Car pulling to the right on initial hit...

[b1valiant]

I have a 4 link strut car that I seem to be having some isseus with. never had any issues with the old engine til now. The new bullet it about 200+ more hp than the old one. Also about 120lbs lighter. Anyway car goes right at the release of the button, drives straight and true after that but always right at the hit. It also tends to wheelstand a bit in good air. The car was scaled and numbers all looked good, dont have them in front of me but I was about 18-20lbs heavy on RR. Car runs low 8's here but was in Vegas running 8.40/50's. I will post a little video someone else took of the car. Mine is toward the end of the video the gray and orange car last two passes on the video. Anyway looking for advice, critisism etc. We have tried a bunch so dont be afraid to ad any input. Oh yeah explain it in laymans terms as i am thinking I have missed something.

Here is the video clip..Remember i am at the end of it.
http://video.google.com/videoplay?docid=-5088549478582500118

[itsabird]

look's like the wheelie bars are unloadeing the car. if you have adj. shocks up front, you can stiffen them to slow the front end down some, also stiffen rebound in the rear, to take some hit out of the car.

[b1valiant]

If you can slow it down you will see the car is headed right before it gets to the bar..I have tried front struts loose and stiff with no change.

[fla1976]

Have you had it checked to see if the frame is squared?

[itsabird]

If you can slow it down you will see the car is headed right before it gets to the bar..I have tried front struts loose and stiff with no change.you are hitting the tire's hard, it look's like you are useing up 75% or more of your wheelie bar gap, before the car start's to rotate, caused from smashing the tires, did you make any adjustment between these two runs?

[bjuice]

are you saying the car is 20lbs heavy on the right rear with you in the car ? :shock: :shock:

i am no professional chassis tuner but i have had guys scale me car who are and we have always ended up about 15 lbs heavy on left rear.

if you think about it..the car tranfers to the right rear..if your already 20lbs heavy on right rear...

again i am really not qualified enough to give chassis lectures..can only repeat how my car was set up in the past...


P.S.

where you from ? the backdrop at the track is BEAUTIFUL !!!!!!!!!!...SO IS THE TRACK !

[rob41willys]

What have you done with the pre-load on the four link bars? If anything. You said new engine is lighter and more horse power, that can change the rotation of the rear end. The tire with the most load will push the car off coarse. in your case to the right meaning there is more load on the left rear. Keep in mind that all chassis are different and will react differently to changes. Also that with previous adjustments with the lower horspower engine might not be the same with the new engine and more horsepower. Good luck

[b1valiant]

The video is from Las Vegas. I am from Northern California and the car is usually .4 and 5mph quicker here.

We have scaled the car and to this point only added an additional flat of preload. Have played with the shocks and added weight to the nose of the car as well. The car goes right as soon as the button is released. While I agree the bars may be steering it the fact remains if you can see good video and slow it down the car goes straight right as soon as the button is released.

I am looking and listening to all. We plan to ad more preload to the car but just curious if there is a point where you have gone to far with preload, or is this even possible? Maybe masking another issue. We have checked the chassis and rear end and all appears well. I am questioning one of the rear shocks right now. Just looking for input.

[zipper06]

I'm not a chassis tuner either, but you can switch the shocks left to right to check them out, also maybe add a 1/2 lb of air to the right side slick. I watched the vid also, and that other Baracuda was hitting the left wheelie bar first and hard, but running straight. I once had a car that i ran airbags for the rear suspension with 50/50 shocks (a long time ago) and i had to put 8 lbs more air in the right bag, if i didn't it would take out the right side guard rail. It wasn't as fast as your car but it did run 148 mph, that was before the full adjustable shocks were available.
I don't have the solution, just bringing up a couple point. Billy Shope probably has a much better answer than most people on here and for sure knows his stuff.
Here's his web site, and if he's not looking on tonite you can probably PM him, i think he's listed at the top of the page or look thru some of the threads here and find one of his post.

http://home.earthlink.net/~whshope/

JMO

Zip.

[FullTimeRacing]

you guys don't think he needs to heat the tires up a bit more

[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?!?
http://i222.photobucket.com/albums/dd105/blowncuda/5112316-AlAlquire-1.jpg

[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.
http://www.printroom.com/gallerythumb20/102490%5C2009041206063272740822.JPG

[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 .