Clu7ch I think you will find that coils that wound tighter, meaning closer together will compress at a different rate than more open coils. Thats the answer I got when I raced motorcycles and they had progressive springs.

 

yeah, i've seen the ones where they have the strut/shock with the little bolt thing that's reall easy to get to and you just turn it out a few times and change the handeling.

 

Here's the classic definition of progressive rate springs. See if this explains it.

A spring with an increasing spring constant. For example, if the first inch of spring motion requires 100 pounds of force, the second inch would require more than an additional 100 pounds, and the third inch would require still more. Progressive-rate springs become stiffer as they are compressed, unlike single-rate springs, which have a fixed spring rate.

 

thanks Glen, that makes sense now.

 

so worth it....or not....?

i wish someone on here had them.....

 

In the right application they are most definitely worth it. The idea is to allow a compliant ride for the first inch or so of compression, so they swallow up the small stuff, like rumble bumps and cracks. Great for cars with smaller sidewalls, and poly or no bushings in the suspension. Cars with tall sidewalls and squishy rubber bushings will feel too soft on the open road. Progressive springs are more tuned to someone who has a performance enhanced wheel and suspension setup.

As an example, If you put the 480-600 lbs progressive springs on Soarings car, he probably wouldn't like it, stating something to the effect that the car feels too soft and mushy. Put straight 620s on my car and I wouldn't like them, stating something to the effect they rattled my teeth out of my head. Give me the progressive springs and Soaring the straight 620s and we are both happy campers.
We have very different front ends only sharing the same shock.

As for the progressive springs from Mustang plus, they'd probably work somewhat OK in a 6 cylinder car, but (IMO) they are way too light for a V8, especially in a lowered application. Eibach makes some proper progressive wound springs more in line with the specs I quoted above. And their rate rises much quicker than what I see in the picture from Mustangs Plus. Which is very important on a lowered vehicle.

As the old cliche goes, there is more than one way to climb a tree

HTH,

 

ok, im very interested in this at the moment.....i have thin profile, 17x8 inch wheels......and want a firm ride (think bmw or something) but not as if i just skilled suspension and welded the spindles to the frame or something u know???

where can i find these for 1968 coupe with a 302...??? i cant seem to find them anywhere....any help, thanks.

 

http://www.performancecenter.com/pro...+Applications/

found some "universal" ones but i dont know if thats universal enough to go with my car......its sorta oldish...

anyways, whats a good sport-tune type of spring rate? like 400? 500?

 

You will need to contact an Eibach dealer. IIRC, they do not have off the shelf springs for classic Mustangs. Of course things may have changed with the popularity. They make them though, just takes a good dealer to get it right.
A basic set would be about a 450-650 lbs, something along those lines depending on your unsprung weight and overall weight. Nothing real wild, nor too big of a spread. That should be fairly accurate for anything short of a big block/C6 combo.
You can spec the initial rate as well as the tender contact point and the main rate. I like a fairly short tender point, from the static sag point, with a close spread like I mentioned above, this keeps the suspension from blowing through the travel too fast, or over working the shocks. Just don't forget that you have some static sag when you setup your tender point. A good dealer should be able to walk you through the whole thing. I would suggest knowing at a minimum the weight of the front end, if not the individual weight of each corner.
Do a little study on this stuff, and also know where in the stroke your shock valving changes. That will help you pick out a real nice set of springs.

Good luck,

Scott

 

i believe summit has some but i dono about the weight things.....

http://store.summitracing.com/partde...5&autoview=sku


what is a 180-600 lbs one??? is that really soft or really stiff??????? can u explain how the numbers go...?