Cal Club Autocross Forums

GS

Does it have a chance

Stock shocks are complete bollocks apparently. Until some good aftermarket options are available, no one really knows.

James Feinberg (sp) ran his in Lincoln. it performed poorly but he believes with shocks it can be extreemly compeitive. there are already shocks made for the car in europe, he has ordered a set for the car. It seems that GS is becoming a smaller car class.

It may very well not remain classed in stock based on how it behaved on course at nationals

Gary Thomason wrote:It may very well not remain classed in stock based on how it behaved on course at nationals

Ouch. This thread needs pics.

John Stimson wrote:

Gary Thomason wrote:It may very well not remain classed in stock based on how it behaved on course at nationals

Ouch. This thread needs pics.

it wasn't that bad! it barely showed some light under both inside tires when the driver yanked at the wheel at the end of a 6 cone slalom (finish of west course).

it barely showed some light under both inside tires

That might be a wee bit of an understatement there Marshall...

Making judgements with tape measure data seems kinda crude. Do any agencies or watchdog groups still do J-turn roll-over tests? That's where they put outrigger skids on it and try to flip it. Of course it couldn't account for R-compounds, but real world relative risk would seem useful.

Mike Simanyi wrote:

it barely showed some light under both inside tires

That might be a wee bit of an understatement there Marshall...

I was standing right there on one of it's runs ( i was helping fix timing light issues on the other course). I only saw a couple inches and only briefly off the ground. I didn't see every run though, did I miss a worse example?

Bill, the NHTSA does do a dynamic rollover test as part of its rollover ratings. Not flipping in such a test doesn't mean the vehicle is safe, which is why the NHTSA also uses the static stability factor (height of the center of mass, divided by the track width) as the main factor in their published "rollover probability" ratings. The SCCA uses the NHTSA's ratings as a basis for determining which cars are allowed to run in stock on race tires. "Tape measures" only come into play if there isn't published data on the vehicle's SSF or CG.

Yeah, it was a pain to track down the data, but they did evaluate rollover on one 500 model and the result was "no tip". So their findings were strictly mathematics based. As long as they used legitimate CG height, that's pretty valid. Our "accounting" for CG height by measuring roof height is kinda sketchy. Sunroof? Aluminum sheetmetal? A low CG car with extra headroom?

But maybe the best we can do with what we've got. Personally I'm a seeing-is-believing kinda guy, so I like the dynamic test supplemented with actual behavior at events. That said, even the Fiat commercials show the guy clowning around and lifting a wheel.

Most models have had the SSF published by NHTSA's safercar.gov web site. Now they offer it as "rollover probability", but Marshall dug up the formula they use to calculate that from the SSF, and it's possible to back-solve. As it turns out, the 1.3 SSF limit is equivalent to a 14% rollover probability limit with a "no-tip" result in the dynamic test.

The "overall height" criterion is only used as a backup in case SSF data isn't available, or if the car has been modified so that the SSF can't be calculated. The safety folks seem to think they've determined a pretty reliable correlation between overall height and CG height. I'm somewhat skeptical too, but what cars does it unreasonably exclude? It seems more likely that there are cars included that shouldn't be...E30 BMWs, for example?