Clutch

With the engine and transmission out of the car, I decided to replace clutch parts. I had no reason to think that the clutch was worn, but much of the work involved in clutch repair is in separating the engine and transmission. In this picture, the engine is on the right (hanging from the yellow-orange strap) and the transmission is on the left. The clutch is the circular part in the middle. Pushing on the clutch pedal separates the internal clutch disks and allows the engine and transmission to spin at different speeds. This is necessary to begin moving from a stop or to change gears.

Unfortunately, only three clutch parts are readily available for the Sunbeam. One is the pilot

bearing, which holds the transmission shaft aligned with the engine. They are pressed into the center of the engine’s crankshaft and difficult to remove without special tools. The shade tree mechanic can use hydraulic forces by filling the inside of the bearing with grease and then compressing the grease with a cylindrical object with same diameter as the inside of the bearing. Because the bearing is in a blind hole, there is nowhere for the grease to go when it is compressed. This puts pressure on the bearing and it pops out. The bearing is the bronze colored cylinder on the black tool.

If you look carefully, you can see that the edge of the bearing is damaged along the outside edge (closest to the grooves on the tool). Glad I ordered a new one.

The new bearing is the center of the picture on the right was easy to install using a socket and hammer to drive it into the crankshaft. I realize that a socket and claw hammer may not be the approved tools for bearing installation, but they worked. The key is to drive the bearing evenly, putting equal pressure on the full circumference.

Next is the clutch disk. This fits between the engine flywheel and the clutch pressure plate. The flywheel is the large circular object at the rear of the engine and the clutch disk is the smaller plate with springs in the middle and a rough, slotted material at the outer edge. The black plastic tool in the center holds the parts together during assembly. This is what I used to drive out the bearing in the pictures above.

How does the clutch work? The flywheel is bolted to the engine and the clutch disk attached to the transmission shaft via splines. The groves on the alignment tool fit into the splines as would the transmission shaft. In consequence, the clutch disk and the transmission spin together at the same speed. On the right you can just see the transmission shaft in the center. It is the only shiny silver part.

The last main part of the clutch is the pressure plate. These are no longer manufactured, and I therefore used to one that came with the car. The pressure plate is connected to the clutch pedal and is the large cylindrical  part in the center of the picture. When the pedal is depressed, the pressure plate moves away from the clutch disk and allows the flywheel to spin independently. When the pedal is released, the pressure plate squeezes the clutch disk against the flywheel, and the resulting friction brings the transmission up to the same rotational speed as the engine.

The last available clutch part is the release bearing. This pushes against the pressure plate when the clutch pedal is depressed and allows the clutch disk and flywheel to spin independently. The old one on the left side of the picture shows some wear of the bearing material on the top. Did it need to be replaced? No, but easier now with the engine and transmission out of the car.