Cushman Technical Bulletin on the Disc Clutch

The article below was reproduced from copy of an original Cushman Technical Bulletin issued in February, 1959 and it covers the removal, overhaul, and replacement of the disc clutch. The original print of the article was too blurry to post here and it was scanned into a word processor with optical character recognition software. The text is identical but the page layout and font used are different from the original bulletin.

CLUTCH
The clutch is a break in the power flow from the engine to the transmission and rear wheel. It provides a method of stopping the scooter while the engine is running and allows for shifting gears in the transmission. The clutch is composed of three discs on a shaft. Two of the discs, the driven disc and floating disc, are connected to the engine crankshaft and turn when the engine is running. The third disc, or clutch hub with lining, is free to turn on the shaft and is connected to the transmission by means of the drive belt. This disc is between the other two discs, and is the one with the lining. It turns when the scooter moves. As the three discs are pressed together, they are forced to turn together, transmitting engine power to the transmission.

The clutch discs are disengaged when the engine is running at idle speed. As the engine speed is increased, the discs are forced together by action of centrifugal weights. When gear shifting is desired, the discs are disengaged with the clutch pedal. When the engine speed drops down to idle speed, the clutch automatically disengages.

The clutch hub is mounted on needle bearings. These should be cleaned and repacked at least every six months, or 2500 miles.

Needle bearings are very hard and wear- resistant, but very small, so considerable care should be taken to keep them clean and proper position during packing. Remove all dirt from the clutch and engine with compressed air if possible. Be sure that the grease used in the bearings is free from dirt particles.

Remove the belt from the clutch. Disconnect the release lever from the release rod, and lift the throw out bearing from the clutch.

Remove the nut and lock washer from the crankshaft. Place a knockout of the proper size and thread it on the crankshaft and screw it down tight. Be sure that the end of the crankshaft rides on the bottom of the knockout; otherwise, the threads on the crankshaft will be damaged. Place a bar behind the clutch in such a position as to pry the clutch off. Pull on the bar and strike the knockout a hard sharp blow with a heavy hammer. Repeat this process until the clutch comes free, checking the knockout for tightness between each blow.

The needle-bearing sleeve will probably stay on the crankshaft when the clutch is removed. Leave it in this position and clean off any accumulation of dirt and old grease. If the sleeve should come off with the clutch, merely hit it out of the needle bearings, and clean it.

Inspect the needle bearings. If the needles do not run parallel to the centerline of the crankshaft, they are badly worn and should be replaced. Likewise, if there are spaces between the needles and they do not fill the bearing race, or if any of the needles have a flat side, they should be replaced. Installation of new needle bearings requires special tools and we recommend that you have this done by your authorized Cushman dealer.

Clean the needle bearings and apply a thin coat of lithium base grease to the bearings and to the space between the bearings. Do not over-pack bearings, because excessive grease will leak out and get to the clutch linings, but be certain all needles have a liberal coating. Coat the bearing sleeve with grease before replacing clutch.

Replace the bearing sleeve (if removed), and the key on the crankshaft, and then, replace the clutch, being sure that the keyways are lined up and that the key is in the proper position. Replace the lock washer and nut on the crankshaft and tighten. It is of the utmost importance that the clutch nut be tight at all times.

The distance between clutch facing and floating disc should be 1/32" to 3/32". This adjustment is maintained by removing shims, as facings wear, or adding shims when new facings are installed. These shims are on drive pins which connect the clutch discs to drive flanges. To remove these shims, loosen the nuts holding the clutch together and cut shims off with side-cutting pliers and Tighten nuts. When new clutch facings are installed, replace the shims. (See Fig. 19) CLUTCH RELEASE: The clutch release lever should have 3/8" clearance between it and the clutch throw out bearing when the engine is stopped. If this adjustment is not maintained the clutch will either slip or not release properly.

Loosen the adjusting nuts on the clutch pedal rod and adjust them so that a 3/8" bolt can be inserted between the release lever and the throw out bearing. Tighten the adjusting nuts securely