the outer edge away from the caliper.

In the photo above, you can see the wheel balancer weight ring behind the wheel indicated by the green arrow. Also, as a point of reference, the red arrow points to a small, but visible, gap between the wheel and the front hub. While this has nothing to do with the wheel balancer, it does show that Toyota wheels are typically "lug-centric" or centered by the wheel lugs. It is this very gap that tells you that, because if there is a gap between the wheel and the hub, the hub can't be centereing the wheel (as in a hub-centric design), so it therefore must be lug-centric. And it is interesting to note that the Centramatic wheel balancers are also a lug-centric design, they have an oversize center hole to clear the hub.

One potential consideration is that the balancer disc effectively blocks air from flowing in through the wheel, kind of like those "dust shields" for reducing brake dust on your wheels. Toyota uses an inner brake shield around the brake disc. This shield is prone to filling with mud and snow when driving in those conditions. I had been considering cutting this shield back. However, it can't be just be removed as it provides important spacing for the hub spindle attachment mechanism and also supports the lower attachment point for the flexible portion of the front brake lines. However, in my case, my new crossover steering arms provide a brake line mount on the steering arm itself, necessitating some modification to the shield. So, grabbing my air-powered nibbler and metal-cutting band saw, I went to work removing the bulk of the shield. I had my axle apart anyway both to install the new steering arms as well as replacing the birfield joints, but I imagine it would be possible to trim the shield in place if desired. This is an optional step and I'm not advocating the need to do this, just documenting what I did. You can see the cut away brake shield in the preceding caliper-clearance picture.

Road Test:

According to Centramatic:

"It is not necessary to balance your wheels prior to installation but it is advised to insure maximum performance."

At slow speeds, there is a definite "shoop-shoop" sound as the shot rolls around inside the tube. Once you get above 25 MPH, the sound stops and the balancers start working. Interestingly, once the shot settles into place, they stay quiet until you drop below about 5 MPH. The balancers seem to work fine with my slightly out-of-balance BFG M/Ts.

With the new HySteer crossover steering setup, did install a steering stabilizer, to control the front end wobbles when hitting bumps. It was not needed for normal driving, but did help dampen the wobbles when hitting bumps. I also increased my caster angle and this seemed to help, too.

Update:

So, I decided to see how the balancer would stand up to a set of lumpy, 33x15.50 bias ply SuperSwamper TSL/SX tires, the score:

Centramatic: 2
Swampers: 2

Looks like a dead heat to me. The somewhat out of balance front tires worked great, no wobble or vibration after you warm them up to eliminate the bias-ply flat spots. The rear tires, on the other hand (which both had ~15 oz. of lead weight removed when they were shaved) are not quite able to balance out. I can feel them smooth out, then start to shake, balance out again, etc. I took the two rear tires in to have them re-balanced. They each took about *20* oz. of lead to (sort-of) balance, so no wonder the wheel balancers were not able to control these monsters. Anyway, with the weights and the balancers, the ride is now finally smooth, I can easily run up to about 70 MPH (at which point my 22RE engine is about maxed out :).

For off-road use, I've found no problems, so far. After a recent snow run, in which one bead picked up a handful of wood chunks after climbing up a tree root lined trail, I found this didn't upset the balance at all.

And now after 11 years of use, I can say I am still running these balancers. Have used them on 5 sets of tires now over the years and the last few sets, are ones that I mounted and "balanced" myself. In doing so, I think I have now easily saved the cost of the balancers with money (and time) saved at the tire shops. I use an inexpensive tire mounting tool from Harbor Freight and use a simple bubble balancer with stick on weights to do a quick static balance on the tires after I mount them (probably not required, but I think it is a good idea) and then the balancers take over.

Available from:

Centramatic Perma Balance
1300 East Belknap Street
Fort Worth, TX. 76111
Ph: +1(817) 332-3636
FAX: +1(817) 870-1866
TollFree: +1(800) 523-8473

email: centra2@centramatic.com