Troy-Bilt Bronco CRT User manual

Service Manual
MTD Products LLC - Product Training and Education Department
FORM NUMBER 769-01529
11/2004
Small Frame Troy-Bilt Tillers

0
TABLE OF CONTENTS
Engine: ............................................................................................................................ 1
Forward clutch cable adjustment: .................................................................................... 1
Forward clutch cable assembly replacement: ................................................................. 3
Drive belt replacement: ................................................................................................... 5
Forward return spring replacement: ................................................................................ 6
Transmission removal: .................................................................................................... 7
Transmission disassembly: ........................................................................................... 12
Transmission assembly: ................................................................................................ 21
Forward Idler lever Pivot: .............................................................................................. 32
Reverse clutch cable replacement: ............................................................................... 33
Reverse clutch cable adjustment: ................................................................................. 35
Reverse drive belt replacement: .................................................................................... 35
Reverse idler pulley assembly: ...................................................................................... 37
Transmission pulley: ...................................................................................................... 37
Transmission oil fill plug: ............................................................................................... 38

Troy-Bilt Small Frame Tillers
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TUFFY TILLER
ABOUT THIS SECTION:
NOTE: This section covers the Tuffy rear tine
tiller, model 21A-630B063 with Serial Number
1B212G80447. This section has been techni-
cally written to follow along with the Troy-Bilt
Factory School.
UNIT FEATURES:
• 3.75 Hp, 4-cycle engine
• Power forward
• 14” tilling width
• 10” tine diameter
• Adjustable tilling depth up to 6”
• 10” Agricultural Tires
1. ENGINE:
1.1. Identify the engine that is powering the tiller, and
refer to the Engine Owner’s Manual for more
information.
2. FORWARD CLUTCH CABLE ADJUSTMENT:
2.1. Remove the spark plug boot from the spark plug,
and ground it to the engine. See Figure 2.1.
Figure 2.1
Spark Plug Boot
Grounded
Spark
Plug
2.2. Make certain the forward clutch bail is fully
released. See Figure 2.2.
2.3. Measure the overall length of the coils on the for-
ward clutch spring with the forward clutch bail
fully released using a dial caliper. See Figure
2.3.
2.4. Record the forward clutch spring measurement
_____.
Figure 2.2
Clutch Bail
Fully Released
Figure 2.3
Coil Length - Fully Released
Troy-Bilt Small Frame Tillers

Troy-Bilt Small Frame Tillers
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2.5. Squeeze the forward clutch bail to the upper
handlebar. See Figure 2.5.
2.6. Measure the overall length of the coils on the for-
ward clutch spring with the forward clutch bail
fully contacting the upper handlebar. See Figure
2.6.
2.7. Record the forward clutch spring measurement
_____.
2.8. If the second measurement (spring coils
extended) of the forward clutch spring is
between 1/16” and 3/16” longer than the first
measurement (spring coils not extended), the
tension is correct.
2.9. If the second measurement (spring coils
extended) of the forward clutch is too short (less
than 1/16”), the tension is too loose. Continue
through this section.
2.10. If the second measurement (spring coils
extended) of the forward clutch is too long (more
than 3/16”), the tension is too tight. Continue
through this section.
2.11. Release the forward clutch cable.
2.12. Loosen the hex jam nut securing the clutch
cable assembly in position using a 3/8” wrench
and a small adjustable wrench. See Figure 2.12.
2.13. Un-thread the hex jam nut until it is half way up
the adjustment screw.
2.14. Grasp the adjustment screw with one hand and
loosen or tighten the forward clutch cable until
the proper adjustment has been achieved. See
Figure 2.14.
Figure 2.5
Upper Handle
Clutch Bail
Figure 2.6
Coil Length
Bail Engaged
Figure 2.12
Hex Jam Nut Loosened
Clutch Cable
Adjustment Screw
Figure 2.14
Forward Clutch Cable
Jam Nut
Hold
Rotate

