Open Belt Primary Assembly Instructions and Diagram


Before installing the Ultima Belt Drive System you must remove your entire existing primary drive. This also includes the pressed on transmission mainshaft race used with chain drive inner primary bearings.
As stated earlier the Ultima Belt Drive System requires the use of a 1989-1993 type starter drive shaft which utilizes the larger 1/4-20 fastener. We also suggest using any of our heavy duty Ultima Thunder Fire Starters part # 70-220 thru 70-229 which incorporate both 89/93 and 94/Later style drive shaft bolt arrangements. These starters are available in 1.4, 1.75, 2.0 and 2.4 Kw configurations.
Ultima Belt Drives utilize a slightly longer center distance between the pulley?s and will require that you loosen the transmission mounting bolts to allow the transmission move back approx .040?.
At this time we suggest inspection of your Charging System. Ultima Belt Drives are designed to work with most 32 amp Charging System on the market today. Later model 38, 40 and 44 amp systems may interfere with the Motor Plate. While you are inspecting the alternator we highly recommend that you install a new Crankshaft Seal on the engine replacing the existing seal with a High Quality double lip seal and installing the seal with the steel face out. Belt Drive Units require a dry environment free from Oil and by flipping the oil seal you ensure any crankcase pressure and oil will stay in your engine. This is also a great time to inspect the transmission sprocket and seal for wear and to ensure the sprocket is tight.


When Assembling Street Style Belt Drive Assemblies no Preassembly is required on the Motor Plate.
Drag Style Belt Drives Require the outer Cover Spacers to be installed prior to assembling onto the motorcycle.

1. Locate the 2 different length Outer Cover Spacers #56

2. Install the 3 shorter outer cover spacers #56B into the Motor Sub-Plate # 5 using Hardware # 66 Black Oxide finish with Red Loctite. Torque to 18-22 ft lb

3. Using Red Loctite Install the remaining 5 long outer cover spacers with set screws into the Motor Plate. Motor Plates are drilled through so you can access the allen head from the inside. Put the Hex side of the set screw into the motor plate. Use Red Loctite on Outer Cover Spacers

4. A good way to tighten the outer cover spacers is to use on of your 5/16-18 bolts and a Jam Nut.This will allow you to get some torque on the spacers.

5. The Motor Plate and Motor Sub-Plate Ready for assembly

6. Install Outer Cover Caps onto the Outer Cover using Blue Loctite.Torque to 18-22 ft lb. Note the bolt clearance notch location on the motor pulley cap to the outer plate.


Ultima Drives use 6 bolts to fasten the Motor Pulley to the Pulley Insert. Install these bolts using Red Loctite and Tighten to 18-22 ft lb torque. All Ultima Drives include the Stock offset Spacer. The Following Spacers are available separately for Wide Tire Applications.
MWM # 58-606 .250? Offset
MWM # 58-607 .500? Offset
MWM # 58-608 .750? Offset
MWM # 58-609 1.00? Offset
MWM # 58-610 1.25? Offset


Install the Motor Plate and Motor Sub-Plate without the rubber o-ring for the inner primary to engine. Remember the center distance will be different with the Ultima Belt Drive so it will require you to move the transmission. Align the motor plate to the engine and transmission then install the mounting bolts for the engine and trans snug only.
You might need a dead blow or plastic hammer to seat the motor plate over the transmissions dowel pin. With the motor plate mounting bolts lightly snug to the engine and tightened to the transmission look to see that the trans is sitting square on the frame. Shimming is generally not required but needs to be inspected for spaces no larger than .030?. If all looks good begin by pulling the transmission mounting nuts tight.
Next run the the Motor Plate to the engine bolts tight. Next check the motor plate to trans mounting bolts for tight. If all aligns well your ready to Start removing the Motor Plate to engine and trans bolts to apply RED Loctite one at a time. Torque all to 18-22ft lb.


1. Install the clutch Basket Assembly onto the transmission mainshaft.
Apply RED Loctite to the mainshaft nut and torque to 55-65 ft lb.

2. Install the Stator Rotor Washer and any Shims that were present. Ultima Belt Drives are not as sensitive as chain drives to pulley alignment as the clutch basket acts as a guide but proper alignment should be checked. To insure a completely dry running primary many people use a bead of clear RTV Silicone at each spline to insure no oil will travel between the shaft and spline.
Install the belt and front pulley at the same time. It can be tricky to align the splines with some tension on the belt. Once you get the spline started you can tap the pulley on lightly with a dead blow or plastic hammer.

