Table of Contents

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IH: Transmission & Final Drive

1971 - 1985 Sportster Four-Speed Constant Mesh Wet Clutch Transmission Specifications

Clutch

  • Type
    • Wet - Multiple disc
  • 1971-1978 1)
  • 8 Drive plates (37985-71), 8 Driven Plates (37992-71A), with an outer drive plate (37987-71) and retaining ring (11053).
  • Back to Front : Backing Plate-F-S-F-S-F-S-F-S-F-S-F-S-F-S-F-S-Outer Drive Plate with retaining ring.
  • Capacity: 1900 in-lbs (158.33 ft lbs.)
  • Set up Spring Pressure
    • 1971: 234 lbs. 2)
    • 1972: 257 lbs. 3)
  • Spring adjustment
    • 1971 - 1973: 11/32 in. from outer surface of outer drive plate to outer surface of releasing disc 4)
    • Late 1974 & later: Fixed spacers standard length 1.530 in. 5)
  • Clutch bearing: .0005 - .002 in. loose 6)
  • Periodic adjustment of the clutch is required every 2,000 miles to compensate for lining wear. 7)
  • Adjustment may also be necessary with the clutch slipping under load or dragging in the released position. 8)
  • 1979- Early 1984 9)
  • Capacity: 174 ft lbs.
  • Spring Adjustment- Fixed spacers standard length 1.530 in.
    • Free Length- inner- 2-25/64 in.
    • Free Length- outer- 2-25/64 in.
  • Clutch Shell Bearing on clutch gear: .0000 - .0010 in. loose
  • Late 1984-1985 10)
  • Capacity:174 ft lbs.
  • Spring Force (engaged): 304 lbs.
  • Spring Force (dis-engaged):260 lbs.
  • Clutch Shell Bearing on clutch gear: .0000 in. - .0010 in. loose

Adjusting Clutch Release Mechanism

Clutch adjustment is recommended every 2,000 miles to compensate for lining wear or when clutch slippage under load, or when clutch is dragging in released position. 11)

  • Loosen adjuster locknut at primary case and turn adjuster inward until there is a large amount of free play at hand lever. 12)
  • Remove access plug from primary cover to view adjusting screw. 13)
  • Loosen adjusting screw lock nut and turn adjusting screw inward until it becomes harder to turn (starts to release the clutch) and continue turning (app 2 more turns) to be sure clutch is dis-engaged. 14)
  • Adjust all free play out of control cable by turning adjuster outward. Do not put any tension on cable. With all slack in cable taken out (no play at hand lever) tighten the adjuster locknut. 15)
  • Ready for final clutch release adjustment: Loosen the locknut and back off the adjusting screw until the clutch is engaged (pressure is off the screw) then turn screw inward until the point of no free play. Then turn the adjusting screw outward 1/4 - 1/2 turn to establish the correct amount of free play and tighten the lock nut. Check free play at hand lever. you should have 1/8 in. free play. If not, adjust sleeve and tighten lock nut. 16)
  • If clutch slips or drags after these adjustments, it may be necessary to inspect / adjust the clutch springs and / or clutch release mechanism for defects. 17)

Primary Drive (engine to transmission)

Year Model(s)Engine SprocketClutch Sprocket
1971-1978 all models 18) 34 Teeth59 Teeth

Clutch Sprocket Assembly

1971-1978 XLH
1979 XL
1979-1980 XLS		(37716-71A) 19)20)
1971-1978 XLCH
1979 XL, XLS		(37717-79) 21)22)
Early 1979 XLCH37701-71A 23)
1981-Early 1984 XL, XLS, XLX37716-81 24)
Late 1984-1985 all models
Clutch Shell & Sprocket
w starter gear		36791-84 25)

Primary Chain

  • Type primary: 3/8 in. pitch triple chain 26)
  • Looseness: 5/8 to 7/8 in. slack (cold engine) - 3/8 to 5/8 in. slack (hot engine) 27)

Kick Starter

On the XLCH, the kick starter provides a means of starting the engine by manual power. When the pedal is moved in a downward stroke, ratchet teeth of the starter clutch gear and the starter clutch are engaged, transmitting force to the clutch sprocket, primary drive chain and to the engine sprocket. 28)

