How to Set Bump Steer on a Dirt Mod

A "dirt mod" is the shortened name for dirt modified racer, which is a type of race car that's specifically designed for dirt racing. "Bump steer" is a term used to describe an inward or outward pull or turning of a front front wheel as it moves up and down. On bumpy terrain, such as a dirt track, bump steer can cause the steering wheel to be jerked from your hands. Bump steer is caused when the tie rods don't follow the same arcs as the upper and lower steering arms. Correct this by aligning the tie rods or adjusting the tie rod length.

Instructions

Tie rod alignment

1

Loosen the lug nuts on both front tires of the dirt mod.

2

Measure the distance between the leading and trailing (front and back) ends of the two front tires with a tape measure. The difference between the two measurements is an indicator of how much the toe is off, or of how much the bump steer needs to be corrected.

3

Jack the dirt mod up, place jack stands underneath the front frame and then remove the front tires completely.

4

Place a clamp on the steering arm to keep it from moving as the front suspension is shifted up and down.

5

Find the tie rod ends which are mounted to the steering knuckle.

6

Loosen the adjusting sleeve nuts with a socket set.

7

Pull the adjustment sleeve to the inside of the vehicle to pull the leading edge of the tire toward the engine. Push the sleeve forward to push the leading edge away from the racer.

8

Measure the distances between the front and rear ends of the two front tires. If the distance between the front and rear leading edge of each front tire is within 1/8 of an inch, the bump steer will be corrected. If it is not within 1/8 of an inch, reposition the adjustment sleeves until it is.

9

Tighten the adjusting sleeve nuts with the socket set.

10

Remove the clamp from the steering arm, replace the tires and lower the vehicle after removing the jack stands.

Tie rod length

11

Loosen the lug nuts on both front tires of the dirt mod, jack the vehicle up and secure jack stands under the frame. Remove the lug nuts and the front tires.

12

Place a clamp on the steering arm to keep it from moving as the front suspension is shifted up and down.

13

Attach the plate of a single-dial bump steer gauge to the hub with nuts and a wrench. The swing stand on the gauge should be placed on the ground directly on the side of the hub.

14

Swing the gauge dial to one side of the plate and the roller part of the gauge to the other side. Start the vehicle and allow the wheel to move. If the roller and the dial shaft move together the same amount and the dial doesn't change reading, there is no bump steer. The moving dial will denote the amount of bump steer adjustment needed and if the tie rods are too long. Remove the gauge from the hub, test the opposite side and remove gauge completely.

15

Use a socket set to remove the bolts at the outer tie rod end at end of the steering rack next the wheel on the front driver's side wheel.

16

Slip the small end of a ball joint separator between the tie rode top end and the steering knuckle and tap on it with a hammer to separate the two.

17

Use a knife to cut the straps that hold the steering rack bellows.

18

Loosen and remove the inner tie rod from the steering rack with a wrench and then pull out the inner and outer tie rods out as a single part.

19

Replace the tie rods with new rods based on the measurements calculated from the bump steer gauge.

20

Connect the new inner and outer tie rod ends with new bellows by twisting them together to the length required.

21

Screw the new inner tie rod into the steering rack by hand and then tighten with a wrench.

22

Connect the outer tie rod end to the steering knuckle by tapping it into place with a hammer. Replace the outer tie rod nut with the socket set.

23

Repeat Steps 5 through 12 to replace the tie rods on the other passenger front.

24

Replace the front tires and tighten lug nuts with lug wrench. Remove the jack stands and lower the dirt mod to the ground.