coil -over marketing and general understanding perhaps ties w oil and apex seals for the amount of smoke
as i said a few years ago in post one of my suspension thread, the first decision to make w re to coil overs is
WHAT IS THE SPRING RATE?
the ideal set of coil overs offers spring rate options.
the FD spring rate is
front 263 pounds per inch, 4.69 Kg/mm
rear 195 pounds per inch 3.48 Kg/mm
rear is 42.5% of total
front 350 6.25 Kg
rear 255 4.55 Kg
rear is 42.1% of total
overall rate up 32%
notice they kept the OE balance. that's why this setup is so good.
the ideal coil over setup offers you OPTIONS as to spring rate.
IMO, the ideal street and modest track setup is 8/5
front 448 pounds 8 Kg
rear 280 pounds 5 Kg
total 728 up 159% from OE
rear is 38.4% of total.
the slightly lower rear spring rate allows higher hp (than stock) FDs to hook up the rear coming out of a corner. perfect.
as i said.... OPTIONS. if you are running slicks on a road course you will generate more Gs and need additional rate.
my pick is
front 672 12 Kg
rear 448 8 Kg
any more rear spring than 42% w a modded FD and you will be losing time and rear grip.
remember as to springs....
rate is pounds per inch and it is cumulative. that means that the first inch of travel is 672 and the second inch is another 672 or 1344 and the third inch is 2016!
your corner weighs 750 plus some additional weigh transfer minus unsprung weight.
for every inch of wheel travel you get spring travel of .605 in the front and .68 in the rear.
you want about 2.5 inches of wheel travel or about 1.5 inches of spring travel for control.
you also want a linear rate until the spring is fully loaded... not an abrupt stop or around you go.
in the majority of cases too much spring is slow.
take a very close look at real racecars. you will need to exempt all aero packages such as NASCAR at Daytona where job one is to not allow ANY air under the car and to hell w mechanical grip. also open wheel cars as they run high downforce and the springs merely hold the car off the track. check out the cars at Martinsville for body roll, or for that matter Phoenix this weekend.
i am drawn to any coil over packages that offer an array of springs.
BTW, i am working w a vendor to offer 8/5s and i think they are on their way. i am not planning to be a vendor, just helping get the right stuff on the FD.
the spring rates i use come from my Longacre Digital Spring Rater. i also had a shock dyno.
what is your rear spring rate %?
Last edited by Howard Coleman CPR; 03-01-13 at 11:26 AM.