REPAIR TOP GEAR SET FOR MERCRUISER #1 OR ALPHA GEN I.
1) Remove outdrive and remove top from bottom, see water pump instructions.
2) Remove front cover nut with special Merc tool. A 1/2" iron bar through the center works instead.
3) Remove top oil level screw and be sure oil is gone.
4) Pull thr entier assembly out of unit and set on bench on clean cloth.(save the shim set behind the assembly)
5) Remove top cap with 12 point 3/8 socket, rotate 1/8 turn and lift.
6) Lift vertical shaft assembly out and set on clean cloth.
7) Remove two bottom seals and wash housing out.
8) Remove the yoke nut and washer from gear yoke and remove stack of parts. (wash all parts)
9) If you are just resealing some of the following instructions will be unnecessary.
10) The order of parts is as follows, cover nut, pressure plate, seal carrier, lip toward bearing, stacked bearing, gear.
11) If you are only changeing seals change the seal in the seal carrier and two seals in the housing and skip ahead.
12) Remove the stacked bearing from the drive gear, inspect both, look for burnt or overheated marks on bearings.
13) Check pre-load on bearing set (put in vice and tighten slowly while turning the bearing continue till tight)
14) While tight the bearing should turn without bumps or hesitation or roughness, if outer ring is loose replace set.
15) Sand seal surface on yoke, and replace if badly groved in seal area.
16) On the vertical assembly, press the shaft with out with a smaller shaft from bottom ( removes shaft from gear)
17) Remove bearing from shaft by placeing shaft in vice with brg against jaws, drive shaft out.
18) To remove the lower bearing, if gear is good. set sideways in vice block below gear so it will not move.
19) Drive a sharp chisel into the crack between gear and bearing to drive it off.
20) Re assembly: Press shaft into lower brg (new 'o' ring) press brg top and bottom.
21) Replace races in housing and cap using slap puller with 2 jaws to remove them.
22) Place vertical assembly in housing without seals and replace cap.
23) If old shimming is good the gear should spin free but require some effort to turn it. The exact correct value of7-10 inch/pounds can be checked.
******If too hard to turn bearings fail, if too easy gear shifts position******
25) Replace U/Joints if they stick or have slack, or are old.
26) Remove cap and vertical assy, install the lower seals and replace assy and cap.(new 'o' ring on cap)
27) With all parts on yoke and tight, install 'o' ring in slot and insert into housing with shims in place and tighten nut.
28) Check that no feelable slack exists between gears (both moove together)
29) Although there is no slack, the gears cannot touch , therefore if the u/joint is mooved rapidly 1" back and forth a tapping sound from the gears backlash is audable from outside.
30) Although with this meathod of assembly the unit should live, have a certified mechanic check shims and seals.
31) Be sure the unit is filled with oil from the bottom.
32) Replace the unit on the bell hse.
33) Check oil under the drive the next morning and check level after first trip.