Suspension question

[767Jockey]

I have a Contemporary with a Jag rear. The car has non ride height adjustable Koni's in the rear, and the springs were 11" high, 350 rate. It rides higher than I'd like. Jeff's rode the same way, and he put in 10" high, 250 rate. The height is perfect, however he occasionally rubs tire to fender. I was thinking of either going to 10" 275 rate, or 10" 225 - 475 variable rate springs. Questions I have are:
What's more responsible for the ride height change, the spring height reduction or the reduction in rate?

Is there a downside to ride or handling in using the variable rate springs?
For those of you who have a good understanding of these things (I certainly don't) what do you recommend that I do?
Thanks.

[cobred]

If you are going from the 351 to an FE motor you may want to wait until the car is finished and you drive it a little to see how it sits and rides. The springs would be an easy swap later on.

[jschiller]

My ERA uses the same Jag rear and ERA specs the rear springs at 10" 250 lbs/in. As far as the clearance goes, you will need to decide how much wheel travel is going to cause a tire to rub in the wheelwell. As you will need 1000 lbs of downforce to compress the 4 springs 1 inch, you won't be seeing much deflection in the rear unless you hit a really big pothole in street driving. Also consider the shock, is it going to bottom out before the spring does? If so, broken shocks will result.

John

[double ugly]

Spring rates are all over the map depending on who you believe, original
cars had something like 325 to 380 lbs / in,
some specs today say 600 front, 450 rear, I've seen higher and lower by
100 lbs and some claim the light springs should
be at the front...
Tom's Motorsports: Racing specs are
Front Springs 650, rear springs 500
Toe front and rear 1/8" toe in
Camber Front -3/4 degree
Camber Rear -1/2 degree
Caster +2.5 degree, should match right and left best as possible
There you go. If you're as confused now as I am, that was the intent.

[767Jockey]

Clear as mud, John - thanks.

[lovehamr]

This may be to simple but have you considered just removing one third to one half of one coil? This should lower your ride height while changing your spring rate very little and can be done with an abrasive wheel or the venerable “flame wrench.” Just in case you're wondering; it will raise the rate slightly but you shouldn't have the rubbing issues associated with the lower rate springs. As far as what it will do to your handling; well, with the lowered ride height and minutely raised rate I doubt there will be much of a change at all. If anything it will probably more favor over-steer but I'd give that a shot first before buying new springs. JMHO

Steve