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NOTE: Rotate the forward clutch cable clock-
wise (towards the forward clutch bail) to increase
tension, or counter-clockwise to decrease ten-
sion.
2.15. Perform the forward clutch spring measurement
procedures to make certain the adjustment is
within specifications.
2.16. Tighten the hex jam nut up against the forward
clutch cable end using a 3/8” wrench and a small
adjustable wrench.
NOTE: Make certain the forward clutch cable
end does not rotate when the jam nut is tight-
ened.
3. FORWARD CLUTCH CABLE ASSEMBLY
REPLACEMENT:
3.1. Remove the spark plug boot from the spark plug,
and ground it to the engine. See Figure 3.1.
Figure 3.1
Spark Plug Boot
Grounded
Spark
Plug
3.2. Loosen the hex jam nut securing the forward
clutch cable assembly to the adjustment screw
using a 3/8” wrench and a small adjustable
wrench. See Figure 3.2.
3.3. Remove the forward clutch cable end from the
adjustment screw by rotating it counter-clock-
wise (away from the forward clutch bail).
3.4. Remove the forward clutch cable from the lower
handle bracket using a pair of needle nose pli-
ers. See Figure 3.4.
Figure 3.2
Hex Jam Nut
Forward Clutch Cable
Adjustment Screw
Figure 3.4
Lower Handle Bracket
Forward
Clutch Cable

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3.5. Remove the lower cable tie securing the forward
clutch cable to the lower handlebar using side
cutters. See Figure 3.5.
3.6. Remove the hex flange screw and large flat
washer securing the belt cover to the lower
cable mounting bracket using a 3/8” socket. See
Figure 3.6.
3.7. Slide the belt cover down the forward clutch
cable until it is out of the work area.
NOTE: The upper portion of the forward clutch
cable will not fit through the belt cover.
3.8. Loosen the hex jam nut securing the forward
clutch cable to the lower cable mounting bracket
using a 3/8” wrench and a 7/16” wrench. See
Figure 3.8.
3.9. Slide the forward clutch cable out of the lower
cable mounting bracket.
3.10. Pivot the forward clutch cable’s Z fitting rear-
ward, and remove it from the forward idler lever.
See Figure 3.10.
3.11. Remove the lower portion of the forward clutch
cable from the belt cover.
3.12. Install the new forward clutch cable in the
reverse order above.
3.13. Perform the Forward Clutch Cable Adjustment
section.
Figure 3.5
Cable Tie
Clutch
Cable
Figure 3.6
Hex Flange Screw
Large
Flat Washer
Belt Cover
Figure 3.8
Hex Jam Nut
Forward Clutch
Cable
Z Fitting
Idler
Lever
Forward
Figure 3.10
Z Fitting
Forward
Idler Lever

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4. DRIVE BELT REPLACEMENT:
4.1. Remove the spark plug boot from the spark plug
and ground it to the engine. See Figure 4.1.
4.2. Remove the hex flange screw and large flat
washer securing the belt cover to the lower
cable mounting bracket using a 3/8” socket. See
Figure 4.2.
4.3. Pivot the belt cover on the forward clutch cable
until it is out of the work area.
Figure 4.1
Spark Plug Boot
Grounded
Spark
Plug
Figure 4.2
Hex Flange Screw
Large Flat Washer
Belt Cover
Clutch Cable
4.4. Remove the belt from the engine drive pulley
and forward idler pulley. See Figure 4.4.
4.5. Remove the belt from the transmission pulley.
See Figure 4.5.
4.6. Install the new belt in the reverse order above.
NOTE: Make certain the belt keepers are cor-
rectly positioned prior to installing the belt cover.
4.7. Perform the Forward Clutch Cable Adjustment
section.
Figure 4.4
Drive Belt
Drive Pulley
Forward Idler Pulley
Figure 4.5
Transmission
Pulley
Belt

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5. FORWARD RETURN SPRING REPLACE-
MENT:
5.1. Remove the spark plug boot from the spark plug,
and ground it to the engine. See Figure 5.1.
5.2. Remove the hex flange screw and large flat
washer securing the belt cover to the lower
cable mounting bracket using a 3/8” socket. See
Figure 5.2.
5.3. Pivot the belt cover around the forward clutch
cable until it is out of the work area.
5.4. Remove the upper hook of the return spring from
the right engine bracket using needle nose pli-
ers. See Figure 5.4.
5.5. Remove the lower hook of the return spring from
the forward idler lever using needle nosed pliers.
See Figure 5.5.
NOTE: There are two holes at the bottom of the
forward idler lever. The right lower hole (in the
operators position) is used for the Tuffy tiller.
5.6. Install a new return spring in the reverse order
above.
Figure 5.1
Spark Plug Boot
Grounded
Spark
Plug
Figure 5.2
Hex Flange Screw
Flat Washer
Belt Cover
Clutch
Cable
Figure 5.4
Upper
Hook
Right Engine Bracket
Return Spring
Figure 5.5
Lower Hook
Forward Idler Lever
Return Spring

