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TorqueBox 5-Speed Right-Side-Drive (TB5-RSD)

The torque output of an engine is proportional to the bore and stroke.  Engines make torque and drivetrain components take torque.  It is torque, not horsepower that destroys clutches, transmissions and drive belts.  The torque capacity of a transmission is proportional to the gear width and the center distance between the two shafts.  All stock Harley transmissions and aftermarket transmissions have a center distance of 2.5″. By increasing the center distance 20% to 3.0″, the Torquebox conservatively increases the torque capacity to 250 ft-lbs, continuous duty! In the early Torquebox design stages, the goal was set to design a continuous duty 250 ft-lb gearbox that visually looked like a 450 ft-lb gearbox on the outside. We achieved this by taking design cues from classic race-bred American superchargers and not having any excess material, anywhere. We achieved our goal. The Torquebox is available as a 5 or 6-speed, left or right side drive. All frame, starter, and clutch interfaces are identical to stock 1990-1999 models.

  • Compatible with most Evo Softails and custom builds
  • Two rail shift form system with common fork used three times
  • 2” diameter shift drum suspended by two radial ball bearings mounted to a fixed spindle axis
  • Ratchet pawl has overshift inhibitor (up and down) and is mounted on two radial ball bearings. Shift lever shaft cross sectional area is 65% larger than stock.
  • Ignition kill and neutral switches top mounted for easy dwell timing adjustment.
  • Shift system lever ratio is 35% less than stock. Bearing mounted shift shaft yields low system hysteresis. Short, tight shifts are the result. 
  • RSD comes with choice of 29 tooth zero offset pulley, 23 tooth or 24 tooth .2” chain sprocket
  • RSD can be upgraded with various offset chain sprockets and sizes to suit application. No pulley option available due to tight actuator spider size
  • LSD comes with choice of pulley or sprocket
  • LSD can be upgraded to all pulley and chain sizes and offsets to suit application
  • Shaft material is super strong 9310 – the best steel made – this isn’t standard by any means. Gears material is 8620. Very large 8.125 diameter pitch gear teeth. The gear teeth are 2x circumferentially thicker than stock.
  • Tooth flanks are finish-ground after heat treat. AGMA class 12 grade gears.
  • Housing is all billet construction from 6061-T651 aluminum. We start with 95 lbs of aluminum and end up with 17 lbs of case and 78 lbs of chips
  • 5 year limited warranty

 Benefits

  • Highest torque capacity available
  • Crisp, smooth, certain shifting
  • N-1-2-3-4-5-6 shift pattern for false-neutral avoidance.
  • 1990-2006 Softail
The TorqueBox 6-speed Right Side Drive comes with a 29-tooth zero offset pulley.  RSD can be upgraded with various offset chain sprockets and sizes to suit your application. No pulley option is available due to tight actuator spider size.

      Materials

      Starting out with a 6061-T6 billet chunk of aluminum that weighs in at 95 lbs. This creates the framework for the TorqueBox’s ability to handle 250Ft/lbs of torque.  Getting whittled down to a 17 lb case that is both structurally and aesthetically pleasing with design cues from a 8V-71 blower. The guts needed to match this.  So both mainshaft and countershaft are cut out of the best steel made, 9310.  The gears are cut out of 8620 and are a class 12 grade on the AGMA scale.

      Torquebox Top Cover Features

      Shift Drum

      All TorqueBox are fitted with N1 shift drums.  For 5 speeds this makes the shift pattern N-1-2-3-4-5 and for 6 speeds it makes the shift pattern N-1-2-3-4-5-6.  Along with N1 these racing transmissions are fitted with ignition kill shift drums.  This makes for clutchless, wide open throttle shifts down the 1/4 mile and stop light to stop light!  The ignition kill system will need to be wired into your current ignition system.

       

      Shift Drum Detent

      Frictionless Detent System

      A 3/8” primary ball bearing is cradled by, and rolls on, 50 secondary micro ball bearings. In turn, the cradle is part of a plunger that actuates during shifting and is guided by a tertiary linear micro ball bearing system. 

      Shift System

      The TorqueBox uses a two rail fork system.  This makes it possible to increase the width of the fork to provide more support and smoother shifts.  Also featuring 1 common shift fork used 3 times to achieve commonality.  We didn’t stop at the forks and fork rods, a heavy duty shifter pawl was in need.  The shifter pawl design makes shifts short and crisp. This system delivers a lever ratio that is 35% less than stock.  The heavy duty shifter pawl rides on two radial ball bearings for smooth, repeating shifts. 

      Clutch Actuator

      Right and Left side drive units are both equipped with a 1.5″ bore hydraulic slave cylinder.  This provides easy holding (depending on clutch) at the drag tree before you go into clutchless ignition kill shifts.  You will need a 11/16″ bore master cylinder, brake and banjo bolt. 

