Got bump steer? You know, that annoying steering wheel jerk that you feel when your rig hits a bump. Yeah, the same one that causes the truck to swerve at high speeds and your asshole to grab the seat tightly. My 79 Ford did I also had a turning radius rivaled by the Titanic. The solution? Crossover steering.
Most American ¾ and 1 ton 4 wheel trucks use a short drag link parallelogram steering set up. This means that the steering gearbox connects to the wheel closest to it by a short link. That wheel is connected to the other wheel by tie rods. The link that connects the gearbox to the wheel is called a drag link because it drags the wheel when the gearbox turns. Usually this drag link is around 10 to 14 inches long. This set up is fine until your rig is lifted. When you lift your truck the steering gearbox rises because it is bolted to the frame but the knuckle stays in the same place. Now the drag link is too short and is operating at an angle. The angle is what causes the bump steer. I tried a drop drag link that is bent to absorb the angle but it really didn't help.
The best solution is to decrease the angle of the drag link. One way to decrease the angle is to make it longer this is the net effect of crossover steering. Crossover steering involves creating a new drag link that connects the gearbox to the wheel on the opposite side of the rig. As usual we've got two parts to the conversion, the labor operations and the parts needed.
Labor ops:
- Turn the pitman arm (the arm that is attached to the gearbox) 45 degrees. Instead of
pushing backwards we now need the gearbox to push side to side.
- Remove the old steering arm from the driver side knuckle, swap the cap from the
passenger side knuckle to the driver side knuckle.
- Install aftermarket steering arm on the passenger side knuckle
- Decide on the type of joint you want to connect the pitman arm to the steering arm (tie
type or Hiem joint)
- Have machine shop mill you a new drag link to length.
Parts needed:
- 4 inch drop drag link around $60 from 4 Wheel Parts Wholesalers (Ford and Dodge use the same link Chevy [Saginaw] boxes are different)
- Crossover steering arm around $200 from Dynatrak
- Hiem joints only buy quality joints at around 70$ each x 2. Or tie rod type ends
at half the cost.
- Custom Drag link around 100$ from machine shop.
- Total cost of parts around $400 plus alignment
- Also, you'll need an axle with a flat top knuckle. Ford's reverse cut disc brake Dana 60's make from 77 ½ to 79 are good to go. Others may need to be machined down.
Installation:
- Start by removing the old Pitman arm and drag link with a pickle fork or tie rod puller
- Install the new drop Pitman 45 degrees off with the end of the arm pointing to the rear of
the truck. You'll find that the steering gear is indexed in four places allowing for only 4
positions of the pitman arm.
- Remove the driver side stock steering arm and the passenger side top cap, if you're
careful you can reuse the paper gaskets on both of these parts. Swap the top cap to the
driver side and toss the stock steering arm.
- Install the crossover arm on the passenger side knuckle
- Install the tie rod or Hiem ends on the pitman and steering arms.
- Make sure that the wheel is centered and measure the length between the rod ends this
will be the length of your new drag link. Be accurate you don't have much of a fudge
factor here.
- Install the new drag link
- Fire up the truck and have a buddy cycle the wheel from lock to lock a few times while
you watch to make sure the new link is clear of all cross members, shock etc.
- Take the rig in for a front-end alignment
- Project done
Hiem joint or Tie rod ends?
A Hiem joint is an industrial joint commonly used on racecar suspensions and tractors.
They are commonly known as rod ends. You can get them from Jegs or from Moore
bearing. They are much stronger than tie rod type ends but they wear out faster. They are
also expensive. You get what you pay for with Hiem joints don't skimp if this stuff
fails you could lose steering! If you do use Hiem joints make sure that you washer your
retainer bolt and use a cotter pin and nylock to insure that the drag link wont disconnect
if the joint fails. Hiem joints will only come with 13/4 inch stubs. To be safe you need to
have at least 1 1/2 inches of thread inside the drag link. So if you use Hiem joints, measure
the drag link extremely carefully.
Tie rod ends are a ball and socket type of joint commonly used on vehicle front ends.
They aren't that strong but they do last a while. If you use them get the biggest ones you
can. Try for around 7/8" to avoid failure with oversized tires. Again, buy quality only.
I opted for Hiem joints and got ¾ inch joints from Moor bearing these are heavy-duty graspable joints rated to 50,000 pounds per sq inch. Soon I intend to convert my tie rods to these same joints. That way the entire front end can be serviced with one identical joint. Dynatrak now makes a crossover conversion kit for 78-79 Fords at around $500.
The ends result is the complete elimination of the bump steer and a better than stock turning radius. The new drag link came in at roughly 32 inches as opposed to the stock one at around 11 inches.
