Like the title says......I need some help determining instant center. If any of you drag race guys have the software or brainpower I would like to email some pictures and numbers. My current setup is wrong and Im looking to make adjustments.
Here's a website for you...FOR FREEEEEEEEEE! (Sorry, been hearing too many Sit 'N' Sleep commercials with Larry Miller latelly) http://inductionmotorsports.com/im/
When we're at the track, we plot it on the floor of the trailer. With car on the ground, measure heigth of two rear four bar points[vertical distance]. Work of the trailer floor and using wall as ground, transfer these heigth measurements. Then measure forward from rear four link points to front mounting points. Plot that distance on trailer floor. Now, measure vertical heigth of forward four bar mounting points. Now, take a straight edge and extend top and bottom bar until they intersect.Gives you IC, length and heigth.Quick and slightly crude, but works.Dont know if you want a drag race starting point, but IC at two thirds of wheelbase[ex; 90 inch wheelbase, 60 inch center] about 4 to 6 inch vertical should get ya going.
What kind of rear suspension do you have? Ladder bar instant center is the front pivot point of the bars. 4 link instant center is the intersecting point of the 4 link bars if a line was drawn through them forward. Larry T
Old time tech. How about a set of old frame repair centerline guages. You can pick up centerline and datum plane fairly well. Can probably find a set at at local swap for under $100.00 . Hi Tech. There are several laser software aided frame dimensioning systems being used in todays frame and unibody repairs . Dimensionally accurate to 1mm. including upper body . Used $8k to $12K . New $15k to $25k.
That link works well. I need to get my actual weight front and rear to get it right. Thanks for the replies and info.
I see in another thread that you made some changes and went to the track. What did you do? How did it work? Inquiring minds want to know! Larry T
Thanks for asking. First pass I ran an 11.42 and last time I ran a 11.52, 11.53, 11.54 so I think I am headed in the right direction. Still plenty of room to improve though. at the launch it footprints the tire, the tire expands back up and almost creates a buck. I think a stiffer sidewall might be the right direction, or a shorter tire that would create less tennis ball efect. I run a 31" tire. for the first time I can see the front tire come off the ground....although it is minimum. The Torque arm mount is now adjustable and I had it in the mid range setting. I also put a set of QA1 double adjustable shocks on and I had them set tight to slow the axle from pushing down away from the chassis. I made two good passes at 11.42 and 11.47.......The little lady videotaped the launch so I can try to learn a little more today. I have a coach that is helping me make the right changes.....I dont know enough to understand the concept. Would you believe that car weighs 1200 on the front tires and 1300 on the rear tires?
The Jalopy Journal
