I think you guys have it pretty figured out but I will lend another bit of information for stock legal shocks. I went through a lot of information from the SEB and such when I built the shocks that I ran on my Crossfire.

The aftermarket shock must be within +- 1 inch of the stock shock while fully extended. The spring perch must be the same distance from the lower mounts as the stock shock is.

The bump stop must contact the shock at the same point in the suspension travel as stock as well so you would need a longer bump stop if you have a shorter shock body.

Where I was able to play with the rules some is in the shock being fully extended on the work bench. I got a clarification that the fully extended is meant while sitting on a work bench NOT on the car. We installed a rebound spring in the shock so that it would remain stock in length when sitting on the work bench but would increase in length just over an inch when bolted to the car. This allowed an extra inch of rebound travel which is huge on an open diff RWD stock class car. The car put the power down quite a bit better once I put those shocks on the car.

 

Where does it say this? I came to the same conclusion as Matt from reading the rules.

 

Yeah!

 

Overall fully extended length has to be within 1", and the overall length at the initial bump stop contact can't be longer than stock. With the consequence that the bump stop cannot engage earlier than stock. There is nothing wrong with delayed bump stop contact due to a shorter shock body or a shorter bump stop, under the Stock rules.

 

this is to easy.

apparently my head is so big that I can't run anything with a roof.

FM last year, some STR fun and most likely ES Miata at Tours and Nationals this year.

 

"You can beat Sal. His head is so big it may not fit in the car."
Quoted from an email Dave Newman sent me

 

I'm curious: Do you feel this is a good thing? If/when you wear a hole in a fender liner isn't your car illegal in STR or even AS?

Someday you're going to find a big enough bump to bottom out any spring rate. My experimentation with a CSP Miata and an AS S2000 shows that bumpstop engagement/stiffness can be used to tune at-the-limit behaviour quite dramatically on bumpy surfaces.

The more I read, the more I realize we autocross on much bumpier lots that most on this forum. I've worn holes in my front fender liners (inside by the upper frame rail and outside where it attaches to the fenders) with 225/50R16 Dunlop Z1 tires on the stock AP1 wheels, Penskes, and a 1.5" Ankenny bar. That's with the bumpstop engagement point being within 0.1" of the stock parts.

 

Holes worn in the liners are not illegal. They used to be but the rule was changed. I can't remember when but it's been over a year.

Also, the compression damping found on a Moton acts a bit like a bumpstop. Hitting the bump stops when I was on Konis happend MUCH more often. That's one reason I disliked those shocks. They had less compression and I hated the feeling of blowing through the compression stroke and waiting for the rebound to control the car.

If you do a search on my username, the history of my experience with Motons will be laid out. It's pretty funny. The more I know and learn, the more I love those shocks. They really shine on bumpy lots. The first time I installed them on the CRX, I was blown away. The car felt like it was floating on a cushion of air. None of the track irregularities bothered the car at all. Anyway....

The tires rarely make contact with the frame. I am used to rubbing the fenderlirners as I did in STS so a little rubbin never hurt anything. It's a gauge to how low the car should be. No rubbin means drop it some. A little rubbin means you're as low as can be and a lot of rubbin means raise it.

 

That's for stock, I read that shocks are very open in ST almost any length.


14.5 SHOCK ABSORBERS
A. Shock absorber bump stops may be altered or removed.
B. Any shock absorbers may be used. Shock absorber mounting
brackets which serve no other purpose may be altered, added, or
replaced, provided that the attachment points on the body/
frame/subframe/chassis/suspension member are not altered. This
installation may incorporate an alternate upper spring perch/seat
and/or mounting block (bearing mount).

 

I was responding to the discussion about the stock rules for shocks and bump stop, and I specified that those were the Stock rules in my statement.