3. Install the motor pulley nut using RED Loctite and Torque to Mfg recommended Specification.


1. Ultima Belt Drive utilize the old style 900cc sportster steel drive plates and 9 special size fiber plates designed to provide a very adjustable Clutch Package.
When Installing the Clutch Pack Install the Thick .119? Steel Plate First then Alternate Fiber/Steel. The Last Plate you install should be Fiber.

2. Check the pressure plate screws to ensure they are all tight and the heads of the bolts are sitting below the plate surface. Install the clutch adjusting screw using a small amount of high temp grease on the thread and especially on the Clutch Pushrod end. Don?t get to much grease out there ?Remember this is a DRY clutch.

3. Align the witness marks on the pressure plate and inner clutch hub as shown when assembling.

4. Check the Inner Stud Alignment using the clutch spring collar flipped over with the flange side in. The Collar should pass through the pressure plate freely a minimum of 1/4?. Straightening is generally not required but if needed straighten the stud by using a small brass drift.

5. Install the clutch springs and clutch spring guides with the flanges out. Install the Clutch Spring nuts until you measure .350?+/- .010 from the face of the pressure plate to the face of the spring guide as shown. This sets the Spring at approx. 1.250 installed height. For higher power applications go in to .100? measured max for 1.000 installed height. Ultima Belt Drives come with a standard pressure spring for most applications under 120 hp.
MWM #96-245---Barnett # MT-53.
Pressure 35lb @1.250
51lb @ 1.000
The clutches grip is adjusted by the spring tension and your clutch lever pressure goes up with spring pressure. For Higher Horsepower Applications we offer MWM # 58-776
Barnett # MT-88.
Pressure 42lb @ 1.250?
68lb @ 1.000?

6. Install your starter motor to the Motor Plate then install the starter drive gear assembly in the order shown using Blue Loctite. The Starter Drive Gear should be a Minimum of .150? from the clutch basket starter ring gear once installed. Apply some High Temp Grease to the Starter End Cap bushing then install the cap using Blue Loctite. Torque to 18-22ft lb.


1. Install Motor Pulley and Trans Pulley Caps using Blue Loctite. Snug bolts only. Install the preassembled outer support plate assembly starting with the clutch basket side. With a small hit of the hand pushing towards the clutch basket side the outer support plate should snap in. Snug the outer support plate with the 2 center bolts only. Using the Starter Motor With the plugs out of the engine rotate the belt drive a few times to insure the pulley caps get centered. Get 2 or 3 bolts tight on the caps?120-140 in lb. Remove the outer support plate and torque all pulley cap bolts.

2. After all Pulley Caps are tight reinstall the outer support plate using Blue Loctite.
Torque Bolt to 15-18ft lb.

3. Check your kickstand clearance to the belt pushing down on the belt then adding at lease 1/2?. Use MWM # 5-190 Adjustable Kickstand Leg Stop if needed.

