[camlifter]

i'm building willie bars and have a few ?'s for those using them, what size does the axle need to be and how much preload are you giving them, these are going to be air powered with a switch to raise them in second gear so to much wheel speed should not be a problem, thanks.

 

[johnt]

John,

The axle that the wheels ride on should be 1/2" minimum. Make sure to use wheels with bearings. I don't use any preload. I just set them about 1/8" - 1/4" off the ground and I get plenty of downforce. Just get your slicks nice and hot and you'll be able to put your foot to the floor, unless you're making sick torque.

If you're going to use a pneumatic ram of some sort, you'll need a good sized one. Just how big will depend on the geometry and angles of your bars. On a hard launch, the bars will need support several hundred pounds.

John

 

[camlifter]

thanks for the reply, i'm going to use an old air shock for the down force with a 3 way valve to bleed off the pressure and a spring to return the bars, this is going on my srt-4 so the rearend weight is pretty light, car weighs 3000lbs and is about 70-30 front to rear, best 60' is 1.80 and need to get that down to low 1.7's or better, i'm planing to have some preload to make up for some of the give from the air shock compressing, hoping that won't be much, thanks for the insite, john