Suspension Analysis Done. - Lateral-g Forums

Musclerodz · #1 10-03-2005, 02:12 PM

For those that don't like to hear "mine is better than yours", here is some hard numbers for ya. These numbers are not absolute as I have not started fabricating yet. Hopefully I won't have to change anything too much.

Based on 1" dive 2* roll:

bump steer .00"
roll center height 1.79"
roll center migration .01"
camber gain -.50*
caster gain .22*

Analysis was done by Marcus at SC&C using C5 knuckles, Cobra R&P, custom lower a-arms, and proprietary parts from SC&C for the rest (upper a-arms, steering arms, upper ball joint). I also have to build a one off sub for this car as well due to the raised floor and to be able to pick up the points as defined by the analysis. This thing should hopefully go around the track as if it were on rails. I am still learning this stuff so what I can't answer I will get Marcus to help answer.

Mike

sinned · #2 10-03-2005, 06:54 PM

Cool Mike, those numbers look pretty good. I'd really like to see the actual graph as obtaing absolute zero bump steer throughout the range of travel is impossible. Marcus is pretty bright and I'm sure he just shot you the best of the results though the rest of the range probably is on par for a one off design. It would be nice to see the RC migration animation as well; see what it actually does through a corner.

Mean 69 · #3 10-03-2005, 08:19 PM

Looks like a pretty good start. The migration numbers, and bump steer look really nice. The camber gain, although not "the" most important aspect, looks a bit modest at .5 degrees/inch, you might try to shorten the upper arms a smidge, or better, lengthen the lowers and see if you can bump this up just a little. It's not bad, especially if the rest of the stuff is good.

These numbers are a start, but there is a whole lot more to it. What about scrub radius, FVSA, and side-scrub numbers? Track width? I ask because I see that the rack chosen is a standard production rack, in order to get the steering numbers (i.e. bump steer) looking as good as they do, the control arm pivots MUST have been located according to the rack/ackerman/inner tie rod location requirements. Do you have the inner tie rod mounting width handy for the Cobra rack? Seems to be a very popular piece used on many of the vette equipped front units.

Looks like you are on the right track, for track days, you'll likely have to dial in a good amount of negative static camber, but probably not more than -2 degrees or so, give or take. More than this might cause squirrely front tramp under really heavy brakes, probably not too much an issue though. Have fun with it!

Mark

Musclerodz · #4 10-03-2005, 09:52 PM

These are dynamic numbers

FVSA 155.2"
caster 6.3*
scrub radius .14
track width 59.5" (I have bumped it out from stock and will be flaring the
the fenders like the Bank's Camaro)

I will be running stock C5 rear wheel specs on C5 knuckles . I will be running adjustable upper arms which will help make track setup easier.

Yes LCA's will be custom made to pick up same pivot as R&P. Standard Cobra or GT rack mount locations are 24" apart. Cobra rack is slightly too wide and I will have to play with arm lengths to get it correct. I was more interested in a GOOD production rack I could easily get if I needed to that would not cost a fortune or have to special order. Most people use the Fox Body GT racks, but after a lot of research on CC.com, I found I could use an '03 Cobra with excellent feedback but would need to install the shorter GT arms.

Marcus has a bunch more stuff on the suspension including the graphs that I have not got yet as what he sent I am still trying to absorb. He did say that the numbers I have are to the point that any change to make something better, made something else worse.

Mike

sinned · #5 10-03-2005, 10:09 PM

Quote:

Originally Posted by Musclerodz

I will be running stock C5 rear wheel specs on C5 knuckles . I will be running adjustable upper arms which will help make track setup easier.
Mike

Keep in mind when running these adjustable upper arms that any adjustments you make to alignment actually change the UCA length and therefore affect every one of the analysis results previously posted.

Musclerodz · #6 10-03-2005, 10:21 PM

Quote:

Originally Posted by dennis68

Keep in mind when running these adjustable upper arms that any adjustments you make to alignment actually change the UCA length and therefore affect every one of the analysis results previously posted.

Yep already ran that through my head. Once set up per analysis, any changes will be spefically counted to return back to as designed. Once we come up with a track setting then it will be a matter of counting the turns, shims, or slugs for race day.

Mike