Thursday, July 30, 2009

After 25 years of sitting around, my Le Mans gearbox was seized up very tight. Time to take it apart, clean it up and make sure everything works smoothly.

Dismantling the box is easy. Remove the six screws that hold the top shifting assembly to the case and lift it off. Remove the clutch release parts. Remove the 4 bolts inside the bell housing and remove the bell housing from the gearbox.

At this point, I liberally doused the gears with WD 40 until things moved freely.

Lock the gearbox by engaging two sets of gears, then remove the split pin and nut holding the Drive flange on the output end of the gearbox and remove the flange.

Undo the retaining screw that holds the speedometer drive gear to the rear housing and withdraw it. Undo the 4 nuts retaining the rear housing and remove it.

Lock the gearbox as before and remove the split pins and nuts from both ends of the layshaft.

Return each gear pair to the neutral position and rotate the main shaft until the two missing teeth on the engagement dog line up with the teeth on the layshaft drive gear below. This will allow for clearance so that the first motion shaft can be easily drawn forward.


Remove the castellated nut from the front of the mainshaft and tap the mainshaft until the rear bearing clears the case. Put a spacer between the rear bearing and the case and gently tap forwards until the bearing is free of the fitted portion of the shaft. Remove the bearing and lift the assembly from the case. At this point, all parts should easily slide off the main shaft. Take note of their placement prior to doing so.


Layshaft removal is equally simple. Tap either end of the shaft and the bearing at the opposite end will slide out. Each gear and spacer will fall out as the shaft is withdrawn.


At this point, I used a bench grinder fitted with a steel wire brush to clean all the rust from the gears and polish the shafts. I cleaned the bearings to make sure they were good. Two were, two were not. The large bearings are RMS 9's and the small ones are RMS 6's. Each are readily available from your local bearing supplier. I also fitted a new seal to the rear housing. The original is a brass and felt seal which is no longer available. I replaced it with a Federal Mogul ( National Oill Seal ) part # 39713, also readily available.