FLAT RATE SHIPPING!  No hidden fees and NO TAX! Only $12.95 in the continental. U.S., no matter how large (or heavy) your order is!  Save $$$ ... order everything you need NOW! 

No special club to join... just great low prices every day.

Gear Sets at bottom of page.

Transmission Parts - - Drivetrain Index

Please note: When comparing prices to others, please be aware that some companies do offer lower pricing by buying engines or trannys unassembled, and then put them together themselves (thus, have no factory warrantee). All parts and/or engine, tranny, etc., sold at STCC are 100% factory assembled and warranteed.

PLEASE NOTE: Transmissions are not returnable except for manufacturer defects. TERMS


Baker Drivetrain Kickstart 6-speed Transmission for a 4 speed frame



Baker Drivetrain Kicker Tranny comes with both brass and rubber kickstart pedals.


True overdrive provides a 500 RPM drop in 6th gear for reduced vibration and improved fuel mileage.
Gear ratios are first 2.94, second 2.21, third 1.60, fourth 1.23, fifth 1.00 and sixth gear .86:1.
Available in Polished or Raw transmission cases by S&S Cycles.
Have chrome plated top covers, kickstart covers and kick arms.
Includes a solid brass and solid rubber kickstart pedal.
All gears are finish ground on diamond coated tooling after heat treating to produce a super fine surface for holding exact tolerances and eliminating gear mesh noise.
Kick starter gears are heavy duty for years of service.
Back-cut gear dogs with lead-in ramps on the gear pockets provide smooth shifting with positive engagement.
Includes 23 tooth drive sprocket.
Provision for electronic speedometer sending unit.
Includes instructions and a manufacturer's statement of origin. 

Baker Drivetrain: Made in the U.S.A.

Note: Due to the extended length of the kick start side the rear exhaust pipe, oil tank and electric starter mounting brackets may have to be modified. Some inner primary covers require modification to clear the sprocket nut. Case clearancing may be necessary for some starter motors.

Part #: M70310 - Polished Case Transmission, Fits Big Twin 4 speed frame with 1970/Early 1984 primary drive ... $3,885.80

Part #: M70311 - Raw (as-cast natural) Cast Transmission, Fits Big Twin 4 speed frame with 1970/Early 1984 primary drive ... $3,885.80

Baker Transmission for Softail, 5 speed or 6 speed.

6 speed

Chrome and Polished

Made in U.S.A.



More BAKER at bottom of page.


All gears are finish ground on diamond coated tooling after heat treating to produce a super fine surface for holding exact tolerances and eliminating gear mesh noise. All gear dogs have lead-in ramps for positive gear engagements. Redundant shift drum detents (roller type & plunger type for positive neutral finding). Anti-Overshift inner transmission shift linkage with improved shape return spring for dependability. Polished case with chrome plated top cover and side cover.
Lightened steel pulley with 32 teeth. 2.94:1 close ratio first gear adds approximately 5 miles per hour of usable first gear.
The 6 speed has a .86:1 ratio top gear and will reduce RPM by approximately 475. These transmissions include a single wire type neutral switch designed for 1984/1997 Softail models and can be used with an electronic speedometer sensor.
The 6 speed version is best suited for large displacement engines.
A Manufacturer's Statement of Origin is included. Made in the U.S.A.

6 Speed Transmission, Fits Softail Models 1990/1999 - Part#:M70331 ... $3417.00 including free shipping*


Powerhouse 6 Speed Transmission assembly for Softail 1990/99, cast case.

Cast Case

Powerhouse 6 Speed Transmission assembly for Softail 1990/99, polished case.

Polished Case


If you have ever been cruising on the highway and tried to upshift into top gear just to find out your transmission is already in fifth gear, then that is all the proof you should require that you need a 6 speed transmission. Not only will this complete transmission assembly reduce vibration at highway speed, it will also improve fuel mileage. At 75 miles per hour, the .86:1 overdrive ratio will produce a 475 RPM reduction when shifting from fifth gear. A 2.94:1 close ratio first gear will add approximately 5 MPH of useable first gear. The second, third, and fourth gear ratios remain the same as OE. Fits Softail models 1990/1999.

Part#:M70313 - Cast Case, Fits Softail models 1990/1999... $1283.75

Part#:M70315 - Polished Case, Fits Softail models 1990/1999 ... $1373.75

Part #: M70362 - Black Finish, Fits Softail models 1990/1999 ... $1251.00



Powerhouse Complete 5 speed tranny for Softail 1990/99, cast case

Cast Case


Powerhouse Complete 5 speed tranny for Softail 1990/99, polished  case

Polished Case


  • Available with "as cast" case finish or polished case finish.
  • Features chrome plated top cover, side cover, shifter rod lever and speedometer sensor block off plate.
  • Includes 32 tooth steel pulley.
  • Gear ratios are the same as OE.
  • Just add oil and hook up the clutch cable.
  • 12 month Manufacturer's Limited Warranty.
  • Includes Manufacturer's Statement of Origin.
  • Fits Softail 1990/1999.

