COOPER S 4 SYNCHRO GEARBOX LAYGEAR

Cooper “S” Lay gear. Manufactured in the U.K. for all pre-rod change. 4 synchromesh gearbox gears were the same except for the lay gear and 1st motion shaft. The Cooper S and 1275GT had a closer ratio with a 18 teeth 1st motion and 29 teeth (15,20,25,29) 22G1040 lay gear. The 25 teeth were 3″ diameter whereas the standard ratio lay gear with same teeth count was 1/8″ wider so beware. One of the most sought after 4 synchromesh  remote gearbox close ratio gears. The most certain identification is done be inspecting the lay gear. If it is a 22G1040 lay gear you have a close ratio box. While you are inspecting the lay gear be sure to check the inner surface of the lay gear which serves as the outer race of the lay shaft bearings. This surface can breakdown resulting in premature failure of both the bearing and the shaft. Ist motion shaft to go with this has 18teeth – 22G1371 14mm nose main shaft or DAM3167 with later type 18mm nose main shaft. These have been fitted to Rod change gearboxes with layshaft modifications required when owners required a closer ratio gear set.