Bar it or Not

4 Nov

Race day is on 8 Nov, this coming Sunday.

With the crazy weather lately, I wonder if it will be a wet track
to contemplate then.

No matter if it is wet or dry, I will j enjoy and learn more of
the chassis and improve my driving.
What better way to improve than it is to race, right?

Talking about learning, I am looking to understand more about
the removable torsion bar that come with the GP10 chassis.
What net effect will there be when it is use or remove, what is
the effect of it when it is mount with a different direction etc.

And I come upon this article, although it from a tonykart
perspective I would think the general principle applies too

The rear torsion bar, the bar which is transversely mounted between the two main rails, behind the axle bearing hangers.
There are a few different variations of the rear torsion bar. Basically, there is the fixed or welded in place bar.

Most commonly or versatile is the removable rear bar. With the removable rear bar, you have many options. Typically you see what would be described as a rear blade. The tube is flattened between each end creating a tube which can be attached with clamps. However, the character of the tube is changed when the middle has been flattened. When flattened the tube is now able to be flexible in the horizontal position. When positioned perpendicular to the ground, the bar becomes very strong and less capable of flexing like a normal tube, and strengthens the rear of the chassis. Other forms of the rear torsion bar can altered by using a conventional tube, however, changing the type of material, outside diameter, or, the wall thickness. I have even seen some manufacturers use alloy, or cast blades to arrive at a pre-determined characteristic.

Essentially, the rear torsion bars effect is as follows. When the track is low grip, or you have an oversteer condition, you can use the blade in it's most effective position, Perpendicular to the ground. This keeps the rear from lifting as easily, and sets the tire back down sooner, thus giving more rear grip. If you want a little less rear grip, you may consider just the installation of a standard tube, or even less, perhaps the blade in its least effective position, parallel to the ground. If you have an understeer condition, you would not install the rear bar. This would allow the chassis to function as normal and let the inside wheel travel its regular distance, thus creating a longer duration of lift and ultimately less drive, (or grip) off the corner.

Front removable axle, or torsion bar, or front transverse axle. Sometimes the front axle on chassis are removable. In most of the newer homologated for sure the front axle is removable. When the front axle was reintroduced, it was basically to make the front of the chassis stronger. At that time because of several factors, 40mm rear axles, tire compounds, and construction horsepower, etc... the chassis were suffering from a lack of front grip, generally producing an understeer condition. Some manufacturers utilize larger diameter front axles to strengthen the front of the chassis. However, this is still not enough. Then came the introduction or reintroduction of the transverse front axle. This made the chassis more positive on turn in and cured the problematic understeer. However, with every action, comes a reaction. The net was better when you have a severe understeer but, if you can work around the implementation of the front axle, the overall lap times are faster. It is just like the rear end of the chassis, if the front is too planted, you can loose lap speed just as if the rear end is too planted. Therefore, you will see most new chassis without a transverse axle, or with the front axle removable, or with the installation of clamps or some other variation of this system. Some manufacturers use different tubing diameters, or wall thickness in the front axle to vary the strength, as another part of refining the package, or tunability.

http://www.danskkartingcenter.dk/GoKart/Teknik_-_Siden/Torsion_Bars/torsion_bars.html