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6. TRANSMISSION REMOVAL:
NOTE: Perform the Drive Belt Replacement sec-
tion through forward drive belt removal, prior to
performing this section. See Image Below
6.1. Loosen the hex nut securing the forward clutch
cable to the lower cable mounting bracket using
a 3/8” wrench and a 7/16” wrench.
6.2. Slide the forward clutch cable out of the lower
cable mounting bracket.
6.3. Pivot the forward clutch cable’s Z fitting rear-
ward, and remove it from the forward idler lever.
6.4. Remove the lower portion of the forward clutch
cable from the belt cover.
6.5. Set the belt cover aside.
6.6. Remove both self tapping hex flange screws
securing the tine hood to the right and left hood
brackets using a 3/8” socket. See Figure 6.6.
Remove Drive Belt
Remove
Drive Belt
Figure 6.6
Self Tapping
Hex Flange Screws
6.7. Grasp the upper handlebar and pivot the unit
onto it’s nose.
6.8. Secure the handlebar from above.
6.9. Pivot the trailing shield up.
6.10. Remove the hex screw, bushing, lock washer
and lock nut securing the drag bar to the bottom
of the transmission using a 1/2” socket and
wrench. See Figure 6.10.
6.11. Remove both hex flange screws securing the
hood brackets to the transmission assembly
using a 1/2” socket. See Figure 6.11.
Figure 6.10
Hex Screw
Lock Nut
Lock Washer
Figure 6.11
Hex Flange Screws
Hood
Brackets

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6.12. Remove the depth regulator assembly and drag
bar assembly. See Figure 6.12.
NOTE: There is a cut a way in the tine hood to
allow the depth bar’s spiral pin to pass through.
See Image Below.
6.13. Lower the unit back onto the tines.
NOTE: Make certain the unit is resting on the
tines and not on the trailing shield.
6.14. Raise the front of the tiller up until the wheel
assemblies are off the ground. See Figure 6.14.
6.15. Remove both hair pins and clevis pins securing
the wheel assemblies onto the wheel shaft using
needle nose pliers. See Figure 6.15.
6.16. Remove both wheel assemblies.
Figure 6.12
Depth Regulator Assembly
Drag Bar
Hood Brackets
Cut A Way
Cut A Way for Spiral Pin
Figure 6.14
Raise the Unit Up
Wheels off Ground
Figure 6.15
Hair Pin Clevis Pin

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6.17. Remove the forward return spring from the right
engine bracket using needle nose pliers. See
Figure 6.17.
6.18. Pivot the forward idler lever inward.
6.19. Secure the upper handlebar in position from
above. See Figure 6.19.
NOTE: The unit needs to be stabilized before
removing the transmission.
Figure 6.17
Return Spring
Right
Engine
Bracket
Idler Lever
Figure 6.19
Upper Handlebar Secured
6.20. Remove both sets of hex screws securing the
left and right engine brackets to the transmission
using a 1/2” socket. See Figure 6.20.
6.21. Remove both self-tapping hex screws securing
the lower forward cable mounting bracket to the
left engine bracket using a 3/8” socket. See Fig-
ure 6.21.
6.22. Grasp the front of the unit and raise it up until the
front support can be removed.
6.23. Lower the front of the unit until the pulley/belt
guard is setting on the ground.
Figure 6.20
Hex Screws
Engine
Bracket
Transmission
Figure 6.21
Self-Tapping
Screws
Cable Mounting Bracket
Engine Bracket

