The introduction of the Knucklehead and the 4-speed in 1936 marked an epoch in the history of American motorcycles. Many consider the period of 1936-84 the holy grail of Harley fuckin Davidson. To carry on that legacy we developed the BAKER 4-speed, available with ratchet top or jockey top lids. The external architecture of our cast (A356-T6) 4-speed transmission case was modeled after factory cases to capture all the details and character of the original design. But we made many functional upgrades to address shortcomings of the original design like leaks, serviceability, and durability. The loose rollers on the maindrive gear were replaced with a radial ball bearing. The bronze bushings on the gearset were replaced with caged needle bearings. We added a provision, hidden in the back of the case, for an electronic speedo but retained the traditional worm gear speedo provision on the front of the case. The stock Fred Flintstone shift detent was replaced with a snot-slick linear ball bearing detent for that smooth ‘snick-pop’ shift quality you expect from us.
– Vintage sand cast (A356-T6) design that holds true to the original 1936 through mid 1980’s.
– Hidden transmission vent designed into the Ratchet and Jockey Top covers
– Billet steel machined and case hardened shift systems (FL, FX and N1) that rotate on Permaglide bushings, for a smooth repeatable shift each time; see technical section.
– BAKER Klassic Gears come standard.
– Modern 4 speed gearset made out of 8620 gear steel.
– Gears ride on needle bearings, not bronze bushings.
– Vintage cast kicker cover with traditional 1 piece release rod and BAKER Heavy Duty throwout bearing.
– Direct bolt-in on most models; see technical section for instructions and 65-69 fitment.
– 5 Year limited warranty
Case Finish Options
You have 3 different options for case finish on the 4-Speed.
Shift Drum Options
We manufacture 3 shift drums for the 4-speed; the FX & FL types with conventional shift patterns and N1 style. Put an FX drum on a FL tranny and stomp down on the shift lever to upshift. Same thing if you put a FL drum on a FX tranny. The N1 drum takes the FX pattern and relocates neutral down below 1st for a N-1-2-3-4 pattern as an alternative to the standard 1-N-2-3-4 pattern. Great for foot clutch and performance applications.
We manufacture 4 different length mainshafts for the 4-Speed; the 1936-64, 1965-69 (1st year of electric start), 1970-E84 and a 1970-E84 splined mainshaft for a modern clutch setup. To see our mordern Splined Shovel Clutch Click Here. BAKER does not make the late 84 (diaphragm clutch) style tapered mainshaft. All mainshafts are designed for caged needle bearings for 3rd gear, no more metal to metal like stock.
All BAKER 4-Speeds come with our Klassic Kicker Gears standard. Made out of 1018 HR Steel, tumble finished to around a 20 micro and heat treated to 50-55 RC; these gears roll smooth as glass.
Kicker Cover Options
We manufacture and sale 6 different kicker covers making the 4-Speed completely customizable. Kicker covers come in different finishes ranging from the standard chrome cover to the raw replica cover. To see the full line of kicker covers available Click Here. Depending on the choice of cover and finish, charges might apply.
4-speed gears and shafts are manufactured with 8620 steel. Vacuum carburized heat treat gives a case hardness of 58-62 Rockwell ‘C’. Gear tooth profiles are ground and finished with diamond tooling after heat treat to correct the tooth distortion that naturally occurs when you put a chunk of steel in a very hot furnace. Take off the shifter lid on our 4-speeds and turn the shafts; you will hear silence because the involute profiles are perfect. The designers of this transmission back in the 30s would be envious of the improvements we made to their design with modern manufacturing processes. We added lead-in helical ramps on the shift clutches to improve shift quality. All bronze bushings were replaced with modern low friction bearings.
Case Options & Provisions
The 4-Speed Transmission case was modeled after the factory 1936 and 1965 cases to capture all the details and character, but we made some modern improvements as well. Our 1936-64 case is a no ear case which utilizes the stock style speedo gear drive while our 1965-E84 is an ear case. Both cases have the option to use the speedo gear drive location but we also molded an electronic speedometer mounting boss to follow the ear on our 1965-E84 case only. By tucking the electronic speedometer provision mount by the ear you can conceal any modern components keeping your bike looking stock. The electronic speedometer would utilize a stock 1996-2006 speed sensor, PN 74437-96. Pending what type of electronic speedometer you use, an additional speedometer recalibration box might have to be purchased, BAKER PN 95E-56A.
