Group: I again need to borrow from the collective wisdom of the group, this
time concerning Spitfire rear leaf springs.
I have a customer with a Spit-Six that has excessive positive camber. The rear
is built using the higher ratio GT6 diff, an early GT6 rear spring, and early,
narrow axles. I am well aware of Kas's recommendation to de-arch the springs
on the early non-pivot type spring to 3.5", but what complicates this is that
the owner used the GT6 spring, which has eight leafs instead of the seven
leafs used in the Spitfire. Obviously the GT6 used the additional leaf to aid
in support of the extra weight in the rear, but, I do not know which leaf to
remove to make the spring have the same rate as the Spit. I do not have any
non-pivot type in the shop to measure the leaf lengths.
Do any list members have a Spit non-pivoting leaf spring available to measure
the spring lengths? Perhaps a lister has been through this before?
I know I will more than likely still have to de-arch the spring, but at least
we can get closer to the desired height/rate by removing the unwanted leaf.
I also have another question for the group.
Perhaps all the engineering degrees are getting in the way of common sense, or
vice-verse. If the distance between the eyelets on the spring are X, wouldn't
de-arching (flattening out) the spring spread the eyelets further apart
(straightening out a curve)? Wouldn't this move the top of the vertical links
out farther? Wouldn't that add positive camber? We know we de-arch to add
negative camber (we have all seen it happen), but my mind keeps asking why it
doesn't go more positive. My son, who is also a Aerospace Engineering student
at UTA, and I have put pencil to paper together and come up with the tops of
the links moving outward. but nature is contradicting us.
Some incite please.