Spring rate help Please!!!

[fasterpatrick]

Okay, I'm running out of things to work on before the snow melts (ya right it may never melt). I need to get the ride height settled, I need to know if I could do this with just springs or an I going to need to change out shocks as well.

Here is the corner data.

Front:
Wheel weight = 599 lbs.
Shock ext. = 17 in.
Shock comp.= 11.62 in.
Desired ride @ 14 in.
Inner pivot to Shock= 8.75 in.
Spring length = 12 in.
Control arm length = 11.75
Angle of Shock off vertical =30 deg.

Rear:
Wheel weight = 650 lbs.
Shock ext. = 18.75 in.
Shock comp.= 12.5 in.
Desired ride @ 16.25 in.
Inner pivot to Shock= 11.75 in.
Spring length = 14 in.
Control arm length = 16 in.
Angle of Shock off vertical =10 deg.

Okay, all you really smart guys help me out with this. What spring rates do I need, I'm so confused.
Patrick

[Tim Brewer]

There is no exact firm answer. But, a good starting point would be 325 rear and 375 front. Just contact your shock manufacturer for length. That's really all you need to know.

[Barnsnake]

It calculates to 310 Front and 355 Rear.

[RICK LAKE]

fasterpatrick Pat what are you going to do with the car???
I know this is a question asked over and over again.
Auto cross, road racing, drag racing, cruiser and car shows??
Does the car have front and rear sway bars??
What size tires and rims are you running??
Was the weight done with 1/2 tank of fuel, all the fluids full, and you in the drivers seat?
What size diameter are the sway bars and what ends are on them?? What shocks do you have??
What kind of ride are you looking for?? There is a trade off of handling for soft riding car. Just the different between 15" tires and wheels and 17" tire and wheels is a huge driving differents.
The biggest thing I have seen in the last couple of years is bigger sway bars and lighter spring loads. This gets the car to feel the road better. The jury is still out. If you are looking for handling also check the bumpsteering. Most cars are out on this adjustment alone. Rick L.

[fasterpatrick]

fasterpatrick Pat what are you going to do with the car???

I know this is a question asked over and over again. I don't mind answering
Auto cross:Maybe
Road racing:No
Drag racing:No
Cruiser and car shows:Spirited driving and runs, local show stuff nothing major.

Does the car have front and rear sway bars??
Yes 1" front / 3/4" rear

What size tires and rims are you running??
245-40 on 17 X 8.5 front; 275-45 on 17 X 10.5 rear.

Was the weight done with 1/2 tank of fuel, all the fluids full, and you in the drivers seat?
No quarter tank of fuel, and my 200lb butt was not in the car.

What size diameter are the sway bars and what ends are on them??
Part A, refer to question 2; Part B, Rod end links.

What shocks do you have??
QA1 PromaStars bearing ends (not poly bushings).

What kind of ride are you looking for??
Firm but not a buckboard, ridden in the latter no like at all.

There is a trade off of handling for soft riding car. Just the different between 15" tires and wheels and 17" tire and wheels is a huge driving differents.
The biggest thing I have seen in the last couple of years is bigger sway bars and lighter spring loads. This gets the car to feel the road better. The jury is still out. If you are looking for handling also check the bumpsteering. Most cars are out on this adjustment alone. Rick L.

Yes I know that, I put a lot of time into getting the geometry to work right I just need to get the car to settle into the sweet spot. I have done a fair bit of research into shock characteristics and would like to use longer stroke and the softer spring approach and add the bump-stops to the shocks to prevent bottoming.