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IH: Transmission & Final Drive

1957 - 1970 Sportster Four-Speed Constant Mesh Dry Clutch Transmission Specifications

Clutch

  • Type: Dry - Multiple disc (7 friction plates, 7 steel plates between a steel backing plate and a front releasing disc)
    • Back to front: Backing plate-S-F-S-F-S-F-S-F-S-F-S-F-S-F-Releasing disc
  • Capacity: 1900 in-lbs. (158.33 ft lbs.)
  • Set up Spring Pressure: 150 lbs.
    • Spring adjustment: 3/16 in. from inner surface of spring tension adjusting plate to outer surface of spring cup flange
  • Clutch bearing: .0005 - .002 in. loose
  • (1970) - .0005 - .0029 in. loose
  • Clutch cover: Must be leak proof. No gasket sealer
  • Clutch release rod movement: .095 - .115 in.

Adjusting Clutch Release Mechanism

  • Loosen clutch release rod adjusting screw lock nut and rod adjusting screw. Clutch release worm (inside the sprocket cover) should seat against it's stop when clutch handle is fully extended. If lever doesn't fully seat, check for cable binding in housing.
  • Adjust cable length by turning the adjusting sleeve (at hand lever) so the clutch release worm does not quite return against it's stop. This will hold the hand lever in it's fully extended position at all times.
  • Tighten clutch release rod adjusting screw until hand lever has 1/8 in. free play before clutch starts to release (slight tension).
  • Tighten locknut without disturbing the current cable setting.

Primary Drive (engine to transmission)

Year Model(s)Engine SprocketClutch Sprocket
Standard1966 & Earlier XLCH
1967 & later XLH, XLCH
34 Teeth59 Teeth
Optional1966 and Earlier XL, XLH
1967 XLH, XLCH
34 Teeth59 Teeth

Primary Chain

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

Kick Starter

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.

  • Minimum clearance between clutch teeth on starter clutch gear and clutch with starter in up position: .040 in.
  • Crankshaft endplay: .001 - .007 in.

Electric Start

On 1967 and later model XLH, an electric starter motor and Bendix type drive unit engage the ring gear on the clutch to crank the engine.

Gear Shifter

  • The shifter is located on the right side of the engine and is foot operated transmitting force through the gear shift shaft, actuating pawl carrier, pawls and gear shifter cam.
  • The shifter cam moves shifter forks which slide a series of gear clutches on the mainshaft and countershaft into mesh with the various gears to obtain the desired ratios.

Transmission

  • Overall Gear Ratios are the number of engine revolutions to drive rear wheel one revolution.
Overall Gear Ratios
Year Models1st2nd3rd4th
Standard1966 & Earlier XLCH
1967 & Later XLH, XLCH
11.16:18.08:16.11:14.42:1
Optional1966 & Earlier XL, XLH
1967 XLH, XLCH
10.63:17.69:15.82:14.21:1

Transmission Oil Capacity 1957-1970: 1) 2): 1.5 pints / (24 oz) / (710 ml)

Final Drive (Trans to Wheel)

Year Model(s)Transmission SprocketRear Wheel Sprocket
Standard1966 & Earlier XLCH
1967 & Later XLH, XLCH
20 Teeth51 Teeth
Optional1966 & Earlier XL, XLH
1967 XLH, XLCH
21 Teeth51 Teeth

Torque Specs

Clutch Hub Nut150 ft lbs

Mainshaft Group

  • 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: .004 - .009 in.
  • (1970) .003 - .009 in. with all axial play removed
  • Third gear
    • On shaft: .002 - .003 in. loose
    • End play: .015 - .025 in. loose
    • (1970) .012 - .030 in

Countershaft Group

  • Countershaft end bearings: Retained needle roller bearing
  • Bearing fit on shaft ends: .0005 - .002 in. loose
  • Bearing fit in case: press
  • 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.
  • Drive gear
    • On shaft: .001 - .0025 in. loose
    • (1970) .0005 - .0030 in. loose
    • End play: .004 - .009 in.
  • Clearance between clutch faces
    • Countershaft low an third gear: .038 - .058 in.
    • Countershaft second and third gear: .038 - .058 in.
    • 1970
      • Mainshaft clutch gear and second gear: .043 - .083 in.
      • Mainshaft third gear and second gear: .043 - .083 in.
      • Shifter end play: .010 - .030 in


1)
1959-1969 HD Sportster FSM pg 1A-3
2)
1970-1978 HD Sportster FSM pg 1-1
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