Vintage Jag Works' logo

Moss Gearbox

The Moss gearbox was used in Jaguar cars up through the 1964 model year generally and the Mark 2 for another year or two. While the design of the gearbox did not change, the gears were made in three different machining processes during those years and they do not replace each other by simply counting the teeth. Mismatched gears that were not made by the same machining process will nearly always make noise when rotated under load.

When the synchros on second, third and fourth gears become worn, they will not shift properly anymore, even if you know the proper shifting technique. Resorting to slow shifting, crash shifting or double clutching are only temporary tactics to get the car to a point where you can remove the transmission from the car and rebuild it.

We developed a process about twenty years ago where we re-machine the synchros and make them work better than they ever did. We carefully examine all the internal parts and repair or replace those that are no longer serviceable. If low gear is noisy, new mainshaft bearings in many cases will cause low gear to be quieter. In addition we also go through the shifter and top cover of the transmission to ensure the proper function of the detents and shift rails. Sometimes the nose of the mainshaft is worn out. In that case, we sleeve the front of the shaft to give it new life.

These are very robust transmissions and in most cases have been abused for 20 of their 40-50 years. Rebuilding the transmission and getting it to shift correctly again should add another 30-50 years to its life. Please click here to see current rebuild base prices.