Should I go to the 140 springs to lower the rear of the car, adjustable perch shocks or both? The car has stock (?) springs. Car is going to see aggressive street/auto-x use.
Thanks
Mike Allen
San Antonio, TX

bilsteins w/ adjustable perches and 140s are what i run on my street driven car. rides/handles good.

others will chime in about koni's

Just put on some 110's and the Bils will be going on soon.

.....b

P.s. Welcome to the CLUB Mike

4 bags of cement?

180's and koni's

Money says your 100# sprngs are worn out, so they are sagging, so the 140# springs you are thinking about will actually raise the rear. Figure out the weight of spring you want, and get either the adjustable perch kit, or shocks that have the adjustable clips (Koni or Bilsteins)

For an agressive street?AX car, the 175#-200# is good, but whenn you end up getting the rear end that stiff, you will want to stiffen the front T-Bars up along with a bigger sway bar. I run 200# rear springs, 22mm torsion bars and a 23mm Sway Bar. It is neutral, but I can adjust the sway bar for more under or oversteer.

Worn out is probably right. I had my stock 110 lb springs tested after the rear kept getting lower. They measured 68 lb. Now run 140 lb Eibach and Konis.

Actually the stock 914-4 springs were closer to the 68lb you had tested. The 914-6 had 100lb springs IIRC. At one time it was popular to upgrade the stock springs to the 914-6 units. Now most people prefer an even more aggressive setup, especially for dual use (street/autox).
You can increase the stiffness gradually by adding 140's and a big adjustable sway bar up front (on a soft setting). Then add stiffer rear springs and torsion bars in the future if you become a more frequent and competetive autocrosser.
Two theories on shocks: 1) Konis for adjustability - soft on the street and hard in competition. 2) Bilsteins for excellent grip in all conditions without adjusting, but the bilsteins add spring rate as well.
I have been using standard Bilsteins for street and track since '84. In fact the rears have been in continuous use since then and only now am I planning an upgrade as the damping rates aren't optimum for a car with 250# rear springs and slicks.