A Sexy Six-Speed | Rivera Primo Powerdrive 6-Speed Transmission Install

Rivera Primo Powerdrive 6 Speed Transmission Install Upgrade

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While visiting our pals at Rivera Primo in Whittier, California, amongst the belt drives and SU carburetors, we spied a fully polished jewel of a six-speed bagger transmission. Wanting to know more about the Powerdrive 6-speed LSD ($1,949), Ben Kudon, the marketing whiz at Primo, walked us through the technology behind its newest tranny and offered one up for an install. The transmission is made for upgrading '93-98 touring bikes to six-speed, but we wanted to make it work on our project '89 FLHS. Doing this would get rid of the FLHS's bulky frame-mounted oil tank and make room for upgrades such as an air ride compressor and controller.

01. To get things started H-D tech, Kevin, removed the rear wheel.

We couldn't get the straight dope on whether this or any other late-model touring transmission would fit on this old frame, so we decided to man-up and try and get it to work.

Basically the transmission is comprised of parts completely made in America. The case is made from a single chunk of billet aluminum that is polished to a mirror-like finish. Yes, it may be a sweet-looking tranny, but it's what's inside that's the real thing of beauty. Packed into the case are six forged gears, which are all back cut for durability and easier shifting. The 2.94:1 First gear leads way to a 2.21 Second, 1.60 Third, 1.23 Forth, 1.00 Fifth, and an 0.860:1 overdrive Sixth. This gearset was chosen by Primo after much testing and they found it to provide great off-the-line acceleration while offering smoother cruising at high speeds. Also in the case are hardened shafts as well as support blocks, a billet oil fill tube and top cover, and grade-8 hardware to hold it all together.

After taking the bike to Harley-Davidson of Anaheim Fullerton, we found it only took a little forethought, as well as some slight modificatins to both the new transmission and the old swingarm, to get it to fit. Follow us as we show you how it was done.

02. The swingarm, which holds the rear of the trans in the frame was also removed.
02. The swingarm, which holds the rear of the trans in the frame was also removed.
03. The front of the trans was unbolted from the rear of the engine and removed.
03. The front of the trans was unbolted from the rear of the engine and removed.
04. The stock trans (left) has a bulky bolt-on oil tank that is housed in the frame of the bike, where as the Primo trans (right) has the oil tank neatly built-in like a late-model Harley.
04. The stock trans (left) has a bulky bolt-on oil tank that is housed in the frame of th

05. Kevin checked the fit of the swingarm on the bench to make sure it didn't bind and had enough room to fully articulate without hitting the new trans.
05. Kevin checked the fit of the swingarm on the bench to make sure it didn't bind and ha
06. We found that the top and bottom of the front of the swingarm had to be clearanced with a die grinder a few thousandths to fully clear the new trans.
06. We found that the top and bottom of the front of the swingarm had to be clearanced wi

07. The new Primo transmission was then slid into the frame rails. This was where we hit a bit of a snag.
07. The new Primo transmission was then slid into the frame rails. This was where we hit
08. The oil pump on the Evolution motor interfered with the front mount of the Primo six-speed trans case (arrow).
08. The oil pump on the Evolution motor interfered with the front mount of the Primo six-
09. We had to clearance a 1/2-inch section of the front trans mount with a die grinder to get it to fit on the older motor.
09. We had to clearance a 1/2-inch section of the front trans mount with a die grinder to

10. Once the trans case was modified it fit without any further issues.
11. We then tightened the front mounts to factory specifications.
12. The swingarm was installed and checked for proper articulation.

13. The swingarm axle was properly tightened and the six-speed conversion was done.
13. The swingarm axle was properly tightened and the six-speed conversion was done.
14. As you can see the new transmission had plenty of room in the old frame and looked like it could have been the stock transmission.
14. As you can see the new transmission had plenty of room in the old frame and looked li