Usage:
Four-Speed Gearbox Components
(1) Housing. (2) Main shaft. (3) Sliding gear. (4) Sliding gear. (5) Needle rollers. (6) Freewheeling gear. (7) Thrust washer. (8) Bearing. (9) O-ring. (10) Gasket. (11) Washer. (12) Slotted nut. (13) Cotter pin. (14) Bearing. (15) Gear. (16) Snap ring. (17) Gear. (18) Gear. (19) Counter shaft. (20) Drain plug. (21) Bearing. (22) Gasket. (23) Cover. (24) Seal. (25) Output flange.
Disassemble Four-Speed Gearbox
Start By:
a. remove shuttle assembly and four-speed gearbox
1. Remove two bolts and lock washers securing parking brake lever (27) to shift cap (26).
2. Remove two bolts and washers securing neutral start switch (28) and shift cap (26) to the gearbox.
3. Remove the neutral start switch and shift cap. Discard gasket (29). This must be replaced with a new part during assembly.
4. Remove cotter pin (13) from slotted nut (12) and end of main shaft (2).
5. Remove slotted nut (12), washer (11), gasket (10), and o-ring (9) from end of main shaft (2).
6. Pull output flange (25) with attached parking brake drum (30), straight off main shaft (2).
7. Separate output flange (25) from parking brake drum (30), if necessary, by removing nuts, lock washers, and bolts.
8. Remove six bolts and washers securing cover (23) to housing (1). Remove the cover and gasket (22).
9. Press seal (24) out of cover (23). Discard the seal. This must be replaced with a new part during assembly.
10. Press main shaft (2) from the output (threaded) end through bearing (8). Take care to prevent damaging the threads on the main shaft.
11. Support gears (3), (4), and (6) to prevent them from falling when the main shaft is removed.
NOTE: Needle rollers (5) will be loose and may fall inside the housing. Be sure to collect all 39 needle rollers and save for assembly.
12. Remove main shaft (2) by sliding it through gears (3), (4), and (6), and out the input side of housing (1).
13. Remove gears (3), (4), and (6), needle rollers (5), and thrust washer (7) from inside housing (1).
14. Remove bearing (8) by pressing it outward from the inside of housing (1).
15. Pry snap ring (16) out of its groove in counter shaft (19). Let the snap ring rest on the smooth part of the counter shaft.
16. Press counter shaft (19) from the input side of the housing, toward the output side. Bearing (21) will be pushed out of the housing. Press until the counter shaft is free of bearing (14).
NOTE: If bearing (14) remains on counter shaft (19), the bearing will have to be removed before performing the next step.
17. Slide gears (15), (17), and (18), and snap ring (16) off counter shaft (19) while pulling counter shaft and bearing (21) assembly out of the housing.
18. Pull bearing (21) off counter shaft (19).
19. Remove bearing (14) by pressing it to the inside of the housing.
20. Remove two screen plugs (31) from housing (1). If the screen plugs are torn or damaged, they must be replaced with new parts.
21. Wash bearings thoroughly in a suitable solvent. Dry the bearings immediately after cleaning and lubricate with a light coat of clean oil. Do not dry bearings by spinning with compressed air.
22. Make sure retaining rings fit snugly in grooves in all bearings. Make sure bearings rotate smoothly. Replace bearings if any damage exists.
23. Wash all other metal parts in a suitable solvent.
24. Check all gears for chipped, broken, or otherwise damaged teeth and splines. Make sure splined gears slide smoothly onto the shafts.
25. Check the two shafts for stripped, twisted, or broken splines. Look for cracks or other damage to the shafts.
26. Inspect seal and bearing surfaces on shafts and inside housing for scratches or wear. If damaged areas can not be cleaned up by light polishing, the parts must be replaced.
27. Repair or replace any damaged parts before assembly.
Assemble Four-Speed Gearbox
1. Slide small gear (18) and then large gear (17) onto the splined length of counter shaft (19). Gears (17) and (18) must be oriented so that the rounded edge of the teeth face away from each other.
2. Install snap ring (16) into its groove on counter shaft (19). Make sure the snap ring fits tightly in its groove to secure gears (17) and (18) properly.
3. Slide gear (15) onto the end of the counter shaft. The long shoulder of gear (15) must face gears (17) and (18).
4. Set bearing (14) on the end of the counter shaft. Retaining ring on the bearing must face towards gear (15). Press the inner race of bearing (14) so that it is seated squarely against gear (15).
5. Set input side of housing (1) on a flat work surface. Insert counter shaft (19) assembly inside the housing. Push on the end of the counter shaft to install bearing (14) into the bore of housing.
6. Set bearing (21) on the large end of the counter shaft. Retaining ring on the bearing must face the outside of the housing. Press the inner race of the bearing so that the bearing is seated squarely against the gear shoulder of the counter shaft.
7. Set the housing upright. Make sure the counter shaft rotates smoothly on bearings (14) and (21).
8. Hold freewheeling gear (6) in place inside the housing. The small diameter teeth on the gear must face the inside of the housing.
9. Insert main shaft (2) from the input side of housing, through freewheeling gear (6). The small diameter teeth of the gear should rest against the splined shoulder of the main shaft.
10. Lift the main shaft up inside housing (1). Install sliding gear (4) and sliding gear (3) onto the splined length of the main shaft. Make sure the shift collar part of sliding gears (3) and (4) face each other.
11. Install a set of 39 needle rollers (5) between main shaft (2) and freewheeling gear (6), as follows:
a. Lift freewheeling gear (6) until it touches bottom of main shaft (2).
b. Install half of the needle rollers at the top of the main shaft.
c. Slowly lower the freewheeling gear, allowing the needle rollers to roll to the bottom of the main shaft.
d. Move sliding gear (4) towards the freewheeling gear so the two gears mesh together. This will hold the freewheeling gear in a centered position.
e. Install the remaining needle rollers at the top of the main shaft.
12. Install thrust washer (7) onto the main shaft, against the freewheeling gear. Make sure all needle rollers (5) stay in place.
13. Brace the input end of main shaft (2). This will hold the main shaft in place while installing bearing (8) in the following step.
14. Set bearing (8) on the output end of main shaft (2). Retaining ring on the bearing must face the outside of the housing. Press the inner race of the bearing to seat the bearing in the housing.
15. Install a new seal (24) into cover (23). The seal must be flush with the outside edge of the cover.
16. Install a new gasket (22) and cover (23) onto the housing. Secure with six bolts and washers.
17. Install parking brake drum (30) to output flange (25), if removed. Secure with bolts, lock washers, and nuts.
18. Apply a light coat of oil to the outside sealing surface of output flange (25). Install the output flange onto the main shaft, through seal (24). The output flange must be set against bearing (8).
19. Tape the threads on the end of main shaft (2). Install a new o-ring (9) and a new gasket (10) onto the main shaft over the taped threads.
20. Remove tape from the threads. Install washer (11) and slotted nut (12) on the main shaft.
21. Tighten slotted nut (12). Insert cotter pin (13) through slots in nut (12) and end of main shaft (2).
22. Install two screen plugs (31) into housing (1).
23. Install a new gasket (29), shift cap (26), and neutral start switch (28) onto the gearbox. Secure with two bolts and washers.
24. Install two bolts and lock washers securing parking brake lever (27) to shift cap (26).
End By:
a. Install shuttle assembly and four-speed gearbox