Steering Sweep and Toe
Technical Director for Compkart
If you've been in a collision recently (or just through wear and tear) and your kart isn't tracking straight or your steering input is irregular from right to left, you may want to check your steering sweep and your toe.
With your steering sweep, you're making sure your kart turns in either direction at the same angle. Toe is how open your steering is or where your wheels are facing. Toe-in is your wheels facing in and toe-out is your wheels facing out. You're checking to make sure your kart is heading straight down the track with a straight steering wheel. Slighty off on toe and you're scrubbing unnecessary speed down the straights.
We begin the steering sweep by removing both front hubs off of the stub axles and loosening your tie rod tubes (figure 1). For this particular tip, we're using the Sniper V2 Alignment System where one sits on each stub axle and are held in place by two magnets (figure 2). Each comes with your typical bubble level and you'll want those at level. Make sure to turn on the actual lasers as well.
With the tie rod tubes loose, the lasers level and on, you now need a tape measure -- preferably with metric units. Find a center point on the kart (we prefer the gas tank mounting bar) and hold the tape measure firmly straight out beyond your laser line. When you turn your wheel, you should see the laser point come across your tape measure (figure 3). Turn until the steering opens up and the laser starts to come back; make note of that point where it starts to come back.
Now go to the other side and do the same. Make sure you are measuring off the same side of the tape measure as you were the other side. Measuring one side to the top of the tape measure and the other to the bottom will throw off your alignment by a few millimeters. If your laser stops at a different position than the other, roll out or in your tie rod tube to the measurement you took note of earlier. You may have to go back and forth a few times to get it perfect.
To prepare ourselves to align the toe, we'll need to center our steering shaft. You can always look from the backside down the steering shaft and center the arm that holds the tie rods. Or, using anything that is partially opaque, like a piece of clear plastic or a paper towel, you can turn the wheel until the lasers are right on top of each other. Once you have that, you can check on both sides where your lasers are at, which should be at 0.
On a chassis without front-brakes, we recommend 2mm open toe total. That's 1mm on each side (figure 4.1). For front-brake applications like KZ or DD2, you have more weight on the front so the front closes a little bit more, and for that we recommend 4mm total -- 2mm on each side. As we always suggest, check with your chassis manufacturer to make sure what's best for you.
With your toe in place, it's time to tighten down your tie rods. Hold your tie rod tube stable in one hand while you spin your nuts tight up against the tube with your other. Then, you want to use one wrench to hold the tie rod tube from spinning on the ball joint while also tightening down the other nut nice and firm. With the tie rod tightened, you want to check to make sure you have full movement on the ball joint and that you're not bound up, reducing the freeness of your steering.
- Remove front hubs, loosen tie rod tubes, and attach Sniper laser alignment system (figure 1 & 2).
- With your tape measure, find a center point on the kart and pull the tape measure straight out beyond your laser line (figure 3)
- Turn the wheel until you see your laser point against your tape measure start to come back as the steering opens up. Make note of that point.
- Repeat step three on the opposite side and match both of your measurements together, turning your tie rod(s) to accomplish that.
- Align the steering shaft to straight by either looking down it from the backside and centering the arm at the bottom, or use a partially opaque material to match your lasers on top of each other in the center of the front end.
- We're going for 2mm total open toe for lighter weight applications without front brakes (4mm with front brakes). That's 1mm on each side, and to do so, we move the laser 1 dot forward on each side (figure 4).
- Using one hand, hold the tie rod tube while spinning the nuts tight against it. Grab your wrenches and hold the tie rod tube from spinning on the ball joint while tightening down the nuts nice and firm. Do the same to both sides.