4 link setting

richter69 wrote:you need to be in it, or at least your equivalent anyway.

DILLIGASDAVE wrote:Does the car have shocks or struts on the front, and is their extension valving adjustable? If so how tight/loose is the front valving currently set from "full tight"? If they are on the loose side of their extension valving range you can try to tighten the extension some. This might help to slow the nose coming up as fast.

I will have to check the front adjustments. It has a full strut frontend.

Does the car have wheelie bars that you can use to help generate some wheel speed and aid in keeping the nose down?

They are spring loaded and cant get them to stiften up, getting new ones.

If no wheelie bars do the rear shocks have any valving adjustability? If so and if they have the extension valving currently set on the looser side of it's total range, you can try to tighten up the extension a little (to slow down the speed of initial hit some). This might help to generate some more initial wheel speed, and help keep the nose lower.

If the front & rear shocks/shocks (or struts/shocks) are already adjusted with their extension valving at/near full tight, you can try to generate some additional wheel speed another way by increasing the air pressure a little each pass until the nose starts coming down.

Having big torque/power to work with on a big tired car doesn't automatically mean a longer I/C will always be better. Some of the Outlaw Pro Mods around here run an I/C as short as 40-45", and some run way out around the 75-80" (or more) range, and some are somewhere in the middle. But then some of these guys do have electric shocks and start the pass with the shocks locked out at full-tight. So in some cases their actual working I/C has much less effect on the car/launch.....down track it's another story though when the timers back the shocks off and the I/C comes back into play and more active.

the shocks are double adj and the setting is 4 clicks on the bottom and not sure about the top, a couple of turns it seems.

And of course if you run out of usable chassis adjustment to work with and have a MSD digital box you could always fudge the timing around at the start of the pass to help keep the nose down.

The crooked launch just sounds like either the side-to-side preload is off a little, or possibly staggered slick rollout/staggered air pressure numbers. If it's a preload deal either adjust one of the top 4-link bar's length a little, or adjust one of the anti-roll link's length a little. It could also be caused by incorrect (or unwanted) wheelie bar height stagger too if you have w/bars. If you're setting the initial side to side preload setting with the car on jack stands (the "hanging method") you don't need the driver's weight in the car (because the car is on stands). If you're setting the initial preload with the car on the ground (or on "set-up" blocks) the car needs to have the total race weight in the car (fuel, water, oil, & driver weight).

HorsinAround wrote:Pardon my ignorance, but could someone educate me please? I understand the LF, LR, RR, RF weights and how the bias % is caluclated, but what is the cross and the IC and how are they calculated. Also someone mentioned an anti-roll bar, can someone post up a picture of a 4 link setup with an anti roll bar installed. Finally are there any good books on setting up a 4 link suspension?

LF. 588. RF 585
LR 570. RR 600

Cross 1158. IC. 49.29

Front bias% .504
Rear bias%. .503
Left side bias%. .497
Right side bias% .509

cool40 wrote:i'm sure no 4-link guy but i'd think with your corner weights it should work good.shock/strut settings,tire roll out,and even wheelbase can cause your problems.first thing i'd do is make sure the rearend is square in the car.

Moodyblues wrote:..........and the setting is 4 clicks on the bottom............

HorsinAround wrote:...........what is the IC and how are they calculated..........

DILLIGASDAVE wrote:

Moodyblues wrote:..........and the setting is 4 clicks on the bottom............

Are we talking 4 clicks starting from full-loose, or 4 clicks starting from full-tight? This can often be a point of confusion since people don't always start counting from the same starting point.

HorsinAround wrote:...........what is the IC and how are they calculated..........

A car's I/C (instant center) is the actual (with a ladder bar) or theoretical (with a 4-link) pivot/leverage point in the rear suspension where two opposing actions happen at the same time during the launch. (A) the rear suspension tries to lift the car upward from this pivot/leverage point, and (B) the rear suspension tries to push/plant the slick's tread & sidewall downward into the track surface from this pivot/leverage point. A ladder bar's I/C is the front rod-end, a 4-links I/C is the theoretical point where the top & bottom bar's centerlines would cross each other if their centerlines were extended forward.

A car's C/G (center of gravity) is the theoretical balance point in a car where it would balance perfectly if hung from that point. The C/G's front/rear placement is calculated by weighing the front of the car vs the rear of the car. The height off the ground of the C/G is a little harder to calculate. But a number of drag chassis books out there say to just use at/around the height of the cam shaft off the ground as a good guess.

jbozzelle wrote:Have you checked rollout? Swapped tires side to side to see if that makes a difference?

Moodyblues wrote:Dave I am showing my ignorance here........4 clicks from the bottom out of 12, so Im guessing 4 clicks from loose? I will check the Koni manual

richter69 wrote:weight on the nose....

richter69 wrote:you will be shocked at what 5-10 pds will do........