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lilsumo
09-09-2011, 06:17 PM
i have a 04 laser (not lazer) swing arm on both sides and i am looking for some help on a starting setup.

First off, I have no scales and no access to them till i buy a set this winter.

I am looking for spring and shock advice.

Right now it has 300 lb on the rears and nothing on the front, i have a bunch of shocks that came with the car but none installed.

the swing arms measure 14.750 inches from center to center of bolt holes. Springs are on the swing arms and both shocks behind. I can not run coil overs.
I have a J bar and the pull bar is just one solid bar running from the top of the rear end to the chassis. I have to run that kind of bar cause of the rules. It does have a 90/10 shock above that.

The bars run backwards, the swing arm comes from the front and hooks to the birdcage, but the top bars run to the rear of the car. Is that normal?

I did some math and saw that with a 300 lb spring that i have 194 lbs at the wheel. How much do you normally need at the wheel?

Any advice would be appreciated it.

racin6mod
09-09-2011, 09:57 PM
metric or chevell front clip? need to know that to help on front springs. it sounds like a basic swing arm.look at the rayburn lm it's the base design for most swingarm chassis.

lilsumo
09-09-2011, 11:59 PM
guess you need to know that, lol

Its a metric clip with metric lowers, it has tubular uppers but not adjustable.

dirttrackrocker
09-10-2011, 09:46 AM
The 300's sound like a good starting point on the rear. You have to remember that a swing arm takes a heavier spring because it is mounted to the lower arm instead of the rear itself. The 300 puts you in the 175 neighborhood at the wheel.
With a metric front and metric lowers you are gonna be a lot heavier than you would think on front springs. I learned this the hard way.... Most posts you see are gonna talk about 600-750 pounds in the front. Thats with a Chevelle clip, or a metric with nova lowers. For a metric metric, you need to be up around 1000. Heres a little formula to help you.

Chevelle lowers have a 36% ratio, Nova lowers have a 30% ratio, Metric lowers have a 23% ratio. Meaning if you have a 650# spring in a Chevelle you have 234# at the ball joint. (650 x 36% = 234) so to get close to that with a Metric you need to have a 1000# spring (1000 x 23% = 230)

Hope this helps.

HEAVY DUTY
09-10-2011, 05:11 PM
Most 15 inch swingarms have about a 43% motion ratio which means you need to be at 450 or so on rear springs.The last post is right on on the front springs.You figure the rear swingarm motion ratios the same way that the lower a arms are figured, which is center of front eye to center of spring divided by the total length, and then square that number.example 10" divided by 15" =.66 x .66 = .43 450 spring x .43=193.5 which is your spring rate at the swingarm. Angle,width, CG, and roll center also plays a part in the equation.You could run softer on the LR but I would say anything softer than a 400 on the RR wont have any sidebite.

lilsumo
09-13-2011, 09:39 AM
Ok cool, i see how the ratio works now, makes it easier to choose springs.

On the front are you guys saying it need to be 1k on both sides?

little36racr
09-16-2011, 04:26 PM
call John at Laser. 419-394-5906. He will be able to help you.

I had an 04 laser that was 4 bar spring behind but front same as yours and I liked it with 800 lb springs across the front.