Transmissions

How to: Build An Old Skool Bobber

Old Skool is kool. A fact celebrated by Wolfgang Publications in their new book. No theme bikes here, learn how to build a real American motorcycle based on a Panhead, Shovelhead or Evo engine. Don’t buy expensive new parts, build your own bobber or chopper from mix-and-match swap-meet parts.

Written by Kevin Baas, the Kennedy High School shop teacher with the Build-a-Chopper class, this book takes a back-to-basics approach to motorcycle assembly. As Kevin says, “if you can’t buy it cheap, adapt it, and if you can’t adapt it, build it from scratch.” Follow along as Kevin explains which engines fit which frames, and which transmission and primary drive is the best fit behind a particular V- Twin. The back half of the book includes three start-to-finish assembly sequences done with Kevin’s high school class utilizing early and early-style engines, drivetrains and components. Part of Wolfgang’s new Biker Basics series, the old skool Bobber book is available for $24.95. This 144 page book uses over 350 color images to illustrate some kool parts and even kooler motorcycles.

Here’s a sample chapter out of the book.

Transmissions
Four, Five or Six Speeds?
The transmission, which transfers the power from the motor to the rear wheel, is something that should be thought about in detail before making a decision as to which model to buy. Although a great old-skool transmission would be the traditional four-speed, kick-start running jockey shift, this system offers many more safety risks than a typical foot shift setup. And for long road trips, or high speed traveling, the jockey shift can cause major headaches. The four-speed H-D transmission, used from 1936 to 1984, evolved from gate shift, to ratchet top, then rotary top. The four-speed is the preference for the true old skool crowd, and often has a kicker already installed. However, if you don’t already have one in hand they often cost more than the newer five-speeds.

The suicide setup should be reserved for the experienced rider who can handle the added risks. A more modern, efficient option is the five and six-speed transmissions which are manufactured by a wide variety of companies. These provide a nice low first gear to get off the line quick, but also keep the rpm’s down in high gear. The five-speed transmission came into production through Harley in 1980. Although the four-speed was still used on some models, the five-speed eventually took over for good when the four-speed was dropped from production.

There are five and six-speed transmissions available in the traditional four-speed case if you want the vintage look, otherwise new Softail-style transmissions can be used in almost any rigid frame designed to accept pre-’99 drivetrain. By using an adjustable transmission plate you can mate new-style transmissions to old-style frames, to add new technology to old skool class. An adjustable plate is recommended to allow for perfect alignment of the transmission with the primary.

Various Transmission Styles & Specs
A few comments on transmissions: H-D, Big Twin four-speed transmissions are basically the same except the FX models, which came with different ratios than the FLH models. Also, the clutch pushrods varied as follows: ‘41-’64 used a 13 inch rod. ‘65-’69 used a 13-1/4 inch rod. ‘70-‘75 used a rod measuring 13-7/8 inches. ‘75-‘84 used a rod with a dimension of 13-3/4 inch.

The pushrod length started to change when electric start was added (the mainshaft became longer). There were some different throwout bearings used along the way as well, which necessitated a longer or shorter clutch pushrod. I still prefer the early style, before they went to the less heavy-duty, wafer-style throwout bearing. The older style lasts forever, while the later-style has a snap-ring that often comes off and the bearing is a poor design. The ratchet-style shift top worked well but then came the cow-pie style and even though the linkage set up is sloppy, it shifted smoothly. Five-speeds mainly added a closer ratio and are better yet. Most people think they’re getting more top end gearing out of a five-speed, but both use a one-to-one top gear. A five-speed offers closer shifting ratios and is generally smoother and easier on the gear train. Six-speeds provide a nice low first gear and an overdrive sixth, though the actual overdrive ratio changes from one brand and model to another. The right-side-drive five and six-speeds came about when tires went to 230 and 250, no longer did builders have to offset the transmission to the right by as much as an inch. In my opinion, a 200 rear is as big as it should get on a Bobber.

There are the “retro” four-speed transmissions which come in different configuration for four, five, and six-speed gearing. There is the ratchet top, rotary top, and the jockey lid style. But if you’re reading this book the last thing you will be worrying about is the over-the-top fat tires, skinny is the way to go!

Weyland form Solutions Machining gave me some information on the differences in the various transmissions: “There’s a large amount of hype with regard to four, five, and six-speed transmissions. Many of these claim to be better for nothing other than that extra gear or two that you pay for. Here’s the bottom line as far as I’m concerned – I don’t care if you have TEN gears. The two most important issues are where (in the rpm range) it calls for shifting with regard to your riding style, and the final gear ratio.”For many, many years people automatically assumed that because a transmission had five or six-gears that they were overdrive transmissions. Wrong.

Nowadays, there are overdrive gear sets available, but you need to be aware when shopping for a transmission so you get exactly what you want. In the end, like most other things, it’s all a matter of personal preference.Four-speeds (when built properly) last just fine. They do, however, require more attention to detail as far as maintaining proper tolerances is concerned. Still, their design and aesthetic reflects an era when craftsmanship was valued over production numbers. This aesthetic is immediately evident when one sets an early transmission next to a late one. Five-speeds are more of a “Lego-block” type of transmission, and are obviously more cost effective to produce. That said, they have evolved to be a pretty serviceable transmission, even if they do lack any inherent aesthetic appeal.