  • Minimum clearance between clutch teeth on starter clutch gear and clutch with starter in up position: .040 in. 29)30)
  • Crankshaft endplay: .001 - .007 in. 31)32)
  • 1979 was the last year you can outfit a Sportster with a kickstarter 33)

Electric Start

On the XLH, an electric starter motor and Bendix type drive unit engage the ring gear on the clutch to crank the engine. 34)

Transmission

  • Overall Gear Ratios are the number of engine revolutions to drive rear wheel one revolution. 35)
1971- 1985 model(s) Overall Gear Ratios
1st2nd3rd4th
1970-1971 XLCH36)11.748.506.434.66
1970-1973 XL, XLH
1972-1973 XLCH37)		11.168.086.114.42
1973-1981 all models38)39)10.637.705.824.22
1982- Early 1984 all models40)10.027.255.493.97
Late 1984-1985 all models41)10.017.255.493.97

Transmission/ Primary Oil Capacity 42) 43): 1.5 pints (24 oz) (710 ml)

Final Drive (Trans to Wheel)

Year Model(s)Transmission SprocketRear Wheel Sprocket
1970-1971 XLCH44)19 Teeth51 Teeth
1970-1973 XL, XLH45)
1972-1973 XLCH46)		20 Teeth51 Teeth
1973-1981 all models47)21 Teeth51 Teeth
Early 1979 XL, XLCH48)19 Teeth
20 Teeth
21 Teeth 		51 Teeth
Late 1979-1981 XL, XLS, XLX 49)21 Teeth 51 Teeth
1982-1985 XL, XLS,XLX 50)21 Teeth48 teeth

1971-1985 Torque Specs

1979 - Late 1984 Torque Specs

Clutch Hub Nut51)110 - 150 ft lbs
Mainshaft Nut52)35 - 65 ft lbs
Access Cover Screws53)13 - 15 ft lbs
Drain Plug54)14 - 21 ft lbs
Primary Cover Screws55)80 - 110 in. lbs
Chain Tensioner Stud Nut56)8 - 12 ft lbs

Late 1984 - 1985 Torque Specs

Mainshaft Nut Locking Screw57)50 - 60 in. lbs
Mainshaft Nut58)35-65 ft lbs
Access Cover Screws59)13 - 15 ft lbs
Drain Plug60)14-21 ft lbs
Primary Cover Screws61)80 - 110 in. lbs
Chain Tensioner Stud Nut62)8 - 12 ft lbs
Stator Screws (4 slotted)63)20 - 35 in lbs
Stator Mounting (4 hex socket)64)20 - 35 in lbs
Stator Mounting Torx fasteners65)30 - 40 in. lbs

Mainshaft Group

  • 1971 - 1978 66)
  • Clutch gear ball bearing in case: .0001 - .0012 in loose
  • Ball bearing on clutch gear: .0001 in. loose - .0009 in. tight
  • Clutch gear on mainshaft: .001 - .002 in. loose
  • Mainshaft right side roller bearing: .0006 - .0014 in. loose
  • Mainshaft end play: .003 - .009 in. with all axial play removed
  • Third gear
    • On shaft: .002 - .003 in. loose
    • End play: .012 - .030 in. loose
  • 1979 - Early 1984 67)
  • Clutch gear ball bearing in case: .0001 - .0012 in loose
  • Ball bearing on clutch gear: .0009 in. tight
  • Clutch gear on mainshaft: .001 - .002 in. loose
  • Mainshaft right side roller bearing: .001 - .0034 in. loose
  • Mainshaft end play:
    • No axial play (minimum)- .003 in.
    • With axial play - .020 in.
  • Clearance between clutch faces:
    • Mainshaft fourth gear and second gear: .028 - .058 in.
    • Mainshaft third gear and second gear: .028 - .058 in.
  • Late 1984 - 1985 68)
  • Clutch gear ball bearing in case: .0001 - .0012 in loose
  • Ball bearing on clutch gear: .0009 in. tight
  • Clutch gear on mainshaft: .001 - .002 in. loose
  • Mainshaft right side roller bearing: .001 - .0034 in. loose
  • Mainshaft end play:
  • Minimum - .009 in.
  • Maximum - .015 in.
  • Clearance between clutch faces:
  • Mainshaft fourth gear and second gear: .028 - .058 in.
  • Mainshaft third gear and second gear: .028 - .058 in.

