FWD posi trac with a Wheelie Bar
FWD posi trac with a Wheelie Bar
(OP)
The physic's of using a wheelie on a front wheel drive make sence (at the drag strip). I have a friend with a posi trac fwd, who am trying to convince that the use of a wheelie bar will effectively decrease his run time. The arguement I am getting is that when adding wheelie bar (length)to the car, he will not be able to steer to maintain a straight line (the car tends to pull). I do not see how this will create any great impact to the car. Is there something I'm missing?





RE: FWD posi trac with a Wheelie Bar
Normally a FWD drive vehicle with a greatly forwardly biased CG will understeer severely. Yet, with almost all the traction available to the vehicle being at the front end, the vehicle will tend to oversteer dramatically at high speeds. It is quite common to see very fast FWD drive drag cars wiggling the back-end back and forth as they approach the traps. In many memorable cases the vehicles have even spun complete 360s! Not a lot of fun at 140+ MPH.
Unfortunately the only real solution is retractable bars. I say "unfortunately" because retractable bars have been banned by every governing body (here in the US at least). All-in-all, it's not an issue for a vehicle that has trap speeds below 130, or so. Or an E.T. higher than about 10.20. In those cases, the addition of wheelie bars will not noticeably impact steering. Then again, with times like that there's no reason to be running the bars in the first place.
It's all a juggling act between enough traction bar/spring tension to keep 60 foot times low, yet maintaining steering control at the big end.
Good Luck,
Bryan Carter
RE: FWD posi trac with a Wheelie Bar
Curt