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6.24. Pivot the upper handlebar assembly up until the
pulley/belt guard is flat on the floor. See Figure
6.24.
6.25. Secure the upper handlebar in position from
above.
6.26. Remove the transmission assembly from
between the engine brackets and front assem-
bly. See Figure 6.26.
NOTE: A small pry bar can be used for assis-
tance, if necessary.
6.27. Set the unit on a bench.
6.28. Remove the forward return spring from the for-
ward idler lever. See Figure 6.28.
NOTE: There are two holes at the bottom of the
forward idler lever. The right lower hole (in the
operators position) is used for the Tuffy tiller.
6.29. Remove the hex screw and belleville washer
securing the transmission pulley to the drive
shaft assembly using a 1/2” socket. See Figure
6.29.
Figure 6.24
Pulley/Belt Guard
Pivoted Forward
Figure 6.26
Transmission Assembly
Engine Brackets
Figure 6.28
Forward Return Spring
Forward
Idle Lever
Two Holes
Figure 6.29
Hex Screw
Belleville Washer
Transmission
Pulley

Troy-Bilt Small Frame Tillers
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6.30. Remove the transmission pulley, key and front
support washer from the drive shaft assembly.
See Figure 6.30.
6.31. Remove the hex screw securing the forward
idler assembly to the transmission housing
assembly using a 1/2” socket. See Figure 6.31.
6.32. Rotate the transmission horizontally 180°.
Figure 6.30
Transmission Pulley
Key
Front Support Washer
Belleville
Hex Screw
Figure 6.31
Hex Screw
Lock Washer
Shoulder Washer
Forward Lever
Idler Pulley
6.33. Raise the rear of the transmission up and set it
on a 2” x 4” block. See Figure 6.33.
6.34. Remove the hex screws and lock nuts securing
the right and left tine assemblies using a 9/16”
socket and wrench.
NOTE: Record the orientation of the tine assem-
blies for correct installation. See Image Below
Figure 6.33
2” x 4”
Hex Screw &
Lock Nut Hex Screw & Lock Nut
Right
Left
Hex Screws and Lock Nuts
Left and Right Tine Assemblies

Troy-Bilt Small Frame Tillers
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6.35. Remove both large E-Clips from the right and left
sides of the wheel shaft using a large flat blade
screwdriver. See Figure 6.35.
7. TRANSMISSION DISASSEMBLY:
7.1. Thoroughly clean the wheel shaft and tine shaft
using contact cleaner and a shop rag. See Fig-
ure 7.1.
NOTE: Lubricate both shafts before assembly.
7.2. Remove all four hex flange screws securing the
front transmission cover and gasket to the trans-
mission housing assembly using a 1/2” socket.
See Figure 7.2.
7.3. Remove the front transmission cover and clean
it.
7.4. Position a suitable oil drain pan directly in front
of the bench. See Figure 7.4.
7.5. Rotate the transmission 180° to the right and
drain the transmission assembly into a suitable
containers.
NOTE: When refilling an empty transmission,
use only GL-4 gear oil having a viscosity of SAE
85W-140 (Part Number GW-1360A) or SAE 140.
The Tuffy transmission will use approximately?
ounces of gear oil.
Figure 6.35
E-Clips
Wheel Shaft
Figure 7.1
Wheel Shaft
Tine Shaft
Thoroughly Clean
Surfaces
Figure 7.2
Hex Screws
Front
Transmission
Cover
Figure 7.4
Drain Pan
85W-140
Gear Oil
GL-4
Transmission
Assembly

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7.6. Allow all of the gear oil to drain from the trans-
mission case assembly.
7.7. Rotate the transmission 180° to the right until it
is in the upright position.
7.8. Remove the front transmission cover gasket
from the transmission using a scraper. See Fig-
ure 7.8.
7.9. Remove all four hex flange screws securing the
rear transmission cover and gasket to the trans-
mission housing assembly using a 1/2” socket.
See Figure 7.9.
Figure 7.8
Cover Gasket
Wheel Worm
Figure 7.9
Rear Transmission Cover
Hex Screws
7.10. Remove the rear transmission cover gasket from
the transmission using a scraper. See Figure
7.10.
7.11. Remove the remaining lower hex flange screw
securing the rear bearing cap to the transmis-
sion housing assembly using a 1/2” socket. See
Figure 7.11.
7.12. Break the rear bearing cap free from the trans-
mission housing at any overlap position using a
punch and hammer.
Figure 7.10
Cover Gasket Tine Worm
Figure 7.11
Short Hex Flange Screw
Rear Bearing Cap Transmission
Overlap Point

