Click on a pic to enlarge:

1977 4 Speed Transmission 1)	1977 4 Speed Trap Door 2)
1978 4 Speed transmission 3)

• Type
  • Wet - Multiple disc

• 1971-1978 ⁴⁾
• 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. ⁵⁾
  • 1972: 257 lbs. ⁶⁾
• Spring adjustment
  • 1971 - 1973: 11/32 in. from outer surface of outer drive plate to outer surface of releasing disc ⁷⁾
  • Late 1974 & later: Fixed spacers standard length 1.530 in. ⁸⁾
• Clutch bearing: .0005 - .002 in. loose ⁹⁾

• Periodic adjustment of the clutch is required every 2,000 miles to compensate for lining wear. ¹⁰⁾
• Adjustment may also be necessary with the clutch slipping under load or dragging in the released position. ¹¹⁾

• 1979- Early 1984 ¹²⁾
• Capacity: 174 ft lbs.
• Spring Adjustment- Fixed spacers standard length 1.530 in.
  • Free Length- inner- 2-25/64 in.
    • Wear limit: 2 - 11/32 in.
  • Free Length- outer- 2-25/64 in.
    • Wear limit: 2 - 11/32 in.
• Clutch Shell Bearing on clutch gear: .0000 - .0010 in. loose
• Clutch Plate max. warp-age: .010 in.

• Late 1984-1985 ¹³⁾
• 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

Clutch adjustment is recommended every 2,000 miles to compensate for lining wear or during clutch slippage under load, or when clutch is dragging in released position. ¹⁴⁾

• Loosen adjuster locknut at primary case and turn adjuster inward until there is a large amount of free play at hand lever. ¹⁵⁾
• Remove access plug from primary cover to view adjusting screw. ¹⁶⁾
• 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. ¹⁷⁾
• 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. ¹⁸⁾
• 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. ¹⁹⁾
• 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. ²⁰⁾

Clutch Sprocket Assembly

Primary Chain

• Type primary: 3/8 in. pitch triple chain ²⁹⁾
• Looseness: 5/8 to 7/8 in. slack (cold engine) - 3/8 to 5/8 in. slack (hot engine) ³⁰⁾

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. ³¹⁾

• Minimum clearance between clutch teeth on starter clutch gear and clutch with starter in up position: .040 in. ³²⁾³³⁾
• Crankshaft endplay: .001 - .007 in. ³⁴⁾³⁵⁾
• 1979 was the last year you can outfit a Sportster with a kickstarter ³⁶⁾

On the XLH, an electric starter motor and Bendix type drive unit engage the ring gear on the clutch to crank the engine. ³⁷⁾

1971-1974

• 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. ³⁸⁾
• 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. ³⁹⁾

1975-1976

• To convert shifting from right side to left side, the shifter pedal was moved to the left side of the motorcycle and connected through a cross shaft linkage system to the shifter mechanism on the right side. ⁴⁰⁾

1977-1985

• The shifter shaft was redesigned again (34628-75) for 1977 and up models but still leaving it on the left side of the bike. ^{41) 42)}

1977-1985 shift lever shaft 43)

• Overall Gear Ratios are the number of engine revolutions to drive rear wheel one revolution. ⁴⁴⁾

Transmission/ Primary Oil Capacity ^{51) 52)}: 1.5 pints (24 oz) (710 ml)

• Measuring the spacing is tedious. With the trans assembled and fixed in a vice by the bottom edge of the trap door, ensure that none of the parts make contact with the vice while you are turning the gears. Try not to drop the trans on the floor too many times while setting this up To proceed, the trans must be firmly set up so that you can run it thru the gears. ⁷⁵⁾
• To measure the gear spacing consistently hold the assembly in such a way that the gears do not move around while you are measuring. You have to press inward lightly on the end of the shafts or on the outermost gear, then ensure that they stay in place while you proceed. Hold the two parts that you are measuring so that they do not move while you are measuring. But do not be too aggressive with this keeping things from moving - you want to simulate what it will be like in a running setup. You do not want to cram them together, just do it enough that every time you do it you will get the same result. ⁷⁶⁾
• So you need at least three hands, possibly more, one or two to hold the assembly from moving and changing the spacing while you are working, and another one or two to manage the feeler gauge. It can be done with just two though ⁷⁷⁾
• There are only a few options in setting the spacing. I believe that the best you can do is to get somewhere in the range. The shift forks must be in place - one of the options to adjust spacing is to replace the shift forks with different sizes. ⁷⁸⁾

Mainshaft

• On the mainshaft, measure between the tips of the dogs on 4th and the face of 2nd; and measure between the face of 3rd and the protrusion from 2nd. ⁷⁹⁾
• When setting mainshaft clearances, shims have no effect on fork setting so this can be done in either order ⁸⁰⁾

Countershaft

• On the countershaft measure the space between the tips of the dogs on 1st and the face of 3rd; and measure between the face of second and the protrusion from 3rd.
• When setting up clearances on the countershaft, especially if your current shift fork isn't getting you into tolerance and needs to be replaced with a different offset… ⁸¹⁾
• Do the fork spacing 1st, then shim for end play because on the counter shaft there are shims that go on both sides of c-shaft low gear (17t). ⁸²⁾
• The shims (2 shims on 73> type gear, one on 72< speedo type gear) on left (shaft) side of 17t gear will affect fork spacing. So, you can use them to your advantage with forks. ⁸³⁾
• When changing them for fork spacing after c-shaft has been shimmed in case will require you to re-shim in case for end play because you have changed the deck height of the c-shaft assembly. ⁸⁴⁾

• 1971 - 1978 ⁸⁵⁾
• 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 ⁸⁶⁾
• 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 ⁸⁷⁾
• 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.

