Mkos1980

iTrader: (8)

I've read most of the post on spring selection but it seemed alot of questions in those posts ended with no answer. I see differant weights and so forth. What determines what weight spring is needed and height? I'm looking to go from 25in-28 inches in front. No more no less. Car is weekend cruiser and part time track car. I 've seen most people go 8in , in front but their only setting the distance to 26inches with little room to play. I was thinking maybe a 9in spring and 900lbs? 8in 250lbs in the rear? I've emailed GC with no responce and also called them with no answer for the last few days. Any thoughts. Car has an Iron Block LSX swap and Spohn K member and UMI arms. Stock WS6 spring are in it now with no isolator up front. Distances are 28 in front and 28.25 in back.

blyth18md

Rear springs might be too short and a little too stiff. Id be thinking 175-225 range, but that is just going from memory 8" seems short for the rear, you may want to double check that.

87350IROC

iTrader: (2)

I would recommend 9" springs, front and rear.

I currently have 8" fronts and 10" rears.
With this setup I can adjust the fronts from on my strut mounted bumpstops (24") to 26.5" With a 9" spring you could easily reach 28" while still getting down to the bump stops. I think a 9.5" spring would be perfect but good luck finding one.

For the rear with my 10" springs, I can get as low as 26.5" with the stock rubber isolators. 9" springs would be perfect. FYI, stock bump stops have the rear sitting at 25".

My front measurements are with Spohn a-arms and k-member. Your mileage may vary. A point on the Spohn k-member. It uses the inside diameter of the spring for location. The weight jacks have a larger ID than the springs. You will need to make up this different with something. I chose to use some heater hose. It fits very tight.

I settled on 25.5" front and 26.25" rear. It rides nice at this height and is not a major pain to drive. Just what I wanted. I went with 850lb fronts and 175lb rear springs.

I think your combination of 900/250 is way to rear heavy for a stock style suspension. These cars seem to work well with about a 5/1 front to rear spring pressure ratio.

DBLTKE

iTrader: (1)

Well I've got 8" 800lb springs in the front and 10" 200lb springs in the rear with 36/24 sway bars. I did a lot of research before choosing my springs rates. I use my Camaro for autocross and found there to be a lot of initial understeer during turn in, finally settling down to neutral while in corners with the stock front to rear ratio with 285 width tires front and rear. To get rid of any understeer I decided run a higher rear spring rate than most in comparison to my fronts.

I think your rear is a bit high as well, a 225lb rear spring would be better suited for a 900lb front and a 250lb rear would go well with a 1000lb front. As long as you have equally sized tires front to rear. Once you start running staggered tire size favoring the rear then you want a little more rear spring rate.

IMO you should use a 9" 900lb front, 9" 200- 225lb rear (the higher the rear spring rate the easier it is to induce oversteer), you should pick depending o your preferred driving style.

87350IROC

iTrader: (2)

I can understand that for an autocross car. In my experience 5:1 is perfect for medium-high speed cornering. Which is what I care about. For low speed cornering I can believe a looser setup would be desirable. Like you said, assuming same size/type tires on front and rear and factory ratio sway bars.

I know you said you are using 36/24 sway bars but you sig shows 36/22. With 36/22 I can imagine you would need more rear spring.

Mkos1980

iTrader: (8)

Just ordered the 9/9 900/200 combo.

Mkos1980

iTrader: (8)

Accually Trevor from GC called and said all they have was 9.5in springs for the front so I went that route.