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Written by Vic R   

The most important handling adjustment is made before the kart reaches the track. The kart must be scaled and adjusted to ensure optimum performance. The desired weight distribution is achieved by scaling and adjusting the chassis and moving around weights. Improper weight distribution can cause front end push (understeer), excessive or insufficient load on any one tire, chassis binding, and lack of side bite in cornering among many other problems. An improper weight distribution can also lead to incorrect diagnosis of handling problems at the track. The following weight distributions are a good starting point:

  • 42% Front Weight
  • 58% Rear Weight
  • 50%:50% Left/Right Weight

These are just recommended starting points. Weight can be moved around at the track to change the handling characteristics of the chassis. Moving weight to the front of the kart will provide more front end grip while moving weight to the rear of the kart will provide more rear grip. Weight can also be moved vertically up or down. Moving the weight vertically upwards will provide more grip in the location of the weight while lowering the vertical position of the weight will have the opposite effect. Keep the side to side weight distribution as close to 50%:50% as possible.

Seat Placement/Adjustment

The seat placement is the single most important weight adjustment on the kart and is done before weight distribution analysis. Perfect seat placement may result in almost perfect weight distribution before any weight is even added to the kart. Consult your local dealer for specifications for your specific model.

Factors to Check Prior to Performing Weight Distribution Analysis

The following processes are all very important to ensuring accurate weight distribution analysis.

  • Ensure that the floor is level.

This can be done by purchasing a 2 metre leve (5-6 ft) and checking the floor where the centrelines of the front and rear axles will rest. The floor should also be checked along both sides of the kart across the width of the wheel base. Compensate for an unlevel floor by placing shims under the appropriate corner scales.

  • Set toe and centre the steering wheel.

If the wheels are not cantered during weighing, the geometry of the kart, mostly the castor, will cause the corners of the kart to be loaded incorrectly. The readings on your scales will then be false

  • Set castor and camber
  • Set spindle heights at desired height.
  • Check tires to make sure they are at race settings.
  • Add weight in appropriate places to approximate fuel and/or oil.

Remember, however, that fuel and oil weights are dynamic. They will change during a race.

  • Replicate racing conditions.

When the driver is in the kart, it's critical they maintain a normal driving position as movements will effect readings. Wear full race gear during weighing to have the highest level of accuracy possible.

  • Zero all scales.

Adjusting Kart Weight

Kart weights are usually not at the desired specifications after the first weighing. If distribution is off, and weight is needed, begin to place the appropriate amounts in the appropriate places. If you are way off on your side to side weight distribution than recheck your factors effecting weight distribution. You might have to move the seat just a little bit to obtain the correct weight distribution. If you are at the limit of your specific weight class than you might have to live with weight distribution that is not perfect. If you are under your specific class weight limit, add weight to the appropriate locations. Do not place any lead shot inside the frame. The weight will shift during cornering and cause handling problems.

Although overall side to side weight distribution may be correct, individual front or rear side to side distribution may be sligthly skewed. Your front wheels should weigh within 2KGs of each other while the same applies to the rear wheels. If this is not the case, recheck all of the factors effecting weight distribution given above and reweigh. If the problem still exists, you may have a chassis problem.

Once final weight placement is determined, secure all weight properly.  Be sure to cross drill and safety wire or safety clip each one. Most sanctioning bodies require double nutting of ballast as well. Be sure to consult your rule book. If your weight is not secure, this can cause serious problems for other drivers at the track if your weight comes loose. Not only does this have the potential to cause injury and equipment damage, it is basis for disqualification during a race.