7 steps to a killer clutch

Radio Control Car Action, Apr 2003 by Bess, Stephen

A clutch-system malfunction is one of the more common reasons for a nitro vehicle to break down. Unless properly maintained, the flywheel and clutch nut may loosen, clutch shoes might break or melt, and dutch-bell bearings may seize. The good news is that with a little maintenance, you can easily avoid some of the most common clutch-related problems. Here's what to do:

1

Remove the engine from your vehicle; to do this properly, follow the instructions supplied. You'll have to loosen the engine-mounting screws and disconnect the throttle linkage and the fuel tubing and remove the exhaust.

2

Remove the clutch bell and clutch shoes by loosening the screw or removing the clip that holds the clutch bell on the engine. Underneath the clutch bell, there are clutch shoes; pull them off their pins using your fingers or a flat-head screwdriver and set them aside. Circular 2-shoe clutches may be pried directly off their pins, but to remove 3- and 4-shoe clutches, you must carefully pry the springs off the crankshaft clutch nut. Note how the springs are "loaded"; it's important for reassembly.

3

Scuff the clutch shoes and clutch bell with a Scotch-Brite pad. If you've run a gallon of fuel or more through your nitro vehicle, the clutch shoes may be glazed and worn. A new clutch shoe looks dull (almost like a pencil eraser), but a used clutch shoe will have developed a glaze on the surface that contacts the clutch bell. This slick, shiny coating causes the clutch shoes to slip and overheat, and the result is excessive wear. If you ignore this long enough, the shoes and maybe even the bearings will eventually fail. Remove the glaze by scuffing the clutch shoes and clutch bell with a Scotch-Brite pad. Scuff the clutch shoes lightly until you've removed the glaze. Rub a piece of Scotch-Brite pad around the inside of the clutch bell to remove any glaze or any other buildup there as well. Wipe the parts with a clean, dry rag or spray them with nitro spray cleaner or compressed air.

4

Inspect, clean and/or replace the clutch bearings. The clutch bell spins on ball bearings or a plastic/metal needle bearing. Over time, the bearings' lubricants dry up or burn off because of heat. Eventually, the bearings will seize. With the clutch bell removed from the engine, pull the ball bearings or needle bearing out of the clutch bell. Give the bearings a shot of nitro cleaner; then reinstall them on the crankshaft. If the bearings feel gritty when you spin them, replace them before they seize completely. If the bearings still work smoothly, relube them with a drop of bearing oil and reinstall them.

Tightnne the clutch nut. Grasp the flywheel using a pair of pliers or a flywheel wrench. (OFNA and Bruckner sell excellent wrenches that won't scar the flywheel.) Tighten the clutch nut securely with a nut driver or a socket of the correct size. Don't tear a bicep tightening the clutch nut, but make sure it's securely fastened so that your flywheel can't spin off during a bashing session.

Reassemble the clutch in the reverse order from which you disassembled it, after you've given the parts one last wipe-down. Any traces of oil or grease may cause the clutch to slip or even melt when it's subjected to heavy loads.

Be sure to install the shoes facing the same direction as they were before you removed them. Also, if you have a 3- or 4-shoe spring clutch, be sure to "load" the spring. Put a drop of thread-locker on the clutch-- bell screw, and tighten it securely. Again, do not tighten it too hard; just use enough force to fasten it securely.

Reinstall the engine, and be sure to check the gear mesh before you tighten the mounting bolts. Your car is back in action!

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