Regarding the issue of "adjustable" clutches, I have some questions and comments...
Exactly what does "adjustable" mean?
It has been stated that one can change springs, shoes, and even modify the weight of the shoes (shaving), etc. but that "mechanical" adjustments are not allowed.
From this we can draw the conclusion...
The ability to "tune" the clutch engagement to a drivers individual car and track conditions is clearly desirable (as opposed to an exact "Spec" clutch setup with exactly prescribed springs, shoes, flywheel, bell etc. that cannot be modified in any way).
So then what exactly does "adjustable" mean? After all, from the moment that you allow any "change" from a "spec" clutch you are really allowing "adjustment" regardless of what you call the "modification" or "change" and, as we have concluded, the ability to "alter" the characteristics of the clutch is clearly desirable.
It has been suggested that the meaning of "adjustable" is a "mechanical" adjustment. From this clarification and the acceptability of alterations and modifications to clutch components (i.e. shaving shoes) can it be concluded that a more clear rule would be:
***Changes that alter the "characteristics" of a clutch can be made without limitation as long as the change comes from a physical modification or the addition, removal or replacement of a component in the clutch but NOT a solely mechanical change.***
This seems to be the current state of explanation thus far...
We can then conclude the following....
The M2C adjustable flywheel, which can be "tuned", "adjusted", or whatever you want to call it, by adding or removing set screws from the flywheel, is LEGAL. Specifically it is legal because you are adding, removing or replacing a component to effect a "change".
The Fioroni "Vario" clutches are all ILLEGAL. This is because they posses a "mechanical" adjustment which allows you to change the "characteristics" (specifically the spring tension) without adding, removing, modifying or replacing a component.
The Buku clutch is ILLEGAL for the same reason.
However, if the Buku design were changed so that instead of turning an "adjustment" screw to effect the "change" you instead removed and replaced a "spring seat" to effect a change, then this version would be LEGAL.
So, a driver would have a box of tiny different (perhaps color coded) "spring seats" (sounds a lot like a box of different springs, gold, red, black, 30 degrees, 35 degrees, etc, doesn't it...) that they could swap out to "tune" their clutch to different track conditions. And of course because modification of components is allowed then a savvy driver would have these seats hand ground to length to give him exactly the levels of tension he was looking for in advance...
And this is better why?
And who is going to tech a rule like this? Someone running around trying to determine if a person is running a Vario clutch, or what version of Buku, the Original "Speed Tune" or the new "Quick Change GT Legal" version.
The simple reality is, the ability to make "Adjustments" or "tuning" or "alterations" or whatever you want to call it, to improve your performance on the track is a GOOD thing. If it wasn't clearly desirable then everyone would be demanding a "no modifications spec clutch".
Why then is the term "adjustable' being used at all? It reality, it has nothing to do with "adjustments", "adjust-ability, or "tuning"....
It has EVERYTHING to do with Centax or more specifically "Axial" style clutches. Obviously no one is interested in these "on-road" clutches being allowed. It's clear that they are the SOLE source of this issue in the first place. Unfortunately the term "adjustable' was initially used synonymously with "Centax" in the beginning of this discussion well before the range of currently used off-road clutches were considered.
Now later, after the term "adjustable" has been added to a proposed rule (for no real reason other then trying to clearly prohibit Centax or Axial clutches), it must be interpreted to be able to consistently and repeatably make a ruling on clutch legality in a practical manner by a wide range of potential techs and tracks. So we must stumble, case by case, through the VERY wide range of "completely legal for off-road racing" clutches that exist in the world.
Of course, we see all of the above issues arising, which seems to be the exact opposite of what everyone is looking for ... Simplicity and Clarity.
I would suggest that there is a very clear delineation that should be applied instead...
The simple prohibition on Axial (or Centax) style clutches, and/or the mandate that all clutches be Radial (to use a more accurate term). This completely clear and simple delineation could be easily identified and inspected, and is completely clear to understand. (Yes, I know the first question is going to be what about the Werks Power clutch?. The Werks clutch is clearly a "radial" clutch. The spring tension is on the axis but is irrelevant. The TORQUE DELIVERY comes from the shoes traveling out on the radius (hence "radial") and engaging the clutch bell just like every other "Off-Road" clutch.)
I submit this for consideration and, more importantly for the purposes of starting out with a rule that in the future can Practically be included in a Sanctioning Bodies rules, which a prohibition on "adjust-ability" could never be for now obvious reasons...
and, propose the simple rule.
Clutches: Axial (Centax) style clutches are prohibited.
(and if you wish to add: "Only Off-Road, Radial style clutches are allowed.")
Short of a rule like this one, the prohibition on "adjustable' clutches is in for a long, detailed and argument filled journey, which of course makes it that much more likely no one will pay attention to it anyway and I doubt that this is the goal of these discussion...