Partial front Suspension assembly
 

...or more of a mock-up really. I'm trying to figure out if I can get my ride-height set right from the get-go. I hope my calculations are somewhat accurate.

http://www.chevelles.com/showroom/up...6362/SUSP1.JPG

I partially assembled it with no height adjusters installed (just the 9.5" 700# AFCO springs). The crossmember sits 2.5" off the floor. Adding approx. 1750 pounds of sprung weight, will drop it about 2.5".

(700# x 2 = 1400#/inch)
1750/1400 = 1.25" compression
1.25 x 2 (because the lower ball-joint is 2x the distance away from the pivot) = 2.5" lower
2.5 - 2.5 = 0" cross-member to ground. (almost low enough :D )

The height adjusters are 2.875" high at their min. height.
2.875" x 2 (lever of A-arm again)= 5.75" clearance at the crossmember

WAY TOO HIGH!!!! That's almost stock height :D

I'm thinking I should cut 3/4" off the height adjusters, and get it down to about 4.25".

Here is some more eye candy
http://www.chevelles.com/showroom/up...6362/SUSP2.JPG

R & D will pay hugh dividends in the end. The math doesn't always work out. Make sure your engine is in and the body is on. I had to go with 18" up front with 20's in the rear to receive a 1" difference in the frame height. I also used 3" lowering springs all the way around. Don't forget the additional space needed for proper header clearance. :)

R.P.

well said roger cut nothing till you are alot closer to a complete car,the last time i cut for appearence, no front sheet metal on the car , :willy: those springs are now shop springs. the headers were on the ground.

Cutting from the adjusters won't be a problem, I will still have 2.5" upward adjustment at the springs, equating to being able to adjust the ride height 5" upward. Worst case-scenario, I'll need to dissassemble the front end, and raise the adjusters up if I cut too much off.

Looking at that top picture it looks like have serious camber gain problem. I know My car sitting like that with no springs and the lower arms bottomed has all negative camber and no positive...............are you using tall spindles? Aren't You concerned about those adjustable upper arms changing Your camber curve as You adjust for static camber and caster? How do know when they are the "right" length for geometry? Just curious.

Dan, he's going to gain negative. What's wrong with that?

The arms won't affect the curve; only the geometery as a whole.

In the top pic, the upper arms are threaded out to get the spindle to sit straight up on purpose... the reason is, I didn't have any spare lugnuts handy, and that was the only way I could get the wheels to stay on using only gravity :willy:

My main concern at this time is figuring out my ride height... overall, I'm looking for a great performing setup, but I don't have the experience or know-how to set it up to its maximum potential, nor will I ever push it hard enough to need it set up that way. I just want a suspension that can outperform what I will have the cahones to push it to.

One day I may want "more" out of it, and the adjustable uppers allow me the ability to set to the exact length I want them.

5.75 is no where close to factory height.... My front CM is 5.75 off the ground and with our crappy roads(Alberta) I had a few problems with my exhaust last year. I'll try and load a pic for ya.

-Matt

It looks lower in person but it'll give you an idea of how it sits.

-Matt

The picture looks like He's gaining positive camber, that's why I asked. I just havent seen good results with adjustable upper arms. In fact I had to take some off a Camaro recently because it just wouldn't drive right. You couldn't get enough caster to not be darty and have neg. camber. Just wondering if anyone has had good luck with those uppers?

Yeah, actually the arms are not supposed to be used to set initial alignment. You should still use the shim packs to baseline it and use the arm links for track fine tuning.

But doesn't doing that fine tuning change the length of the arm and there for the camber curve and the geometry? How do You effect one without effecting the other? How do You work from a base line setting when everything changes all the time?

The changes during the track tuning process are fairly small and won't effect the geometry enough to cause problems. Typically the street alignment is done with shims and a race setup is done while on the machine using the links. That way the links can marked and easily duplicated at the track.

I agree that using adjustable arms does change the UCA length which in tun changes pretty much every aspect of the geometry as a whole, but as long the changes are small the geometry changes are minimal and not of any consequence.

Hmmm... that's not quite what I had in mind. I was thinking I could have it aligned for the street with no shims, and then have it aligned for the track with shims, keeping the arm lengths locked in. That way, it would be easy to duplicate the alignment specs multiple times from track-days to street-driving without needing to take it to someone who knows what they are doing on the alignment rack. :_paranoid

Assuming there are no major differences in length from one side to the other, would there be any problems doing it this way?

My dad owns some old alignment equipment (got it when he bought out another body-shop's frame equipment) but neither he nor I have ever used it. :willy:

That works too Derek, just a little more time consuming. It would be easier to produce repeatable settings that way, now why didn't I think of that. :rolleyes:

Hmmmmmmmmmmmmm................... :_paranoid

Time to give Marcus a call?