[fallingat120mph]

Originally Posted by Bill Verburg

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

Thanks for the information. My old mechanic in San Antonio would draw out similar examples and was very strict on what his shop would do/not do in regards to lowering. I always appreciated his dedication to the engineering from the factory.

I have addressed "issue 3" and looking into "issue 1 & 2"...

Much appreciated!

Originally Posted by PeteKz

Erik: Listen to Bill V about not lowering your car much beyond the stock settings, unless you install struts with raised spindles.

Second, If you have read some of the other recent threads about suspension setup, you will notice that I am a fan of the Koni Sport externally adjustable shocks. The external adjustment knob allows you to easily tune the ride to your preferences, and even change them quickly for when you go to the track or AX course.

See this video: https://www.youtube.com/watch?v=JzSzoESEhCQ

I have the Koni Sports (adjustable) in one of my shopping carts and my only concern is longevity. Hard to tell what folks are talking about in the threads when they claim they had issues with Konis but don't get specific. I really do like the idea of adjustable shocks - and have read extensively about the Koni(s). Have an updated fully adjustable suspension on my adventure motorcycle and it is a game changer.

Always good to get responses from you two and again, thank you!


Erik