Are all lowering springs progressive rate springs... Some manufacturers advertise this like crazy and i'm wondering if its all just marketing... I would make more sense to me that all aftermarket lowering springs out there are progressive. If they are not, how can you tell which springs are and which springs are not (other than marketing).

You can do a search here on this, I think the info has been posted before, but I believe the only progressive rate springs are the H&R race springs and the Eibach Sportline.

David -

The springs that come w/ Ground Control adjustable spring system are linear in both front and rear.

All springs that have both loosely wound and tightly wound coils are progressive to some extenet , that means that about 90% of all lowering springs for the x cars are indeed progressive.

The word progressive is actually the wrong term. In most marketing info, as well as many tech people call it progressive (including myself at times).

Springs that are wound closer together and farther at the other end are variable rate springs. That means as a spring compresses the rate increases. Many import coils have this charteristic, but are not variable. They have that same wind but the closer coils are dead coils. Dead coils (the coils when installed in the car touch) do not make up much of the spring rate. They are used so when you say go over a bump and the shock extends that the coil does not rattle around.

I do not know what most companies do, but we base whether we are going to do a variable rate spring or linear spring on testing and ride quality.

Hope this helps.

Just to add a little.......Most lowering springs are progressive because it is a compromise of ride, lowering and suspension function.

The springs have to be a minimum length such that they still pull wheel back when the suspension is fully extended (albeit weakly with progressive springs because the spring rate is low fully extended and the spring preload is very low)

To lower the vehicle, the initial spring rate is low such the spring compresses greater than the stock spring under the weight of the vehicle. This results in the lowering.

With progressive springs, most of the low spring rate portion of the spring compresses completely (usually not all of it). A small amount of the low spring rate portion of the spring is left such that the ride is decent with small road imperfections. But the second the low spring rate portion fully compresses (coils touching), you get a kick in the pants!!! (from the high spring rate portion of the spring)

If you like a cushy ride, you may even look for linear springs because if they are of similar length fully extended and actually lower the vehicle, the springs are softer than stock. They may even work better with the stock shocks (valved for linear springs). I have always wondered how Echo springs would work (ride and lowering). Maybe like a Caddy......

Some of the spring sets come with linear or near linear front springs to give a better ride. The sacrifice you pay for the "better" ride is the posibility of bottoming out since the spring travel is less (lowered). I've done this a couple times with my Teins (no big deal). Almost all the rear springs are progressive because the travel of the rear suspension is not near what the front strut is. This is also why the rear spring rate is commonly higher for the XA/XB. The only linear rear lowering spring that I am aware of is the Spy springs with 1.25" drop. Perhaps some of the 1" drop springs are as well.

By the way, what ever happened to Spy springs??? No one talks about them anymore. They used to be the "springs to get" when the Scions first arrived.

They stopped making them I believe ,one problem with them was that they would sag, not a problem in my book , not 100% sure tho.

If you like a cushy ride, you may even look for linear springs because if they are of similar length fully extended and actually lower the vehicle, the springs are softer than stock.
Thats probably why there aren't many linear springs for the xb. The Ground Control linear springs are actually very stiff though. They accomplish this by making them very short. Great if you want a very stiff suspension, but a pain in the ___ when the springs fall out of the rear when you jack the car up. One of the reasons that I switched them out for the HKS which are progressive, but with a lower spring rate.