FC/FF maximum width measurement

[DaveW]

I just submitted this request to the CRB:
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Title: Maximum width measurement

Class: FC

Request: Rule clarification/modification question/suggestion:

I just read the August 2018 preliminary TB:

FF 1. #24678 (John LaRue) Request to change how to measure overall width In the GCR FF/FC dimensions table 4, add the following: "H. Maximum width - To be taken at the widest point on the wheel at the horizontal axle centerline."

That pretty much defeats what I thought was the original intended purpose of the maximum width measurement rule change - to eliminate the possibility of being declared illegal because of tire width, toe or camber settings.

It would not be that much harder to measure at the two opposing points on the horizontal wheel centerline and take the average of the two. To determine which opposing point is wider, both would have to be measured in any case.
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Measuring just one point on the opposing rims makes little sense if the intent is to eliminate setup variations from the measurement.

[Purple Frog]

This is a rule written by people who don't have to enforce it.
A nightmare for a tech inspector to accurately measure.

Not to mention it will allow cars to be ~2" wider than the rules we lived with for 30 some years.

I am guessing the reason for it was with the advent of radials and their more extreme negative camber settings folks would have to possibly shorten A-arms to get the front max width narrow enough. This enables a car that was at max width with bias tyres to switch to radials without having to change the suspension.

[S Lathrop]

This was not an issue when cars were running bias ply tires with small diameters and modest camber settings. It has become an issue singe the adoption of "spec" tires and especially "spec" radial tires that are very much larger in diameter than the original tires that the bulk of the cars were designed around.

The toe settings that may render a car illegal are often the result of what the tires require to work properly. Often those tires are required to compete in SCCA sanctioned events.

[chrisw52]

This is a rule written by people who don't have to enforce it.
A nightmare for a tech inspector to accurately measure.

Not to mention it will allow cars to be ~2" wider than the rules we lived with for 30 some years.

I am guessing the reason for it was with the advent of radials and their more extreme negative camber settings folks would have to possibly shorten A-arms to get the front max width narrow enough. This enables a car that was at max width with bias tyres to switch to radials without having to change the suspension.

if that's the case, it would be nice to have a clarification in the rules to address this..

[2BWise]

This was not an issue when cars were running bias ply tires with small diameters and modest camber settings. It has become an issue singe the adoption of "spec" tires and especially "spec" radial tires that are very much larger in diameter than the original tires that the bulk of the cars were designed around.

The toe settings that may render a car illegal are often the result of what the tires require to work properly. Often those tires are required to compete in SCCA sanctioned events.

But SCCA doesn't spec a tire in FC. This may be a side effect of the radial tire adoption in FF, but I don't see it being an issue for FC. Maybe the rule should be split between the 2 classes.

[problemchild]

But SCCA doesn't spec a tire in FC. This may be a side effect of the radial tire adoption in FF, but I don't see it being an issue for FC. Maybe the rule should be split between the 2 classes.

This was an issue on F2000 VDs over the last decade, as tire construction, and desired alignment, required minimizing the lengths of lower front A-arms, and sometimes modifying those A-arms. AFAIK, with narrower wheels, and tires, it was not so much of an issue with FF.

If that is the concern, why not just add a few mms to the current rule. We needed this rule change a decade ago. Not sure why now. As I understood it, it was the non-VD car builders who objected to the rule change then, so why they are presenting this rule now, is perplexing. Perhaps an explanation is needed.

[John LaRue]

The rule was changed a few years ago to measure at the centerline so as to eliminate the issue of excessive cambers throwing cars over the limit. This was done proactively to try to accommodate those cars that had been built to the limit in light of the new radial in FF. It might be an issue in FC where the radials are being run, but since they are not currently the pick in club racing it is not a current concern.

Because toe could likewise impact a car built to the edge the question was raised as to where the measurement was being taken. The FSRAC recommended the language that you see in the prelims. DW raises a valid question and has submitted another letter seeking further clarification - that will be taken up by the FSRAC on their call next month.

If the allowed width is increased there would be nothing that would keep someone from building to that number and then raising the same issues.

[Lotus7]

FF 1. #24678 (John LaRue) Request to change how to measure overall width In the GCR FF/FC dimensions table 4, add the following: "H. Maximum width - To be taken at the widest point on the wheel at the horizontal axle centerline."

That's as nebulous as those "maximum track" regulations some series have.

Why not simply say "the car as it comes off the track must pass between two solid metal posts xx inches apart" ?
And for practicality, use a go-no-go width gauge that looks like the worlds largest vernier caliper. F4 series recently introduced it. Simple, inarguable. Onus is on the competitor to allow for sidewalls if applicable.

