Cal Club Autocross Forums

I assume that Appendix A Prepared Class X 1. BODYWORK AND STRUCTURE (Appendix A page 185) supersedes Prepared Category 17.2 BODYWORK AND STRUCTURE (page 115) for XP only. In other words, chassis prep for XP is more limited then what's allowed in the rest of the Prepared category and that limitation is spelled out in Appendix A page 185.

Am I correct?

John Coffey wrote:I assume that Appendix A Prepared Class X 1. BODYWORK AND STRUCTURE (Appendix A page 185) supersedes Prepared Category 17.2 BODYWORK AND STRUCTURE (page 115) for XP only. In other words, chassis prep for XP is more limited then what's allowed in the rest of the Prepared category and that limitation is spelled out in Appendix A page 185.

Am I correct?

I'd say "in addition"

as it says, "XP vehicles must conform to the rules in Section 17 except as noted herein." so, the appendix A stuff is exceptions. Like, you can use wings, and can use any engine, etc.

Then why does this paragraph exist for XP:

1. BODYWORK AND STRUCTURE
a. Chassis components attached by removable fasteners (e.g. bolt on
subframes) may be modified or replaced without penalty.

Is the intent of that rule to allow bolt-on subframe mods without the weight penalty incurred by:

17.2.D. Replacement of any chassis component (e.g. subframe) in its entirety
by one of alternate construction, unless specifically permitted,
shall result in the vehicle being “in excess” of these rules and weight
penalties and/or competitive adjustments may apply.

And since there doesn't appear to be any weight penalties in XP I guess it really doesn't matter.

That sounds exactly right. The XP specific rule gives you a free pass to change bolt on subframe components without incurring a weight penalty.

XP has to follow the rules of the Prepared category (chapter 17), but there are additional allowances and exceptions to those rules, given in Appendix A.

Those exceptions do state that cars that are "in excess" as defined in chapter 17, are not eligible for XP.