|The MGA With An Attitude
BALANCING Bent Wheels - WL-107A
I have just about concluded that there never was any such thing as straight steel wheel for the MGA. I suspect they were all slightly out of plane from original assembly, some worse than others. In the early 90's I was breaking steel wheels regularly (stress cracks) while autocrossing nearly every weekend. I broke at least a dozen wheels and threw out several more that were too far out of whack to use. I finally sold the last half dozen wheels more recently, so I have gone through at least two dozen steel disc wheels. Of those at least two thirds of them were at least 1/8 inch out of plane. I think it is almost futile trying to buy more wheels with wishful thinking that they may have less than 1/8 inch run out.
1/8 inch out of plane is no problem at all, as long as the wheel is round and concentric. Up to 1/4 inch out of plane is serviceable, except it looks weird to a casual observer when it wobbles while driving on it.
There will be a problem with computerized spin balancers that may specify more than one pound of weights per wheel when they are 1/4 inch out of plane. They tend to put two four-ounce weights together on one side and another half a pound on the other side half way around, trying to eliminate a very small lateral vibration that results from being out of plane. Most people would never notice such a minor aberration while driving an MGA, so all the extra weights used for dynamic balancing may be a waste of effort.
I balance mine on a static balancer (bubble balancer) with just two small weights on the outside where they can be seen. I run a black marker around the weights so if they get knocked off it is obvious where they belong, and can be easily replaced. Static balancing was SOP in the 50's and into the early 70's, before spin balancing machines took away the requirement for a technician who can think for ten seconds at a time.
I still have a steel spare wheel that is 1/4 inch out of plane with one pound of weights from prior spin balancing. When I need to use it occasionally (once every 10 years or so) it seems to run smooth enough, but does bother some people to see it wobble. Please don't ask how old is the tire.
Radial run out is much more important than lateral run out. For the spin test you need to put the indicator on the cylindrical surface of the outer rim. If it runs concentric within 1/16 inch it should be okay. If the radial run out is greater than 1/16 inch it is either junk or needs straightening along the rim. Local divots in the rim are a result of hitting road hazards.