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I backhalfed my 67 GTO, I am using an S&W Race car back half kit. I have Strange coilovers in the car with 12 inch tall springs. The spring rate is 170. I have the adjusting nut all the way down and the car sits about 3 inchs too high. Can I use a shorter spring to bring the ride height down.
 

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This is a drag car, right?

Unless your car is very heavy, I think your springs are too heavy. For an example, my 2300 lb. Vega only needs 95# springs on the rear. It has 1150lbs. of weight on the rear. I'd bet you won't need more that 110# or 130# springs unless your car is extremely heavy.

A lighter spring would allow you to lower the car and crank the adjuster up, thus increasing the stored energy in the spring.

Measure your shock travel from fully compressed to fully extended. Try to set up your desired ride height with the spring adjuster in the middle of the travel, and maintain about 70% of your measured travel for extension and 30% for compression.

You may need to adjust your shock mount height, also.

If you're not sure what I mean, PM me and I'll try and explain it better.


Randy
 

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My car weighs 3150 with me in it and I use 130 lbs springs in mine. And no you can't use a shorter spring because the shock travel will be sacrificed. You have to use the length they were designed for.
 

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What Randy said... except I might argue that at ride height there should be 30% extension and 70% compression.

I like the extra extension so that when the car launches and it gets some suspension separation, the shocks don't top out. If the rear shocks top out, it will IMMEDIATELY spin. I have my car set up nearly neutral with just a TINY touch of separation.

I run double adjustable shocks all the way around and have the compression setting adjusted relatively firm. Then, I tune the traction with the extension setting.

Now, I'm definitely not a suspension expert but I do run a 4-link car and I have it dialed in pretty well. Most all of my experience over the last 20 years is with 4-link style cars. All I can do is relay what works with my stuff.


Randy
 

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Ah yes... burned again by the drag versus road race thing.
I was thinking road work while Randy is optimizing the launch. For optimizing launch Randy is entirely correct.

Note that is going to take an even softer spring BTW.
 

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My 3750 lb '70 Malibu uses 125 lb rear coilover springs mounted on Koni adjustables. The fronts are 450 lb.
 
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