1974 Non-Stock Wheel Balance Question

[Paul L.]

A few months ago I had a Gary R. rebuilt/blueprinted steering box installed on my 1974 by a local GM dealer. An alignment was done at the same time. The car has never driven and tracked so straight and true since I bought it in 2008. Kudos to Gary!

But I have always had a minor (very) steering wheel shimmy beginning at ~50mph. It is just a small irritant that normally can be fixed by a wheel balance. So back to the GM dealer last week. They gave it a try on their very old balancing machine but concluded that the wheels have "too much offset" for their equipment. That puzzled me....but to their credit I was not charged. They recommended that I find a shop with a Hunter GSP9700 Road Force Balance machine. (In fact they apparently send out C5/C6 wheels to be done elsewhere??)

I have found a shop with that machine. But in the experts' opinions here will that do the job?

The wheels are Centerline clones from Enkei. The tires are 235-60R/15.

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[Joe L.]

Re: 1974 Non-Stock Wheel Balance Question

A few months ago I had a Gary R. rebuilt/blueprinted steering box installed on my 1974 by a local GM dealer. An alignment was done at the same time. The car has never driven and tracked so straight and true since I bought it in 2008. Kudos to Gary!

But I have always had a minor (very) steering wheel shimmy beginning at ~50mph. It is just a small irritant that normally can be fixed by a wheel balance. So back to the GM dealer last week. They gave it a try on their very old balancing machine but concluded that the wheels have "too much offset" for their equipment. That puzzled me....but to their credit I was not charged. They recommended that I find a shop with a Hunter GSP9700 Road Force Balance machine. (In fact they apparently send out C5/C6 wheels to be done elsewhere??)

I have found a shop with that machine. But in the experts' opinions here will that do the job?

The wheels are Centerline clones from Enkei. The tires are 235-60R/15.

Paul-----


If it can't be gotten right with the Hunter machine, then I'd say you need to start looking for a bad wheel or tire. That Hunter machine is pretty much as good as it gets.

Keep in mind that you could also have an imbalance problem associated with a disc brake rotor. No matter how right you get the wheel balance, if the rotor is out of balance, you'll still have problems.

[Paul L.]

Re: 1974 Non-Stock Wheel Balance Question

Thanks Joe,

I'll check the front rotors but the last time I looked they were OK. I replaced front calipers and pads about 2,000 miles ago.

The minor shimmy starts at 50-60mph and goes away at 70mph. Very strange.

The GM dealer has served my Family well for many years (my DD is an Impala and I am looking to a Cruze soon). But in the last couple of years they have shyed away from my C2 and C3 Corvettes. Given that most of their technicians are younger than my car I think I know why. They simply can't read codes from them.

I'll try the speciality tire shop and see what happens. I do like those wheels, and they are not damaged, but I may go back to stock rally wheels in the spring. Meanwhile I'll keep driving for the next few weeks before winter storage. Possibility of frost close by tonight! But strangely in the 80s on Thursday....Bizarre weather.

[Terry M.]

Re: 1974 Non-Stock Wheel Balance Question

Paul-----


If it can't be gotten right with the Hunter machine, then I'd say you need to start looking for a bad wheel or tire. That Hunter machine is pretty much as good as it gets.

Keep in mind that you could also have an imbalance problem associated with a disc brake rotor. No matter how right you get the wheel balance, if the rotor is out of balance, you'll still have problems.

As Joe says the Hunter GSP9700 is as good as it gets, however, that or any machine is only as good as the person using it. They are extremely sophisticated machines and require someone well trained to operate them. Some shops have such a person, some don't. I doubt many of us have the skills to tell the difference. You can Google the name of that machine and find a page that will give you the locations of that machine near you. I am not suggesting the shop you were referred to is good, or bad -- I only wish to point out that owning the machine is only the start of a good balance job.

I believe that machine is capable, in the right hands, of determining if a wheel is straight or bent.

Oh and Paul: If you can tell if a rotor, or anything else, is out of balance by looking you are a better man than I am Gunga Din.