Prep Differences Between SM and ITx

G

Greg Amy

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Staff member
Can someone detail for me what is allowed in Spec Miata that is not allowed in Improved Touring? In other words, what is it about a fully-prepped '99+ SM that is not compliant to ITS? Or what about a '90 or '95 SM that is not compliant for ITA?

For background, I'm asking for Scrutineering purposes in Super Touring Light. There's a lot of confusion - and outright cheating - that is causing some consternation among scrutineers.

I'd make a personal comment about "leave it to the Spec Miata crowd to f**k up a good thing" but I won't...

- GA
 
Mainly power steering rack. SM allows one to de-power the rack. The cars were available with manual racks but 99% are de-powered, mainly because manual racks are hard to find and can only be purchases new(new 99' manual rack is $580.)

On 1990-1993 or 1.6 cars, SM rules allow the later torsen dif. but it also is not IT complient.

SSM rules do not require a kill switch
 
rear diff carrier and some allowed suspension (brake?) component swaps between years with same body but different engine is a big SM allowance difference from IT. SM has to maintain more stock components and only recently was allowed over-bores and the like and then only with added weight.

you see a fair amount of double dipper SM guys in IT who are in breach of IT rules. I'm sure you see the same in ST. ST requires one hell of a scrutineer.
 
mossaidis said:
I believe SM folks swap transmissions beyond the spec line years listed in IT. Jerry - please confirm.
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although its possible, there really is no difference, gear ratios are all the same...
how would you know if a 142 Volvo or Opel GT has the original gear box???
 
I guess tranny codes. I know there's the rules and there's cheatin. Doesn't sound like trannies swapped out of an 90 into 98 or vice versa is cheatin'.
 
I would think that the 99+ SM's are running SM weight and taking out their RP's...keeping them legal for ITS. No allowances for those cars that would be illegal in ITS come to mind except ride height, but that applies to all three versions (1.6, 1.8 and 1.8 99+).

I can't think of anything for the 1.8's that would be illegal for ITA either except the mentioned de-powered steering rack for all years.

The 1.6 is a different issue. Conversion to the 94-05 diff assembly is legal in SM but not in IT as has been stated too, but they probably have the 4.3 gear in there per the SM rules, not that it matters.

Why types of issues are we seeing that are resulting in problems? As long as they are running IT weights, the cars are certainly not more potent.
 
Pulling the RP and running SM weigh on a 99', without a manual rack, that's the problem, it's not SM or ITS.
 
De powering is legal and cheap. I dont recall the manual rack being 580.00 faster than the power rack.

But im a cheap IT7 driver.
 
99' manual racks are rare used....
New they are about $400. plus core charge of $150.
They don't take a core unless its a manual :-( and Mazdaspeed won't take the core, you need to find a deal willing to take it back.......
 
Andy Bettencourt said:
Why types of issues are we seeing that are resulting in problems?
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I don't want to get into the details, but it's a combination of regs ignorance (in the true sense of the word, not intended to be derogatory) and willful intent. As Chip noted, you almost need to be a rocket scientist to figure out the allowance matrix, and you need to be 100% on top of the regs of three separate categories - one Regional Only - to ensure you've got it right. And, some folks are taking advantage of that by intentionally trying to mix-n-match regs, with the intent to maximize performance to collect contingencies and points in the Majors events.

My goal is to produce an at-a-glance matrix so that the competitors will be able to efficiently decide what config to run, and for the scrutineers to efficiently tech the cars' configuration. In addition, I'm going to ask the CRB to require STL competitors that are not running to STL-specific prep to declare, on the side of their cars, what config they're prepped to.

STL has, without a doubt, benefited from explicit inclusion of other classes into its folds. I just want to ensure that this inclusion does not end up alienating other competitors from joining in. Come in clean and you are most welcome to join us; come in trying to cheat and piss all over the class and I'm gonna be busy writing a lot of paper...

- GA
 
Maybe I just wasn’t taking advantage of the rules in IT when I ran an ITA Miata, but my impression is that a built SM motor does not comply with IT rules:

Spec Miata 9.1.7.1.h.2
A valve job will consist of only three flat angles; radius cuts are not allowed. A 45 degree seat angle must be used, which may vary in width from .030 inch to .050 inch. To narrow or correctly position the face angle, a bottom angle of 70 degrees must be used. To narrow or correctly position the face angle, a top cut of 30 degrees may be used. All angles must stay on the cast steel block portion of the seat. The angles must not extend off the seat into the aluminum casting at the top or bottom of the seat.

And have someone who has built a full-on IT car read through 9.1.7.1.f (cylinder head). I never was sure about SM’s unshrouding of valves meeting IT rules, or the reference to plunge cutting in 9.1.7.1.f.3.
 
ner88 said:
Pulling the RP and running SM weigh on a 99', without a manual rack, that's the problem, it's not SM or ITS.
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I think that happened to 99 SM cars somewhere around my garage all weekend last NHMS event. Guys were pulling RP off their 99 SM to run ITS... and doing nothing else. (shrug)
 
Prof. Chaos said:
Maybe I just wasn’t taking advantage of the rules in IT when I ran an ITA Miata, but my impression is that a built SM motor does not comply with IT rules:

Spec Miata 9.1.7.1.h.2
A valve job will consist of only three flat angles; radius cuts are not allowed. A 45 degree seat angle must be used, which may vary in width from .030 inch to .050 inch. To narrow or correctly position the face angle, a bottom angle of 70 degrees must be used. To narrow or correctly position the face angle, a top cut of 30 degrees may be used. All angles must stay on the cast steel block portion of the seat. The angles must not extend off the seat into the aluminum casting at the top or bottom of the seat.

And have someone who has built a full-on IT car read through 9.1.7.1.f (cylinder head). I never was sure about SM’s unshrouding of valves meeting IT rules, or the reference to plunge cutting in 9.1.7.1.f.3.
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Me thinking if IT allowance for "balance and blueprint" in combination of allowable engine tolerances as define in the factory manual applies here. but don't know...
 
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In addition to the diff housing & steering rack stuff mentioned previously...

9.1.7.1.p.8 -- Honk..honk.. (but at least the washer bottle can go)
9.1.7.4.c -- Updating subframe braces to those from a '97. That wouldn't be legal for a 1.6l
9.1.7.4.l -- Strut brace not allowed for 99+'s in SM (allowed in IT)
9.1.7.6.a -- Not limited to 13+lbs/wheel in IT
9.1.7.8.d -- IT not limited to OEM door mirrors and restricted location as in SM rules
 
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