Rear Coilovers... Spring rates Question??

[Wish4svts]

Im about to put some rear coilovers on my 96 cobra ( MMR Stock location ones), and need to know what spring rate best suits me. My cars intended use is:
First: Show car
Second: Drag
& Third: Auto X

I want it to sit nice and low but be able to raise it up some when the slicks go underneath it. What length and rate of spring am i looking at?

[Jonny00GT]

First question...what's on the front. You want a balanced ride, yeah?

If your ride is well balanced right now, you need to calculate your wheel rate. Take half your current spring rate, if you have solid axle and 1/3 of your current spring rate if you have IRS. (i.e. if you have 300lb stock location springs, you need 150lb coil over springs for strait axle. If you have IRS, you probably have a rate closer to 600lbs, so 1/3 of that is 200lb coil over springs)

As far as height goes, you should be able to adjust that as much as 6" over all on most kits so you can lower it for the street and make a few turns of the collars and get it up to clear your slicks. I don't know about the rears, but on my MMR front coil over the 14" springs were a little on the long side, so I went with 12"s.

If you don't like the balance of your ride currently, the guys at MMR and Maximum Motorsports are pretty helpful. Or you can search on corner-carvers.com.

Good luck!
-Jonny

[Wish4svts]

Its got D&D coilovers on the front. the suspension was mostly setup for some auto x. I think im going with a 11 inch, 150lb spring as it seems like a good median for all that i want the car to do.

[Trick Pony]

Its got D&D coilovers on the front. the suspension was mostly setup for some auto x. I think im going with a 11 inch, 150lb spring as it seems like a good median for all that i want the car to do.

What springs rates are you running up front?

[Wish4svts]

I honestly don't know about the front, they were on it when I bought it. I would guess pretty stiff as he was building it for auto x. Bilsteins up front, konis out back.

Thoughts on a good street strip length and rate?

[TENGRAM]

I think the order of your priorities is gonna need to change unless one is eliminated entirely. You can drag race an auto x car but trying to auto x a drag car is futile.

[Wish4svts]

Alright, how about this. Since i dont want to eliminate either but im also not trying to set records, which would be better..... An Auto x/street spring that I drag race on also, or a Strip/street spring that i auto x on???

[Wish4svts]

Or am i still being to unreasonable that I cant have both since theyre so far apart?

[Trick Pony]

If you want it to handle you absolutely need to know your front spring rates in order to intelligently select the rear rate. If you mismatch the front and back wheel rates your handling balance will be off and it will either have understeer or oversteer tendencies. Ideally you want to make the balance fairly neutral so you can steer with the throttle to transfer weight where it is needed while cornering.
The springs usually say right on them what the rates are so I'd pull a wheel and take a look.
As far as drag racing usually rear wheel rates close to stock work well and then you run soft springs up front. But of course that will handle like shit.
Coilover springs are really easy to swap out. I actually run 2 different sets of springs on my car - one for handling and one for drag. If you do that and then run adjustable dampers that's about the best compromise you can achieve without making other major changes every time you want to go from drag to handling. If you run the same ride height with both sets of springs then your alignment and pinion angle won't change.