My next mods are set (RR, headers, cat pipe, plugs, wires). I've now been researching a future round of mods (shocks, springs, LCA relo brackets).

I want to drop the car only .75" - 1.0". That eliminates the Eibachs. SLP is out because their spring rates look a little soft. 1LE springs would not drop the car but they would tighten it up the way I want. I'd consider those but GM no longer stocks them and I haven't found 'em ANYWHERE. Hotchkis fits my drop requirement but the progressive spring rate also looks like it starts a little soft. BMR appears to be closer to what I need. I'm a little concerned that the rear progressive rate is too stiff for my rear bar (1LE too for that matter). I'm going to call Strano eventually but first I wanted some first hand or second hand info if possible.

FWIW here are the specs:

Model Front Rear Ride Drop

OEM GM 292 114 0.00"

GM 1LE 360 130-180 0.00"

Eibach Prokit 377-600 94-160 1.50"

Hotchkis 285-525 100-140 1.00"

SLP Level 1 223-448 97-136 0.75"

BMR 310-550 145-170 1.00"

You can see where I think that the SLP and Hotchkis might start off too soft. The pro kit is too low for me. 1LE might satisfy me but I might as well go pan for gold in the river. BMR is progressive front and rear. Isn't it hard to get a non adjustable (read reasonably economical) to properly damp a progressive spring? Any thoughts? How about the brackets? Useful with only a 1" drop?

The car will still see the strip occasionally. I would also like to start attending the occasional auto-x. It will mostly see *ahem* "spirited" back road driving though

 

The SLP Eibach's are 300-450 up front, and I am 99% sure they are stiffer than that out back.

 

1LEs are 360#, and as said the .75" SLP lowering fronts are 300-450, which would effectively be more than the 1LE, not "softer".

You could always get the 1LE and cut a bit off, bringing it around the 400+ mark depending how much you cut, I wouldn't take off too much though, but obviously you wouldn't want to.

I have also heard the Hotchkis drop is unrealistic and is much more than 1", but I dont know first hand. Even lowering these cars a bit can seem drastic perhaps, because they are already fairly low (when compared to a 4x4 Mustang). Look under your crossmember, and between the front fender area and you will see there isn't all that much to be done before you run into problems anyway. When I first dropped the car before alignment I couldn't even see between the fender and front tire without getting on the ground, I was at -1.6º camber and around a 2" drop.

 

Does cutting a linear spring affect the spring rate? I understand why it would on a progressive spring, but do not think the height of a linear spring affects the rate.

 

Anybody know where I could get 1LE springs? I have the part numbers but I believe GM is no longer stocking them.

I'd like a slight drop but its not a requirement. Performance comes first, appearance second. *shrug* At least then I wouldn't have to play with the relo brackets.

 

Yep, it will do so on a linear or non-linear spring for the same reason. Height doesn't have anything to do with it, you are correct on that. # of "active" coils, wire diameter, and mediun spring diameter are used to determine spring rate.

http://www.stockcarproducts.com/pstech10.htm

This page simply requests spring OD so I assume they built in the division required to get mediun OD, which is simply total OD - wire diameter.

 

That one is always going to be debated, I like the feeling of a lowered car, but there can be too much of a good thing, and the car is already semi-low as is. A local guy who races the car is near stock ride height, although he does have front and side air blockage (none in the rear of course), basically home-made GFX with a rubber bottom to hug the ground without breaking. He is running 800# coil over fronts, and I think a 150# rear. Books will cover the math involved (once you get the dimensions) to figure what you are doing to the car if you raise or lower it, as far as roll center and etc which changes when you raise or lower the car.

Some other folks I've come across agree that lowering a car is over rated as far as actual lap times go, I imagine it depends a bit on what car were talking about and the speeds being seen and probably numerous other things. Most actual track cars however dont have to deal with bumps so much, so they can afford to run very stiff springs and low ground clearance, and will gain lower drag and COG that way, and wont have to worry so much about suspension travel.

 

Would you care to share the GM part #'s you have for the 1LE stuff? I have access to a bunch of stock GM springs and can't tell what is V6, V8 or 1LE. I need some part numbers to identify them.

 

No problem. I found most of them here.....
http://www.1le.net/

 

I looked at that site and couldn't find any numbers that matched up with the stuff I have seen.
One set of rear springs that I have seen were from a 2002 WS6 Vert TA though. I thought for sure that those would be 1le springs. The sticker on them said "NNU" and had the GM part # 10305134.

 

WS6/SS convertibles never had 1LE springs. '96-'99 SS/WS6, plus very early 2000 (11/99 and earlier build date) had the 1LE springs. Cars built after 11/99 did not have them. The numbers on 1le.net match the part numbers on the springs of my '98 1LE Z28.

 

According to this site they do have 1le springs just like the 98 1le.
I saw the strut and it was an fe4, so I guess I just assumed that the back stuff was as well. Maybe the year is off or something.

 

Has anyone found a place to order the GM 1LE springs? It seems they may not be available anymore.

 

I think that your best choice would be the Eibach Pro-kit. They did not lower my car that much. Maybe 1.25". The handling is phenomenal, and the ride barely even changed. I think that these would be perfect for you. Go to the link in my sig to view the drop. I fit 11's on the back, so the drop must not have been that drastic. Hope this helps. Let me know if you have any questions. Later,

Brian

 

The pro kit definately looks like a moderate drop, still a good deal of suspension travel. My car looks seriously slammed compared to a Pro Kit car, so thier 1.5" drop claim if thats what it is, is erring on the side of safety I think. If your worried about big speed bumps it looks like a good set of springs to go with, even though I know JimS on the board has complained of them - my springs require me to drive very slowly over some large bumps, but I make it over everything, and I have about 2.5" clearance at my lowest point.