Rules clarification/interpretation

[JSG1901]

It was brought to my attention this past race weekend that the GTS rules regarding tube-frame cars are a little confusing despite our attempts to make them less ambiguous. I'd like to (try again to) clear that up.

 

Currently, the rules read as follows:

 

...Tube frame cars will be classed according to the Non-D.O.T. table regardless of tire choice. Tube frame cars running Non-D.O.T. tires will be bumped into the next higher class. “Tube frame” is defined as: “A car intended solely for racing, whose main structure or frame is fabricated from an assembly of tubing, and that cannot be driven with the tubing removed.” Modification of suspension and drivetrain mounting points alone does not constitute a tube frame.

 

While the definition of "tube frame" is pretty clear, what isn't as clear are these two statements which are contradictory:

 

• Tube frame cars will be classed according to the Non-D.O.T. table regardless of tire choice.

• Tube frame cars running Non-D.O.T. tires will be bumped into the next higher class

 

One possible way of interpreting this would put every tube frame car running slicks through a series of escalations, eventually making them all run in GTSU regardless of original class. That, of course, is not the intention. What is the intention is to require tube frame cars to work at a power-to-weight disadvantage to their non-tube framed competitors.

 

Therefore, to make it as clear as possible, the grid below represents the power-to-weight ratios required of tube-frame cars in GTS. These are the ratios we will use for tube frame cars at this year's NASA National Championships and I will have them added into the GTS rules in place of the current questionable and confusing language.

 

GTS1

• Race 22.0:1

• DOT 20.0:1

 

GTS2

• Race 18.5:1

• DOT 16.0:1

 

GTS3

• Race 14.5:1

• DOT 12.0:1

 

GTS4

• Race 11.0:1

• DOT 9.0:1

 

GTS5

• Race 8.5:1

• DOT 7.2:1

 

GTSU

• No limit

 

So, in other words, in all situations, a tube frame car will run with the next-worst power-to-weight ratio from its own or the adjacent class.

 

Please take a gander at this. I'm open to any suggestions about how to state this more clearly.

[UKRBMW]

Scott - just a thought and I'm not an engineer so this maybe completely erroneous. Hopefully folks that are smarter than me can provide more info. And all of this is a bit premature considering I haven't really seen any tube frame cars in GTS in our two regions.

 

Most tube frame cars I've seen are extremely light - 2,200-2,500 range. With new compounds coming from BFG and GY, plus A6 grip it would seem you're basically running same power to weight as a standard car on slicks. I don't think it's a big deal in GTS1-3 since most run DOT and there is a large spread in hp/wt. But getting in GTS4-5 that advantage goes away since the spread is only 0.5. Tube frame cars I've seen have some pretty awesome suspension setups, engine completely behind front axles helping with a really good balance in the car. It would seem those advantages should easily overcome the difference between a slick and A6 type tire.

 

Does anybody have direct experience with them? Any insight?

[JSG1901]

UKRBMW,

 

You may very well be right, and it's possible we should do something more radical with this rule. This would be a great time to start that discussion but if we're going to make meaningful changes to the rules we should do it at the end of the year when we have our normal open period for new rules suggestions.

 

My reason for making this clarification now, mid-year, was because I know of at least one driver considering bringing a tube frame car to GTS and who specifically asked what the rule meant. Once I read what it actually said, I decided it was either incomplete or confusing, or maybe both, so I've moved ahead with what I think is the intention of what's there today.

 

Given that, it would be a great discussion/debate to have.

 

Scott

[UKRBMW]

Thanks Scott. That was my intent to get some conversation going. I'm by no means an expert in this area, just soliciting some opinions.

[cstreit911]

I think it does call for more discussion.... We won't allow a lot of year/make/model cars in our series... ...because they aren't pure German. However we'll let Billy Bob's Carolina chassis shop hang some BMW bodywork on his circle-track chassis and "Go Racin' GTS!" What is an OEM engine on a tube-frame car? The one from the marque that the bodywork resembles the most?

 

UKRBMW,

 

You may very well be right, and it's possible we should do something more radical with this rule. This would be a great time to start that discussion but if we're going to make meaningful changes to the rules we should do it at the end of the year when we have our normal open period for new rules suggestions.

 

My reason for making this clarification now, mid-year, was because I know of at least one driver considering bringing a tube frame car to GTS and who specifically asked what the rule meant. Once I read what it actually said, I decided it was either incomplete or confusing, or maybe both, so I've moved ahead with what I think is the intention of what's there today.

 

Given that, it would be a great discussion/debate to have.

 

Scott

[scottbm3]

I think it does call for more discussion.... We won't allow a lot of year/make/model cars in our series... ...because they aren't pure German. However we'll let Billy Bob's Carolina chassis shop hang some BMW bodywork on his circle-track chassis and "Go Racin' GTS!" What is an OEM engine on a tube-frame car? The one from the marque that the bodywork resembles the most?

 

I agree with Chris. I thought we originally had a more exact definition of a "Tube Frame" car and how much of the basic chassis had to remain in place.(main unibody stucture etc. etc). I think a complete tube frame chassis with a skin body does not meet the Spirit of our series.

 

 

-Scott B.