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7.13. Remove the rear bearing cap from the transmis-
sion housing using a scraper. See Figure 7.13.
7.14. Identify if there is a rear bearing cap gasket.
NOTE: There are different thickness rear bear-
ing cap gaskets available to take up the end-play
for the drive shaft assembly.
7.15. Remove the sealant from the rear of the trans-
mission housing.
NOTE: Use gasket eliminator during assembly.
7.16. Remove the sealant and gasket (if used) from
the rear bearing cap.
NOTE: Use gasket eliminator during assembly.
7.17. Remove the rear bearing cap shims. See Figure
7.17.
7.18. Measure the overall thickness of the rear bear-
ing shims using a dial caliper. See Figure 7.18.
7.19. Record the measurement _____.
NOTE: This is for future reference.
7.20. Thoroughly clean the exposed portion (front) of
the drive shaft.
7.21. Hold the support washer and front tapered roller
bearing into the front race.
7.22. Slowly push the drive shaft assembly rearward
and out of the transmission assembly. See Fig-
ure 7.22.
NOTE: If the front portion of the drive shaft will
not pass through the roller bearing, a rubber
mallet can be used for assistance. Do not us a
hammer.
Figure 7.13
Rear Bearing Cap
Transmission
Housing
Sealant
Figure 7.17
Rear Bearing Cap Shims
Figure 7.18
Dial Caliper
Shims
Drive Shaft Assembly
Tapered Roller Bearings
Race
Rear Front
Support
Washer
Transmission Assembly
Figure 7.22

Troy-Bilt Small Frame Tillers
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7.23. Remove the front tapered roller bearing and sup-
port washer, and inspect them for wear or dam-
age.
7.24. Inspect the rear tapered roller bearing assembly
for damage or wear. See Figure 7.24.
NOTE: The rear tapered roller bearing and race
can not be ordered separately, they are pur-
chased with the drive shaft assembly.
7.25. Remove the front drive shaft oil seal using a flat
blade screwdriver. See Figure 7.25.
7.26. Remove the front internal snap ring using
medium retaining ring pliers.
Figure 7.24
Rear Tapered Roller Bearing
Race
Drive Shaft Assembly
Figure 7.25
Front Oil Seal
Internal Snap Ring
Race
7.27. Remove the front tapered roller bearing race by
lightly tapping on the perimeter with a small
punch and a rubber mallet.
NOTE: The race should be gently pushed into
the center of the transmission housing for ease
of removal.
7.28. Open the jaws of a vice and set a section of pro-
tective material into it. See Figure 7.28.
7.29. Set the transmission assembly into the jaws of
the vice and secure it.
7.30. Inspect the wheel shaft assembly for wear or
damage inside the transmission case. See Fig-
ure 7.30.
Figure 7.28
Vice
Protective Material
Transmission
Assembly
Figure 7.30
Wheel Shaft Worm Gear
Spacer
Spacer
Bronze Bushing
Bronze Bushing
Lubrication Cut A Way

Troy-Bilt Small Frame Tillers
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7.31. Inspect the tiller shaft assembly for wear or dam-
age inside the transmission case. See Figure
7.31.
7.32. Remove the left and right oil seals from the
transmission housing, at the wheel shaft, using a
long 3/16” flat blade screwdriver. See Figure
7.32.
NOTE: Make certain the transmission oil seal
bores are not damaged during removal.
7.33. Remove the left and right retaining rings secur-
ing the wheel shaft in position using medium
retaining ring pliers. See Figure 7.33.
7.34. Remove the external shims from right and left
sides of the wheel shaft using a small hook tool
and a stick magnet. See Figure 7.34.
Figure 7.31
Tiller Shaft Worm Gear
Spacer
Spacer
Bronze Bushing
Bronze Bushing
Figure 7.32
Oil Seal
Wheel Shaft
Figure 7.33
Retaining Ring
Wheel Shaft
Figure 7.34
External Shims
Wheel Shaft