5 replies to this topic

[blamkin86]

Hi folks,

I'm Bill Lamkin, relatively new E Production racer - I'm in need of a little help and I thought of you guys.

I'd like to clarfify what the *stock* track specfication is, for both the pre-99 cars, and the post-99 cars. The purpose of this effort is that I believe the spec line for the production miatas is incorrect, and I've asked the CRB to fix it. They've tabled and referred the issue, and I'm trying to help.

I've looked at the factory 99 miata service manual, and am not having any luck finding track specifications. Here's a link to an online PDF:
http://www.boostedmi...ce%20Manual.pdf

Here's the important Production rule from the GCR on track:

9.1.5.c.4. Track specifications will be set at 103% of the car’s stock track plus 2.5 inches.

In addition to this rule, each prod car also has a spec line, including track. Here's the max track listed on the spec line, for BOTH the NA and NB (level 2 prep) cars:

1483/1509
(58.4/59.4)

Unfortunately, the numbers I've been seeing on the interwebs for track spec, times 103% plus 2.5 inches, are way, way wider than the spec line that I quoted above. I'll avoid posting the numbers I've seen to avoid poisoning any data.

In any case- thanks for any help finding a specific reference book on the factory track specifications. I need both cars - the NA and the NB... and of course front and rear track for both cars.

Thanks in advance,
--Bill

[Bench Racer]

Bill, go to this site & look at the track widths. Then call Mazda motorsports to confirnm. I found these same numbers in a couple other places. http://www.miata.net...ment/index.html

I couldn't find the track width in the FSM for the NA.

When I figure the NA using the 1.03% plus 2.5 inches I get the front at 1515.8 mm & the rear at 1534.34 mm as you stated considerable wider that the spec line.

You also might might give Jesse a call.

[blamkin86]

Thanks for the link, but I can confirm that those track numbers are wrong.

I have a copy of the factory "1999 Service Highlights" manual, which shows that, in 1999 mazda widened the rear track by 10mm over the NA. Those specs show a difference of only 2mm in the rear track. Also I seriously doubt they narrowed the front track.

I do think I'll call Mazdaspeed - they at least should have access to all the manuals.

I wonder how the Spec Miata track spec came about. Maybe someone just found a stock one and measured it or something.

[Mike Collins]

Spec Miata track is based on measuring a number of cars with what the SMAC felt was the widest legal wheel offset. We have a very small cushion in our number but not enough that buying a one off set of wheels would make a difference.

[blamkin86]

Thanks Mike - so you're confirming that you directly measured rather than using some printed factory spec. That's what I needed to know. Thanks again.

[Mike Collins]

Thanks Mike - so you're confirming that you directly measured rather than using some printed factory spec. That's what I needed to know. Thanks again.

Correct