The easiest way to lower the front end of a car is to use smaller diameter
tires. But given that one needs 13" wheels to clear the brakes and control
arms, 20" slicks are about the lowest you'll get. A big benefit of using
tire diameter to adjust a car's height is that no changes to the suspension
geometry are introduced. Actually most of what I'm saying in this message
applies to the big Triumphs as well as the small chassis cars.
Next time you are looking at the front towers on a Spit, imagine a line that
goes through the bolts holding the inner upper A arms to the towers. Notice
how close the shock's top pivot point is to this axis. And notice how close
the bottom pivot point is to the trunnion. Moving the shock mounts away from
these pivots will introduce what would likely be less than desireable changes
in the way the shock moves in relation to the control arms. You could get
binding, or enough loss of motion that for some movements of the suspension
your effective wheel rate approaches infinity. This is usually not good.
And moving around the shock location also would change the ratio of spring
rate to wheel rate. Maybe for the better, maybe not. I don't know for
sure. To refresh your memory the spring rate is a measure of the force
required to compress the spring some distance. The springs on Killer are
425 pound springs, which means that 425 pounds of force applied to the spring
will compress it one inch. Wheel rate is dependent on spring rate as well
as the geometry of the suspension. Maybe while I'm working on Killer over
the next few weeks I'll measure the wheel rate, which tells you if force F
is applied, the car will lower by D inches. If the spring were straight up
and down and the suspension travel was limited to simply vertical (sliding
pillar?), the wheel rate and spring rate would be the same. With the shock
and spring at an angle, the rates are different.
If you really wanted to putz around redesiging some things, you could lower the
car by shimming the front suspension towers up from the frame, making new mount
points for the lower control arms and the front engine mounts. This could be
a lot of work. And most likely you'd get the same effect as just putting in
springs with a shorter fitted length. More on that in the next installment.
mjb.
|