Toro 8125 User manual

Fig.1
The model 8125 isnew. Itfeatures rear discharge
with adiecastaluminumhousingand is agear
drivenself-propelledmower.Fig. 1.
Itis a zone startmodelwiththeflywheelbrake
system.When the bail isreleased, both the engine
and blade will stop within the3-secondtime limit.
Anotherfeature is anadjustabledrivenpulley
which controls ground speed. It is located under
the pulley cover.
SAFETY WARNING:
Disconnect the spark plug lead.
Remove two screws and lift cover off. Fig. 2.
.Fig. 2
With the engine operating at3200 rpm,the ground
speed can becontrolled tooperate at 2.4, 2.6, 2.8,
3.0 or 3.2 mph.
MODEL 8125 SERVICING AND REPAIR
CHANGING GROUND SPEED.
Fig. 3
Loosen the nuton the idler pulley bracket which
will release the tension on the belt.Removethe nut
and thickwasher fromthe top of thedriven pulley.
When a spacer or spacers are not used, they are
storedontop
of thepulley under thenutand
washer.Fig. 4.
Fig. 4
SERVICE BULLETIN REFERENCES 20-1
OCTOBER 1984

Withno spacersbetween thepulley halves, the
ground speed is 2.4 mphat 3200 rpm.Add
one
spacer
between thepulley halves, the speed in-
creases to 2.6 mph.
Twospacers 2.8 mph. Three
spacers
3.0 mph. Fourspacers 3.2 mph.
Fig.
5
The lower half of the pulley iskeyed to the driven
shaft in the transmission. Fig.
6.
After the groundspeed has been selected, assem-
ble the top half of the pulley onto the shaft. Fig.
7.
Fig. 7
Slide the pulley down making sure the two halves
are assembled correctly. Fig. 8.
Fig. 6
Fig. 8
Placethe extraspacers on top of thepulley,assem-
ble the washer and nut. Tighten the nut. Fig.
9.
Fig. 9
20-2 SERVICE BULLETIN REFERENCES
OCTOBER
1984

Movethe idler brackettoapply tension on belt and
tighten idlerbracketnut.Fig. 10-A. Beltshould
deflectapproximately3/8”withfirmfinger
pressure. Fig. 10-B.Rotate engineseveral times to
seat belt ingrooves. Recheck belt tension andad-
just as necessary.
To replacethebelt, remove thepulley cover.
Loosen the nut on the idler pulley bracket which
will release tensionon thebelt.Fig. 12.
At this time, the belt can be rolled off the driven
pulley, or you can separate the pulleytoremove it.
Fig. 10-A Fig. 10-B
BELTREPLACEMENTPROCEDURES
A special beltis used todrive the transmission.It
was specially designed and manufactured foruse
only on this mower.
NOTE:
Useonly the belt available fromLawn-Boy No other
belt will function properly on this mower.
SAFETY WARNING:
Disconnectthe sparkplug lead.
Fig. 12
It isnecessary to remove the engine when replac-
ing the belt.
Remove the blade nut, blade and collar. Remove
three screws securing muffler and crankshaft sup-
port. Remove muffler.Fig. 13.
Fig. 13
Fig. 11
SERVICE BULLETIN REFERENCES.. 20-3
OCTOBER 1984

Removethefourboltsthatretainthe engine totheInstall a new exhaustgasket.Fig. 16.
muffler plate. Fig. 14.
NOTE:
Hold theengine while removing these bolts.Don’t
let it drop.
Fig. 16
Place the new belt over the drive pulley andset
engine back onto the muffler plate. Fig. 17.
Fig. 14Don’t disturbthe newexhaust gasketwhen putting
Lift the engine up and remove the old belt.
Also
remove the old exhaust gasket and dispose of it.
the engine in place.
Fig. 17
Fig. 15

Block one sideofmower up. Fig. 18. Clean the
threads of theengine mounting bolts withLOCQuic
Primer, Part #384884. Apply OMC Ultra Lock, Part
#388517 to thethreads of the bolts andassemble
all four into the engine mounting holes.
Clean the threads ofthethree mufflerscrews with
LOCQuic Primer, Part #385884. Apply OMC Ultra
Lock, Part #388517 to the threads.
Assemble the muffler, crankshaft support (flange
down) and start the three screws.
Fig. 18 Fig. 20
Tighten allfour engine mounting bolts to150-190
in.Ibs. (11-15 ft. Ibs.) Slide crankshaft supportgauge, Part #609968 over
the crankshaft with the thin wall of gauge going
between the support and crankshaft. Fig. 21.
Fig. 19
Fig. 21
SERVICE BULLETIN REFERENCES 20-5
OCTOBER 1984

