3 replies to this topic

[Brian Ghidinelli]

I'm on the board this year for SFR and we are trying to answer which tires crossover cars should run or if they are free. Here's what I have as the list of things that makes an SM illegible to crossover without a regional or GCR allowance as scoured from sm.com, miata.net and the GCR:

From SM to ITA/ITS:

• Depowered steering rack (original manual rack is legal)
• Removing corner windows or replacing with NACA ducts
• Updated rear subframe braces (couldn't find a source for this)
• Torsen diff in the 1.6 car
• No minimum ride height rule means many cars are below the IT/ST minimum
• Head work: 3-angle valve job and 30-degree top cut on seats is not permitted in IT (note)
• 94-97 weight at 2365# is 15# under the ITA minimum (2380#)

From SM to STL/STU:

• NACA ducts permitted if < 50in² in size
• 9.1.4.F.7 doesn't allow removing the corner window although it does say "enough open area for the driver to exit in an emergency shall remain open at all times"
• Torsen diff in the 1.6 car (I can't tell if this is permitted or not under 9.1.4.M.1 - pg 453)
• No minimum ride height rule - cars may be below the STL 5.0" or STU 4.0" minimum
• Head work: 3-angle valve job and 30-degree top cut on seats is not permitted in STL (9.1.4.3.B.3 only permits manifold and head port matching; I'm not clear on what the limits are, if any, for STU?)
• 94-97 weight of 2365# is 33.5# under the STL minimum (2398.5# = 1800cc * 1.3 * 2.5% for RWD)
• 9.1.4.E.5 does not permit any chassis modification to make additional clearance for drivers seat. This would render some cars illegible that have massaged/notched the transmission tunnel to fit a head protection seat.
• 9.1.4.F.3 requires cars with driveshafts to have 2 steel 360" loops to prevent the driveshaft from dropping if a U-joint fails
• 9.1.4.3.E.2 states that cars equipped with OEM ABS "may" use the OEM system only as installed. Does that allow disabling per SM requirements?

1) Anything missing or incorrect above?

2) As I read this, if you have a Miata with any of the above items done to it, and you wish to run in ITA/ITS per a regional allowance in the supps (that does not include an open tire allowance) or run in STL per the GCR allowance (pg #443), you would have to be a fully compliant SM and therefore run Toyos. Correct?

3) The rules for STU are sort of undefined which I think reflects the World Challenge background. I'm not really sure what limits exist for motor/drivetrain/etc?

The tricky part seems to be a less-than-fully prepared Spec Miata may be able to cross over and not have to run Toyos while "real" spec miatas do.

(small side note for SFR members: our ITA/ITS crossover allows tires to be free, but STL does not. trying to understand all of the options)

Edited by Brian Ghidinelli, 03-30-2011 02:43 PM.

[Johnny D]

Hey Brian,
Here are some threads I posted some things on.
http://mazdaracers.c...ch=1
http://mazdaracers.c...wtopic=296&st=0

Also
"(small side note for SFR members: our ITA/ITS crossover allows tires to be free, but STL does not. trying to understand all of the options)"

If there giving away free tires please let me know.
The term may be "open" your looking for.
J~

[Brian Ghidinelli]

I want to confirm as best as possible the list of things that would require a car to be entered as a Spec Miata (the exception list above) which would trigger being fully compliant and therefore having to run Toyos. Even if a miata runs in Spec Miata, only certain things make it illegal for IT or ST regardless of regional supps.

At a minimum, tech needs to know those differences and ideally I would like to clearly tell people what their choices are.

[Johnny D]

Brian,
I suppose it would be way to complicated if you had a SM and ran it in Group 5, you would have to follow SM rules.

Real complicated would be if you had a SM, they had an SM class in Group 5.

SM is group 7 for everyone following along.
J~

FYI, This was in the Reg Sups but I don't see it now.

STL - a region only class added by SCCA National for Spec Miatas will be included in SFR Group 5. STL creates a Super Touring class for cars with engines 2.0L and below (with STL-specific restrictions; see GCR 9.1.4.3). Miatas in STL must be fully SMT compliant (including tires).