ChampCar Endurance Series

ChampCar Tech Desk

Official channel for ChampCar technical questions, interpretations, and VPI requests.

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The Tech Desk is for rules clarifications and technical questions. It is not a post race tech line, a place to protest results, or a place to fish for how other teams built their cars.

Most questions can be answered by reviewing the current BCCR Rulebook. Please read the applicable section before submitting a ticket.

If your question is already covered clearly in the BCCR, your ticket may simply be answered with a reference to the rulebook section.

VPI request checklist

For all Vehicle Performance Index (VPI) requests you must include:

  • Year, make, model, and trim level
  • Engine size and engine horsepower
  • Drive type: FWD, RWD, AWD, or 4x4
  • Transmission type: automatic or manual
  • Car weight and all factory options that affect performance
  • A link to the vehicle on automobile-catalog.com or another site with full specifications if it is not listed there

Requests that do not include all required info and research will be denied without review.

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2020-01-10 - Miata rear differential gear ratios
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2020-01-10 - Miata rear differential gear ratios

Q.
I want to confirm I am reading this rule correctly.

4.7.8. Rear-end gear-ratios are open to all OEM differentials available for that year, make, and model or chassis generation (excluding specialty high-performance models not listed on the VPI table).

Does this allow us to run a 4.3 ratio in a 1997 Torsen differential since the NA generation had both a 4.1 and 4.3 ratio?
We are running a 97 driveshaft, stub shafts and half shafts.

A.
I believe the 4.30 ratio was only available in the 1.6 NA and the 1.8 had 4.10 with the Torsen from 95 to 97. 
So you can run it.

Verified 7-2-24 by TECH

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Article Details

Article ID:
44
Category:
Drivetrain & Axle
Date added:
2020-01-10 15:56:55
Views:
1,722
Rating (Votes):
(300)