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Mustang II suspension issue

8K views 47 replies 12 participants last post by  mainstreetprod 
mainstreetprod

Where are you located? I likely know someone near you with a spring smasher to figure the rate, then we can recommend something in about the same rate but 3-4" longer. I'd imagine that spring is coil binding or getting too close to coil bind and the rates will sometimes get way off when you're that close to coil bind.
 
So adjusting the nut downward will lower the height? I assumed the reason they were adjusted so far upward was to get the car down on the ground. Also, it seems to me like the spring characteristics will change as the nut is adjusted down - coils will open up, suspension will have a lot more travel, and ride should improve. A compressed spring with little travel should have a rougher ride.
It doesn't work like that exactly.
Coil spring rate is dependent on three things. The wire diameter, the width of the spring and the number of coils.
On coil overs, you aren't changing any of the above unless you run the adjuster up to the point some coils are touching. That reduces the number of active coils and makes the spring stiffer but your lose the travel to soften the ride. Assuming they are not touching, or coil bound as we call it, all your doing is adjusting the relative position of the spring to the frame of the car. Basically adjusting the ride height and that's it.
If the car weighs 4000lbs, the front weighs 2000lbs and each corner weighs 500lbs, than 250lb spring would compress 2". Moving the nut up or down doesn't change the amount of weight the spring has too hold up. In this case it's 500lbs.
A longer 250lb spring lowers the nut but still compresses 2". A short 250lbs spring raises the nut but still compresses 2".
The idea is too find the weight the spring has to hold up, selecting a rate that holds up the car and is still long enough to put the adjuster nut somewhere in the range of it's adjustable range.
In your case, the spring is too short if you want to keep the ride how it is(coil binding), it's too soft and too short if you want a stiffer ride( coil binding and won't hold up the car).
So now you have to decide what your want. A softer or stiffer ride? The same ride quality but not bottoming out?
If it's just ride height and you're okay with the quality then you need 3-4inch longer spring in the same rate so the adjuster nut can have more upward travel to set the ride height where you want it.
 
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