C2 67 rally wheel trueness - what to do?

[Timothy B.]

I searched the archives and didn't find what I was looking for. From the experience of the group, how true should a 67 rally wheel spin (or any wheel for that manner) before it starts to cause a noticeable problem? Since these are steel wheels, I suspect that GM didn't make them all that perfect to begin with. I have two out of four wheels that are pretty good according to the tire shop, 1 that is marginal and one that is the worst. He didn't tell me any numbers about how they were. The guy told me to just put the worst ones on the back, but I would like to know if there is a tolerance rule of thumb or any other guidance on how much wobble can be in a wheel and not cause a noticeable problem.

Also, assuming I decide that 1 or more of my wheels need attention, can they be straightened? Thanks in advance for your advice.

[Kent K.]

Re: C2 67 rally wheel trueness - what to do?

Tim ---- How true is the spare wheel? If it was my car, I'd put the worst wheel in the spare tire compartment or, if it is all that untrue, find another one to replace it.
Regards, Kent #6201

[Timothy B.]

Re: C2 67 rally wheel trueness - what to do?

Here is a photo of the setup I used to get a quick measurement of wheel runout (wobble). I ran the dial guage on the inside bead area so that I didn't have to remove the trim rings.

Rough measurements were:

Front: About 20-30 thousanths
Rear left: About 55 thousanths
Rear right: About 60 thousanths

[Timothy B.]

Re: C2 67 rally wheel trueness - what to do?

From a post in another forum, it seems that there might be a spec for runout of 1/16" and the same number for concentric relative to the spindle.

I suppose that if I go by the 1/16" spec then I am just in on the rear as 1/16" = ~63 thousandths? Since both rear wheels are at the max, seems like they might be a problem. I tried to check rear toe in using a fixture I have that reads off of tire tread, and I measured about 1/8" toe OUT at first, then rolled the car 1/2 tire rotation and then measured about 1/16" toe IN!! The overall diameter of the tire of course magnifies the runout as measured at the tread.

Suggestions/comments?

[Patrick H.]

Re: C2 67 rally wheel trueness - what to do?

The rally rims on my Dad's 72 had a couple of issues too. I suspect that there is a lot more variance to these than we'd like to believe.

We had the wheels and tires "Road Force Balanced" on a Hunter 9700 machine. Using this machine, the tire shop found out which tires fit best on which wheels, and adjusted them all to fit. The car rides and drives superbly now, so even if one is a little off I think it's so much better than it would have been 30 years ago that it doesn't make a difference.

Look for the Hunter 9700 machine in your area if you can.

http://www.gsp9700.com

http://www.gsp9700.com/pub/technical/4127T/4127t.cfm

Patrick

[Timothy B.]

Re: C2 67 rally wheel trueness - what to do?

Patrick, that Hunter machine seems like a great piece of equiptment, but short of calling all over the place how do you find out who has one. I wonder if Hunter can tell you where in your area they sold one?

[Timothy B.]

Re: C2 67 rally wheel trueness - what to do?

Wow, I just discovered on the website you sent that they DO have a link to find them in your area. Great!

[Duke W.]

Re: C2 67 rally wheel trueness - what to do?

Measure toe by making tire crayon marks on the tire tread where you can measure across the rear of the tires. Then roll the car forward until the tire marks are at a point where you can measure across the front. This eliminates inaccuracy due to tread or wheel lateral runout. You must place the tape at EXACTLY the same points on the tire on both the front an back side. Make the measurement multiple times until you achieve consisent results. If you get inconsistent results, there's something wrong with your technique or the trailing arms are flopping around. Take a measurement across the rear, roll it forward and measure across the front, then roll it forward until you can measure across the rear, again, and you should get the same measurment. It's all in the technique.

Of course, this will just tell you TOTAL toe in. It will not tell you if the toe is distributed equally between both wheels, which is a requirement for good tracking and handling.

What are your wheel lateral runnout measurements?

Duke

[Pat #25912]

Re: C2 67 rally wheel trueness - what to do?

Tim, if I remember correctly, up to .030-.035 Total Indicated Runout is acceptable. TIR is measured by using a dial indicator as you have done, but on both sides of the wheel and averaging the two readings. Pat