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Dealer Service 23
5WPMAN0705 (Rev. 5/9/2008)
Horizontal Shaft Seal Replacement
1. Disconnect and remove the driveline from the
gearbox.
2. Remove vent plug (27), Figure 14, and siphon gear
lube from housing through this opening.
3. If the leak occurred at either end of horizontal shaft,
remove oil cap (11) and/or oil seal (1). Replace
with new one (see Seal Replacement, page 21).
4. Fill gearbox with SAE 80W or 90W gear lube until it
runs out the level plug.
Remove Gearbox from Mower
1. Disconnect and remove the rear driveline from the
gearbox.
2. Remove vent plug (15), Figure 15, and siphon gear
lube from housing through this opening.
3. Remove gearbox stand (2) from mower deck by
removing four hex screws (8).
4. Remove four cap screws (14) and washers (13)
and remove shield (12) from gearbox.
5. Remove castle nut (6) and hardware from output
shaft of gearbox.
6. Remove sheave (3) from gearbox.
7. Remove four bolts (10) that attach gearbox to
gearbox stand and remove gearbox.
Disassemble Gearbox
1. Remove top cover (28), Figure 14, from housing.
Turn gearbox upside down and pour out remaining
gear oil from gearbox.
2. Remove oil cap (11) (to be replaced).
3. Remove snap ring (10) and shim (9) from input
shaft (5).
4. Support gearbox in hand press and push on input
shaft (5) to remove bearing (8).
5. Remove gear (7) from inside housing.
6. Remove oil seal (1) from front of housing (to be
replaced).
7. Remove snap ring (2) and shim (3) from front of
housing.
8. Remove input bearing (4) by using a punch and
hammer from outside of housing.
9. Support housing in vise in a horizontal position.
10. The castle nut (23) and cotter pin (24) are already
removed with the drive sheave. Remove the snap
ring (18), washer (20), and seal (19).
11. Remove output shaft (12) and bearings by using a
punch and hammer and tap on top to drive down.
12. Inspect gears for broken teeth and wear. Some
wear is normal and will show on laded side. Forged
gear surfaces are rough when new. Check that
wear pattern is smooth.
13. Inspect vertical and horizontal shafts for grooves,
nicks, or bumps in the areas where the seals seat.
Resurface any damage with emery cloth.
14. Inspect housing and caps for cracks or other
damage.
Reassemble Gearbox
(GM3060, GM3072 shown, GM3054 similiar)
Refer to Figure 14.
NOTE: Repair to this gearbox is limited to replacing
bearings, seals, and gaskets. Replacing gears, shafts,
and a housing is not cost effective. Purchasing a com-
plete gearbox is more economical.
1. Clean housing, paying special attention to areas
where seals will be installed.
2. Wash housing and component thoroughly. Select a
clean area for gearbox assembly. Replace all seals
and bearings. All parts must be clean and lightly
oiled before reassembling.
GM3060 & GM3072
3. Install upper output bearing (13), shims (14), and
snap ring (15) on output shaft (12). Use new shims
equal to the thickness of the original shims.
4. Press output shaft assembly into housing from the
bottom opening.
5. Install spacer (16), lower output bearing (13),
shims (17), and snap ring (18) in bottom of
housing.
GM3054
1. Install shims (14), upper output bearing (8), spacer
(16), lower output bearing (8), shims (17), and
snap ring (15) on output shaft. Use new shims
equal to the thickness of the original shims.
2. Press output shaft assembly into housing from the
bottom opening.
3. Install snap ring (18) in bottom of housing.
All Models
4. Apply grease to lower seal lips (19), and press seal
over output shaft (5), using a round tube of the
correct diameter. Be sure not to damage the seal
lip. Press in housing so that the seal is recessed.
5. Insert protective washer (20) (GM3060 & GM3072
only) by hand.
6. Install snap ring (21) and position it together with
seal (19) by pressing it into position. Verify that the
snap ring is seated properly.