Tighten all three screws to 142-170in. Ibs.,12-14
ft. Ibs. Fig. 22.
Fig. 22
Assemble the collar, bladeand nut ontocrankshaft.
Tighten blade nut to 45-50 ft. Ibs.
NOTE:
If the blade nut has been on and off four times it
should be replaced.
If not replaced, apply OMC
Ultra Lock tothreads of crankshaft before install-
ingnut.
SAFETY WARNING:
Check the torque of all fasteners under the deck.
fortightness.Aloosefastenercanbecomea
.thrown object.
Assemble thebeltonthe drivepulleyofthe
cranksha’ft. With the idler pulley bracketloose, the
belt should assemble over the driven pulley very
easily.Fig. 24.
Fig. 24
Movethe idler pulleystoapply tension on belt.Cor-
rect tension willbe approximately3/8” deflection
withfirm finger pressure. Fig. 25. Rotateengine
several times toseat beltingrooves. Recheck belt
tension and adjust as necessary.
After completing the belt replacement,start and
runthemower to checkoperation of the drive
system.
Fig. 25
Fig. 23
20-6 SERVICE BULLETIN REFERENCES
OCTOBER 1984

Fig. 27
Fig. 29
BULLETIN REFERENCES 20.7
OCTOBER 1984

To prevent dirt from entering insideof the wheel,
apply Lawn-Boy “A” grease in the groove of the
wheel cover. Fig. 30.
The transmissionassemblyisfilledwith “A”
grease at thefactory and should notrequire addi-
tional lubrication. However,
if seepageof the lubri-
cant is noted coming fromaround the seals
or from
the transmission housing gasketarea (Fig. 32-A),
greasecanbeaddedthroughthe zerk fitting
located on, the lower sideof the transmission. Fig.
32-6.
Fig. 30
Every
50 hours of operation the rear wheel bolts
should be lubricated. Removeand clean the wheel
bolt, liberallyoil the bearing and each felt washer
andreassemble.Fig. 31.
Fig. 32-A Fig.32-6
Should itbe necessaryto add lubricanttotransmis-
sion, watch for an
upward movement ofthe clutch
armwhen putting greasein.Whenmovement
is
noted,stoptheflowoflubricantimmediately.
Fig. 33.
NOTE:
Do not put an excessive amount in transmission
because there is a possibilityof a pressure build-
upresulting inseal failures.
Fig. 33
20-8 ................................................................................................................................................................... SERVICE BULLETIN REFERENCES
OCTOBER
1984

FRONT WHEEL MAINTENANCE
It is not necessary to lubricatethefront wheel
bolts.
For engine,exhaustandbladeservicingrefer
to
their respective sections in the Manual.
TRANSMISSIONSERVICING AND REPAIR
WARNING:
Disconnect the spark plug lead.
Remove the hairpinretainers and detach the han-
dle from the brackets. Lay the handle down over
front
of mower. Fig. 34.
Remove thedrivenpulleyassemblyfrom the
transmission. Fig. 36.
Fig. 36
Removethe 7/16” nut from long transmission bolt
thatretainstheclutch cablebracketandspring
assembly totransmission. Lift thebracket, springs
andarmassembly offtransmission. Lay to one
side.
Fig. 34
Remove two screws and lift cover off. Fig. 35.
Fig. 37
.Fig.35
SERVICE BULLETIN REFERENCES 20-9
OCTOBER 1984

An “0” ring is preassembled on thehubofthe
clutch arm before final assembly.When removing
the arm from the transmission, the
“0” ring slides
off into the holeand around thesquare shaft of the
shift fork. It willhave to be removed from the hole.
Fig. 38.
Remove the rightrear wheelbolt with a314” socket.
Fig. 38
To free the transmission from the housing,remove
the shoulder bolt and nut.Fig.
39.
Fig. 39
Fig. 40
Using a pair of expansion pliers,removethe retain-
ing ring from end of shaft. Fig. 41.
Fig.
41