[problemchild]

As Mike pointed out, it is a nightmare for tech people, but how would any car owner measure distance around a car at multiple points on a wheel (or even one point).. Does every FF/FC owner and every tech inspector need their own 80 sq foot measuring table with lasers or whatever measuring technology is required (including climate controlled room). Or do we all need our own jigs? While I know one FF racer with such a table, I don't think it is feasible for most of us.

Measuring maximum width with a Go-No Go gauge works fine, as FRP does it ...... or just two posts and a tape measure ...... is just fine. Change the dimension a few mms to help out the few cars that may need it, and if a few people want to build new A-arms to exploit the rule change ...... let them. Like a few lbs of arguable downforce, a few mms of track is not going to start a revolution.

Unfortunately, this current group of SCCA politicians cannot seem to get anything done ..... as in no spec tire in FV after 55 years, but they seem to be insist micro-managing with busy-body rule changes. What we need, is rules of inclusion to promote affordable participation and growth.

[John LaRue]

As Mike pointed out, it is a nightmare for tech people, but how would any car owner measure distance around a car at multiple points on a wheel (or even one point).. Does every FF/FC owner and every tech inspector need their own 80 sq foot measuring table with lasers or whatever measuring technology is required (including climate controlled room). Or do we all need our own jigs? While I know one FF racer with such a table, I don't think it is feasible for most of us.

Measuring maximum width with a Go-No Go gauge works fine, as FRP does it ...... or just two posts and a tape measure ...... is just fine. Change the dimension a few mms to help out the few cars that may need it, and if a few people want to build new A-arms to exploit the rule change ...... let them. Like a few lbs of arguable downforce, a few mms of track is not going to start a revolution.

Unfortunately, this current group of SCCA politicians cannot seem to get anything done ..... as in no spec tire in FV after 55 years, but they seem to be insist micro-managing with busy-body rule changes. What we need, is rules of inclusion to promote affordable participation and growth.

There is nothing that prevents the use of a no-go gauge as you suggest; it seems completely plausible to me. The reason this was addressed was due to an inquiry as to where the measurement was being taken and whether it accounted for toe, not a desire to micro manage the rules. I submitted the letter after receiving a call on the issue. Hope you are having a great day, nice to see you at the track!

Cheers,

John

[problemchild]

So we had a rule, based on some degree of common sense, that both competitors and tech people, could check compliance with minimal complexity (two boxes and a tape measure). Because of some legitimate concern that some legal cars were now illegal, due to changed tire technology, instead of changing the value in the rule, SCCA created a new rule, which neither tech people nor competitors can actually measure without custom made equipment. Since we have no accurate way to measure, we just assume our cars are legal, and no one can accurately measure it anyway.

Now that someone is questioning a stupid rule, we are trying to make it more stupid, by introducing more parameters that cannot be measured. John says that a No go-Go gauge is fine with him. So that means that tech people will now be provided with 7' long gauges that can be adjusted for height to meet the cenerline of every tire combination used in FF and FC (and CF?) so that the distances between specific points on wheels can be checked for compliance. So how are John and I supposed to measure our own cars for compliance ..... or do we just assume that because they were legal to the previous common-sense rule, they are now legal to the current stupid rule, or the forthcoming clarified stupid rule?

Race car wheels, whether steel, magnesium, or aluminum, ....... whether fabricated, forged, spun, or cast ...... have a huge variation in the external width of the wheel, although considered the same width wheel. Some wheels have curled up flanges, with significant differences of curl, even in different production runs from the same supplier. Some have machined edges, some flat, some tapered. Many have damages or repairs to the outer rim edge. Considering all the complexity of measuring the width on the wheel rim, is the irregularity of wheels not a factor, and open to exploitation? I expect that a racer with very expensive light wheels could run more actual track than someone with cheap scuzzy heavy wheels.

Maximum width - To be taken at the widest point on the wheel at the horizontal axle centerline."
What if the spokes of the wheel protrude further than the rim portion? Do we measure at that point?

[DaveW]

After some discussion, there is a possibility of reverting to the original rule which allowed simple measurement. Stay tuned.

[stonebridge20]

The Thompson majors results from this past weekend.

And there's concern about how to measure maximum width in FF and FC ?

[John LaRue]

[QUOTE]Maximum width - To be taken at the widest point on the wheel at the horizontal axle centerline."
What if the spokes of the wheel protrude further than the rim portion? Do we measure at that point?[/QUOTE

I think you can figure that one out on your own.

[Gary_T]

Maximum width - To be taken at the widest point on the wheel at the horizontal axle centerline."
What if the spokes of the wheel protrude further than the rim portion? Do we measure at that point?

