Spring Rate????

[_Duke]

Spring rates how do you know which is best for your application?

I will be running coilovers with a 12" spring
The car is extremely light. Right now with no motor I can pick up the front of the car so even after I add a ~600lb big block probably still looking at ~1000lb +/- a few on the front end.
The car will only be used for drag racing

[monster.]

Well, what is the spring rate currently. The easiest way to describe it is, if you increase your spring rate, you would increase the force it takes to compress the spring. If you decrease the rate, you get the opposite.

Is this a road race setup, or drag. Spring tuning depends on what kind of driving you plan on doing.

[_Duke]

Currently a steel rod bolted in place of where the coilover will be, So that would be a pretty stiff spring lol

bought the car as a project trying to get it going. It was previoulsy set up with a small block and don't know the spring rate.

Drag use only

I was thinking around 200lb springs???
I figured I would through it out there and let the suspension gurus tell me if I was close

[monster.]

I wish there was a cut and dry value I could suggest based off what info you gave. Strictly drag racing, i'd go with a lower spring rate (front & rear) vs. a higher spring rate for autocross, etc.

Shooting from the hip, and excuse the huge range, but for drag racing I've seen rates as low as:

Front: 175lbs/in - 350lbs/in
Rear: 85lbs/in - 200lbs/in

To do it right, going to have to factor in rear spring rate and total vehicle race weight (driver, fuel, etc.) as well.

What kind of car, that f-body? I'm sure someone would chime in with an F-body. I havn't tuned a GM suspension in my short existence on this planet

[JeffB]

What kind of car? I have 175# on the mustang in the front. I am thinking of putting 150# on. I have no clue on what I am doing though My reason is the front comes up real fast and comes down very slow. Maybe that is what I need? I want to lower mine in the front more too, sits a tad high for looks.

[monster.]

200lbs/in front spring rate would fall into that range. Chassis tuning is tedious to nail it down right. That would be a good rate to start at for sure, watch those corners though at 90mph.

[monster.]

What kind of car? I have 175# on the mustang in the front. I am thinking of putting 150# on. I have no clue on what I am doing though My reason is the front comes up real fast and comes down very slow. Maybe that is what I need? I want to lower mine in the front more too, sits a tad high for looks.

What struts are you running 90/10, 150lbs/in would make it come up even faster. Adjust the coilovers for front ride height.

[_Duke]

So it sounds like I'll start around 200 or so... What ever I can find a deal on

Going in a 72 Vega Chassis Car
http://motownmuscle.com/forums/showthread.php?t=109407

Found these online...

Gross Vehicle Front Spring Rate Rear Spring Rate
Weight (lbs) (lb./in. approx.) (lb./in. approx.)

2000 185 85
2350 200 95
2500 215 120-140
3000-3500 250-350 150-200



Spring Rate Total Weight on Front Wheels
250 Under 1200 lbs.
350 1200 - 1500 lbs.
450 1600 - 2000 lbs.
550 2000 - 2400 lbs.
650 2400+ lbs.

[1BADAIR]

the type of suspension/location of the spring is the most important.
a 1/1 suspension(like a true macpherson strut may not require as much spring as a long/ short arm suspension where the spring is about 1/3 the way out on the arm

[JeffB]

What struts are you running 90/10, 150lbs/in would make it come up even faster. Adjust the coilovers for front ride height.

It has strange adjustable struts, I need to adjust the coilovers to lower the front. Not sure if it will go faster, but it will look better. I snaped a pic of how it sits before I adjust them. My cell take some bad pic lately