• 1971 - Early 1978 ⁸⁸⁾
• 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 ⁸⁹⁾
• 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 ⁹⁰⁾
• 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.

• There were two different countershafts made for the Sportster 4 speed tranny. In the first picture below, the left one is used on both Ironhead and Evo models from late 1984 until 1990, ⁹¹⁾⁹²⁾ the last year of the 4 speeds.
• The shaft to the right in the first pic shows an Andrews version of the earlier style ('58-early '84)^{93) 94)} countershaft with the oiler hole in a hollow shaft ⁹⁵⁾.
• The oiler plug in the trapdoor catches oil and gravity feeds it through the counter shaft to 1st gear. It will get some amount of splash lube without it, but not as good of a jet of oil as if coming from the plug. ⁹⁶⁾ The oiler plug sticks outside of the case 7/16“. ⁹⁷⁾
• Before installing the oiler plug, set it off to the side until after you've set / checked your final countershaft endplay. otherwise it'll be in your way. ⁹⁸⁾
• The oiler plug should be a tight interference fit. It should go in and stay in with the engine running and vibrating and carrying on. Upon dis-assembly, many are found to be loose or rather the hole has probably been worn from the aluminum being smashed in and out of a few times without heating the aluminum trapdoor to expand it. This is why you should ALWAYS heat aluminum engine and gearbox casings, wheel hubs etc, with a propane torch before removing or installing bearings. Doing it cold works once, maybe twice, then the hole is worn out. ⁹⁹⁾
• To fix a loose oiler plug, you can take the plug to a machine shop and get them to knurl it. That will increase the diameter by a few thousandths. Then re-install it with Loctite. I would use the red, it is the strongest. But you will then need to use a propane torch to break the Loctite to get it back out. ¹⁰⁰⁾
• You can also peen the hole to retain the oiler. ¹⁰¹⁾
• Late '84 and up trap door does not include a countershaft oiler plug. When installed in this newer trapdoor in older applications, it may easily hit and scrubb the back of the stator due to being too long. It will either need to be machined down for your clearance measurements or the old style trapdoor must be used. ¹⁰²⁾

4 Speed Trans Countershaft comparison 103)	Early style HD 4 Speed Trans Countershaft 104)	Oiler Plug in '77 tranny 105)
Oiler Plug & Countershaft Needle Roller Bearing 106)

• There are 4 different versions of oem 'pawl carriers' and 5 oem versions of the 'pawl carrier support' (shift tower).
• Here the towers are in order:

1) Used on k models107)	#2/#3/#4) next 2 pics. No pic of #3 but the text should suffice.108)

109)	#5) changed for clearence of the '77-'90 shifter shaft coming in from the left 110)

Next is the old Trock cast iron tower. By far the best shift fork control Never breaks, best of both worlds. 111)	Left '72-'76 Shift Tower (taller shaft than on the right)	Right '77-'90 Shift Tower 112)

The FSM has no details on how to remove them and what specific tool to use. ¹¹⁴⁾

• For the countershaft bearings, select a socket (and extension) that just fits inside where the bearing is seated. Drive old closed end (and new) bearing from right to left with the socket/extension and a hammer using only light blows. The new bearing's max install depth is flush with outside of case (min depth is .030” left outside of case). For the trap door countershaft bearing, carefully remove the oiler plug without damaging the “snout”. Drive bearing out in the same manner with socket against printed end of bearing. Install new bearing 1/16“-3/32” below flush with inside edge of door. ¹¹⁵⁾
• Clutch gear bearing requires removing large snap rings, lightly hammer the clutch gear out with a small piece of wood between hammer and shaft. You can even thread the large nut on so it is on flush with the end of the shaft for support. Then the bearing needs to be pressed off. New bearing gets pressed onto the clutch gear until it is flush to the gear and install it into trap door. ¹¹⁶⁾
• An alternative for the needle bearing in the clutch gear: Find a washer that's the same size as the bearing and cut two flat places in the edge of the washer so it will pass through the bearing, turn it flat against the inside of the bearing and use a threaded piece of 5/16 rod through the bearing and washer, put nuts on each end of the rod and use a larger socket to pull it into. ¹¹⁷⁾

• The standard size for the 23 loose mainshaft rollers is .1562“ ¹¹⁸⁾.
• Question: When does fitting oversize rollers result in MORE running clearance? ¹¹⁹⁾
• Answer: when the same quantity of oversize rollers are fitted to a 'cageless full compliment bearing'. ¹²⁰⁾
• Below are two true geometric constructions of 23 rollers. ¹²¹⁾
  • 1st one is standard rollers packed into the tightest circle possible. No clearance roller to roller.¹²²⁾
  • 2nd one is same but with +.0008 rollers.¹²³⁾

¹²⁴⁾ Factory size of: Main Race is 1.305 dia.¹²⁵⁾ Mainshaft is .991¹²⁶⁾