That's easy, just turn the wheel so the spokes aren't on the horizontal centerline.

Gary

[DaveW]

That's as nebulous as those "maximum track" regulations some series have.

Why not simply say "the car as it comes off the track must pass between two solid metal posts xx inches apart" ?
And for practicality, use a go-no-go width gauge that looks like the worlds largest vernier caliper. F4 series recently introduced it. Simple, inarguable. Onus is on the competitor to allow for sidewalls if applicable.

After some discussion, there is a possibility of reverting to the original rule which allowed simple measurement. Stay tuned.

As I said - stay tuned.

[problemchild]

That's easy, just turn the wheel so the spokes aren't on the horizontal centerline.

Gary

But the rule does not say you can do that. You are suggesting that we use common sense, but there is nothing about this rule that allows or suggests the application of common sense.

Common sense would suggest that we restrict maximum width by measuring maximum width.

[LenFC11]

Ahh Greg.. using common sense in scca?? Over rated..

[John LaRue]

The rule was clarified several years ago for the measurement to be made at the axle centerline. This was done so that the cars that had been built to the limit would not be declared illegal if they ran high cambers. A pretty simple and elegant solution IMHO. When questioned it was clarified to be at the horizontal centerline.

Troll on gentlemen.

[S Lathrop]

A much more productive conversation might be how maximum width should be measured. Then people could check their cars and have confidence that they are legal or know that they have to make changes.

This is just for discussion. I would take a carpenter's square, place it against the tire, and inline with the axle. place a mark on the ground that will be the edge of the tire. Next hold a straight edge against the tire, level and at the axle center. Measure from that edge to the square. Say that number is 1/2 inch. Do the same thing on the opposite side. measure the distance between the marks on the ground and subtract the distances to the wheel center. That number will be the maximum width of the car as the current rules require. This would be the measuring procedure and anyone can do it and it is a one person job.

Maybe instead of changing the rules, lets establish how we will check cars for compliance.

When I was racing in FV and FF years ago, I would always carry the tools to measure anything that I thought people might question my car about. Never had to use my tool but I have loaned them out a time or two.

When teh rules for FF and FC were separate, FF did not have a maximum width rule.

[Purple Frog]

"This is just for discussion. I would take a carpenter's square, place it against the tire, and inline with the axle. place a mark on the ground that will be the edge of the tire. Next hold a straight edge against the tire, level and at the axle center. Measure from that edge to the square. Say that number is 1/2 inch. Do the same thing on the opposite side. measure the distance between the marks on the ground and subtract the distances to the wheel center. That number will be the maximum width of the car as the current rules require. This would be the measuring procedure and anyone can do it and it is a one person job."

Remember to keep the square perpendicular to the track of the car during those measurements.
I am assuming you are putting some sort of straight-edge across the rim at the horizontal axle centerline to measure that offset to the square.

A workable solution. Not as fast as the large caliper I used in the pro series. But adequate.

[problemchild]

Ahh Greg.. using common sense in scca?? Over rated..

Yes, and it is considered trolling to point out common sense solutions.

When it takes a paragraph to describe how to measure maximum width at the wheel centerline ...... on one end of one car ..... most of us would conclude that the process was neither eloquent or feasible, and another solution to measuring maximum width is required.

[S Lathrop]

Yes, and it is considered trolling to point out common sense solutions.

When it takes a paragraph to describe how to measure maximum width at the wheel centerline ...... on one end of one car ..... most of us would conclude that the process was neither eloquent or feasible, and another solution to measuring maximum width is required.

Given how the rule is written, how would you measure the width of a car? I put that procedure up for discussion only. I have seen cars ruled illegal only to have the ruling changed because the measurements were not done correctly.


The simplest solution would be to have a rule that measures the car width at the widest point. The car fits in the box or it does not.

As an example, If I were to change a Zink Z16, a car built in 1978, to 4 degrees negative camber, the width at the front of the car will increase close to 2 inches. 2 inches does not account for the effect of increasing the tire diameter by over an inch as is the case with the spec FF tire compared to the original bias ply tires. This is a rocker front suspension car. and the rocker is not adjustable. The rules were changed to accommodate the change is setup required by different tires.

Describe to me how you would measure the maximum width of a car given the current rules

[LenFC11]

I agree.. easiest way is very simple.. fits in the box or does not..

[DaveW]

I guess I opened one by posting my letter to the CRB.

While I am not seriously opposed to almost any definition SCCA decides is the final version, I am not willing to leave the meaning of maximum width undefined, meaning that my new front (and rear) suspension could be designed to an incorrect interpretation of a yet-to-be-finalized rule.