Match Transmission to the Frame
It is important to be sure, whatever transmission you choose, that it will bolt up correctly in your frame. Custom rigid frames are available which can use softtail-style Harley-Davidson transmissions, or the older four-speed style transmission, with the need of only the proper transmission plate. Five and six-speed transmissions use the same mounting configuration so they will fit any rigid, seat-post style frames, or softail frames built before 1999 when the Twin Cam was introduced. Most of the rigid frames out there utilize the same components as the Evolution Softail, but be aware ‘99 and up Twin Cam parts will not work without major modifications.

A frame such as the ones Sucker Punch Sally’s, or Spartan Frameworks, sell will accept four, five, or six-speed transmissions, as long as you use the correct transmission plate. Companies are now realizing what a wide variety of custom parts are being used to build bikes so adjustable transmission plates can be purchased which allow for any of the three styles of transmission to be used. Hank Young offers a great, high quality, adjustable plate that we used to fit our transmissions in our four-speed rigid frames (our school project bikes farther along in the book).

I asked George Counes, of Spartan Frame-works, about the frames he builds and the transmission options and this is what he said: “I build all my frames with four-speed transmission mounts. The four-speed mounting system is stronger than the five or six-speed setup. I like four-speeds (except cow-pies), as they are better for a jockey setup, the kicker doesn’t look like an afterthought, the final drive is the same as a five-speed, you don’t have to cut the starter bracket off, and best of all, you can put a slop-top lid on for every day riding and then throw a ratchet lid on for drag racing. To mount the five and six-speed transmissions in my frames requires a 3/8 inch thick transmission adapter plate, that way you can mate my a four-speed frame with a five-speed transmission.”

“For the five and six-speed transmissions I put a relief in the seat post to clear the lid, and the fifth-mount is slightly foreword. This would have to be done to most four-speed frames to accommodate a five or six-speed. The five and six-speed, and right-side-drive transmissions mount to the frame in the same way. A five or six-speed kick-only transmission can be mounted in my frames without the use of a motor plate or an aluminum primary and the transmission plate or the frame will not break.”“As for stock or other after market five-speed frames running a five or six-speed transmission with no inner primary or motor plate, I gusset and beef-up the whole area under the transmission mounts to make sure the mounts won’t fail.”

Suicide – not for Beginners
They call them “suicide” set ups for a reason, it is more dangerous! A true suicide shift refers to a non-rocker-clutch style set up where the bike must be put in neutral if you want to come to a stop and take your foot off the clutch. This set up is not for the faint of heart, and should only be used by riders who know their bikes well and know how to ride. Combine suicide shift and no front brake, and your daily rides become a quest to just make it to your destination safely. When stopped on a hill with a suicide set up, you must really be in tune with your bike and the clutch system to keep from stalling.

Also, if you have no front brake, it is even more difficult to hold the bike still while you try and step on the clutch, get the bike in gear, and get it moving forward without rolling back into the car behind you, or stalling the motor. This set up is NOT recommended for a novice rider and should only be attempted by experienced, skilled riders who can handle running this set up without having to think too much.

I have had this set up on my Panhead since the first day I built it, and I will admit to avoiding certain streets and hills for a while until I felt comfortable riding the bike and operating the clutch system. Now when I ride it I don’t even think about it and can stop and start anywhere without problems. When I am riding along with friends they are amazed how quickly and smoothly I can shift the bike with the suicide set up, almost as if I was running a foot shift. Like anything, practice makes perfect and the more you ride and practice the better you will get. The rocker clutch style allows the rider to lock the clutch in, which lets them put both feet down at a stop while the bike is still in gear. This was a standard piece of equipment on the older Harleys that utilized a hand shift. Although it does allow a bit more room for error on the rider’s part it should not be taken to be the magic fix all for hand-shifting issues.

Transmission Options – Baker Drivetrain
Baker Drivetrain’s contributions to the Old Skool are the best-kept secret in the business. Known for premium drivetrain innovations found on newer custom bikes, or later stock H-Ds, Baker Drivetrain also produces a high quality six-into-four gearset to improve upon old technologies.

The Baker six-into-four is a 1970-to-early-1984 Shovelhead four-speed case that houses a Baker Overdrive six-Speed gearset. The six-into-four is available with or without the kicker assembly which includes both a stock rubber kick pedal and a brass pedal. It features the new Baker Klassic Kicker Gears, which are a smoother, stronger, and quieter improvement to the current OEM replacement gears made offshore. These gears are also available separately. This transmission is available with a raw, show polished, or wrinkle black case and a 33-tooth pulley. Baker Klassic Kicker Gears are an American made alternative to the offshore monopoly on OEM 1936-1984 kicker gears. Features include: Rounded teeth for smoother, quieter rolling and a reinforced stop-peg to prevent breakage in the transmission. All the gears are made from 4140 heat-treated steelA N-1 Racing Shift Drum on a Bobber? Yes, this is great for bikes with foot clutches. A N-1 shift pattern, which is a pattern with neutral before first gear instead, of neutral between first and second, eliminates the hope and guessing of finding neutral before you have to take your foot off the clutch and step on the ground for balance when stopping. That is, “neutral is all the way down to get your foot planted on the ground.” This is especially helpful with jockey shift linkage that loses a lot of the “feel” when looking for conventional neutral. Baker has found this to be a handy and popular solution to embarrassing stalls or slamming into stopped cars.

The Baker Special Request six-Speed “Franken-tranny” for Softails, is a special transmission with a six-into-four door, which allows a kicker assembly and a sixth gear on a Softail five-speed case. It’s your choice whether or not to have the starter ear removed for kick-only applications. Call Baker for more details.Other Old Skool components include an outer bearing support for six-into-four transmissions and a hydraulic clutch actuator for six-into-four or conventional four-speed transmissions.

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