I have a 91 Firebird. I'd like a very stiff ride so it'll handle and to deal with a ground-clearance issue. I've been looking at the AGX adjustable struts by KYB. There is a similar strut by KONE or Bilstein. What strut is best for me? The stiffer, the better Any ideas?

Yes, do a search.

Shock valving is not about 'stiffness' necessarily. It is about resistance and smoothness or quality of valving. Cheap shocks can be stiff valved and harsh. Good shocks can be valved "stiffer" so to speak but with smoother resistance.

I will give an example. Take a popular offroad shock like a Rancho. It is a mid priced shock and is valved stiffly to resist body movement of a heavy 4x4 truck, but that truck also has very large forgiving tire sidewall that will also damper bumps. Cheap cost valving techniques inside the shock body will cause the low speed vavling to rapidly increase when the shock compresses at higher piston speed sending the stiffness through the roof, THEN it slacks fff slightly with absolutely no valving for a small movement when it changes direction from compression to rebound, or rebound to compression. This is poor stiff valve quality.

What you want is increased damper rates 9resistence with good quality valving that monitors flow well even in change oof direction. Also vlving hat does not go through the roof in increased stiffness with increased piston speeds. Alos LASTLY, you want a shock that controls oil movement an keeps it the coolest for comsistancy and not fad strength when hot (Overworked- trust me, shocks take alot of work just driving accross town)

A shock like a Koni will increase damper resistance ESPECIALLY the rebound rate which is what controls body roll movement in transistions.

you basically get what you pay for. A cheaper shock is just that...lessers quality.

Dean

Also,
Ground clearance issues is more of a coil spring thing, not so much a shock thing.

The lower you go the higher rate the spring generally needed to control the car from bottoming out (this gets so much more detailed, but for sake of your question I will answer it accordingly)

The rebound is a somewhat fixed value based on coil spring rate recoil and roll weight. However, the compression valving is to assist the sping rate dynamically in holding up the chassis more towards static position in braking, acceleration, and cornering. Ultimately, it is the combined total of shock compression AND coil rate that hold each corner dynamically, but however, once the car's weight has settled into that fullrange of motion, it rests solely on the coilspring as the shock discontnues to move.

In lowering a car you really want to keep the same spring rates as the car would ride higher, but in doing so, you need to keep the roll centers in proportion with the center of gravity (this is call roll couple). WWhen the car is lowered and the roll centers are not corrected (like 99% of cars lowered) the coil rates increase to fight the increased roll leverage of the larger roll couple. This is where shock valving will cause the so called harshness. people are not decreasing compression valving when they increase coil rates and the ride gets harsh.

yet, if you keep the spring rates lower on a lowered vehicle, you run the risk of grounding out. Over the counter shocks for the most part are designed for a car usually at stock height or at most one inch lower than stock.

This is why lowering a car "the correct way" is so expensive and high tech.

I still recommend Koni Yellows for over the counter shocks and struts. The are best valved for anything you do ti the car modification wise compared to all other competitorswheen it comes to performance cornering.

To us idiots - that means the springs have more to do with clearance than the shocks/struts. Shocks/struts control the rebounding of the spring, the spring compression controls the initial dive of the car on a bump. Progressive rate springs mean they get "progressively" more resistant to compressing the farther they compress - that way the ride is smoother on small bumps, and "stiffens" so-to-speak as the spring compresses further.

If you are having issues towards the rear, you can add air bags inside the springs for $80 - they will help reduce the amount of compression of the spring depending on the amount of air in them. If up front, not sure - never seen airbags for the fronts. Check out www.airliftcompany.com if interested in the bags. Could also maybe add an extra spacer (ie isolator) on top of each spring to increase clearance a tad.