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DD6: Direct Drive 6-Speed Builder's Kit

From an engineering standpoint, it is difficult to design a machine or mechanism that achieves multiple objectives with minimal compromise. An amphibious car is a good example. A few have been manufactured over the years, and they achieved the goal of navigating on land and water, but did neither very well. On the other hand, a Swiss Army knife achieves multiple objectives with minimal compromise. You can snatch the cork out of a wine bottle or kill somebody all with the same widget. The DD6, or Direct Drive 6-speed, combines 3 technical approaches to achieve the most advanced transmission gearset design available for your Big Twin with minimal compromise. First, 1st through 3rd gears are straight cut (spur) for strength during maximum acceleration with no parasitic axial thrust. Secondly, 4th and 5th gears are automotive style helical gears for quiet and smooth operation as highway speed approaches. Lastly, 6th gear is direct drive which means there is no underdrive or overdrive in top gear which translates into 99% efficiency for minimum parasitic loss, minimum wear and tear, and maximum fuel efficiency. But we didn’t focus solely on the gearset, we made this sucker shift like glass. The sequential motion of the hard chrome plated forks is controlled by a fixed spindle radial ball bearing mounted shift drum. Hard chrome guarantees long fork life with minimal imposed friction on the fork groove of the gear. The fixed spindle drum design eliminates any chance of binding or imposed friction about the axis of drum rotation. Drum rotation is controlled by a roller detent and actuated by a BAKER shift pawl with a anti-overshift feature. To make finding neutral an easy chore, we mounted a redundant detent on the left side pillow block.
  • Billet 6061-T6 bearing door
  • 1/8″ thick bearing retainer plate
  • Helical & spur gear design gear for quite operation
  • 28 tooth comprocket forged out of 8620 gear steel
  • Regina double row primary chain
  • Fat shoe chain tensioner w/hardware
  • All transmission seals, gaskets and hardware
  • 5 Year limited warranty


  • Smoother shifting
  • Positive, certain shifting
  • Easier-to-find neutral
  • Quieter operation
  • More-efficient torque-handling
  • 1990-97 Softail
  • 1991-97 Dyna
  • 1990-94 FXR
  • 1990-97 FLT-FLH
  • 1998-99 Softail
  • 1998-00 Dyna
  • 1999 FXR
  • 1998-00 FLT-FLH
  • 2000-06 Softail
  • 2001-05 Dyna
  • 2001-06 FLT-FLH

Bearing Door Type: All DD6 bearing doors have the same outer profile as a stock 5 speed so exhaust brackets, torque arms etc. fit like stock. The DD6 door comes with or without an ear. The ear door is for exhaust bracket mounting and does not fit 1993-2006 FL applications.

      Bearing Door
      All DD6 bearing doors have the same outer profile as a stock 5 speeds so exhaust brackets, torque arms etc. fit like stock. The DD6 door comes with or without an ear. The ear door is for exhaust bracket mounting and does not fit 1993-2006 FL applications. Note the images below. The DD6 door bearings are larger providing 25% more dynamic load capacity than stock bearings used through 1998, also uses a 1/8″ bearing retainer plate instead of stock style snap rings.

      DD6 Bearing Doors

      DD6 vs. Stock Comparison


      Redundant Neutral System

      Shift System
      Our 6 Speed shift system with roller detent guarantees smooth shifts every time and our redundant neutral ensures  that finding neutral is a easy chore. We mount a plunger detent on the left side pillow block and cut a plunger track into the shift drum itself.  The plunger follows this track during operation (shifting) and when shifting into neutral pops into a pocket. This system lets you feel that you’re shifting into neutral. No more guessing.  Shift drum features more aggressive timing on the fork groove profiles and is case hardened to 58 Rockwell for wear resistance and crisp shifts. We built our reputation on smooth shifting 6-speed transmissions; our drum designs benefit from the engineering lessons learned.

      FL Case Differentiations
      To see an illustrated example of the differences between FL cases by year, please open the PDF here.

      All DD6 gearsets are made out of 8620 steel, gears are shaper cut before heat treat then precision ground with diamond coated tooling after heat treat (58-62 Rockwell ‘C’). This extra steps ensures not only a quieter gear pair, but enables much tighter backlash control. The gearset is a combination of helical and spur gears to yield silent gear operation. The dog teeth are backcut at a 1° angle to optimize the smooth shift possible, while standard gearsets are cut to a 4° angle.  The mainshaft is unique with 1st main gear being incorporated as part of  the shaft, the countershaft also features a unique 1-piece design with 6th gear.

      DD6 Gearset Layout

      Gears and Shafts Design


      DD6 Shift Forks

      Shift Forks
      Our investment cast shift forks are made out of 4140 then dipped in a hard chrome plate bath for wear resistance, also designed with oil reliefs to ensure proper lubrication and wear resistance on fork blades and shift dogs.

      Available No Cost Options

      • Standard Shift Drum (1-N-2-3-4-5-6)
      • N1 Shift Drum (N-1-2-3-4-5-6)

      Available at an Additional Cost

      27T Comp Sprocket, available on FL models for a more aggressive primary ratio. Not compatible on Softails or Dyna models due to the inner primary design. 

