Scott;
I used a standard three piece spring compresser like the one you described. It
is a little tough getting the hooks in the right places but it did work. I'm
sure there are better spring compressers around but I used what I had. It
worked equally well on the Chevy.
As for measurements, my springs were 12 1/2" long uncompressed before I cut
out half a coil and 9 1/2" installed on the car.
I just calculated the old and new spring rate for this set up. Originally, the
springs calculate out to 236 lbs-in. After they are cut and bent they are
rated at 270 lb-in and the ride height is lowered by .85 inch. I think that is
enough for a street car. It would be better to keep the springs less stiff and
go with stiffer shocks for control. I had this kind of set up on a 1973 Toyota
Corolla and it handled like a go kart!
If the springs are too stiff the car just skitters over rough surfaces and you
loose control. Also it's tough on your kidneys. Unless you are going to race
the car on relatively smooth surfaces I'd stay away from the really stiff
springs. A moderately stiff spring, a lower roll center, better shocks and a
stiffer roll bar will give optimum handling on the street.
Cutting the springs would take care of the extra length as well as increase
the spring rate.
Here is the formula for calculating the spring rate in case you want to do a
littel analysis before cutting those "suspect" springs.
G x d to the fourth power, divided by 8 times N times D to the third power.
G= Torsional modulus for steel, which is 11,250,000
d= spring wire diameter
8= a constant value for coil springs
N= Number of active coils (don't count the top or bottom one which sots
against the seats
D= Mean coil diameter in inches
The values for my springs are:
G= 11,250,000
d= .45"
N= 8 active coils (before being cut- 7 after cutting)
D= 3.125" (this is measured between the coil centerlines not the outside
diameter)
According to the Triumphtune catalog the ratings for uprated springs are as
follows:
Stock= 220 lbs-in
Uprated Raod= 330 lbs-in
Road Lowered= 330 lbs-in
Race Competition= 480 lbs-in
Hope this helps you make a decision.
Greg Wolf
1970 GT6+ "Ian"
A2, Michigan
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