chassis set-up advice

Old 06-24-2008, 11:37 AM
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Default chassis set-up advice

I really could use some insight and understanding into this car-3200 lbs.-51.5% front-48.5% rear-52% left side-104" wheelbase-crank height 12 3/4"-cam height approx 19"-600" alum bb-1100 hp on motor-two stages of nos-first off the transbrake-second on timer at approx .4 later-powerglide trans 1.80 first gear-4.30 rear gear-33x16.5x15 stiff sidewalls-last run with IC of 53 1/2 and 6 1/4 high-am changing to 56 1/4 and 3 1/2-single adj rear shocks set at one softer than med-adj front struts set at full firm-has rear sway bar that is 1 1/2" in diameter and the arms are 7" long-car torque rolls fairly heavily and hits the wheelie bars fairly hard-spins downtrack on the shift-best 60' is 1.158-what should I expect to see from the changes I have made? Generally what should the car do different when you raise or lower the height of the IC but have the same approx. length? What changes should I be making to help 60' times and keep it off the bars so hard? If I want to adjust the car for more "bite", what adjustment and IC numbers should I be shooting for? Don't have any video yet, but hope to soon. thanks for any and all answers and help and insight you can give. thanks again--Micah 6:8
orgjce is offline  
Old 06-26-2008, 11:37 AM
Join Date: Mar 2006
Location: Illinois
Posts: 96

Guessing your COG height is about 18" with aluminum block, your neutral IC would be around 9" at 52 out. There are many ICs that get a neutral effect. 78 out 13.5 high, 26 out 4.5 high. As you can see the farther out the higher they are. The variance for error lies with in the accurate COG hight. The farther out Does not change the effects other that the abruptness they take place. If you are neutral nothing takes place therefor no abruptness at all. Squat or anti squat has less to do with weight transfer than you may want to believe. What it does is promotes compression or rebound that effects the pressure applied to the contact patch. Compression takes away pressure and rebound adds. This can play a part in your case with better than average HP and traction and if you are hitting wheelie bars hard, you evidently have a COG either too high (don't think so) or too far back. Ideally you want 100% weight transfer just leaving a light foot print from front tire and easing down. This is more a COG power and traction deal. Changing IC can only modify it. But to reduce wheel stands you give up traction to accomplish it. You could power up in your case and get a similar result. As they say, If you got it you may as well flaunt it. You got traction and power. Sneak up on over powering that traction. Increased wheel speed will get front down and deter tire shake. It makes more sense than just throwing traction away. To do this effectively you may have to move some weight forward.

As far as torque roll you will find more traction and a straighter pass if it is controlled. This to some extent can be eliminated by getting closer to a neutral IC. You have choices to nullify the rest. You can do weight spring adjustments or preloading a upper right bar or an anti roll bar. Or a combination of these. I prefer getting rear wheel weights as close as possible with ride hight adjustment and preloading right upper bar a flat or two,(shortening it) depending on what it needs. This basically gives you a higher instant center on the right side than the left keeping it from compressing under power. The Roll bar takes energy from the rebounding right wheel and giving it to the left keeping it from compressing. Using only a roll bar only transfers a high % of the energy the rest results in a minor compression on both sides. It is a great back up plan. These are my opinion only everyone knows there is more than one way to skin a cat.
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Old 06-27-2008, 10:20 AM
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