Birel makes three different length hubs: 75mm, 100mm and the 125 mm.

75mm - The short hubs are meant to help free up the kart without having to change the axle. If you use them and the kart went faster, consider going to a softer axle.

100mm - The medium hubs - They come standard on all models and are great starting off point for the 2-cycle classes. Use in 4-cycle racing only to stiffen up the rear before changing to a stiffer axle.

125mm - The longest hubs are for use only if you need a lot of rear bite. These are most common in the shifter kart set up.


Spindle Heights


The spindle heights are an easy thing to adjust. Simply remove the spacer bushings and place them above or below the spindle. If you place the two spacers above the spindle, then you are adding front end bite. If, however, the two spacers are under the spindle, then now you are taking front bite away. When setting up the kart, the most common problem has to do with the steering. Most people say it just pushes, but as the crew chief, be sure to ask in what part of the corner is it pushing in. If a kart is pushing going into a corner, try moving the front tires in. That will help with the turn in of the kart, and should at the same time free up the back a little as it will grip quicker in the front and make the rear of the kart looser. Now if the kart is pushing coming out of the corner or in the middle, then the first step would be to open up the front of the kart. This will help plant the outside of the tire and get rid of any exit push.

HINTS AND TRICKS If you have a driver that can't tell you this information, then read the tires. If you notice wear on the inside edge of the front tire, then the kart is pushing going in. If you notice wear on the middle and outside of the tire, then that indicates exit push. Another thing to try is, if the kart is pushing, try narrowing the back end. If the back is too wide, it creates too much rear grip and cause the front end to "plow" through the corners. Also another trick in set up is that if you have too much or too little rear bite, try playing with the spindle height. It is much easier than changing axles.

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