rear suspension where to start

[sheldonw]

Help me hook decent power. Don't have a dynosheet but it should make 650-750hp maybe more not sure. 3600lbs cutlass.The suspension is basically stock with 90/10 and 50/50 drag shocks no front swaybar poly bushings and a spohn arb, and about a coil cut off the front springs and belltech 1 1/2" lowering springs in the back.

355 sbc 8.33 comp
procharger f1a 18-20psi
afr 195
comp solid roller .585 lift 255 265 @.050
quickfuel 750 blowthrough weiand team g intake
1 7/8 shoenfield headers with 3 1/2" pipes
th400 with a brake and a 10" converter stalls about 3800
moser 12 bolt with 3.73's and a 28x11.50 et streets

I dont have a time slip with this combo but my time with my old setup was a 11.85 @ 113 with a 1.71 60' with a weiand 142 @5psi, nx268h cam and a 2400 stall on 275/6015 bfg drag radials

Anyways it does not hook at all, where should i start what works. lift bars? double adjustable shocks? different springs? instant center, pinion angle etc?

thanks for your help

 

[sheldonw]

come on guys nobody here 60's better than 1.71 what am i doin wrong?

 

[BMR Sales]

Your going to need get some upper an lower rear control arms, relocation brackets will help also. The spohn anti roll bar is ok but your shock setups could use some tweaking. Give me a call and i can help you get your setup better.

 

[UMI Sales]

Hello
I noticed that you are having issues with your vehicle not hooking. Well I would suggest like mentioned above getting rid of the stamped uppers and lowers. I want to mention going with a set of lift bars to allow you lower control arm to be more parallel to the surface also eliminating any issues with wheel hop and increasing your traction performance. I would also go with a set of upper double adjustable to assist on the pinion angle. Another good set up would as far as shocks would be a set of adjustable s.
I would recommend going with a single and then a coil over set up for the front. Below is a link to show you what all UMI Performance has to offer!

http://www.umiperformance.com/catalog/index.php?main_page=product_info&cPath=8_60_72&products_id=83

http://www.umiperformance.com/catalog/index.php?main_page=product_info&cPath=8_60_71&products_id=90

http://www.umiperformance.com/catalog/index.php?main_page=index&cPath=8_57

http://www.umiperformance.com/catalog/index.php?main_page=product_info&cPath=8_64_154&products_id=70

If you have any other questions feel free to ask and I will be more than glad to help!
Thanks
Brad

 

[sheldonw]

thanks guys i'll be in touch

 

[5-door]

Hey look, spammers!

 

[COPO 572]

I'd say those 1 1/2" lowering springs are going to hurt you. Not much stored energy there to help with the plant.

 

[sheldonw]

yea whats the scoop on using coil over springs? just put them in or do i need anything else?

 

[sheldonw]

ok just phoned belltech the springs i have now are 12.71" free height and 171# spring rate.... what spring would i use to keep ride height the same but softer rate

 

[Doober]

It's a simple math/physics equation (F=-kx for all that are interested). We'll say the weight distribution of the car is about 60/40, and it weighs 3200lbs, meaning about 1280lbs. will be on the rear springs.

With the 171lb. spring rate (multplied by 2 gives 342, because of having 2 springs), you can figure the spring compresses about 3.75" (compression=vehicle weight/spring weight, x=1280/342), giving about 9" of total travel left. To get the same ride height, you factor this 9" into whichever spring you decide to go with.

Let's say it's a 16" free height spring. To get the same ride height you will need about 182lbs./in. = 91lbs./in. per spring (using the same formula as above 7=1280/2x, 1280/compression=2*spring rate will also work)

Want to go even taller, say an 18" spring? You'll have 9" of compression here, so the equation will be 1280/9=2x, x comes out to about 71lbs./inch.

To get an accurate reading you need to know how much weight is on your rear tires though.

Let me know if you need any more explanation, or help in figuring out a spring rate or height