After extensive on-bike high mileage testing, we are proud to offer this complete POWER HOUSE 5 Speed Transmission. Simply add oil and install your clutch cable. This transmission features a chrome plated top cover, side cover, shifter rod lever and speedometer sensor block off plate. It includes a steel 32 tooth pulley, allen head cover hardware and all the required mounting stud and alignment pins installed. All gear ratios are the same as OE. Includes manufacturer's Statement of Origin and a Manufacturers 6 month limited warranty.

"As Cast" case. Fits Softail 1990/1999.
Part#:M70307 -
Power House Cast Case 5 speed transmission ... $1162.50

Polished Case. Fits Softail 1990/1999.
Part # :M70314 -
Power House Polished 5 speed transmission ... $1230.00

Part #: M70370 - Black Finish, Fits Softail 1990/1999 (Replaces HD# 33005-99) ... $1,130.50

For wider tires and bigger engines.

Powerhouse Right Side Drive Transmission.  5 speed or 6 speed, raw or polished.

As Cast or Polished Case


Powerhouse tranny shown installed on softail style RSD frame.

Shown installed on Softail Style RSD frame.

Fits Custom Big Twin Right Side Drive Frames.



Powerhouse 5 speed and 6 speed Right Side Drive Transmissions

The Powerhouse Right Side Drive transmissions were developed for wide size tire (250 series) and are best suited for high performance engines. Hydraulic and clutch type side cover. Specially designed cam for smooth shifting with bronze shifting fork.

The Right Side Drive (RSD) transmission, when mounted in a custom RSD frame will allow the use of a super wide rear tire without offsetting the engine. Available in your choice of a 5 or 6 speed with an "as cast" or polished case. Transmissions include a chrome plated top cover, shift rod lever and hydraulic clutch actuator cover. The hydraulic clutch actuator is designed to be used with a 11/16" bore master cylinder and requires a 10mm banjo bolt. The 5 speed version includes standard ratio gears and the 6 speed includes standard ratio gears with a 86:1 ratio 6th gear. For maximum strength all gear are the same width as OEM gears. The 32 tooth pulley will accept a 1 1/2" wide drive belt. The splined main shaft is designed for a 1990/Later style clutch hub. A neutral switch and speedometer sensor block off plate are included. Smooth shifting is accomplished by bronze shift forks and a roller type shift drum detent arm. Includes a 24 month Manufacturer's Warranty and Manufacturer's Statement of Origin (MSO).

Polished Case, Right Side Drive, Hydraulic

  • M70318 - 5 Speed RSD, stock ratio gears ... $1657.50
  • M70319 - 6 Speed RSD, .86:1 overdrive ... $2047.50

Cast Finish Case, Right Side Drive, Hydraulic

  • M70320 - 5 Speed RSD, stock ratio gears ... $1560.00
  • M70321 - 6 Speed RSD, .86:1 overdrive ... $1732.13

Black Finish Case, Right Side Drive, Hydraulic

  • M70365 - 6 Speed RSD, .86:1 overdrive ... $1737.60

Big Twin 4 speed 1952/Early 1979

ratchet top transmission, complete, for early big twin 4 speed motorcycle.


High quality replacement ratchet top with hardware.
Replace the old worn out unit on your transmission with this fresh show piece.
No more searching for all the small internal pieces.
This unit saves you time and money.

Part #: M70550 - Chrome Plated Motorcycle Transmission Assembly, Fits Big Twin 4 speed 1952/Early 1979 ( Replaces HD# 34799-65) ... $369.25
A NOTE ON BAKER TRANSMISSIONS: We carry the entire line of  Baker Transmissions. They are built at time of order, take approx. 2 weeks, and there are many gear choices.  Please call and chat with our tech if you need something special.  We recommend that you buy a Baker Transmission for engines 113" and larger... also, if you are a "hard use" kind of rider.CONTACT

Transmission Parts such as Gear Sets, Builder's Kits, End Covers, Top Covers, Shifter Drum Kit, Rebuild kits, Cases, etc. can be found on TRANSMISSION PARTS page.


Secured by SSL - an authentic COMOCO site.


Don't see what you need?  Contact us.  Chances are we have it.  We have thousands of parts that are not shown online.

PLEASE NOTE: We Do NOT Backorder. If your item is not in stock, you will be notified and given a refund.

FLAT RATE SHIPPING APPLIES IN CONTINTENTAL 48 UNITED STATES ONLY. AK, HI and APO/FPO will have additional shipping fees. We ship within the U.S.A. and to APO/FPO (military addresses; weight and size restrictions apply.). We do not accept foreign credit cards. Please see our CONTACT page for more information.

Prefer to call in your order to Steel Thunder? Call 603-237-8200.


Please note that all prices are subject to change.


Steel Thunder Custom Cycles

531 Bungy Road

Columbia, NH 03576

Copyright 2002-2015 Steel Thunder Custom Cycles©


Thank you for shopping at Steel Thunder Custom Cycles online motorcycle parts store!



Protected by Copyscape Duplicate Content Detection Software