Steering sweep without snipers/lasers?

Chassis Setup, Tires & Handling Forum
1

Maybe my search engine skills are failing me, but it seems every sweep guide uses a set of lasers.

Does anyone have a method to check steering sweep with “traditional” tools?

(Sweep ensures that both spindles turn the same amount at full lock on their respective sides)

2

If I were measuring sweep without lasers, I would do the following. Helpful if you have the type of steering column that will allow you to lightly “lock” it with a vise grips.

  1. Remove the fuel tank
  2. While standing behind the kart, make your best attempt at centering the steering shaft, and lock in place if you’re able to
  3. Check the toe to ensure it’s close. I would do so using bare rims mounted to the spindles. Skip this step if you know the toe is already close.
  4. Standing on one side of the front of the kart, turn the steering wheel towards the opposite side. The spindle on the same side you’re standing will travel outward from the center of the chassis until it reaches a maximum point, past which it will travel back inward for the last few degrees of steering lock. We want to hold it at the “maximum” point for the measurement (again, easiest if you’re able to lock the steering at that point).
  5. Measure from the opposite kingpin to the tie rod bolt on the spindle on the side you’re standing. This is your measurement.
  6. Repeat for the opposite side. You want these measurements to be the same, or within a millimeter.
  7. Re-check the toe and set it to your desired setting.
  8. Unlock the steering column (I’ve accidentally ran an entire heat race with vise grips clamped on the steering column :sob:)

Hopefully this makes sense without visuals.

2 Likes
3

Toe is pretty simple using bare wheels. Lock the steering wheel level and measure from inner to inner on the wheels front and back. Difference would be toe in/out. Also could measure from inner to frame tubes to determine straight steer ahead.

Caster sweep is a little more challenging. I you have a large table that you can put the chassis on, you measure the heighth off the table from the tip of of the bare spindles at various angles of steering i.e. peak high and peak low from the table. Also measuring distance from center height point on the table to the high and low measure points on the table could give you enough data to calculate the caster angle. Tan (angle) = Heighth/Width. Comparing side to side will tell you if something is out of whack. You can use this method to mirror your camber angles too. If the table is level, a bubble gauge can tell you if your camber is positive or negative.

4

I wonder if I got my terms mixed up or plain misunderstood steering sweep.

I was under the impression is that (in this case steering sweep) was to ensure that full lock is the same on each side and that it was done before setting toe. Probably to have a starting point that accounts for unequal tie rod lengths and offset steering column.

Caster sweep I would have imagined is different though.

5

With the offset shaft and different length tie rods, you may not get equal steering sweep (lock to lock), but it should be pretty close. You should however be able to measure the distance from the tip of the bare spindle to center point on the front bar to check for proper steer ahead. You can verify the two measures are the same length and adjust toe then recheck. This is assuming the steering wheel is level and locked.

I have considered drilling a hole through my upper steering block and steering shaft that I could easily lock level with a pin. For now, I have been using the vise grip method Evan talked about.