Shortsters & Big Randy Make The Split

hat began as an unknown inherited bike, turned into an educational, friendship w building divorce! In the summer of 2020, a goosenecked Ironhead came into my possession and a call to Woody from

Shortsters in Hartington,

NE set the wheels of the new build into motion. The notorious weak link in the

Sportster platform is the clutch and transmission.

Given their propensity to self-destruct under heavy power, separating or Divorcing the engine from the transmission has become an acceptable way to keep the proven power plant of the sporty platform viable. Woody has been separating Ironhead motors from their transmissions for a few years. So much so, that they’ve developed a kit and machined the parts necessary so that you can do it yourself in a weekend. Woody offers whole rear hardtail frame sections and a new pro frame kit which allows you to design your own tail

section around the divorced engine and big twin transmission combo. If you’re looking for a budget minded chopper build or want to stand out in a crowd, you can’t beat this conversion. In this article we’re just going to touch on the basics. The full step by step manual is available for free download at shortsters. com. Depending on the year of your Ironhead, there are some variables in the divorce process, the manual points out these differences. This application can also be performed on K-model and Evo-Sportster models up until 1990. For more information on these conversions, contact Shortsters directly through shortsters.com. Follow along with project “Divorster” as we separate the weak link from the Sportster platform and build a beast. Woody with the donor bike and the tail section for the “divorce pending” engine. This divorce process is being done on a complete running engine, therefore once the removal of clutch

basket, primary, oil pump and cams is complete, the engine will need to be sealed to protect it from metal shavings and debris. We used shop rags and silicone plugs in all the openings, then liberally wrapped the engine section in plastic wrap and duct tape. The manual has detailed instructions on where to divorce the motor from the transmission. Woody used a reciprocating saw, die grinder, cutting wheel, and various other hand tools to divorce the transmission case. Nothing here is fancy or out of reach for the average garage builder.

Chad, Woody’s wingman, took over cleanup duties. Using an angle grinder, he smoothed out all the sharp edges and generally cleaned up the appearance of the freshly cut cases. Pre 1977 cases require two holes to be drilled and tapped. The kit available from Shortsters locates these on your existing cases and takes the guesswork out of assembly.

Detailed instructions are in the manual and show where to cut frame tubes. Again, this can be achieved using only basic hand tools. Not pictured are the plugs, provided with the frame kit, used to join the Shortsters rear section with the donor front. Do not weld yet! Test fit with your engine, transmission, and primary belt in place. These will help align the two frame sections prior to welding. Once mocked up and when everything is square, tack weld the frame where accessible

Once everything is in place and the frame has been tack welded together, position the fifth transmission bolt bracket and tack into place as well.

At this point you can also weld your motor mounts together.

We all wish that everything fit like Legos, but building choppers is never that easy.

The cylinders on this engine were exceptionally larger than factory, combining this with a multi-year frame, dictated that relief be set into the seat tube. Again, this is not meant to deter you from attempting this conversion, this is just part of building choppers. If everything lines up as it should, you can remove the engine and transmission and complete the rest of the welding

We chose to leave the oil pump off during mock-up to eliminate possible damage. Now you can reinstall oil pump, cams, and the cam cover as per the instructions in your HD manual.

While not necessary, for cosmetic reasons, we chose to trim the cam cover. On pre-1977, take great care not to trim off this bump. This will give you an oily mess! Once your motor is reassembled and the frame has a final weld, it’s time for reinstallation of the drive train! This can be done in a weekend or you can do it at your own pace. As you can see this is not incredibly difficult but if any of this intimidates you, contact Shortsters (www.shortsters.com) for info, parts and services.