MultiDiskScript

Multiple Disc Coupling Ford Model A

Description

The early Ford Model A coupling was a multiple disc type. There are nine steel plates, four of these have a lining riveted to both sides.

These plates are mounted with plain steel plates in between and one on each end. The driving plates have "teeth" on the outside, these teeth slide in splines inside the flywheel. The driven plates have teeth on the inside, these teeth slide in splines on the coupling drum. The drum again has splines on the inside which match with splines on the coupling shaft. All the plates are pressed together by a heavy spring which is secured by a nut and a splitpen.

Important factors for functioning

There is no adjustment on this coupling itself, only the pedal adjustment is important. However, three factors are very important for a proper functioning of this coupling:

1. The linings must not be too worn and foremost, they must be equal

of thickness all around, in other words: equally worn.

2 The teeth of the driving plates must be able to slide smoothly in the

splines of the flywheel.

3. The teeth of the driven plates must be able to slide smoothly in the

splines of the coupling drum.

All parts and splines must be clean.

Checking, dismantling and remount

To check all this we have to remove the clutch. To do this, we either take the engine out, or remove the rear axle and drive shaft. I prefer taking the engine out, as in both cases one has to remove 11 bolts from the flywheel house.

However, when the coupling is free, it can be taken off the coupling shaft, after removing nut and splitpen, as a packet. This packet can only be dismantled with the use of a special tool, or carefully under a press. The big heavy spring must be pressed down till the pressure on the plates is gone. (fig 1 and 2.) The 5 nuts holding the clutch plates can now be removed and the plates can slide off the coupling drum.

In most situations, the rear driven plate will be tighter on the coupling drum, with a tolerance of 0.002". This last plate can be recognized, because one of the teeth has a groove in it. The reason for this tolerance is, to stop rattling or ticking with a stationary running engine. This is due to the fact that the rear plate moves little compared to the others.

After dismantling clean each part well and check the splines for burrs, if necessary smooth down with a small flat file.

Check afterwards if the driving plates slide smoothly in the flywheelhouse, the same with the driven plates on the coupling drum.

If the linings on the coupling plates are too thin or unevenly worn, they must be replaced. Uneven linings are the reason for wobbling and rattle. Uneven wear of the linings is most of the time due to sticking plates in the splines.

When assembling watch the back driven plate with the mark on one of the teeth. This one comes first (fig. 3), the rest as was. Do not forget the locking rings under the 5 nuts.

The coupling must have a free play of ¾ "