The idea of running a sprung solo seat on a bike that already has a rear suspension never sat well with me. Springs on seats have their purpose, and that is to give a hardtail rider some comfort. If the motorcycle has shocks, then adding a sprung seat is like wearing a belt and suspenders. I’ve seen some builders pull it off and end up with a good look, but no way was it going to fit into the game plan for my Scrambler. I wanted a traditional solo seat, and it had to be easily removable or able to hinge up so I could check the oil. There are lots of ways it could be done, but this is how I did it.
I started out with one of my Hellcat Seat Kits, minus the normal spring mounts on the back of the seat pan. Instead of welding the mounting bungs on, I left them off and welded up the locating holes I punch into the pan. After metal finishing the welds, I machined a fishmouth into the normal pivot bung of the seat hinge so it would sit low on the backbone. I have a special fixture that holds two pivot tubes, and allows me to cut the cove in my lathe. I used to do them in a mill, until Dan showed me that there is more than one way to machine a fish mouth by using a lathe to do it. If you don’t have a mill, or a lathe, you can use a grinder to do the same thing, or even a round file.
I decided on using a set of rubber bumpers for the back of the seat to rest on. Lucky for me, the finest bumpers in the business are made right near me in Fraser, Michigan by Fairlane Products. A trip over to see them netted me two heavy duty bumpers 1 ¼” diameter by 1 ¼” tall. If you don’t live in the Metro-Detroit area, you can find them at http://www.fairlaneproducts.com.
Both bumpers were bonded to a base with a 3/8”-16 tapped hole, so all I had to do was make a pair of threaded mounting bungs so I could affix them to the frame. I used a pair of my normal spring mounting bungs that had damaged retaining pin holes. First I cut the damaged shafts off in the band saw, then drilled and tapped the body in my lathe. That could also be done in a drill press if you don’t have a lathe. I made a small stud to thread into the bung, and threaded the bumpers onto the stud.
Now I had enough parts to be able to locate the whole assembly in place for a look. Everything seemed to fit decent, but I wanted to find a way to hold the seat down. Gravity would do a decent enough job of keeping it down, but it seemed like the easy way out to not figure out a latching system. I considered several different approaches, most of which involved some kind of hinge or spring mechanism. The drawback to using a steel latch, would be scratching the fender when the latch is released. Thinking back to my years of Industrial Fabricating, I remembered a company called Southco, in Lester, PA. The only thing Southco makes are latches, and they had a rubber latch similar to an older Jeep hood latch that seemed like it would work. It could be stretched to provide some drawing force on the seat, and the rubber shouldn’t mar the finish on the fender if dropped. I placed an order for one. It arrived in a couple days, and the size and strength seemed perfect. What wasn’t perfect was the pivot mount, because it was designed to mount to a flat panel and not to round tubing. Opportunity to fabricate! Using a discarded piece of 1/8” steel, I used a hole saw to bore a 1” diameter hole into it. Then, I laid out a pattern and sawed out two tabs. Once deburred, I tack welded them together so I could drill the pivot hole and grind the proper radius along the top edges. By tacking them together, I could be sure that both pieces would come out identical. Next, I made up a dummy spacer that would allow both parts to be held together the proper distance apart (and square to one another) so I could weld them to the frame.
Now I had everything seat, so I used a grinder to remove all of the paint on the frame where each part needed to be welded in place. I set the rear bumpers in their location, shifted them fore and aft several times to get them in the proper orientation, and measured the seat about a dozen times to be sure it was centered on the frame. Once satisfied, I tacked the pivot tube in place, and tacked the bumper mounts in place. Then, I sat on the bike to see if the seat was in a good spot before I added the latch. At this point, I could still adjust the pan an inch or so forward or backward. I ended up moving it back about a half inch, and locked the seat tight to the hinge.
Next, I flipped up the seat and used a magnet to hold the latch mount to the frame, and tack welded the mount in place. I removed the dummy spacer, and installed the rubber latch to the mounts. The latching end of the rubber latch gets captured in a stainless steel keeper that gets welded to the seat, but the keeper was also made for a flat surface and not a curved seat pan. A minute or two with a ball peened hammer allowed me to teach the keeper who was boss, and in short order it was formed the same as the seat pan. Figuring out the best place for the keeper so the rubber latch would be stretched the right amount was a bit of a crap shoot, but I hit it right on the first try with my educated guesswork. This almost never happens to me, so I latched and unlatched the seat about 20 times to be sure I wasn’t missing something.
Wow – almost too good to be true.
I welded up the mounting components good enough so they wouldn’t fall off, but not 100 percent. When the frame comes apart for powdercoating, I will finish all of the welds and do some more metal finishing.
The end result is a nice, vintage looking seat that fits the bike well and looks like it was made for it. The rubber latch allows the seat to swing up for quick and easy access to the filler neck on the oil tank, and securely holds the seat in place when latched. All that’s left is for me to have the pan powdercoated and figure out how I want it covered. If you have a suspended sporty or softail and want to add a solo seat, consider a mount like this as an alternative to using springs that you don’t really need. Some rubber bumpers will get you the right look, without adding a redundant and unnecessary set of springs.