6 into 4

Years ago we came out with the 6-into-4 for Shovelheads. Sales of these transmissions have been a complete shocker and the message is loud and clear: People love their Shovelheads and they ride the piss out of them.  We often get asked “why not a 5-into-4?”. This is because 4-speeds have a 1:1 fourth gear and Evo 5-speeds do as well. This provides no RPM advantage to your old iron. 6-into-4’s have a 1:1 fifth gear and a .86:1 sixth gear; good for a 500 RPM reduction on the highway. Our original 6-into-4 transmission is a direct replacement for the 1970-Early 1984 4-speed. This year we have mainshaft options that allow fitment into wet (diaphragm) clutch model Shovels and 4-speed Evo models that require a longer mainshaft and shorter ones for Pan and Knuckle. Available with different kicker covers.

– 6061-T6 extruded billet case with the nostalgic look of 4-Speed and precision machined for no leaks – 5th mounting stud machined into the case, for pure strength and no weak points – BAKER Klassic Kicker gears, stainless steel kick arm, and bronze pedal standard – Case available with or without primary flange; raw, wrinkle black, or polished – 23 tooth sprocket standard. Optional 24 tooth and 33 tooth pulley – Forged top cover available with or without neutral switch – Modern 5-speed style shift drum and shifter pawl for smooth quick shifts – Electronic speed sensor provision on right rear of case – N1 drum, no cost option, for N-1-2-3-4-5-6 shift pattern – Comes standard with a BAKER 5 Year/50,000 mile warranty

Case Finish Options You have 3 different options for case finish on the 6-into-4.

Raw Bead Blast Finish

Wrinkle Black Finish

Show Polish Finish

Case Options & Provisions All 6-into-4 case options come with a machined in 5th stud. We took the weakest point on other aftermarket transmissions and made it into the strongest point on ours. The 5th stud commonly breaks out of its bolted on plate causing your driveline to tweak in the chassis. The 6-Into-4 Transmission case comes in two different versions. Our 1936-64 case is a no ear case to work with the factory primary. Our 1970-1986 version comes with the primary ear bosses on it. These can be used with stock primary applications, belt drive applications, or running no primary plate at all. We do recommend the use of our bearing support for this application, BAKER PN 6-4SSP-A. Both cases have a provision for an electronic speedometer.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. The BAKER 6-into-4 case does not have a gear drive speedometer cable provision on the case.

Machined 5th Stud vs. Bolted on 5th Stud

No Ear and Ear Cases

Electronic Speedo Provision, shown with H-D PN 74437-96 Speedo sensor

Recalibration Box 95E-56B

6-into-4 mainshafts

 Mainshaft Options

– Late 1984-1986 length mainshaft.  Diaphragm type wet clutch. – 1970-Early 1984 length mainshaft.  Shovelhead mainshaft. – 1970-Early 1984 Splined mainshaft. Shovelhead splined mainshaft. – 1965-1969 length mainshaft.  Panhead/Shovelhead. – 1936-1964 length mainshaft.  Knuckle/Panhead mainshaft.       Shift Drum Options Standard Drum Shift Pattern (1-N-2-3-4-5-6 shift pattern) N1 Drum Shift Pattern (N-1-2-3-4-5-6 shift pattern)

Klassic Kicker Gears

Kicker Gears 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 offer 6 different kicker covers making the 6-into-4 completely customizable from stock to custom build. Our kicker covers come in different finishes ranging from the standard chrome cover to the raw replica cover to the show polished Function Form Hydraulic cover.  To see the full line of kicker covers available Click Here.  Depending on the choice of cover and finish, additional charges may apply.   Top Cover Options The 6-into-4 comes standard with a single pole neutral switch top cover with our hidden vent.  The transmission can be ordered with our no-neutral top cover or you can upgrade to the Voyeur top cover that shows the internal beauty of the 6-into-4.   The 6-into-4 comes in a standard, optional or R-Ratio configuration

Standard Ratios
1st Gear 2.94 / Optional 3.24
2nd Gear 2.21
3rd Gear 1.60
4th Gear 1.23
5th Gear 1.00
6th Gear .86 / Optional .80*
R-Ratio Ratios
1st Gear 2.82
2nd Gear 2.08
3rd Gear 1.60
4th Gear 1.23
5th Gear 1.00
6th Gear .86 / Optional .80*

*Deep overdrive 6th gear (0.80) available as no-cost option, and for use with Large Cubic Inch Motors. Consult with a BAKER Salesman before choosing this option.