  • 1. Complete Assembly
  • 2. 58-706 Motor Plate - Cast
  • 2A. 58-806 Motor Plate - Billet
  • 3. 58-707 Bearing, Ball, Double Row Angular Contact,
  • 4. 58-708 Snap Ring
  • 5. 58-759 Motor Sub Plate (Billet Motor Plate Only)
  • 6. 58-633 Gear Assembly, Starter drive
  • 7. 58-710 Gear, Start Drive, One piece
  • 8. 58-711 Starter Gear Bushing
  • 9. 58-712 Starter Spring
  • 10. 58-713 Starter Gear Spacer
  • 11. 58-714 Spring Stop
  • 12. 58-715 Cover Assembly, Starter Gear
  • 13. 58-716 Cover, Starter Gear
  • 14. 58-717 Bushing, Starter Gear
  • 15. 58-725 Pulley, Motor 45T
  • 16. 58-605 0? Offset Collar, Sprocket Shaft
  • 58-606 1/4? Offset Collar, Sprocket Shaft
  • 58-607 1/2? Offset Collar, Sprocket Shaft
  • 58-608 3/4? Offset Collar, Sprocket Shaft
  • 58-609 1? Offset Collar, Sprocket Shaft
  • 58-610 1-1/4? Offset Collar, Sprocket Shaft
  • 17. 58-726 Washer, 1.655 x .94 x .125
  • 18. 58-727 HTNUT 0.8750-14-D-S
  • 19. 58-728 Complete Trans Pulley Assembly Includes 62, 26, 29, 24, 20.
  • 20. 58-729 Clutch Hub Assembly
  • 21. 58-755 Clutch Hub
  • 22. 58-756 Washer, Clutch Hub
  • 23. 58-757 Snap Ring
  • 24. 58-733 Trans Pulley Assy 71T w/BRG (Includes 62, 26, 27, 28)
  • 25. 58-734 Pulley, Trans 71T Bare
  • 26. 58-735 Gear, Starter Ring
  • 27. 58-737 Bearing, Ball, Double Row Angular Contact
  • 28. 58-738 Retaining Ring, Clutch Assy Outer
  • 29. 58-739 Retaining Ring, Clutch Assy inner
  • 30. 58-622 Clutch Retaining Nut Assy
  • 31. 58-741 Clutch Retaining Nut
  • 32. 95-778 Clutch Rod Seal
  • 33. 58-760 Complete Replacement Clutch Assy
  • 34. 96-83 Clutch Drive Plate, Inner .119 Thick
  • 35. 58-762 Clutch Plate, Friction
  • 36. 96-34 Clutch Plate, Steel .049 Thick
  • 37. 58-770 Pressure Plate Assembly
  • 38. 58-771 Pressure Plate
  • 39. 58-772 Clutch Drive Plate, Outer
  • 40. 58-773 Nut .164-32-S-N (6)
  • 41. 96-245 Clutch Spring - Standard 58-776 Heavy Duty Clutch Spring Kit
  • 42. 58-777 Clutch Spring Guide
  • 43. 58-778 Ny-Loc nut 1/4 - 28
  • 44. 58-779 Clutch Adjuster Assy.
  • 45. 58-780 Clutch Adjuster 0.4375-20x1-HX-S
  • 46. 58-781 NUT 0.4375-20-D-S
  • 47. 58-782 FW 0.4375
  • 48. 58-810 Outboard Support Kit
  • 49. 58-811 Cover, Outer
  • 50. 58-786 Retaining Ring
  • 51. 58-787 Bearing, Radial Ball, Single Row
  • 52. 58-812 Cap One, Outer Cover
  • 53. 58-813 Cap Two, Outer Cover
  • 54. 58-815 Cap, Motor Pulley - w/ Outboard Support
  • 55. 58-814 Cap, Trans Pulley - w/ Outboard Support
  • 56. 58-793A Spacer, Outer Cover 4.360? 58-793B Spacer, Outer Cover 3.920?
  • 57. 58-750 Belt, Ultima / Goodyear 3.35? 8mm 140T +10 58-751 Belt, Ultima / Goodyear 3.35? 8mm 140T -3
  • 58. 58-767 Motor Pulley Cap, w/o Outboard support
  • 59. 58-765 Transmission Pulley Cap, w/o Outboard support
  • 60. 58-797 HX-SHCS 0.3125-18x1.5x1.5-S (4)
  • 61. 58-799 HX-SHCS 0.3125-18x2.25x1.125-S (4)
  • 62. 58-798 HX-SHCS 0.3125-18x0.875x0.875-S (2)
  • 63. 58-774 SCHCSCREW 0.164-32x0.625x0.625-HX-S (6)
  • 64. 58-790 HX-SHCS 0.3125-18x.5x.5-S (6)
  • 65. 58-736 HX-SHCS 0.25-20x0.625x0.625-S (12)
  • 66. 58-794 HX-SHCS 0.3125-18x1x1-S (11)
  • 67. 58-795 SSFLATSKT 0.3125-18x1-HX-S (5)
  • 68. 58-796 HX-SHCS 0.3125-18x0.75x0.75-S (6)
  • 69. 58-775 Clutch Spring Stud (6)
  • 70. 58-718 Starter Bolt .25-20x2.75 (1)

#58-730 Street Style Belt Drive Polished #58-732 Street Style Belt Drive Machine #58-700 Drag Race Style Belt Drive Polished #58-701 Drag Race Style Machine #58-800 Drag Race Style Belt Drive Assembly - Polished - Billet #58-801 Drag Race Style Belt Drive Assembly - Machine Finish - Billet