06-29-2014, 03:15 PM
over the last 11 years, i have had a number of different suspension setups in my car. it all started when i got it, and it had an uber rare set of eibach/techart 150/250 progressive springs on the front which lowered the front end about 1/2" more than i could lower the rear with the eccentrics. i didn't like that, so i began my journey down a very long, very slippery, and very expensive slope.
first, i tried some coilovers, completely spacing on the fact that the torsion bars were holding the car up, and all the coilovers would do at that point was lift the rear.
then, i deleted the torsion bars, making the mistake of installing delrin torsion tube bushings. those things were a pain in the butt, and ultimately i removed them and installed polybronze bushings, which then led to spherical bearings on the control arms, which led to spherical bearings at the front control arms and caster blocks.
i then had to change the struts to ones where i could adjust the ride height. the first time out it was koni yellows sports.
a number of spring rates were played with, each time requiring an alignment and corner balance.
finally, when i determined that i was not going to get what i wanted from the koni yellow sports, due to their fixed compression setting and gas charge preload, i swapped those out for double adjust able hydraulic konis. i also swapped out my single knob simultaneous adjustment shocks for dual adjustable ones.
a few more spring changes, and a few alignments later, i had a car that handled pretty darned well, and cornered great (the two terms meaning very different things)
after recently deciding to spend more time in the car, i felt that the handling could be improved. while both my shocks and struts were hydraulic, and so i didn't have to deal with the jittery jumpy thing that goes with gas shocks and struts, but given the spring rates i was running, it was still a bit rougher of a ride than i wanted. i really wanted the street feel of stock, but have it firm up in the corners. this was clearly a challenge to any car, and especially so on a 968.
what i decided to try was something i had done many many years ago, but had not messed with since. it's called a dual spring setup. basically you put one spring on top of another. generally you use a higher rate main spring, and a lower rate tender spring. together the result is a lower initial rate, and then a progression to your final rate. progressive springs would be better, but having them made would be time consuming, and since you would have to make a few sets until you figured out what you wanted, it would be cost prohibitive.
after doing a bunch of math, i found that what i had to do was a but unconventional, even with this setup.
i ended up in the front with a 300# main spring, and a 300# tender. this gave me a 150# initial rate, just slightly lower than stock, but by the time i loaded it up, it all but compressed the tender, which meant that only at the very first did i have the lower rate. mostly what it does is slow things down when the suspension drops. this means that dips and bumps are really absorbed very nicely.
in the rear, i have a 500# main spring, and a 150/550 progressive tender. after doing the math on effective rate geometry, and load compression, this gives me a 160 to 300 progressive rate. nicely balanced to the front. this is also all but fully compressed under static load, so again, i only see a little bit of what the lower rate is, which again does a nice job of taking the edge off of the bumps.
my shock and strut settings were able to be dialed back a touch, further smoothing things out.
the result so far is a very settled car with a very smooth ride, right up until i toss it into a corner. then it firms up nicely. i have to go out and really play with it, but so far, i am very pleased.
before you run out and think "cool - that's for me" realize that this package would run you about $3.5k by the time you are done. not for the faint of heart to be sure.
p.s. - tomorrow i go in for my 15th alignment/corner balance in the 11 years i've had the car - woohoo!
first, i tried some coilovers, completely spacing on the fact that the torsion bars were holding the car up, and all the coilovers would do at that point was lift the rear.
then, i deleted the torsion bars, making the mistake of installing delrin torsion tube bushings. those things were a pain in the butt, and ultimately i removed them and installed polybronze bushings, which then led to spherical bearings on the control arms, which led to spherical bearings at the front control arms and caster blocks.
i then had to change the struts to ones where i could adjust the ride height. the first time out it was koni yellows sports.
a number of spring rates were played with, each time requiring an alignment and corner balance.
finally, when i determined that i was not going to get what i wanted from the koni yellow sports, due to their fixed compression setting and gas charge preload, i swapped those out for double adjust able hydraulic konis. i also swapped out my single knob simultaneous adjustment shocks for dual adjustable ones.
a few more spring changes, and a few alignments later, i had a car that handled pretty darned well, and cornered great (the two terms meaning very different things)
after recently deciding to spend more time in the car, i felt that the handling could be improved. while both my shocks and struts were hydraulic, and so i didn't have to deal with the jittery jumpy thing that goes with gas shocks and struts, but given the spring rates i was running, it was still a bit rougher of a ride than i wanted. i really wanted the street feel of stock, but have it firm up in the corners. this was clearly a challenge to any car, and especially so on a 968.
what i decided to try was something i had done many many years ago, but had not messed with since. it's called a dual spring setup. basically you put one spring on top of another. generally you use a higher rate main spring, and a lower rate tender spring. together the result is a lower initial rate, and then a progression to your final rate. progressive springs would be better, but having them made would be time consuming, and since you would have to make a few sets until you figured out what you wanted, it would be cost prohibitive.
after doing a bunch of math, i found that what i had to do was a but unconventional, even with this setup.
i ended up in the front with a 300# main spring, and a 300# tender. this gave me a 150# initial rate, just slightly lower than stock, but by the time i loaded it up, it all but compressed the tender, which meant that only at the very first did i have the lower rate. mostly what it does is slow things down when the suspension drops. this means that dips and bumps are really absorbed very nicely.
in the rear, i have a 500# main spring, and a 150/550 progressive tender. after doing the math on effective rate geometry, and load compression, this gives me a 160 to 300 progressive rate. nicely balanced to the front. this is also all but fully compressed under static load, so again, i only see a little bit of what the lower rate is, which again does a nice job of taking the edge off of the bumps.
my shock and strut settings were able to be dialed back a touch, further smoothing things out.
the result so far is a very settled car with a very smooth ride, right up until i toss it into a corner. then it firms up nicely. i have to go out and really play with it, but so far, i am very pleased.
before you run out and think "cool - that's for me" realize that this package would run you about $3.5k by the time you are done. not for the faint of heart to be sure.
p.s. - tomorrow i go in for my 15th alignment/corner balance in the 11 years i've had the car - woohoo!
94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com
"It isn't nearly as expensive to do it right as it is to do it wrong."
(This post was last modified: 06-29-2014, 03:54 PM by flash.)
