Adv Suspension Theory

[KirkEvil]

Is anyone on here familiar with suspension theory? Ive been doing a lot of reading on tech and trying to setup my suspension geometry (Drag setup). Im looking for insight on how changes actually effect a launch and where I should be for my setup.

4l60e, 4000 stall, stock 10 bolt, 315 ET streets

Front setup:
KYB AGX shocks, stock springs, no sway bar and significant weight reduction

Rear setup:
Spohn adj chassis mount TA, CM rod ends
UMI LCA poly/poly
LCA Relocation Brackets, bottom hole
UMI Adj Panhard poly/rod end
SFC's

Im going with summit 3 way drag shocks. I guess I'll start at 50/50 and see how that goes.

I currently have a stock sway bar and looking to upgrade to either a 25mm bar, fixed end links with an airbag in the right rear, or just go with the UMI 1.25" with adjustable rod ends...Opinions on that?

I never got the car scaled, but I found the Center of Gravity (CG), to be 59" horizontally from the rear tire contact (with me in the car). The vertical measurement of CG was set at 20" based on stock values. I never had the car on scales, so the vertical measurement is a ball park value to find the neutral line.

I drew this diagram in AutoCAD to get a better idea of what was going on. This drawing is to scale, and all the angles were found with a magnetic angle finder so it should be damn close to my actual setup.

[NJ Torque]

Say bye-bye to your stock ten bolt and stock 4L60E.

Depending on how serious you are Taylor, Go with a "Drag bar" rather then a sway bar in the rear... I ran my stock sway bar all last year, and well... you seen how that did.

[KirkEvil]

Chris, what kind of 60' times were you getting with the setup on your 98? If I remember correctly, it had a sy3400 stall and 240's duration cam?

Is anyone running the 1.25" drag bar on the street?

[NJ Torque]

On stock shocks front & rear, no front sway 17" DR's with the ST3500 stall I cut a best of 1.59 shorttimes.

The car felt alot better with the 15" DR's, spohn bolt in stock loca sway bar and Q1A's. It got a considerable amount of air then... but then the rear broke.

I have the spohn off my 98, don't know if you'd care to try it out.

[KirkEvil]

Looking around all I find for spohn rear bars are their 25mm bar, does that sound like what you have? Did you install the QA1's, rear bar, and 15" rims all at the same time?

Im kind of leaning towards getting the UMI drag bar so I dont have to deal with adjusting airbag pressure and bouncing. Im guessing the adjustable end links will only add more drive noise and make it stiffer over bumps.

[//<86TA>\\]

Originally Posted by KirkEvil

Im kind of leaning towards getting the UMI drag bar so I dont have to deal with adjusting airbag pressure and bouncing. Im guessing the adjustable end links will only add more drive noise and make it stiffer over bumps.

i have rod ends on my rear sway bar setup, mounted differently from stock so the end links are on the axle side of the bar, but reguardless i have no real noticable noise from the rod ends. So long as they are good ends, and you spray them every now and again with lube to keep them clean, they will be pretty quite.

the large rear bar can however, make the rear of the car a bit loose when you turn at higher speeds, so keep that in mind.

[JSPERFORMANCE]

We can scale your car for you. $70
gives you total weight, front/rear bias, all four corner weights and side to side bias. everything you need to know if you are looking to properly set up your suspension. We can also do the work for you to get the best geometry and weight bias out of your car -labor rate is $70/hour

[S.J.SLEEPER]

I know its a D.D. but here are a couple things I had done to my m6 SS which greatly improved launch. (1.47 60' best on 17" nitto dr's) consistant 1.53-1.59's
stock 10 bolt with t56

front stabilizer removed when going to the track
single rear air bag
anti roll bar

& of course all the same bolt on suspension parts you have too, just used Comp Enginering Rear shocks & Moroso Trick Springs in front

[KirkEvil]

Josh, I would take you up on the corner weighing but Id spend $50 in gas getting out to you. I might as well just buy 2 scales at that point.

Curt! glad to see you are back around and getting wild with turbos. I went with the UMI adj drag bar and summit 3 ways. The summit 3 ways have similar settings to the comp eng shocks with exception to the 80/20. What did you have your shocks set at and what was your power level with those 60' times?

[sweetbmxrider]

realize he does have an m6 to your a4

[S.J.SLEEPER]

Originally Posted by KirkEvil

Curt! glad to see you are back around and getting wild with turbos. I went with the UMI adj drag bar and summit 3 ways. The summit 3 ways have similar settings to the comp eng shocks with exception to the 80/20. What did you have your shocks set at and what was your power level with those 60' times?

that was a few years ago with my 00 SS.
heads/cam/4:10's/m6/lt's w/ ory/Nxpress wet kit 175 jets

shocks were set on 40/60
nitto d.r.'s were @ 17/19psi heated til they started to push
launched @ 5500-5800

N/A aprox:400rwhp + 175 shot

N/A outa the gate. Juice on in 2nd. gear to the 1320

& yes on a POS 10 bolt !!!(blown up planetaries in carrier about every 5k miles)

[KirkEvil]

That middle launch pic looks like your rear wheel is crooked. Poor 10 bolt...

I got the summit shocks today, and hopefully they work better than they look. Matt came over and he obviously has a magic touch for adjusting cheap shocks because I could not figure it out. I'll post an update when I get them installed, Im just waiting on the drag bar now...

[S.J.SLEEPER]

YEAH.... Poor 10 bolt.. But it wasnt as bad as it looks, yes tires are up in the wheelwell but this is a picture of a picture.....understand? old picture using my digital camera to upload it to computer. picture was a lil curled thats why its distorted.

MAN, I miss that car !!!

[KirkEvil]

I got the drag bar and shocks installed. The drag bar end links were adjusted to neutral, I figured that would be the best starting point. The shocks were set to 50/50, and they feel like good stiffness on compression, but a little too bouncy on the rebound.

First driving impression is that the car handles better than what it did with the front sway bar on. The rear does seem to walk towards road grooves a little more but its really not that bad. Theres also some sweet new noises it transmits into the cabin.

I havent had too much time to get into it, but it now dead hooks from a 20 roll on the street...very fun with a 4000 stall.

[sweetbmxrider]

niiiiiice man! so how's that rear fund lookin?

[KirkEvil]

My 10 bolt is a hero. The trans is trying to **** its guts out all the time...

[NJ Torque]

Originally Posted by KirkEvil

My 10 bolt is a hero. The trans is trying to **** its guts out all the time...

Thats what I thought too...

[S.J.SLEEPER]

SO FRONT SWAY IS OUT?

betcha you put it back in and it won't hook so good anymore !!! lol

[thunder]

Originally Posted by NJ Torque

Thats what I thought too...

ominous words