Harley Dyna trike conversion.

[bobscogin]

I'd like input from anyone who has converted a Dyna to a trike. I'm concerned about the structural integrity of the swing arm pivot. There has to be considerably more leverage applied in a trike than it was designed for, particularly in turns. Since the swing arm hangs off of the aluminum transmission housing and gets no support from the frame, can the design handle the leverage applied by a trike axle over the long term? I know there are kits available, but how well was this thought out and tested?

Bob

[Lance65]

Alloy Art Combi Stabilizer Kit - DC-1

This might help . I too am building a '08 Dyna Street Bob . Am planning adding this after I get everything else set up . About $300 is a lot to spend but if it will help in keeping the swing arm from moving around . Maybe someone else has a suggestion .

[bobscogin]

Those will help with stabilizing the engine/transmission assembly, which since the swing arm mounts to the transmission helps keep the rear wheel in line with the frame. However, they don't address the changes in loads applied to the swing arm pivot on the transmission case. In a two wheel application, the swing arm pivot axis inclines with the bike when going around a corner. Convert to a trike and when going around a corner the swing arm pivot has a torsional load applied to it since it's trying to lift the inside wheel.

Bob

[dmillsr3]

I'm not sure that brace is what you need. Champion Side Cars (SCS) has a strong upper motor brace to replace the stock one. The lower mount at the transmission needs the delrin side bushings and good swingarm bushings. Lee H. Mann on this forum can fix you up on the upper brace.

[bobscogin]

The lower mount at the transmission needs the delrin side bushings and good swingarm bushings.

It's the Touring platform bikes (FLT/FLH) that have the outboard "side" isolator bushings, not the Dyna. On those, the swing arm/transmission mount bolt mount bolt goes all the way through the transmission/frame and is supported on it's outer ends by the frame/bushing system. The torsional load on the swing arm in a touring platform trike is transferred into the frame through the isolators. The Dyna swing arm bolt doesn't go through the frame. It only goes through the cast aluminum case, and is cantilevered on the pivot leaving the transmission case to bear 100% of the load.

Bob

[Lee H. Mann]

It's the Touring platform bikes (FLT/FLH) that have the outboard "side" isolator bushings, not the Dyna. On those, the swing arm/transmission mount bolt mount bolt goes all the way through the transmission/frame and is supported on it's outer ends by the frame/bushing system. The torsional load on the swing arm in a touring platform trike is transferred into the frame through the isolators. The Dyna swing arm bolt doesn't go through the frame. It only goes through the cast aluminum case, and is cantilevered on the pivot leaving the transmission case to bear 100% of the load.

Bob

The 2006 and later Dyna that was built by Lehman until 2012 included rear swingarm pin braces for either side to minimize stress on the rear engine mount and swingarm pivot pin connection. Lehman also employed a lateral stabilizer or trackbar mounted to the rear axle and some point on the motorcycle frame to keep the rear end in the center when extreme cornering takes place. This was necessary because the forces exerted on the frame and front end would overpower or flex the down tubes and cause them to strike the head pipe.

If you are doing a Dyna with an EVO engine, 1999 and earlier, a Carlini Torque Arm must be used as well.

[bobscogin]

The 2006 and later Dyna that was built by Lehman until 2012 included rear swingarm pin braces for either side to minimize stress on the rear engine mount and swingarm pivot pin connection. Lehman also employed a lateral stabilizer or trackbar mounted to the rear axle and some point on the motorcycle frame to keep the rear end in the center when extreme cornering takes place. This was necessary because the forces exerted on the frame and front end would overpower or flex the down tubes and cause them to strike the head pipe.

If you are doing a Dyna with an EVO engine, 1999 and earlier, a Carlini Torque Arm must be used as well.

Thanks for your input. That's good advice, and I think it confirms what I suspected. Using a Dyna is more trouble than it's worth. Mine is a '96, and doesn't use the more rigid 4 bolt gearbox/engine interface like the Twin Cams use, making your suggestion of the Carlini torque arm essential. I think I'd be better off going another route and just using the engine/drivetrain in a different chassis that doesn't utilize a transmission mounted swing arm.

Bob

[dmillsr3]

It's the Touring platform bikes (FLT/FLH) that have the outboard "side" isolator bushings, not the Dyna. On those, the swing arm/transmission mount bolt mount bolt goes all the way through the transmission/frame and is supported on it's outer ends by the frame/bushing system. The torsional load on the swing arm in a touring platform trike is transferred into the frame through the isolators. The Dyna swing arm bolt doesn't go through the frame. It only goes through the cast aluminum case, and is cantilevered on the pivot leaving the transmission case to bear 100% of the load.

Bob

Shows how much I don't know about Dyna bikes.