That's how I figured it would perform if I just removed my bars and didn't change anything else.

I haven't plotted my roll centers as a function of pitch and roll, but I'm guessing there is some tuning of the suspension dimensions (within the bounds of STR) that would allow me to decrease the distance between the roll center height (granted this is a dynamic distance) and chassis CG height, effectively increasing the roll resistance. Whether this tuning can actually get the roll resistance to the same level as the "with anti-roll bars" setup, I have no idea. I'm sure it's easier said than done...

 

12-1400lb springs up front is what it will take depending on your existing front bar size.

 

You mean those are the rates that would be needed to maintain the same roll stiffness without altering the roll centers, right? Those are similar rates to what my calcs predict using the same roll center height.

The consensus seems to be that the J's Racing L1/L2 camber joints are legal, per the STR rules. These camber joints feature a different thickness mounting plate to raise the front roll center. So, one could use spacer plates between any of the available lower camber joints (stock, J's S or L series, Spoon, etc.) and tune the roll center height by altering the spacer thickness. If it's feasible to increase the roll center height by a decent percentage, spring rates around 800 lb/in to 1000 lb/in could be used and have the same roll stiffness as a setup that uses unaltered roll centers, similar rate springs, and a front roll bar.

Do people agree that if the J's "L" series camber joints are legal, then ball joint spacer plates would be legal, as well?

 

They are absolutely not legal.

Only the S versions of the ball joint are legal. There was a Tech Bulletin issued in January clarifying the legality of offset ball joints.

 

The rule that allows replacement control arms in ST specifically calls out the ball joint as being included in the allowance. So yes, it looks like ball joints that result in different spacing from the pivot to the mounting point on the spindle are allowed.

Street Prepared had similar wording without mention of the ball joints. But there is a clarification in the February FasTrack that explicitly allows the spindle-to-pivot dimension to be changed in an aftermarket control arm.

 

Yep, it's pretty clear that vertical dimension alterations are not allowed, per the bulletin.

Looks like I'll be running a front anti-roll bar this season.

 

I'm reading the clarified ST rule (the clarification is already in the 2011 online rule book), and I don't see how it excludes offset ball joints. The most restrictive interpretation I can come up with would allow either adjustable arms or offset ball joints but not both. In that interpretation I take the phrase "including ball joints" to mean that ball joints are included in the class of "arm mounts". The word "either" seems significant, so you could not have both an adjustable arm and a replacement ball joint (a subset of arm mounts).

The more open interpretation is that a non-standard control arm or arm mount may include an associated ball joint.

The ST and SP rules (as written in the 2011 online rule book) are nearly identical except that ST says "arm mounts (including ball joints)" instead of just "arm mounts", and SP specifically allows incidental caster change due to the camber kit.

The February Fastrack has a clarification on the SP rule saying not only that a non-standard ball joint is considered part of a replacement control arm, but that the pivot to spindle distance can be different than it is with the standard part.

I don't see how the phrase "including ball joints" would result in a different clarification for the ST rule.

 

Street Touring: Per the STAC, the second sentence of 14.8.I is clarified as follows: “These kits consist of either adjustable length arms or arm mounts (including ball joints) that provide a lateral adjustment to the effective length of a control arm.”

The part in bold is the phrase that restricts vertical dimension changes, as I read it. I missed this bulletin, which is why I was considering changing roll center heights with spacers.

 

Bingo. You've got it right.




I'm not sure what point John is trying to make. The rule clearly shows that alternate ball joints are allowed, but only if they change the effective lateral length of the control arm.

 

I thought drilling the trunk to accomodate the canisters was illegal in STR?