Now when the cam is placed in its correct position there is plenty of clearance between the lower section of the cam and the plunger roller allowing the cam, while installed on the gearbox shaft, to pass into position against the overdrive centre bushing without contacting the pump roller. The shape of the little hook on the top of the “Special Tool” is very important but not difficult to form.
#MGB LAYCOCK OVERDRIVE INSTALL#
It is easiest to install the “Special Tool” before placing the clutch springs in position. When the pump plunger is pushed down against its spring the hooked end of the “Special Tool” engages into the plunger just below the roller and holds the plunger in the down position. The “Special Tool” is inserted through this hole and up the side of the pump plunger. In the filter cavity of the overdrive unit there is a conveniently located hole. After you find out how well it works you may want to get it chrome of even gold plated! This very inexpensive “Special Tool” is made from a piece of coat hanger wire. This is where the little tool mentioned above can help you maintain your sanity. Well, if I know of one sure way to become “disturbed”, it is to try to mate the gearbox to the overdrive the way that they describe! They also add as a NOTE: ”the gearbox mainshaft should enter the overdrive easily provided that the lining up procedure previously described is carried out and the unit is not disturbed.” What they don’t mention is that the gearbox weighs in at some 25 kg so holding it with one hand as illustrated while attempting to align the various components with the other is just a little difficult. They suggest “placing the oil pump cam in position on top of the center bushing (as in the photo above) then carefully threading the mainshaft through the oil pump cam and into the center bushing.” Try Holding a Gearbox at Arms Length Like This for a Few Minutes
#MGB LAYCOCK OVERDRIVE MANUAL#
The factory workshop manual for the Austin Healey 100 illustrates the “recommended” method of installing the overdrive. 8 Springs, 3 Splines, Big ProblemĪs can be seen in the above picture when the pump cam is positioned on the pump plunger roller the plunger spring holds the cam out of alignment with the rest of the bore of the unit.Ĭonversely when the cam is fitted on the partially installed gearbox shaft the pump plunger roller protrudes below the cam and will not allow the cam to slip by into its correct position against the overdrive centre bushing. The other 2 sets of splines are away down in the middle of the overdrive unit, one in the clutch sliding member and the other in the unidirectional clutch. One of the splines is located on the inside of the oil pump cam. The rear shaft of the gearbox mated to these overdrive units has to be aligned with three individual splines while compressing an oil pump spring and 8 clutch springs as the two units are joined together. If you have “been there, done that” skip this part down to the picture with the tape measure in it. Many years ago I made up a little tool which has proved invaluable when attaching an “A” type Laycock-De Normanville overdrive unit to a gearbox.įor those not familiar with this operation a little explanation will help.
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