PN Description Fitment
6402 2.94 1st gear (Standard) 1936-86 FL & FX; good all around gear ratio
6412 3.24 1st gear 1936-86 FL & FX; for heavy GVW applications
64212 R-Ratio 2.82 1st & 2.08 2nd 1936-86 FL & FX; for light hot rods

Notes: -Each transmission is hand built to order. Use the base part number above and add suffixes (with a “-“ before each suffix) to specify the desired configuration: Signature Series: Add a ‘S’ suffix for a polished signature series trans, or ‘RS’ for raw finished case. (DOES NOT INCLUDE NO EAR 6-INTO-4’S) Click Here for Signature Series Page Case Finishes: R=raw/casted, B=wrinkle black, P=polished Drum Option: N1=N1 drum (N-1-2-3-4-5-6 shift pattern) Case Style: Standard case has ‘4-stud ears‘ for primary, specify no ear case by adding NE suffix (1936 style) Kicker Cover: Chrome Die Cast Clutch Arm Kicker Cover Standard. Optional kicker cover suffixes: FF= function formed polished, BPH=Billet polished Hydraulic, BPM=billet polished mechanical, BC=billet cable type, E=electric start Mainshaft: 1970-E84 mainshaft standard, Optional lengths: -36 for 1936-64 mainshaft,-65 for 1965-69 mainshaft, -84 for 1984-86 Sprocket: 23 Tooth Chain sprocket standard. Specify optional 24 Tooth Chain sprocket by adding -24 suffix or -33 for Belt Pulley – 6-into-4 has 2 more gears than a 4-speed and sticks out 1.6” more. Rear exhaust pipe, oil tank brackets, and starter brackets may have to be modified for fitment. – Electric speed sensor provision in case accepts stock 1994-up speed sensors. – Some 1970s inner primaries may require modification for sprocket nut clearance.

1976 Shovelhead, M6402R 6-into-4 Raw, Cycle Shack Exhaust

Recommended Exhausts  With the factory exhaust not fitting in most cases, two different exhaust companies took charge.  Click on either of the link below to check out some aftermarket exhausts that will fit your 6-into-4. -Cycle Shack -Kleiv Motorcycle Products   Recommended upgrades   – 6-into-4 Outer Bearing support, used when not running a inner primary plate – The TTP, ‘Tin Type Primary’ – Straight Kicker Arm; standard length or +1 inch -33-Tooth Trans pulley for belt drive final Click on any of the images below to learn more

6-into-4 Outer Bearing Support, pn 6-4SSP-A

Tin Type Primary

+1 Straight Kicker and Pedal

33 Tooth Pulley

Spectro Oil BD-75140

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 6-into-4 Fluid Capacity Dry: 22-24fl-oz BAKER 6-into-4 Fluid Capacity Wet: 18-22fl-oz




Instructions BAKER 6-into-4 install instructions with exploded views Click Here 1st Gear Design Change 1st Gear Change Addendum-March 2012: Click Here

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M6402R, 6-into-4 70-84 mainshaft, 2.94 1st gear .86 6th gear

H6402P-FF, 6-into-4, polished, 70-84 mainshaft, Function Formed Hydraulic Kicker, 2.94 1st gear .86 6th gear

M402P, 6-into-4 ready for assembly


6 into 4 Signature Series

E6402R-84, 6-into-4, raw case, late 84 shaft, electric start no kicker, 33 tooth belt pulley

E6402R-84, 6-into-4, raw case, late 84 shaft, electric start no kicker, 33 tooth belt pulley

M6402B, 6-into-4, wrinkle black, standard mechanical kicker, 23 tooth sprocket


6 into 4 Signature Series

6-into-4 Signature Series, front right, macro

6-into-4 Signature Series, front right,

6-into-4 Signature Series, front right

6-into-4 Signature Series, close up of emblem

6-into-4 Signature Series, rear right

6-into-4 Signature Series, rear right


1978 Shovelhead, M6402R 6-into-4, Kleiv Exhaust

1978 Shovelhead, M6402R 6-into-4, Kleiv Exhaust

Kevin from Cycle Works Shovelhead, E6402R 6-into-4, Cycle Shack exhaust

Serge McCabe’s 1981 Shovel, M6402R 6-into-4, Kleiv exhaust w/baffles

Serge McCabe’s 1981 Shovel, M6402R 6-into-4, Kleiv exhaust w/baffles

Jay Allen’s Army Tribute Rolling Thunder Bike

Featured in the cult motorcycle movie Choppertown: the Sinners. Check out the Choppertown DVD here Or check out Choppertown on YouTube Here.

Mike Yurko’s Johnny Cash inspired bike with 6into4

I, Mike Yurko, owner of Yurko Custom Choppers, have been using Baker products for over 13 years.They offer the most genuine innovative drive train components in the American V Twin industry.  Their tech center is second to none.Yurko Custom Choppers supports North American Industries not the cheap offshore knockoffs. Keep up the great work Bert!!!


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BAKER DRIVETRAIN| 9804 E. SAGINAW, HASLETT, MI, 48840 |1-877-640-2004| 517-339-3835 | FAX: 517-339-4590 @2012 BAKER INC