Screamin' Eagle Six-Speed Gearset - Lower the RPM

10. Within 15 minutes, the case was completely ground down to match the template. Afterward, the case was cleaned repeatedly to ensure that any and all debris was removed from the case. Even small pieces can wreck a transmission.

11. The new H-D six-speed assembly (in front) was designed with several improvements that enhance the durability of this unit. One of these elements is a thicker chrome billet side door that houses the Sixth gear and uses its additional strength to help the area of the case that was ground down but which still allows for the use of the stock exhaust.

12. First, a new countershaft needle bearing was installed, and then a new main drive gear and its bearing were pressed into the primary side of the case. Then a snap-ring was installed to keep it seated. The rear sprocket/pulley was bolted on to the outside of the main drive gear, and the shift-shaft assembly was also replaced. To help with start-up, everything-including all the bearings-was covered in assembly lube.

14. Next, it was just a matter of sliding the new assembly into the case and maneuvering the forks into the tight clearance at the top of the case. Just before the assembly was in all the way, the shifter fork shaft was installed, aligning all three in the proper places. Then the door was pushed flush with the case. The top bolts were torqued to 125 lb-in, and the lowers were torqued to 18 lb-ft. Lastly, the fork shaft bolt was installed via a new Allen-head plug bolt.

15. Next, four new drum-support block dowels were installed into the case. Then the new shift drum was installed, putting it into its proper position and manually sliding the shifter forks into place within the grooves on the drum. With the old drum, three shifter forks manipulated First and Second, Third and Fifth, and Fourth gear. The new shift drum also manipulates three shift forks that now shift First and Second, Third and Fourth, then Fifth and Sixth gear, respectively.

16. Then the transmission was manually shifted through all the gears while the mainshaft was turned to ensure that the shift forks worked properly. Then the support blocks were tightened and torqued.

18. The old transmission top cover was replaced with a new chrome cover and new gasket. A new clutch-release cover was also included in the kit. All we needed to do was remove the stock cable and install it into the new cover, along with new gaskets. We also needed to install the new longer clutch-release rod in through the mainshaft.

19. The other change needed was the new speedometer sensor bolted into the billet side door while the old sensor hole was plugged. Then we bolted everything else back together in the reverse order of the breakdown. We adjusted the clutch by starting with the basket and tightening the adjustment bolt until it bottomed out. Then we backed the nut in the clutch basket out about three-quarters of a turn. Finally, we snugged the nut and made fine adjustments at the cable. The H-D manual recommends you start with 20 oz. of trans lubricant (synthetic, but it's up to you), 27 oz. of primary oil, and 3 quarts of 50-weight motor oil.

20. With the bike back together, we put about 200 miles on it, then went back to the dyno room. The bike was run at 65 mph; the rpm were around 2,400, and at 75 mph the rpm were about 2,700. This would allow the bike to produce the same horsepower with less effort and less wear on the motor's internals. We also noted that the bike was smoother and quieter while riding at higher speeds (not that we recommend speeding...ahem). In less than a day and for about $2,000 in parts, it was a great addition to this bike for the long run.