[bowtieboy]

Thanks in part to Mitch (BIG part), I now have a set of
LG Super Spring. These things are hard to come by and Mitch led me to the guys post the same day.......and now the deal is done - sitting in the garage.
Can't wait to get them on; needing more spring rate up front.

Thanks again Mitch (IMG:http://www.frrax.com/rrforum/style_emoticons/default/thumbup.gif)

[sgarnett]

The question (which probably should have gone in a new thread) was specifically about autocross, not road racing.

Bumpstops and progressive springs are both intended to increase the total effective spring rate as the suspension approaches the mechanical limit of travel. The idea is to keep the spring softer (relatively speaking) around the normal operating position, but ramp up the rate near the end to avoid the abrupt stop of bottoming out.

The differences are the shape of the rate curve during compression (where and how fast the rate changes) and how much the rate curve changes during rebound due to hysteresis (primarily but not exclusively due to hysteresis in the bumpstop).

That topic (i.e. the relative merits of the differences) has been vigorously debated in other recent threads, so there's no need to repeat it here, and I'm not trying to.

I am installing G2 springs at the front. IF I didn't already have rear spring jacks, and IF I hadn't changed my rear suspension geometry, I would probably still try the G2 rears at a test-and-tune. What is there to lose? I still might try them at a fast smooth lot, though I know my right rear spring would require a shim due to GM's poor build quality (which is why I bought the spring jacks to begin with). If I ever take this car to a road course, I'd certainly take the G2 rears along to try.

Also, the reason I keep bringing up the torque arm in a spring thread is that it affects everything. In other words, it's intended as disclosure - ymmv.

I should also mention that for anyone towing a tire trailer, progressive springs have some off-track benefits. That alone may make it worthwhile to spend the time to figure out how to make it work for autocross.

BTW, my intent is to point out the oft-debated pros and cons (in response to a question), not resolve them. Think of it as a verbose list of topics to search on and draw your own conclusions.