b1valiant

Car works best on a small burnout, believe me we have tried small and John Force style. The left bar absolutely hits first, but the car is already headed right at that point and if you watch it track the bar does not seem to make it any worse. Here at home it will actually stay on the bars past the 60' mark at times.

dparker

Not knowing your chassis, I would say you need a little more preload. I would try one flat at a time to see if there is any improvement. You may be hitting the rear tires alittle hard also. Your instant center may be off alittle.


As you move your actual instant center further forward or below that Theoretical "Line of Instant Center" (Neutral Line) (It is an imaginary
angled line, where you had your tape) The rear suspension hit will decrease, but the front will have a tendency to rise on it's suspension. Likewise, If you move your actual "Instant Center" back or up toward the Theoretical "Line of Instant Center", the rear suspension hit will increase.

As you move your actual or active Instant Center point forward of the Imaginary line of Instant Center (Neutral Line) you will promote more front suspension lift and less rear tire hit.

As you move the actual or active Instant Center to the rearward you will give it more tire hit and greater rear suspension reaction and less front suspension lift.

As you adjust for increased rear tire hit, you will be at the same time be adjusting from less effect of actual bar lift in the front.

When you adjust for decreased rear tire hit, you will at the same time be adjusting for more effect of actual bar lift in the front.

If you reach the Ideal, as the tires hook the car will rotate on the rear axle and will also try to lift the front, as the car is moving forward.

itsabird

i have watched the video over, and over, the thing i am seeing in the first pass, ( right lane) small amount of slip, which is good with that kind of power, otherwise it would dead hook, wad the tire up and go into shake, next, it hook's and the slick actually lost contact with the track, i am assuming both slicks are doing the same thing, if upon contact being regained, the left side slick make's contact first, then it will push the car to the right. i won't say you don't need to adjust preload, but if it were me i would check the spring tension on the wheelie bars first, soften them up a bit, just to make sure that any preload ajustments i made were not influenced by the wheelie bar ajustments.

tigwelder

here's the answer. the car has a bit to much left hand pre load, this is evident from the burnout, the carstarts moving to the right in the water box. to solve this her it is. Take a floor jack with car in a level surface,i.e. pit area, jack it up 2 inches off the ground from the rear. you will see that the left rear tire is closer to the ground. Not what you want to see. on a spooled rear the tire closest to the ground will out run the other tire,causing a dirrectional change. the car darts right because the left tire is ahead of the right.simply put, make sure you are pre loading the right side tire, downn to the ground,if you crank 4 or 5 flats in the down dirrection you will correct this problem. this is a good way to check for sure which tire is hitting first. also after you load the right tire you will need to dial up the right spring on the rear coilover, since you will be extending it and taking away spring pressure this will make the car sit level and equal out the spring rates.also hit the right shock button 2 setting more than the left shock, also make sure the right wheelie bar is 1/2 lower than the left. thx Pro Mod Chassis tunner for many years

markthespark

I watched the video of both lanes. The run in the right lane the right front tire never leaves the ground. In the left lane the left front tire is off the groung 12 inches. Just something I notched.

b1valiant

Well here is a photo from that weekend when it was hooked up. The car is even here?!?

b1valiant

Unfortunately this weekend resulted in another one of these, sorry for the small pic. It is going right but not as bad initially in this case the bars pushed it far right.

dparker

Have you checked the circumference of both tires? even a 1/2 to 3/4 inch difference could cause that also. I just got a set of slicks in they had 109 1/4" and 109 1/2" writen on them. When I mounted them one was 104 1/4" and the other was 103". I aired the 103 to 30 psi and set it in the sun for a while. Remeasured it measured 104 1/2". I'll keep checkin since I was told it will gradually try to shrink back.

bjuice

i double checked with a pro-mod chassis builder this past weekend with you in mind.

He advised his starting point is 70 lbs heavy on the Driver side (with driver in car) when scaling a car .