A while back I posted a query on the upper housing drive gear bearing set. Having fixed it and some adventure figuring it out, here's some info that might be useful for anyone attempting this. Confusion possibility lies with the 2 variants in the 1.50 gearsets.<br /><br />I am asuming you have the manual. If you don't, you may not be able to follow and it does not matter if you don't understand as you should not be attempting this without the book.<br /><br />There are two 1.50 gear ratio sets on this drive, heavy duty and I suppose the other is called regular duty. The gears are dimensionally different and also has different shimming clearances. The book and parts list only make references to the heavy duty gears and one will conclude its the only gearset-not true.<br /><br />In addition to the above, gearsets supplied before D492656 differs from the later uits. The difference lies in the OD of the drive gear hub which holds the bearings, later units are larger by 0.0014". These are supplied on drives S/n D492656 and later. The giveaway is how easily the bearings come off, later units have a slight interference fit and need to be pressed out.<br /><br />On bearing sets, there are 3 bearing sets used on this drive.<br />1. 31-35988A9 for the heavy duty 1.50 gears<br />2. 31-35988A3 for the 1.32 ratio<br />3. 31-35988A12 for the others, incl non heavy duty 1.50. The parts catalog does not make reference to the 1.50 gear. This tripped me and ended up ordering the the -A9.<br /><br />The bearing assembly procedure depends on the gearset. Early units should use the small spacer and the associated preload torque method. For drives after, the new procedure without the small spacer should be followed. <br /><br />Replacement gearsets will be the post D492656 variety, ie, oversized and requires the new preload procedure. Mine is a pre D492656 with later gears.<br /><br />To summarise, if you are going to change the bearings and are using the 1.50 gears;<br />1. Check if its the heavy duty gears to determine the correct bearing set<br />2. Check the bearing fit to determine the assembly procedure.<br /><br />Finally a word that came from a certified mech. Use the later procedure even if you have the early gearsets. Reason is that he has seen units where the outer race spins with the shaft because the preload procedure sets it too tight, this damages the housing. I am not recommending this, just passing this info along. A fellow boater followed the procedure and found the bearing to be extremely tight, I couldn't turn the bearing race by hand.<br /><br />Qystan
