Screamin' Eagle Six-Speed Transmission/GearsetWhat would make a nice day out on the open road better than it already is? A smoother ride? And what exactly do we mean by that, anyway? It's as simple as lowering the high-speed rpm on your bike with an overdrive gear. We all know that the five-speed transmission was a great addition to H-D motorcycles back in the day, but we're now in a new era of even bigger motor sizes with cubic inches in the triple digits. So we need to smooth out the rpm at higher speeds and make them all-day-ride fun. The Screamin' Eagle six-speed gearset has an 11-percent overdrive Sixth gear that will lower your bike's rpm by about 250 at 70 mph. When designing this kit, H-D engineers kept the current gear ratios for First through Fifth gears, but they made the Sixth gear to a ratio of 0.89:1, resulting in a true overdrive.
To help us with the install and show us the easy steps to a smoother ride, we stopped at Anaheim/Fullerton Harley-Davidson in Fullerton, CA, where Matt Cortez walked us through the install of the gearset on our long-term test bike. You may recall this '05 Road Glide from a previous article where we installed everything from controls to sheetmetal to a 103ci kit. Now it was time to keep up with the Joneses and bring the '05 trans up to Harley's '07 Big Twin standards.
The six-speed gearset kits replace the stock gearset in the vehicle without removing the entire transmission case. Gearset kits include all the necessary hardware and require slight modification (template included) to the original-equipment transmission case.
1. Here is the H-D six-speed...
1. Here is the H-D six-speed transmission kit with everything you need to convert your stock trans into a six-speed. This kit comes with all the gears, shafts, plates, bearings, gaskets, and forks. You will need to get a set of primary gaskets and fluid. Before we got started, we made a baseline dyno run to document how the new trans will lower the rpm. At 65 mph, the rpm were around 2,700, and at 75 mph, we were at about 3,300 rpm.
2. To get things started,...
2. To get things started, all the oils were drained from the trans and primary, and the motor oil was removed as well. Then the foot controls, exhaust, outer primary, chain tensioner assembly, and the clutch assembly were also removed and set aside.
3. The starter jackshaft was...
3. The starter jackshaft was removed, and then the starter, along with the front motor pulley. This would allow the inner primary to be removed.
4. Using the H-D puller, the...
4. Using the H-D puller, the bearing race was removed, and then the rear belt pulley was removed and set aside.
5. Working on the exhaust...
5. Working on the exhaust side, the oil-filter spout, clutch-release cover, and speed sensor were all removed. Then the top cover and shift drum and its support blocks and dowels were also removed.
6. The fork's shaft and shifter...
6. The fork's shaft and shifter fork assemblies were also pulled from the gearbox. This allowed for the removal of the side-door mainshaft/countershaft assemblies after they were unbolted from the side of the case.
7. Lastly, the countershaft...
7. Lastly, the countershaft bearing and the main drive gear and bearings were pulled from the primary side of the case using a factory H-D puller.
8. Since the case was now...
8. Since the case was now empty, it was time to use the supplied template for the removal of the exhaust-side fork-shaft mount/hole. The mount hole needed to be removed to have the clearance for the new Sixth gear. All we needed to do was bolt the template in place and grind down the case to match the template.
9. The H-D instructions that...
9. The H-D instructions that come in the gearset explain that an easy way to do this is to drill it out by increasing the diameter (size) of the drill bit. Then clean up the area with a small grinding bit (die-grinder).