Cal Club Autocross Forums

Hi everyone,

Just wanted to clear up some questions I have about running an NA Miata in E-Stock.

— How many of you running Miata's in E-Stock are running an open diff?
— If my NA Miata has a Torsen Diff, is that still legal for the class?
— If I swapped a Torsen Diff into a 94+ Miata, would I still be able to run E-Stock?

I've searched a ton about this topic and got a lot of answers. My main concern is pretty much the open diff question. I just want to make sure that I'm not going to be headed to a class that I can't handle. I ran my V8 Z in CST for a little while and even on my best days I was trampled.

Thanks!

If that dif was available in that car from the factory then yes, you can run it in ES.
If you have a car that didn't come with the Torsen, but it was available in that year, but only combined with certain other options, then you also need to add those options.
Now some options can be ignored because they are also things that the rulebook allows you to change anyway, like shocks and mufflers, and comfort and convenience things like the shift knob...

For instance, if you were trying to duplicate a '94 R-package, you'd have to add the spoiler and the front and rear valance, etc... however, you would not have to run the oem Bilsteins, as those are allowed to be changed for alternate shocks in the stock class rules.

Ah, thank you Robert!

On a side note, how competitive is an NA Miata without the diff? I haven't been autoX'ing enough to be so competitive as to sweat tenths of a second, but I'm just curious how they hold up.

STS NA's are quite speedy ... and they aren't allowed LSD's

Mako Koiwai wrote:STS NA's are quite speedy ... and they aren't allowed LSD's except for
factory standard viscous coupler type units.

Fixed that for ya!

Ed Holley wrote:

Mako Koiwai wrote:STS NA's are quite speedy ... and they aren't allowed LSD's except for
factory standard viscous coupler type units.

Fixed that for ya!

Well that's not quite true either. In STS, no one has the Torsen legally, the 1.6's have the viscous, but the '94-'96 only the base model is legal, as it's the only one with the open diff on the 1.8.

In ES, NA's might have viscous, open, or torsen. BUT... only what that model year, and trim level came with. So no 1.6's can have the Torsen, nor 1.8's can have the viscous, legally.

I've been researching this for two years, I concluded the same as you below, but the majority of people like to say (incorrectly?) only the R-package came with a Torsen.

Craig Naylor wrote: but the '94-'96 only the base model ..{has an}.. open diff on the 1.8. {Others have a Torsen LSD}.

The RallyMiata is a '94 package A.

Jay W