QUOTE(D1A3 @ Feb 29 2012, 02:24 PM)
I have a stock '76 2.0L car and have been pretty successful in AutoX at the local PCA and SCCA level. For PCA, I run in the PA class.
I currently have red Koni's (age unknown) with 90 pound springs on the car. I also have front and rear factory sway bars. The shock/spring combo seem to work well enough for street and reasonably aggressive driving
My problem is that my rear end seems to come up and dance all over the place when I'm AutoX'ing and I'm trying to get it more planted for the upcoming season. I've had folks recommend I upgrade my rear springs to everything from 140 up to 180 lbs.
Any thoughts on what springs I should go with? I'm not looking to replace the shocks and springs or do any other suspension changes right now as I can drive the car very well in AutoX, but want to try and pickup some handling and hopefully a little time.
Below is a pic of my car from behind to give you an idea of what I'm trying to correct.
Thoughts?
Click to view attachmentI appreciate any and all comments! :-)
Hi D1A3,
I agree that you want to REDUCE ROLL in corners. Not only does it take TIME to load and unload the chassis, but roll makes the rear suspension do a LOT of Toe-change: for every 1" a rear wheel compresses (goes up) the suspension on that wheel toes-in .100". At the same time the other rear wheels toes-out a similar amount, creating understeer. A good rear toe setting starting point is "0"
toe and going to static toe-out to allow the rear to move a bit. An oversteery car is quick at lower speed auto-x's
I think starting at 140 lb spring AND stiffening the swaybars will improve the car. Keep in mind that with the mounting of the rear coil-over, the actual wheel rate is 117% X the spring rate.
If you can adjust the swaybars stiffer, great, but you may need to go a size large. Don't make a big jump as the spring rate of the swaybar increase at the 4th power of the diameter. Here's the formua: K = (1,178,000)(D4/LA2)
Swaybars are a great spring to reduce roll while keeping all the wheels on the ground.
I wish I could give SPECIFIC answers, but my car is a V8 track car and I'm running 400 lb rear spings.
Best,
Terry