      6 Speed Ratios for Left or Right Side

      R-Ratio Ratio Z-Ratio Ratio
      1st Gear 2.75 1st Gear 2.61
      2nd Gear 2.05 2nd Gear 1.89
      3rd Gear 1.55 3rd Gear 1.50
      4th Gear 1.18 4th Gear 1.12
      5th Gear 1.00 5th Gear 1.00
      6th Gear .86 6th Gear .95

      5 Speed Ratios for Left or Right Side

      R-Ratio Ratio Z-Ratio Ratio
      1st Gear 2.75 1st Gear 2.61
      2nd Gear 2.05 2nd Gear 1.89
      3rd Gear 1.55 3rd Gear 1.50
      4th Gear 1.18 4th Gear 1.12
      5th Gear 1.00 5th Gear 1.00

      Fitment
      1990-99 Left Side Drive Softail-Based and Custom Right Side Drive Motorcycles

      PN Description
      TB521L R-Ratio Polished LSD 5 spd
      TB621L R-Ratio Polished LSD 6 spd
      TB521R R-Ratio Polished RSD 5 spd Right Side Drive
      TB621R R-Ratio Polished RSD 6 spd Right Side Drive
      TBZ5L Z-Ratio Polished LSD 5 spd
      TBZ6L Z-Ratio Polished LSD 6 spd
      TBZ5R Z-Ratio Polished RSD 5 spd Right Side Drive
      TBZ6R Z-Ratio Polished RSD 6 spd Right Side Drive

      Notes:

      1. RSD comes with choice of 29 tooth zero offset pulley, 23 tooth or 24 tooth .2” chain sprocket
      2. RSD can be upgraded with various offset chain sprockets and sizes to suit application. No pulley option available due to tight actuator spider size
      3. LSD comes with choice of pulley or sprocket
      4. LSD can be upgraded to all pulley and chain sizes and offsets to suit application

      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 TorqueBox Fluid Capacity Dry: 22-24fl-oz
      • BAKER TorqueBox Fluid Capacity Wet: 18-22fl-oz

      Standard Gear Case Finish Examples (Not applicable to all products)

      Chrome

      Polished

      Raw

      Wrinkle Black

      These example finishes are intended to show the exterior treatments of cases, top covers and doors.

      TERM AND CONDITIONS                                                                                         

       

      BAKER Drivetrain reserves the right to change prices, terms or policies at any time without notice.

      Orders can be pre-paid using Visa, MasterCard, American Express, Discover or PayPal.

      All orders not pre-paid will be sent C.O.D. certified check or money order only unless pre-approved for company check acceptance.

      Any orders from outside the USA must be pre-paid in US funds via wire transfer; a $30 transfer fee will apply.

      Prices shown are F.O.B. Haslett, MI.

       

      LIMITED WARRANTY POLICY

       

      BAKER™ transmission assemblies, transmission kits, primaries, and oil pans are guaranteed to the original purchaser to be free of manufacturing defects in materials and workmanship for a period of 5 years from the date of purchase or up to 50,000 miles. BAKER™ clutches, kicker cover kits, belt drives, F6F kit, reverse systems, covers and accessories are guaranteed to the original purchaser to be free of manufacturing defects in materials and workmanship for a period of 2 years from the date of purchase or up to 24,000 miles - whichever occurs first. If the product is found by BAKER™ to be defective, such products will, at the option of BAKER™, be replaced or repaired at cost to BAKER™. 

       

      In the event warranty service is required, the original purchaser must call or write BAKER™ immediately with a description of the problem. If it is deemed necessary for BAKER™ to make an evaluation to determine whether the transmission assembly or transmission kit or accessory is defective, the entire transmission assembly, whether originally purchased as an assembly or kit, must be properly packaged and returned prepaid to BAKER™ with a copy of the original invoice of purchase. If after an evaluation has been made by BAKER™ and a defect in materials and/or workmanship is found, BAKER™  will, at BAKER™  option, repair or replace the defective part of the assembly. 

       

      RETURNS AND EXCHANGES

       

      Any merchandise returned for any reason (exchange, credit or modification) must be accompanied by a Return Goods Authorization (RGA) number or it will be refused. Call BAKER™ to obtain this number prior to returning goods for any reason. There is a 15% re-stocking fee for all returned items. BAKER™ is not liable for any shipping charges. 

       

      ADDITIONAL WARRANTY PROVISIONS

       

      NOTE: Limited warranty does not cover labor or other costs or expenses incidental to the repair and or replacement of BAKER™ products.

       

      This warranty does not apply if one or more of the following situations is judged by BAKER™ to be relevant: BAKER™ OEM transmissions; (these are subject to the OEM manufactures warranty only), Improper installation, accident, modification (including but not limited to use of unauthorized parts, transmission oils or lubricants), racing, high performance application, mishandling, misapplication, neglect (including but not limited to improper maintenance), or improper repair. 

       

      BAKER™ shall not be liable for any consequential or incidental damages arising out of or in connection with a BAKER™ transmission assembly, transmission kit, component or part. Consequential damages shall include without limitation, loss of use, income or profit, or losses sustained as the result of injury (including death) to any person or loss of or damage to property.

       

      BAKER™ transmissions, transmission kits and accessories are designed exclusively for use in American V-Twin motorcycles. BAKER™ shall have no warranty or liability obligation if BAKER™ parts are used in any other application.

       

      If it is determined that a BAKER™ product has been disassembled during the warranty period for any reason, this limited warranty will no longer apply unless you were instructed to do so by a BAKER Drivetrain technician for diagnostic purposes.

       

      The words H-D®, Softail®, FXR®, Dyna®, FLT®, FLH®, Sportster®, and Buell® are registered trademarks and are for reference only.

       

      Questions? Ask us anything:
      Contact us
      Or just call us at 517-339-3835. We're glad to help.

      TorqueBox 5-Speed Right-Side-Drive (TB5-RSD)
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