Micro Sprint Front Axle Squaring
Squaring an axle on a micro sprint car is essential to ensure your car is able to run at peak performance. The front axle needs to be squared to the front torsion bar rack. That way, the front axle is squared to the frame itself and not some made-up place we decided on. It is essential because the car will not handle as well when the axle isn’t square and is sitting in the car at a different angle to the car. If you don't square it, one side of the axle will be ahead of the other side, causing your car to handle irregularly. Not only would that affect the handling, but when you have a torsion bar front end, it will give your front arms a different effective arm length.
Having your torsion bar arms rest equally on both sides of the axle is also important for many reasons. When your arms rest equal distances from the front rack, it will give you a consistent weight transfer from the bars to the axle. If they aren't equal, it will give you a different arm angle and a misunderstanding of how the front end feels. If the axle were to sit closer to the front rack, the weight from the arm would decrease because your arm angle would decrease. You are going to get more weight transfer with a more drastic arm angle, giving you more forward drive. You would have the opposite reaction if the axle were father back from the front rack.
So, we have found the sweet spot to give the correct effective arm length and make the front end feel balanced. It is not a hard thing to do, it just takes a lot of little adjustments to make sure everything is set where you want it to be. Since there are two different lengths, I am going to give you two different measurements to use as a guide.
I first place two-inch blocks under the front axle. I then place the arms on the car as well as the radius rods. I like to start with the left front since there is only one radius rod on that side, and it is to get that one placed. Since the axle I use is 1 3/4" in diameter, I measure to the center of the axle to put a mark. This mark is a consistent reference point when measuring. The left front bar is the farthest from the axle, so that is the longest arm, as well as the longest measurement. I measure from the center of the torsion bar to the middle of the axle and make sure I get it to eleven inches.
Next, I move to the right side. This side gets a little complicated because there are two radius rods to adjust, and the caster needs to be set. I try my best to move both radius rods the same amount so they stay somewhat equal. Both the top and bottom rods move the axle forward and back, but then turning only one to adjust the caster. At this point, I usually have to play a little bit to get my axle square first and get the caster I want to have. Once I get the right-side square, I check my caster to get it where I want. Keep in mind that it will take some fine-tuning to get the axle square and the caster where you want it. The key measurement to shoot for on the right side is 9 1/2", still measuring from the center of the torsion bar to the center of the axle.
For my caster, I don’t have an exact number to shoot for. Since my axles come with 15 degrees already built into them, I shoot between 15 and 20 degrees. The degree depends on the circumstances to squaring the axle. Once the right-side is set, I check the left side to make sure it is still where it needs to be. Again, it will probably take some fine-tuning to get everything square and where you want.