The pinion gear is driven with a spring loadedkey
located inthe shaft. Before removing thegear, turn
it in bothdirections. It turns forwardfreely with a
clicking or ratcheting noise. Thisnoise is created
by thekey droppingover the drivingshoulder of the
gear. Turnbackwardandtheshoulderofthegear
moves up againstthe key which provides the self-
propelling. This willbe found on bothrear wheels.
Fig.
42
When removingthe gear from the shaft, bevery
careful because thekey, being springloaded, can
pop out and be lost. The spring also canbecome
lost.Fig.
43.
Fig. 43
Behind the pinion gear is another retaining ring.
Remove it and slide the wheel cover off. Remove
the leftwheel, piniongear andwheel cover.Fig.
44.
SERVICE BULLETIN REFERENCES 20-11
OCTOBER 1984

Push the bronze bearing and retainers out of the
bracket. Check the bearing surfaces for damage
and wear. Replace
if necessary. Also note the six
lubricating holes in thebracket hub. When grease
flows in, it followsa passage around thehub and
out of each hole into the two holes in thebronze
bearing and lubricates the shaft. Fig. 46.
Carefully pull the transmission and shaft assembly
out of the ‘left hand bracket. Fig. 48.
Fig. 48
Unless there is leakage from around the seals or
gasket, or a failure internally,it willnot haveto be
disassembled.
Fig. 46
The plastic bearingretainers are in twohalves.One
half has a lug or tab that locatesin therecess of
the other half.The slots permit lubrication to flow
into the holes of the bronze bearing.
NOTE:
The bearing andplastic retainerassembly maybe
installed in brackethubas removed or reversed.
Either way is correct. Fig. 47.
Fig. 49
1. InputShaft
2. Driveshaft
3. Trans. MountingBoltHole
4. ControlCableMountingBolt
5. Seals
6. Shift Fork
Fig. 47
20-12 ................................................................................................................................................................. SERVICE BULLETIN REFERENCES
OCTOBER 1984

Remo’ve theinput (worm) shaft
assembly.
Fig.
50
1. Packing
2. InputShaft
& Bearing
3. Worm Wheel
4. “0” RingRetainer
5. ShiftCollar
6. Shift Fork
7. Driver Assembly
8. Bearing & Seal AssemblyFig. 51
and bearing
Fig. 52
1. Bearing
& Seal Assembly 10. DrivenPlates (7)
2. Thrust Race (Thin) 11. Driven Sleeve
3. ThrustBearing 12. Pin
4. Thrust Race (Thick) 13. ShiftCollar
5. Washer(Worm Wheel) 14. Shift Fork
6. WormWheel 15.
“0” RingRetainer
7. SnapRing 16. TransmissionPacking
8. Driver 17. TransmissionGasket
9. Driver Plates
SERVICE BULLETIN REFERENCES ................................................................................................................................................................. 20-13
OCTOBER 1984

Wash andcleanall parts.Inspectfor wear or
damage. Replace any worn or damaged parts.
If eithertheworm or wormwheel are worn or
damaged (Fig.
52), alwaysreplaceboth at same
time. Also,
if one or more of the driver plates or
driven plates are worn or damaged, replace all
of
them.
Whenever complete disassembly of the transmis-
sionis necessary, replacebothpackings and
gasket (Fig.
52).
Correct sequence in reassembly of the driver and
driven plates into the housing isvery important.
If
reassembled incorrectly, the transmission will not
function properly. There are six driver plates (Ref.
2) and seven driven plates(Ref. 3, Fig. 54). Starting
with
a driven plate,place itinthe housing.Next,
assembleadriver plate, then
a driven and continue
alternating withevery otherone being adriver plate
and the last one beingadriven plate. Assemble the
driven sleeve (Ref.
4, Fig. 54) into theplates, turn-
ing
so it willgo all theway down. If ithas engaged
all of the driven plates, it will be fully seated.
Fig.
54
Fig. 53
1. Driver
2. Driver Plate
3. Driven Plate
4. Driven Sleeve
The clutch assembly
will locate between the pin
hole andsnap ringgroove in the shaft.Fig.
55. The
spline end of driver housing will locatenext to the
groovewith the slottedend
of the drivensleeve be-
ing positioned over the pin hole.
Fig.
55
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OCTOBER
1984

Holdingtheclutchassembly in yourfingers, slide Assemblelarge spacer washer intorecessofworm
itontoshaft.Assemblepininhole and slide wheel. Fig.
59.
assembly over the pin. Fig. 56.
Assemble worm wheel onto the spline. Fig.
58.
Fig. 58
SERVICE BULLETIN REFERENCES 20.15
OCTOBER 1984

