How is preload added on a antiroll bar? Are the arms shortened or lenghtend? How much do you start out with? Thanks Mike
Hi Jim The system is a bolt on bar like the HR Part anti roll bar. I also have UMI adjustable upper control arms. Herb Adems 3 way adjustable shocks. In the front I have QA1 coil over 12 way adjustable shocks. I am trying to come up with a set up to get the car out. Thanks Mike
Mike, With that setup, if you can get to a set of wheel scales, you can equalize the rear tire weights with the adjustable upper control arms. This is the only type of "preload" I would recommend. All the anti-roll bar systems that I am familiar with, don't want any preload. They are designed to equalize the traction of the rear tires, by limiting the torque induced roll of the rear end. This allows the right rear tire to plant harder, and also reduces body/chassis flex dramatically. If you can't get to a set of wheel scales, then just set it up neutral, and go out and run it. You probably don't need to worry about the rear wheel weights, as long as they are close. Pay more attention to suspension bind areas, as these are the killer of consistant traction on a lot of cars out there. To look for this issue, the easiest way is to disconnect the shocks, and use a floor jack to run the rear suspension thru it's full travel. You will see and hear if there are any binds. You want the suspension on a race setup to move smoothly thru the full travel. On a stock type setup, I never run the bolts thru the control arms tight, I use a lock nut on the bolt, and just run them a little past "snug". There needs to be no clearnace at those bushings, as they control how the car tracks, but you don't want them beefed down tight either. Also and especially if your running rubber bushings, but even with the poly stuff, make sure the suspension is at ride height, before tightening the bolts. Same with the front suspension arms. Have fun, and let us know how your system works out. JW
I found that read very informative.....Thanks Jim. Looks like I have a little Saturday project on the race car.
Hi Jim What would be a good amount of preload on the upper control arms to start with. I have -2 degrees on my pinion angle. This car is 75% track and 25% street. Thanks Mike
Without the use of a set of wheel scales, I would start out with no preload, and have someone video the car when it launches. If the sway bar is doing it's job, it should leave straight. If you need to correct some twist still, then shorten the RH upper control arm about a flat or so at a time, and re-test. If you can get a set of wheel scales under it, it will eliminate lot of trial and error.. With the scales, I set it so that with the car at race weight, and the driver fully suited up and in position, the rear wheel weights are equal, as long as the LF is heaviest.. which it typically is already due to the drivers weight. JW
A wonderful article A wonderful article…. In my life, I have never seen a man be so selfless in helping others around him to get along and get working.
