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IH: Transmission & Final Drive

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

Clutch

Sub-Documents

* . . . How to Adjust a Dry 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.

Shifter Cam Assembly

  • Shifting problems after considerable mileage could be caused by a loose shifter cam assembly which results in trouble shifting the lever into various gears. It can also cause the transmission to suddenly drop out of gear.
  • The shifter cam assembly is secured to the access cover with a bolt (7/16”x14x1-1/8”), a lockwasher and 2 dowel pins registering in the access cover. If the assembly becomes loose, the (press fitted) dowel pins can work loose from the assembly and into the access cover holes. When the dowel pins have successfully worked their way out of the assembly support, the shifter cam will tip causing a bind in the mechanism. 1)
  • If you’re having shifting problems and you’re sure it’s not because of a dragging clutch (before doing exploratory surgery on the internal tranny parts), try removing the chain cover and check for a loose shift assembly bolt. The bolt may appear tight, but it has been known to bottom out in the hole from being slightly too long which allows it to get tight before full clamping force on the assembly. 2)
  • To properly tighten up the assembly, you can remove the clutch and access cover to check and make sure the dowel pins are properly press fit into the support holes and are a snug fit into the access cover. If the dowels are loose in the cover holes (slight wear), try replacing the standard dowel pins (9220A) with an oversized pair (+0.001 - 9225A), (+0.002 - 9227A) or (+0.003 - 9229A). 3) If the holes are out of round in the access door, the door may have to be replaced. A good machinist could probably re-drill the holes straight to accept bigger pins also. 4)
  • When re-assembling the shifter assembly to the access cover, be sure the bolt and lockwasher secure it tight to the door. If necessary, you can shorten the bolt by 1/16” (or one thread) with a Dremil tool with a metal cutting blade or a hacksaw. If the bolt still bottoms out, the threaded hole is too shallow and the pawl carrier support (34514-52) may have to be replaced. 5)
  • Click here for pics and identification of shifter assemblies: Pics of Pawl Carriers and Pawl Carrier Supports

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

Clutch Sprocket Assembly

  • Late 1957-1966 XL, XLH, XLCH (37702-57) 6)
  • 1967-1969 XLCH (37702-57) 7)
  • 1967-1970 XLH (37700-67) 8)
  • 1970 XLCH (37701-70)9)

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 10) 11): 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

Clutch Gear, Clutch Gear Washer, Needle Bearings & Bushing, Drive Sprocket

1956-1966 KH (engine #1465 →) XL/XLH/XLCH
1967-1969 XLCH 12)
Clutch Gear37450-56
replaced by
37449-56
Clutch Gear Washer35361-56
Needle Bearings (2)35960-54 (closed end)
replaced by
35961-52 (open end)
Clutch Gear Bushing37458-52
Drive Sprocket 21T 13)
1952-1953 K/KK
1954-1955 KH (engine #1689 →) 14)
1957-1959 XL
1958-E1967 XLH
1958-1971 XLCH (except 1959)
35205-52
replaced by
35205-52A
Drive Sprocket 20T 15) 16) 17) 18) 19)
1959-1971 XLCH
L1967-1971 XLH
35198-52
Drive Sprocket 19T 20) 21)
1953-1956 K/KH
L1969 XLCH (engine #69XLCH-5921 →)
35197-52
1967-1970 XLH
1970 XLCH
Clutch Gear37448-67
Clutch Gear Washer35361-56
Needle Bearings (2)35961-52
Clutch Gear Bushing37458-52
Drive Sprocket 21T 22)
XLH/XLCH
35205-52A
Drive Sprocket 20T 23)
XLH/XLCH
35198-52
Drive Sprocket 19T 24)
XLH/XLCH
35197-52

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

Countershaft Low Gear Changes

Countershaft Low Gear -17TChange YearModel(s)Notes
35760-52
1952-1953
K & KK Models
35759-54
1954-1956
KH Model
35760-54
1957-Early 1966 25) 26) 27)
1957XLH/XLCHSingle counter-bore (case side) allowing gear to slip over the right case casting boss.
Cannot be used on Late '66 and later right case with added fillet at the base of the gear boss.
35760-54A
1957-1971 (replacement part) 28) 29) 30)
Late 1966XLH/XLCHReplaced 35760-54 with an added counter-bore on case side to clear the added fillet in the new cases.
35760-54B
1957-1972 (replacement part) 31) 32) 33)
1972


1) , 2) , 3) , 4) , 5)
HD Service Bulletin #541 dated July 15, 1966 pg OC-225
6) , 7) , 8) , 9)
HD Sportster Parts catalog 99451-78B
10)
1959-1969 HD Sportster FSM pg 1A-3
11)
1970-1978 HD Sportster FSM pg 1-1
12)
HD Spare Parts Catalog for all Sportster and K Models 1952-1959 pg 31
13) , 15)
1957-1967 HD Sportster and KH Model Parts Catalog pg 39
14)
HD Spare Parts Catalog for all Sportster and K Models pg 30
16)
1959-1969 Sportster and KH Model Parts Catalog
17)
1952-1959 HD Spare Parts Catalog pg 35
18) , 20)
1953-1963 HD Parts Catalog for Sportsters and K Models pg 38
19) , 21)
1961-1971 HD Sportster Parts Catalog pg 41
22) , 23) , 24)
1954-1976 HD Sportster Parts Catalog pg 57
25) , 28)
HD Service Bulletin #537 dated March 22, 1866 pg OC-221
26)
1952-1959 HD Sportster and K Model Parts Catalog pg 30
27) , 29)
1954-1967 HD Sportster Parts Catalog pg 34
30) , 31)
1954-1971 HD Sportster Parts Catalog pg 34
32)
1954-1976 HD Sportster Parts Catalog pg 45
33)
1954-1978 HD Sportster Parts Catalog pg 51
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