Bumpsteer
Bob Ludwig, Overland Park, KS: I have a '65 Ford Ranchero with a warmed-over 289, a C4 auto, and an 8-inch rearend. I have upgraded the front to Granada disc brakes but cornering is less than desirable both in the front and the rear. The front has a stock Falcon V-8 sway bar and the rear has stock leaf springs. I have replaced the shocks but it didn't seem to make a difference. What can I do to reduce the amount of lean when turning corners?
Jeff Smith: We called Doug Norrdin at Global West Suspension about your car, Bob, and he had some very interesting suggestions. Norrdin has firsthand knowledge of the classic Granada disc-brake swap because he's done this to his wife's '65 Mustang. Unfortunately, the steering arm that comes off the Granada spindle places the tie-rod end in a different location. This causes a mismatch from the arc created by the upper and lower control arm and the arc from the outer tie-rod end when the suspension moves up (compression) and down (rebound). The different arc from the new tie-rod-end location creates what is called bumpsteer. This will be most noticeable when the suspension experiences either maximum compression or maximum rebound; the steering wheel will actually jerk either left or right. The amount felt in the wheel is directly proportionate to the amount of bumpsteer caused by the mismatched steering knuckle.
This is a very common problem with early Mustangs and Falcons, and Global West offers a bumpsteer kit (PN ADJ-43) that will help minimize the problem. The kit consists of an adjustable-height tie-rod end and a performance tie-rod sleeve. To properly position the tie-rod end, you must first set the car's ride height. This leads us to improving the lean you experience in a corner. The best solution is to go to much stiffer (and shorter) front coil springs. Global West offers a Falcon-specific front spring (PN S-23F) that sets the ride height and also (and more importantly) increases the front spring rate from 280 pounds per inch stock to 540 pounds per inch. The stiffer spring reduces the amount of body roll that takes place under hard cornering, and it also lowers the ride height. So before you can address the bumpsteer problem, you should change the springs to set the ride height. You'll also need a bumpsteer gauge, a tool that measures the amount of toe change during suspension movement. You probably don't have one in your garage, so ask circle-track or road racers in your area. One of them is bound to own a bumpsteer gauge, and perhaps you could rent it for an afternoon or pay their shop to perform the work.
As far as other changes, we suggest driving the car for a while with the new front springs and improved bump curve. If the frontend still tends to push in corners, you could try a larger front sway bar. Global West offers a 1-inch version that will be substantially stiffer than the stock front bar. For a more complete look at what Global West offers for your Falcon, which is almost identical to an early Mustang, you can take a look at the buildup we did on the CC '67 Mustang. We used Global's Negative Roll front upper and lower tubular control arms, adjustable strut rods, front springs, a 1-inch front bar, and Koni shocks. In the rear we used Global's higher-rate leaf springs, a Del-A-Lum shackle kit, and Koni rear shocks. We haven't tested it yet, but it sure feels good. The big thing now is to swap our rearend, get rid of that lame six-cylinder, and put some muscle under the hood so we can go play!
Measuring bumpsteer is really not that difficult. It's best done by removing the coil spring. This is a bumpsteer gauge sold by Longacre (PN 7900, $199.95).