My take on this is that if we are measuring to some point or points on the rim, then we should word the width rule such that ALL alignment parameters including tire width are eliminated from affecting the measurement. That means that one could design suspension to this dimension and be assured that the rules would not be violated. That was what my letter intended.

Steve, however, correctly points out, for example, that measuring OA width on the rims at the theoretical wheel center still doesn't assure that rocker-arm-type cars using large negative cambers would not exceed the allowed width w/o suspension modification.

So if one wants a rule that is incontrovertible and easily enforced (i.e., easy to measure at the track), then we are back to the original/literal meaning of maximum width - the outside of the tires. And it is then (as it has always been) the responsibility of the driver/owner/team to assure that the car meets the rules.

On balance, I would prefer the latter so as to not make tech inspections more difficult or subject to differing interpretations than absolutely necessary.

[John Robinson II]

i think i might have helped to start the new discussion as we as we have been constantly changing the db-6 for the new tires, but my question was simply - does wheel mean outside of tire or rim? i remember when FF had no maximum width but FC did, and it was as simple as car had to fit inside a box. i think this was more for wing width, but it was simple.
As far as i can tell, the wheel/tire/rim question still has not been addressed.

john

[Purple Frog]

To me as a mere mortal, I think this is very serious topic if two multi-time national champions are interested in a solution. Just saying.

[R. Pare]

Simplest solution:

If it cannot fit within a box ( or between two poles), is isn't legal.

Funny how that was the interpretation for the first 40+ years of these classes, and no one questioned it.

[Steve Bamford]

Simplest solution:

If it cannot fit within a box ( or between two poles), is isn't legal.

Funny how that was the interpretation for the first 40+ years of these classes, and no one questioned it.

I agree this type of rule adaptation is just one more thing that is not needed in a class that has limited representation at best. I haven’t seen any of these clarifications, adjustments, whatever you want to call them help grow any open wheel class.

I do believe good intentions are put forth however they are simply way over thought. Keep it simple for me stupid & make it fit in the box. If you decide upon a spec tire & it is slightly wider make the box slightly wider allowing whatever reasonable camber can be put in. I shouldn’t need an engineering degree to figure out how to measure the width of my car to see if I’m legal or not.

Be inclusive, not create more barriers, some may not see it this way but ask the guy who buys a car that has run & won before then brings it out & is told it is illegal on one of his first events. See how many more events he will show up at.

[Raceworks]

Given how the rule is written, how would you measure the width of a car? I put that procedure up for discussion only. I have seen cars ruled illegal only to have the ruling changed because the measurements were not done correctly.


The simplest solution would be to have a rule that measures the car width at the widest point. The car fits in the box or it does not.

As an example, If I were to change a Zink Z16, a car built in 1978, to 4 degrees negative camber, the width at the front of the car will increase close to 2 inches. 2 inches does not account for the effect of increasing the tire diameter by over an inch as is the case with the spec FF tire compared to the original bias ply tires. This is a rocker front suspension car. and the rocker is not adjustable. The rules were changed to accommodate the change is setup required by different tires.

Describe to me how you would measure the maximum width of a car given the current rules

And exactly how many Zink Z16's (or any other 1970's cars) are currently being negatively effected by this rule? In the 8 years I've been in FF I haven't seen one that isn't already in vintage or CF. Is someone champing at the bit to spend a couple grand to get their ass handed to them by the Pipers, Swifts, Van Diemens, & Spectrums?

It's kind of like the some of the criticisms of the rule based on hypothetical wheels where the spokes protrude past the rim. Again, theoretically possible but I haven't seen it come up much in a quarter century of racing cars.

Looking at both proposed rule and the new one I don't really see that it makes much difference. Either one can be misinterpreted and in neither case is there any kind of standardized methodology for measuring it. The proposal is somewhat more clear but I can see a variety of ways it can be either gamed or misinterpreted.

The giant go / no-go gauge is probably the best bet for tech or for car preppers. Failing that some plates and tape measures will make do, and if you're at all in doubt make sure you're well inside the "spec" unless you have a great love of arguing & filling out paperwork.

[MotorCade]

Count me in as one of the voices saying: "Will this rule make racing more fun/cheaper/easier?" If not, rethink it. Apply this means of questioning rules liberally across the GCR.

[problemchild]

It's kind of like the some of the criticisms of the rule based on hypothetical wheels where the spokes protrude past the rim. Again, theoretically possible but I haven't seen it come up much in a quarter century of racing cars.

I have seen these wheels in use in the USA. They are close to, if not protruding beyond the rim.
https://www.ebay.co.uk/itm/Weller-Fo...-/252685635322
And there is no spoke to rotate from.

