Baker Drivetrain 6 into 4 Complete Transmission Installation Instructions

BAKER DRIVETRAIN 6-INTO-4 INSTALLATION INSTRUCTIONS

Features

• 6061-T6 billet case and trap door provides more strength over the stock cast case
• BAKER™ Klassic Kickers gears installed with kicker transmissions
• Lower than stock first gear
• Improved neutral location with redundant neutral system and/or N1 shift drum
• RPM reduction at highway speeds in cruising gears
• Short, accurate shifts
• Kicker transmissions include the stainless steel BAKER™ Kick Arm assembly
• Optional 3.24 1st gear available
• Available with 23T or 24T chain sprocket or 33T belt pulley

Application

• 1976-Early 1984 FL/FX Shovelhead (FX with mid controls will require more modification)
• 1936-1964 Models
• Late 1984-1986
• 1965-1969 with modifications
• Custom applications

Exploded view: shift system and final drive

Exploded view: Gearset

Exploded view: Transmission Case

Exploded view: Hydraulic Side Cover

Exploded view: Function Form Hydraulic Side Cover

Exploded view: Billet Mechanical Side Cover

Exploded view: Cable Type Mechanical Cover

Specification and Torque Values

Transmission Fluid:

Getting Started

Thank you for buying another premium, American-made innovation from BAKER™ Drivetrain. There are a few important things to know about the BAKER™ 6-into-4 before installing this gem into your bike. Like most BAKER™ innovations, this is an upgrade and not a stock replacement. Because it is not a stock replacement, there are sometimes minor fitment issues you might encounter during the install. The type of fitment issue varies from bike to bike.

The first issue is usually exhaust clearance. The BAKER™ 6-into-4 is 1 5/8” wider than stock, causing it to sometimes interfere with exhaust fitment. There are companies making aftermarket exhaust that will clear the BAKER™ 6-into-4 with no problem. Most stock exhausts do not clear this transmission. This clearance issue is caused because the BAKER™ 6-into-4 has two more gear pairs, which means 50% more transmission in less than 2 inches of more space.

The only other issue that most folks encounter is due to the fact that the BAKER™ 6-into-4 is a direct bolt in, because of the different options on motorcycles there will be individual component clearance issues. This is caused by the vast array of aftermarket parts that have been available during the 50 years that the stock transmission was used. With varying individual components bike to bike, BAKER™ cannot guarantee individual component clearance. We can however, guarantee our 6-into-4 you’re about to slam in there, so we offer an incredible 5yr, 50k mile warranty on it and you can read all about that in the back of these instructions.

Tools, Resources, Required Parts

• Factory Service Manual For Your Motorcycle
• Factory Parts Manual For Your Motorcycle
• H-D™ Clutch hub puller hand tool
• Common American sockets and open end wrenches
• Impact Driver
• Torque Wrench (reads both in inch pounds and foot pounds)
• Brake Bleeder Pump (for hydraulic type)

Notes: Hydraulic Version Only

• Hydraulic Fluid, BAKER™ Recommends: H-D™ Dot 5 Brake Fluid, PN 99902-77
• Correct length AN -3 Brake Line
• 10mm Banjo Fitting & Washers For Both Ends Of Brake Line
• 3/8”-24 Banjo Bolt For The Side Cover End Of The Brake Line
• 11/16” Diameter Bore Hydraulic Clutch Lever Assembly or H-D™ Assembly

TRANSMISSION INSTALLATION:

1936-1964 Models:

We recommend installing the transmission per your factory service model. If you have ordered the 6-into-4 with the 1936-1964 mainshaft; the dust shield splash guard will need to be modified to clear the splines of the output gear. This application is recommended for use with tin primaries. Stock exhaust will not fit. Your exhaust will either need to be modified or an aftermarket exhaust will need to be installed.

1965-69 MODELS: BAKER 6-into-4 Speeds utilize an early 5 speed spline design for the main drive gear. Using this design requires a slightly offset sprocket to wrap around the modern spacer and drive gear. On 1965-69 models the stock inner primary has a lip which will hit the sprocket before going onto the transmission all of the way. Following these instructions and images, modify your stock H-D primary for proper fitment. These instructions do not apply for aftermarket inner primaries or belt drive motor plates.

Stock 65 Inner| Figure 11

Modification of stock 65-69 inner primary

Looking at figure 11 you can see the inner lip that has to be machined down in order to clear the sprocket and sprocket nut. Machine down this lip; measuring from the ears on the primary down; finish machine should be: .560” / .620” from the ear surface, figure 11. Notice that the threaded holes are now exposed on the casting from machining, figure 12. Chamfer the inner primary ears on the inside edge, breaking the edge .020/.030 X 45, figure 12.

Modified 65 Inner| Figure 12

Make sure to test fit the primary onto the transmission before running. Extra machining clearance might be needed for proper fitment.
After making sure everything fits properly, using four 1/4-20 X .375” set screws plug off the threaded holes. Apply some pipe thread sealant on the set screws then install from the inside, figure 13 Install the primary per your Factory Service Manual.

1970-E1984 Models - With Or Without Electric Start:

Mount the transmission to the transmission plate per your factory service manual.

Now mock up the primary onto the transmission (with the sprocket installed) and make sure there are no clearance issues.

If you are not running an inner primary bearing, we recommend installing our optional bearing support (pn 6-4SSP-A) with the 70-E84 or late 84 shafts.

For models with an oil tank bracket that runs to the transmission, you will need to fabricate up a new ‘Z’ bracket to accommodate the wider transmission.

1984-1986 Models-With Belt Drive Secondary:

The splines on the main drive gear of the 6-into-4 are comparable to a 1982-1984 FXR™. The key way is of a 1984-1989 5 speed and or 1984-1986 4speed.

Belt drive final drive bikes, you must use our 33 tooth pulley (pn32181S). The BAKER™ main drive gear is longer and the bearing and seal system is updated from your OEM H-D™ main drive gear. If you attempt to use the OEM pulley there will be almost a ¼ inch off interference from the pulley to inner primary. The factory pulley measures 1.941” wide. The BAKER™ pulley measures 1.600” wide. The back spacing is different as well as the length of our main drive gear and sprocket spacer.

**All Year

You must use the supplied 3/8-24 (pn37090-6-4) and seal (pn.3125x.875x.250) in the stock clutch nut. For aftermarket clutches with 7/16” adjuster screws you must order adjuster screw pn 37091-6-4 and lock nut (pn36258).