Originally Posted by puttin
I wonder what happened to the spin balancers that used the technique of being mounted on the vehicle and then spun on the vehicle. That way, it took the car into account as well. They utilized a strobe to show where vibration was occurring and indicated where to place the weight(s). bbeane- do you remember those balancers?
That is the hunter machine described in a previous post. Big advantage is they balance exactly as it would be run down the road, including the brakes, and any "as installed" runout in the hub.
Disadvantage could be that each tire/wheel is balanced for that position only.
In theory at least, the hubs are perfect, and the drums / disks were balanced when they were built.
On this subject...
A good wheel / tire shouldn't need much weight to balance, and that weight is most often located opposite the valve stem.
A good wheel / tire should have near zero runout. If you watch it on the balance machine, it shouldn't be moving up or down or side to side.
Anyone who says big truck tires don't need balancing is high on something. Fact is some poeple who own big trucks that do a lot of miles are too cheap to balance them. A tire 36" tall can generate some serious forces from out of balance.
Runout is really important too. when they did the new tires on my pace arrow (I was there, and I watched every move, and I always do) one of the tires wanted a lot of weight. The tech wasn't happy. He rebalanced it 3 times, then finally broke it down and remounted it himself. This time it had no visible runout, and balanced with just an ounce or so.
ALWAYS WATCH EM.
And insist, IN ADVANCE that they spin the tires a second time, and you see the double zeros on the machine. Nothing goes on your rig unless you see the double zeros with your own eyes.
When I did the wilwood race brakes on my camaro, the runout spec was said to be four thousandths of an inch. I checked them with a dial indicator, and 3 of the 4 brand new disks had to be trued (turned) to get within that spec. If you don't check, you don't know it is right.