CLUTCH WITH BLUED SHOES
WHAT CAUSED IT AND WHO’S PROBLEM IS IT? Very simply, it was caused by the kart owner and it is his problem but how you handle it and keep the customer happy is the challenge.
Gearing is very important. If the gear ratio 1: 6 is maintained, for each tooth on the clutch there is 6 teeth on the rear sprocket, there shouldn’t be any problem. Next, if the tires are no larger than 13 inches in diameter, then I can assure you the customer caused the problem. The easiest type of axle for a kart to turn is a stub axle because only one wheel is being turned by the engine/clutch. A live axle has twice as much ground contact and naturally this creates more stress on a clutch. These are things you must be familiar with and can talk to the customer about to explain why he/she ruined the clutch.
Here are some suggestions, in order of probability, that the person might of done to ruin the clutch:
- Stop and go driving with very little clutch lock-up time (driving at full rpm) to cool the clutch down. The longer the child continually drives, the longer the clutch life because it gives the clutch a chance to cool down.
- Child stepped on the brake and gas pedal at the same time because he/she was nervous of the speed of the kart. Riding the brake keeps the speed down but it also puts the clutch in a slip mode which drys up the oil and grease in the bushing.
- Parent tried to slow the kart down by restricting the amount of gas pedal travel or loosened the throttle linkage so the clutch just barely would engage. This causes the slippage and a tremendous amount of heat.
- Two person kart with too much weight. These karts were designed for children and will handle an adult and a child. But two large adults whose combined weight exceeds 300 pounds was not what the kart was designed for and will quickly ruin a clutch.
Blued shoes are a result of over 600 degrees which will dry up any oil in the bushing and anneal the spring so it cannot retract the shoes fully in an idle. Net result is the clutch is a throw away and not worth repairing. If the customer wants to slow the kart down until his child is confident with the kart, have them order the 2:1 gear reduction kit that will reduce the speed of the kart exactly in half.