ChampCar Endurance Series

ChampCar Tech Desk

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

Before you submit a ticket

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.

2020-02-27 - Roll Cage Welds

Q.
Are welds that have been sanded to blend in with some of the cage profile are considered acceptable? Something like in the attached images.

Example Image 1 Example image 2

A.
1. Grinding cannot result in a reduction in the diameter of the tube of more than .050". That would be 25% of the wall thickness (.095 * 2 = .200, .050 would be 1/4). This means the tube better be 1.70" or greater for a 1.75" cage.
2. Grinding marks need to be dressed down with higher grit paper to remove visible scratches\gouges. It needs to look like the rest of the tube in smoothness, otherwise, you have left stress risers that can cause it to fail.

You need to maintain the added cross-section of a weld. That means I expect the weld joint to have some bead height greater than the rest of the tube. 1/16 or maybe 1/8" or more over the base 1.75" diameter. Do not grind the welds flush with the tube to look good. If you booger up a weld you can grind it down and build it back up with a hotter weld (turn the machine up one heat setting, which you most likely needed to do the first time anyway), but it should look like a wider version of a good weld with properly added cross-section that is "burned in" at the edge of the weld bead, not a convex sharp edge that looks like you put a twinkie on a table.

The welds shown in the example images don't look like they had good penetration.
If one weld fails the whole cage fails. Those ground down welds most likely need to redone unless they meet the thoughts above.
If you want to be sure contact tech and send pictures of all the welds.

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