New QA1 Spring replacement question--Spring Rate?

[HPCOBRA]

I have a Classic Roadster Cobra with a 460, cast Iron heads and a Richmond 5 speed. I recent bought a QA1 coil over conversion kit (ms3500). I had an issue with the short rods on the shocks, but fixed that by installing 2 inch extenders. The shocks now are close to the same travel and length of the stock shock. The springs I installed are 500 pound springs. I installed the spring on one side only. The car is resting on jack stands on the other. The suspension moved rather free with no spring installed so everything looks good. With the spring in, when I put a floor jack under the lower arm near the ball joint, the suspension only deflects about an inch when I pick up the one side. The springs are sitting on the spanner nut about .75 inches from the first thread. I can’t wind it down any farther because the locking nut hits the lip of the raised flange on the lower are that was originally used to located the factory coil spring. I took it all back apart and am going to remove some of that flange so that I can back the nut and spring rate off a little. Do these springs relax a little over time? Do they behave differently dynamically when driving , or do you think I have too heavy of a spring? Any help would be appreciated.. Thanks

[noblec5]

Not sure if it helps...I have a 351W, I have 350lbs springs. Normal street highway use only. A friend of mine swiched from 350 to 400 to get better launch response.

I've had no problems launching on street, but he complained of a very soft feel at the 350lb springs and it seemed to float while driving. Once again, i've not experienced this.

Chris

[Silverback51]

I have a SPF with a 385 series engine. I just put my QA1 shocks and springs on over the winter. Due to our lousy weather here in the not so great Northwest, I have not really gotten to put very many miles on the car, but from what I have driven it, they are a big improvement over the original AVO's.

I went with the 400 pound springs, and I will probably buy some 450's in the future. I prefer handling over ride comfort.

[Tommy]

I believe that the spring rate (e.g., 500) is expressed in pounds per inch. In other words, it would take 500 pounds of force to compress each spring by one inch. If you car weighs about 2,000 pounds and that weight is distributed evenly across all four corners, each spring would be supporting aobut 500 pounds and would deflect about one inch. None of this says anything about how the car would feel or handle.

[Ron61]

I had the QA1 shocks and 12 way adjustable rebound set up on my car and I talked to the dealer and told him what engine I was running and what the front end weight was and that I would be racing it. He suggested 450 or 500 pound springs for the handling. As for the shocks not being long enough I have a friend who owns a machine shop and he cut the lower mount and added enough to it so I didn't have to go with extenders as I was afraid they may break in hard cornering. It was a little rough riding on rough streets even with the rebound softened to about 4 clicks, but handled great on track or in corners.

Ron

[JCoop]

Look into Carerra variable rate springs. I put them on my QA1s and love 'em. The best of both worlds: smooths out the ripples but bites when you need 'em.

[HPCOBRA]

Does anybody know what the free length of the springs are suppose to be in the QA1 ms-3500 kit (500#)? They may have sent me the wrong ones.
Thanks

[byron w]

HPCOBRA, mine are 8 1/4 inch, free length. What are yours?

Byron W.

[HPCOBRA]

Same here..about 8.25..

[HPCOBRA]

I modified the lower arm in the area of where the original spring sat. I ground down the lip a little that stood up about .50 inches to capture the spring. This was hitting the locking spanner nut. i will put it all back together this weekend. I did notice that the strut arm adds a bit of suspension resistance with the harder urethane bushings. Have these been a problem for anybody ? Are the traditional rubber better?