Rule Clarification: Body Work and Track Width

[RichardP]

I brought this up last year at this time. It seems likely that I’ll bring it up again next year about this time…


After some issues at Nationals last year, the CMC rules covering fender rolling and modifications were strengthened considerably to try and keep track widths under control. Despite these changes, the allowed track width of a CMC car is still based subjective visual inspections of curved shapes. This is on cars some of which are over 25 years old and have led a very hard life.

Track width is too important of a performance parameter to be subjectively evaluated by an inspector that could come up with a different answer than another inspector reading the same set of rules. The line between someone completely following the intent of the rule and someone pushing the rule a little too far is very blurry.

Creating a numerical track width allows for an easy, non-subjective evaluation of the legality of a competitor. The measurement can quickly be done using tools many competitors already possess. The American Iron series has already grappled with this issue so the tools to measure it should also already be in the tech shed.


Richard P.

[Al Fernandez]

I think in this scenario the issue is not so much how to measure it, but rather what to set the number to. In AI its an easier story since bodywork modifications are allowed. So, if this were to fly...what should the different widths be?

[GlennCMC70]

the main problem w/ this is by limiting track width, you can limit camber on a 4th gen being as its adjusted w/ the lower A arm. this would not be the case w/ the Fords or the 3rd gens. i just wanted that to be known.

[Al Fernandez]

Right you are Glenn...you might limit camber, depending on the width selected, and the competitor's wheels... so the point still is: what could/should the magic numbers be?

[Todd Covini]

The magic numbers should be wider for Ford.

[michaelmosty]

I don't know, I'm still wondering what the front track-width is on the 3rd and 4th gens.

[mitchntx]

I don't know, I'm still wondering what the front track-width is on the 3rd and 4th gens.

You have a 4th gen sitting in your driveway and I assume you have a tape measure.

Or do you want the GM camp to give that to you as well?

[RichardP]

I think in this scenario the issue is not so much how to measure it, but rather what to set the number to?

Maybe we could measure the current cars. Pick three of each eligible model that by the current rules “appear” to be at their maximum width. If you get the same measurement for all three cars, then use that number. When you don’t get the same number, you have validated the need for this rule clarification and you get to make an executive decision.

Realistically, the number you are supposed to pick is the widest number you get that still meets the arbitrary “looks right” test. The intent is not to change anything or anybody’s car. There should be no cost to the organization or the competitors for this. It’s just a way to take judgment out of the process and make sure everyone is meeting the same standards.

Where we are currently, you can have a guy that has maximized his car to what he believes is the extent of the rule but is actually at an unknown disadvantage to the guy who has done a better job at “tweaking” his car.

Within the next month, there are events at Barber, Thunderhill, and MSRH that I know of. I volunteer to measure the entire CMC field at MSRH and create a spreadsheet if you would like. There is a 50/50 shot that I will be at Barber. If I go, I’m happy to do the same at that event, too.


Richard P.

[mitchntx]

As Glenn pointed out, Richard, the flaw is measuring a 4th gen.

Camber is set by moving the lower A-Arm in and out.

I have a different camber setting for TWS, Houston and Cresson. Tracks that require more brake, I use less camber (more tire contact patch). Tracks that have higher speeds, I use more camber (less rolling resistance).

So, my track width might vary 1/2" or more.

[RichardP]

Track width changes with camber on a Mustang too.

So we set the number so that at maximum negative camber you meet it. When you run less camber, you are effectively allowed to use 1/4" wheel spacers. Or it becomes a tradeoff in setup that competitors have to balance. Whatever needs to happen. The current rule is not really a rule at all.


Richard P.