[reidhazelton]

Count me in as one of the voices saying: "Will this rule make racing more fun/cheaper/easier?" If not, rethink it. Apply this means of questioning rules liberally across the GCR.

That was the whole point to the rule clarification. When you add radials, and 3* of camber, the lower outside edge of the tire can be outside the max width. So, option 1 is make every 01+ VD change front arms to narrow the car ($$$$), or Option 2 is to change how the measurement is taken. That costs nothing. There is an implementation/compliance issue however with that change. If the rule was changed to to increase the max width, then people would build a car to that width and we would potentially have the same issue down the road.

[Steve Bamford]

If the rule was changed to to increase the max width, then people would build a car to that width and we would potentially have the same issue down the road.

When was the last new FC built? Someone could modify what they have, like DW, I guess but really is that going to make everyone have to adapt?

[2BWise]

That was the whole point to the rule clarification. When you add radials, and 3* of camber, the lower outside edge of the tire can be outside the max width. So, option 1 is make every 01+ VD change from arms to narrow the car ($$$$), or Option 2 is to change how the measurement is taken. That costs nothing. There is an implementation/compliance issue however with that change. If the rule was changed to to increase the max width, then people would build a car to that width and we would potentially have the same issue down the road.

Is that with the upper control arms as short as possible and the lowers as well? There is a fair amount of adjustment in length thru the rod ends. Just curious if efforts were made to narrow the car with those adjustments or simply achieve the requisite camber.

[reidhazelton]

When was the last new FC built? Someone could modify what they have, like DW, I guess but really is that going to make everyone have to adapt?

I think you own one of the newest ones.

The goal was to allow radials without making most people have to change arms. So, where to measure was defined, and the defined point eliminated the camber variable and kept all previously legal cars, still legal with radial camber numbers. A valid point was raised about the measurement, and it will be addressed I'm sure.

[reidhazelton]

Is that with the upper control arms as short as possible and the lowers as well? There is a fair amount of adjustment in length thru the rod ends. Just curious if efforts were made to narrow the car with those adjustments or simply achieve the requisite camber.

The issue was several people with cars were too wide as previous measured when they installed radials with the camber needed. You really can't adjust the length with the rod ends as you end up changing the center to center distance and then have to pull the arms like a chicken wishbone to get them on the car. So you *can*, but it's not the right way to do it so it's not really relevant in my opinion. You can make the radials fit the width rule with 1* of camber too, but again, not the right way to do it.

[problemchild]

From above.

This was an issue on F2000 VDs over the last decade, as tire construction, and desired alignment, required minimizing the lengths of lower front A-arms, and sometimes modifying those A-arms. AFAIK, with narrower wheels, and tires, it was not so much of an issue with FF.

If that is the concern, why not just add a few mms to the current rule. We needed this rule change a decade ago. Not sure why now. As I understood it, it was the non-VD car builders who objected to the rule change then, so why they are presenting this rule now, is perplexing. Perhaps an explanation is needed.

Has it been a decade since the radials have been in use? We ran 3.5 degrees of camber on Steve's VD with stock parts. Why this complex, poorly written, virtually unenforceable rule now? Just add a few mms to the original common sense rule, if you must, and let Dave W and JR2 build new A-arms if they want. Perhaps Dave should be asking this question to FRP instead of SCCA.

This group of SCCA politicians needs to start focusing on real issues, and stop creating them.

[problemchild]

Not to mention it will allow cars to be ~2" wider than the rules we lived with for 30 some years.

How much did SCCA change the value, when they changed the rule measuring location?

I just measured up a Mygale with Hoosier front spec radials mounted on Dixon aluminum forged wheels at 21 psi set at 4 degrees camber. The difference in width measured at the tires maximum and the wheels on centerline ...... was 1.5" PER SIDE.

Again, the style of wheel will affect the differential, but did the SCCA adjust the value by 3 INCHES? And again, the tire style and construction of each tire will affect the value. There may be dozens of different branded wheels in use and at least a dozen different tires (with front and rears) between the classes..

Yes my measuring was crude ..... as expected ..... I used a vertical bar and digital level, and a vernier, so perhaps we can conclude a tolerance of 1/4", but the difference between the tire and wheel at the bottom was over an inch.

A few inches is a whole lot more than the few mms that could have made the original rule work .
I think a whole lot of people will be building new A-arms ..... and axles .....and brake lines .... and trailers .

[Steve Demeter]

Probably a silly question, but why not go back to the two post rule that Steve L referenced and be done with it. make adjustments to the max allowable a needed to compensate for the camber required with radials?