Countershaft Group

  • 1971 - Early 1978 69)
  • Countershaft end bearings: Retained needle roller bearing
  • Bearing fit on shaft ends: .0005 - .0029 in. loose
  • Bearing fit in case: press fit
    • End play: .004 - .009 in.
  • Second gear
    • On shaft: .001 - .0025 in. loose
  • Low gear
    • On shaft: .0005 - .0016 in. loose
    • End play: .004 - .009 in. (1971-1978)
  • Drive gear
    • On shaft: .0005 - .0030 in. loose
    • End play: .004 - .009 in. (1971-1978)
  • Clearance between clutch faces
    • Countershaft low an third gear: .038 - .058 in.
    • Countershaft second and third gear: .038 - .058 in.
    • Mainshaft clutch gear and second gear: .043 - .083 in.
    • Mainshaft third gear and second gear: .043 - .083 in.
  • Shifter end play (1971-1976): .010 - .030 in.
  • 1979-Early 1984 70)
  • Countershaft end bearings: Retained needle roller bearing
  • Bearing fit on shaft ends: .0005 - .0030 in. loose
  • Bearing fit in case: press fit
    • End play: .004 - .009 in.
  • Second gear
    • On shaft: .001 - .0025 in. loose
  • Low gear
    • On shaft: .0005 - .0016 in. loose
  • Drive gear
    • On shaft: .0005 - .0030 in. loose
  • Clearance between faces
    • Countershaft low an third gear: .028 - .058 in.
    • Countershaft second and third gear: .028 - .058 in.
  • Countershaft end play: .004 - .015 in.
  • Late 1984 - 1985 71)
  • Countershaft end bearings: Retained needle roller bearing
  • Bearing fit on shaft ends: .0005 - .0030 in. loose
  • Bearing fit in case: press fit
  • Second gear
    • On shaft: .001 - .0025 in. loose
  • Low gear
    • On shaft: .0005 - .0016 in. loose
  • Drive gear
    • On shaft: .0005 - .0030 in. loose
  • Clearance between faces
    • Countershaft low an third gear: .028 - .058 in.
    • Countershaft second and third gear: .028 - .058 in.
  • Countershaft end play: .004 - .015 in.


1) , 2) , 3) , 4) , 5) , 6) , 26) , 27) , 28) , 29) , 31) , 35) , 66) , 69)
1970-1978 HD Sportster FSM pg 4-1
7) , 8) , 11) , 12) , 13) , 14) , 15) , 16) , 17)
1970-1978 HD Sportster FSM pg 4-6
9) , 30) , 32) , 39) , 40) , 67) , 70)
1979-1985 HD Sportster FSM pg 6-3
10) , 41) , 57) , 58) , 59) , 60) , 61) , 62) , 63) , 64) , 65) , 68) , 71)
1979-1985 HD Sportster FSM pg 6-31
18) , 36) , 37) , 38) , 42) , 44) , 45) , 46) , 47)
1970-1978 HD Sportster FSM pg 1-1
19) , 21)
HD Sportster Parts Catalog 99451-78B pg 71
20) , 22) , 23) , 24)
1979-1985 HD Sportster Parts Catalog pg 55
25)
1979-1985 HD Sportster Parts Catalog pg 57
33)
dave76 http://xlforum.net/vbportal/forums/showthread.php?t=513989&highlight=speed
34)
1970-1978 HD Sportster FSM pg 4-2
43)
1979-1985 HD Sportster FSM pg 2-1
48) , 49) , 50)
1979-1985 HD Sportster Parts Catalog pg 61
51) , 52) , 53) , 54) , 55) , 56)
1979-1985 HD Sportster FSM pg 6-4
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Trace: • IH: Transmission & Final Drive