Like the stock 1936-64 4-Speed the BAKER 1936-64 cases have an alignment track on the bottom of the case (in between the studs), tongue-and-groove for the transmission plate to prevent lateral movement of the transmission. Any forward and aft adjustment are done through the adjuster boss location for the primary chain. This type of setup ensures a positive alignment when running belt drive applications, where you don’t have a inner primary to lock the motor to the transmission.
All 4-Speed top covers have a hidden vent system which allows the transmission to breathe. Machined into the internal walls of the billet top cover, the breathing system flows through the ratchet cavity and out through the shift cover. Jockey top covers are vent out through the bottom side of the cover just below the neutral switch. Click Here to see all top cover choices and information.
Speedo Gear Drive
All BAKER 4-Speed gearsets come with the gear drive ring installed. Using the list below; pending the year and model of your motorcycle you will have to use the following gear drive unit OEM part number or equivalent for your speedometer to function correctly.
|Year||Speedometer Drive Ratio||OEM Drive Unit PN|
|1936-61||2:1 Ratio, 7 Tooth Drive Ring Gear||67130-36 (11 Tooth Drive Unit)|
|1962-67||1:1 Ratio, 4 Tooth Drive Ring Gear||67130-61 (13 Tooth Drive Unit)|
|1968-80||1:1 Ratio, 7 Tooth Drive Ring Gear||67130-69 (23 Tooth Drive Unit)|
1947-61 FL Models use a 2:1 Ratio Speedometer
1962-80 FL Models, 1971-72 FX Models and 1980-83 Models use a 1:1 Ratio Speedometer
BAKER 4-Speed part numbers and default speedometer gear drive configurations unless specified by customer that they are using the 1962-67 ratio as specified above.
|4-3664||4-speed, no ear case, 2:1 speedo drive||1936-64 FL & FX|
|4-6569||4-speed, 1:1 speedo drive||1965-69 FL & FX|
|4-70E84||4-speed, 1:1 speedo drive||1970-E84 FL & FX|
|4-7090||4-speed, 1:1 speedo, splined mainshaft||1970-E84 FL & FX, see note|
– Part number 4-7090 comes with a splined mainshaft, you must convert to a splined diaphragm style clutch. BAKER offers the Shovel Clutch, for more information on the clutch click the image below.
– Default shifter lid is Ratchet Top Style for all part numbers. To specify Jockey Top add “JT” suffix
4-3664 comes standard with a ‘no ear’ case for tin primary compatibility. All other base part numbers come standard with ‘ear’ cases. To specify ‘no ear’ for other base part numbers add suffix ‘NE’
– Neutral switch is standard on ratchet and jockey top, to specify deletion of the neutral switch add a ‘NS’ to the part number. An low profile threaded plug is installed in place of the switch.
– Each transmission comes with a 23 or 24 tooth chain sprocket. Belt pulleys will not fit on the BAKER 4-Speed.
– The TTP, ‘Tin Type Primary’
– The Splined Shovel Clutch; highly recommended for Big Horse Power applications and durability
– Straight Kicker Arm; standard length or +1 inch
Click on any of the images below to learn more
Recommended Fluid / Level
Picking the right transmission fluid ensures the life and durability of your transmission, that’s why BAKER recommends a fully synthetic GL-5 rated gear weight oil of 75W-140. If a GL-5 rated gear lube is not available, these commonly carried viscosities (weights) will work 75W-90, 75W-140 and 85W-140. BAKER does not recommend the use of Syn3 (20W-50). For Bert’s article on ‘Oil & Spiders’ Click Here
BAKER 4-Speed Fluid Capacity Dry: 22-24fl-oz
BAKER 4-Speed Fluid Capacity Wet: 18-22fl-oz
BAKER 4 Speed install instructions with exploded views : Click Here