Checkto be sure the larger spacerwasher is in the
recess of the wormwheel. Push both bearingsup
against eachendof transmissionassembly.
Assemble the shiftfork in thegrooveof the collar.
As you place the assembly in thegearcase, guide
the lowerend of shift fork intopivot hole. Fig.66.
Fig. 66
Assemble the worm into thegearcase, Turn a few
revolutions to check its freedom. Fig. 67.
Fig. 67
NOTE:
Only Lawn-Boytype “A” grease is approved for use
in this transmission assembly.
If another lubricant
is used, it will result inafailure of the transmission.
FillthelowergearcasewithLawn-Boytype“A”
grea’se until it islevel with gasket surface.Fig. 68.
Fig. 68
Assemble a new gasket and set cover in place.
Fig. 69.
NOTE:
There aretwo assembly dowels molded into lower
case which locate in holes of upper case.
Fig. 69
SERVICE BULLETIN REFERENCES .......................... 20-17
OCTOBER 1984

Assemble the four short bolts into the housings
with theheads on top. Assemble the longbolt from
the bottom up through the longboss. Assemble the
washer,then thenutonthelongboltbutdon’t
tighten until last.Fig.
70.
The correct procedure in tightening the four short
bolts and nuts is to use a criss-crosspattern. The
required torque on each nut is
35-45 in. Ibs.To ob-
tain equaltightness, tighten oneto
20 in. Ibs.,then
crossover
to the opposite corner and tighten to20
in. Ibs. Tighten the other one on same side to 20
in. Ibs. and the fourth one the same.
Check the rotationof the shaft in bothdirections.
If o.k., usethesameprocedureintightening all
boltsto
35-45 in.Ibs.Recheck shaftrotation.
Fig. 72.
Fig.
70
Run all four nuts on short bolts up snug against
housing. Fig.
71.
Fig. 72
Slip the shaft into the self-aligning bearingof the
left bracket assembly.
A twisting motion will posi-
tion the transmission into place in themowerhous-
ing.Fig.
13.
Fig. 71
Fig. 73
20-18.: SERVICE BULLETIN REFERENCES
OCTOBER
1984

Align the transmission with the mounting hole in
the mower housing.Inserttheshoulderbolt
through the mountinghole, install thewasher over
the threads, andassemble tothe transmission.
Fig. 74.
Secure withthenuttightenedto 35-45 in. Ibs.
Fig. 74
Assemble theright bracketassembly ontothe
shaft. Installthree boltsand start the nuts. Tighten
to 142-170in. Ibs. (12-15 ft. Ibs.)
Fig. 75
SERVICE BULLETIN REFERENCES OCTOBER
Before installingthe wheel cover ontheshaft,
apply Lawn-Boytype “A”greasein thegroove.This
grease stops dirt and debris from enteringthe gear
area of the wheel. Fig. 76.
Fig. 76
Assemble the washer, the retaining ring and the
spacer onto the shaft. Fig. 77.
Fig. 77
Apply Lawn-Boy type “A” grease to the keyseats
in the shaft.
Place the small ratchet springinhole of the shaft.
Fig.
78
Fig. 78
.......................................................................................................... 20.19
iR 1984

Place the pinion gear drive key in slot. Fig. 79.
Fig. 79
To install the pinion gear, it will be necessary to
push the spring loadedkey down while sliding the
gear on.Besure the key stays inplace. Assemble
the second spacer andretaining ring.After thegear
isinstalled, turn itforward. Itshould turn freely and
you shouldhear a “clicking” sound which is thekey
moving over andoffthe driveshoulder.Turnit
backward. The drivingshoulderinsidethegear
should come against the key and stop the rotation.
If it doesn’t function as describedabove you have
assembled it backward. Remove the gear very
carefully toprevent losing thekey and spring and
turn thegear end forend andreassemble it. Fig.80.
Apply afilmof Lawn-Boyoil tothe wheel bolts. Fig.
81-A. Assemblethe wheel and tighten the bolt. Also
apply a generousamount of Lawn-Boy
“A” grease
in the planetary gear of the wheel. Fig. 81-B.
Fig. 81-A Fig. 81-B
Repeatassembly procedures followingFig. 76
through Fig.81-B on the left wheel.
Fig. 82
Fig. 80
20-20 SERVICE BULLETIN REFERENCES
OCTOBER
1984