      The DD6 comes in a stardard 3.24 or optional 2.94 1st gear 

      Standard Ratios
      1st Gear 3.77
      2nd Gear 2.56
      3rd Gear 1.87
      4th Gear 1.44
      5th Gear 1.15
      6th Gear 1.00
      Effective Ratios 
      1st Gear 3.24
      2nd Gear 2.20
      3rd Gear 1.61
      4th Gear 1.24
      5th Gear .99
      6th Gear .86

      Standard Ratios- shown above are without the 28 tooth comp sprocket

      Effective Ratios- shown above are with the 28 tooth comp sprocket

      Builder’s Kit Part Numbers

      All Part Numbers Listed Are Standard (Effective) Gear Ratios

      New PN Old PN Description Fitment
      DD6-411L DD411L DD6 Builder’s Kit 1990-97 Softail1991-97 Dyna
      DD6-411 DD411 DD6 Builder’s Kit 1990-94 FXR1990-97 FLT-FLH
      DD6-411SL DD411SL DD6 Builder’s Kit 1998-99 Softail1998-00 Dyna
      DD6-411S DD411S DD6 Builder’s Kit 1999 FXR1998-00 FLT-FLH
      DD6-411PL DD411PL DD6 Builder’s Kit 2000-06 Softail2001-05 Dyna
      DD6-411PL DD411P DD6 Builder’s Kit 2001-06 FLT-FLH


      Builder’s Kit Notes

      • The DD6 is available with a 2.94 optional 1st gear ratio for higher horsepower applications. Change the middle numeral ‘1’ to a ‘0’. example: DD401P
      • The DD6 is not designed to be used in conjunction with belt drive primaries,auto chain tensioners or easy pull clutch kits.
      Complete Build Notes
      • The DD6 is available with a 2.94 optional 1st gear ratio for higher horsepower applications. Change the middle numeral ‘1’ to a ‘0’. example: DD401P
      • The DD6 is not designed to be used in conjunction with belt drive primaries,auto chain tensioners or easy pull clutch kits.


      BAKER Case vs. Aftermarket

      Case Design
      The BAKER Softail case design had all leak potentials in mind during the design. We added stud pads to the inside of the case so that the thread holes for the transmission studs were blind holes, NOT through holes like some aftermarket brands. Looking at the image on the right you can see the difference. 

      Recalibration Box PN 95E-56B

      Special Note

      • Speedo recalibration unit is required for electric speed sensor applications; PN 95E-56B.
      • A + 12MM mainshaft length is available for wide tire applications. (Call us to ensure ordering accuracy)

      Compare the DD6

      See the difference between other transmission kits and our DD6 and OD6. Click Here for a PDF file comparing our DD6 and OD6 gearset against other manufacturers. 

      Click on the image to Compare the DD6 and OD6 gearsets

      DD6 vs. OD6

      Recommended Upgrade

      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 DD6 Fluid Capacity Dry: 22-24fl-oz
      • BAKER DD6 Fluid Capacity Wet: 18-22fl-oz

      Installation Instructions
      DD6 installation instructions with exploded views: Click Here

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




      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.


      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. 


      Due to the uniqueness, low price and assembly outside of typical production process of products indicated as Insider Special products, purchasing these Insider Special products include a warranty so to guarantee the original purchaser to be free of manufacturing defects in materials and workmanship for a period of 1 year from the date of purchase or up to 12,000 miles. We have provided extended options for you to purchase below. 


      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. 


      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.

      DD6: Direct Drive 6-Speed Builder's Kit
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      DD6: Direct Drive 6-Speed Builder's Kit DD6: Direct Drive 6-Speed Builder's Kit
      Customer Reviews
      5.0 Based on 2 Reviews
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      Canada Canada
      • What model motorcycle do you ride? 1992 Softail Springer FXSTS
      1992 Springer

      I've recently installed the DD6 kit and so far have put 1500km on it. This transmission shifts quick! I can bang through the gears just as fast as a motocross bike. First oil change has been done and the oil came out looking like it just came out of the bottle. I would like to mention though... Early bikes will require Baker's Zero offset drive sprocket (I believe 1993 and earlier?) there was no mention of this in any of the specs for this transmission. This delayed my being able to ride by a couple of weeks while I waited for the new Drive sprocket to ship to Canada (Covid didn't help this matter). The oil seal and drive sprocket spacer that ship with this kit are of the (1993? and later style). I opted for a 31 tooth sprocket when I ordered the Zero offset one, hindsight I should have just stayed with the stock 32 tooth one for a bit more top end. My bike has a stock 80" evo with a S&S super E carb and is other wise stock, it pulls this gear no sweat. All in all I'm 100% happy I bought this. I may do a 124" motor at some point and when I do, I'll rear gear with possibly the 34 tooth sprocket for even more top end.

      Robert S.
      United States United States
      • What model motorcycle do you ride? FLSTC Harley Davidson
      New Gears!

      Awesome purchase from start to finish. What a novel idea that you get everything including a new comp and chain for the primary. Could not ask for a better product or transaction. Thanks to everyone at Baker!

      Web Product ID: 5206047619
      Baker Drivetrain Team Illustration