Quote:
Originally Posted by fallingat120mph
Looking at upgrading front and rear suspension and have seen through the years about having a lowered car and using/not using certain shocks.
I am looking at the Bilstein Sports for the rear and Bilstein HD insert for the front. I do have the Boge strut and not sure what is in there.
Only things I've removed for weight is the entire AC system along with center console so weight is pretty standard. Wheels are 16x7/8's. Torsion bars are OEM, swapped from a car with only 65,000 miles on it. Nothing upgraded.
Looking for a nice set up for hard country driving and do take long road trips so am concerned about the sports in the rear. Not adverse to putting HD all the way around.
My biggest concern is with the car being lowered.
Just drove 2000 miles and had no issues, bottoming out, etc...
Some recent shots of the height of the car:
I have read through the years about the sports(rear) and HD(front) and just wanted to hear from some that have had issues/had no issues on lowered cars.
Thanks!
Erik |
hd/Sport are ok, but a bit over damped for stock t-bars, w/ steel wheels you unsprung weight is much greater than w/ alloys so that's a good thing
3 issues w/ lowering
issue 1 w/ lowering is you lose bump travel, you only start w/ a couple of inches at stock ride height and you lose a bit less than an 1" of shock travel per 1 " of lowering
issue 2 is the roll center goes down way more than the amount of lowering due to the geometry, the lower the roll center the longer the roll lever arm and the more roll is induced per the same degree on cornering
issue 3 is the effect on steering, aka bump steer or roll steer, the further the car is lowered the worse the roll steer curve
cure for issue 1 & 2 is raise the spindle height, this is limited by wheel size and design
cure for issue 3 is rack spacers and/or adjustable height steering knuckle
here is a 911 front
a -b is ride height the larger the value the lower the car
stock low end of spec is 103mm, lowered 1" is ~128mm
c - d is the difference in tie rod end height
roll steer comes from the different arcs that c and the outer end of the A-arm go through, when exaggerated they intersect
the dashed lines show the way to the instant center which defines where roll height is
