Yellow Bullet Forums banner

Need a decent staring point for 4 link

5K views 24 replies 7 participants last post by  Bell Racing 
#1 ·
Car is a mild steel tube chassis with 106 wheel base with 1000 hp and weighs 2738 with driver. It has a 32x14.5 slick with 4.30 gear. Weight bias is 49.3 front and 50.7 rear. Currently the IC is set at 43 out and 5 up and will hit the tire at the release of the transbrake and make a 1/4-1/2 revolution and start spinning. Currently the car is running high 5.20's to mid 5.30's at 131 mph with 1.24-1.25 60 ft in the heat. Where would y'all suggest to move the IC to try and pick this up?
 
#12 ·
I would go with getting the spread right on the housing. 10.5 to 11 top close to housing on top. My car I'm bottom hole on housing on bottom top bar in middle hole . Bottom bar is down hill 1/4 . Top bar pulls on the chassis length and angle of top bar is hit on the tire . Bottom bar tires are pushing car forward so if bar is down hill car will squat if bar is up hill will separate . I've found that if my car has bottom bar downhill more then 1/4 car doesn't drive good down track .
 
#13 ·
Forget to mention also set your tires to correct air pressure and all race ready for measurements . I was having trouble with my car of wadding the tires up on the starting line till started taking angle out of bottom bar . At Zero on a 130 track was getting to much wheelspeed but that's just my car you will have to find what your car needs.
 
#15 ·
Yes we ran it last night to test. I only moved the IC to 50 out and 4.5 up. It picked up just a little to 1.22-1.23 60 ft after tightening the rear shocks up to 6 on compression and 8 on rebound. It would carry the front tires about 20-25 feet but still spinning and killing the tire at the hit. I will move out into the high 50 to low 60 range on the next move. Only got two runs last night. Had an electrical gremlin we had to find last night and then there were two wrecks. We will keep working on it until we find the right place.
 
#21 ·
Ok, going to move the IC out to somewhere between 57-63. Have not decided on what height to shoot for yet. I know a couple of you have mentioned what I would consider a fairly high height at 8-9 inches. Can someone explain what a higher height does versus a lower one.

Right now it is still killing the tire at the hit and is yanking the front end straight up instead of driving out of the beams. I am going to tighten the front struts a little more along with the IC change. I will also set the wheelie bars up better. I had both of them at 6.5" and the left one is touching so I will raise it another 3/4".
 
#23 ·
Higher instant center will not squat. Made my car have more wheelspeed on starting line and more traction down track . With car ready to go down the track measure the height of bottom bar holes . Start at 1/4 lower at the chassis make a run . Now raise the body a 1/4 will be zero now . Recheck pinion angle if needed add pinion angle reset preload make a run . I never went above zero and I had plenty wheelspeed .some of theses guys are running a 1/4 above ( chassis bolt higher then housing bottom bar ).way higher hp then I have. My car runs 5.20 to the 1/8 so about the same has your car.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top