Jackshaft SA based jackshaft shift kit

Discussion in 'Transmission / Drivetrain' started by professor, Aug 8, 2010.

  1. professor

    professor Active Member

    The idea has been on my back burner for a long time.

    The Sick bike kit is marvelous and it's usefulness prodded me on.

    My bike would run a tad over 20 mph with the engine wound up on the governor. Seems crazy, but a single speed is stuck there. To go a reasonable speed with the motor at a fast idle is what I wanted. Now the engine fast idles in 3rd gear at (guessing) 15 mph. It will pull up the overpasses in third too. I love it.
    A Sturmy Archer hub was on a bike I got, so I welded a scooter (#25chain) sprocket to the stock SA one (making the big one to not run-out much is a bear). Then welded a coaster brake sprocket on the other side (it fit pretty good- only had to grind off the little nubs on the inside. This one needs to be welded with small fast spots of weld to avoid buggering up the brg. race!
    Four welds- let cool - four welds - let cool - four..... you get the idea.

    A dial caliper is invaluable for centering sprockets and aligning them for welding

    The shifting is strange.
    With the power on, AT ALL, each upclick instantly shifts with a jump.
    If you let off the throttle- it doesn't actually shift (after moving the little lever) until you add some power.
    I don't want this thing slamming like a powershift on gear changes.
    Just a little bit of throttle seems right.
    It is not the set-up for bull in china shop drivers, I think it will break.

    I want to mention how great it is to have an operational governor (am using a HF 79).
    With the throttle drag increased to hold an engine speed ( I am using a derailer lever for a throttle and it has a drag adjustment) - you get to a hill and sudenly, you have cruise control - it automatically feeds in more throttle = speed maintained. If you pull in the clutch for some reason- the engine does NOT race- it just stays where the rpm was that you have. Cool.

    On my little ride yesterday of 14 miles, without the 3 speed hub, I used about two cups of gas giving about 110 mpg. I think with the 3 speed, I can approach 200 mpg with the relaxed engine speed possible now.
    Starting out is easier now too, as low gear is below the former drive ratio.

    In the last pic u can see the left handlebar has the clutch (HT) lever, pedal chain gear selector and SA shift clicker.
    Some pics:

    Attached Files:

  2. GearNut

    GearNut Active Member

    Necessity is the mother of invention, and you have a fine looking invention there.
    I gotta wonder though if the Sturmy-Archer needs servicing and fresh lube. The hard shifting would have my questioning longevity.
  3. professor

    professor Active Member

    Thanks for the concern Gearnut, the hub has a flap type little access for oil and I filled it up while still on the pedal bike.
    The shifting is better (maybe it was me). On a ride last night it was fine.
    I did test out the gearing. It is so cool to be able to snick thru the gears without the engine screaming away. Idle speed in 3rd is more like 20 mph- nice.
    Seems like a very low power motorcycle.
    I think it will go 40 mph but I am not comfortable on a bike at much over 25.
    Probably went up to 35 on my run. Had to see what it would do. Still didn't reach governor limit.
    Downshifting is just clicking down and you eventually freewheel down to where the engine will pull you forward if you don't clutch it.
  4. ibdennyak

    ibdennyak Guest

    Don't underestimate your hub Prof. I have one in a pusher trailer that has been doing fine for about 650 miles. Mine is laced into a 20 inch wheel, so I have all the torque increases before the hub, although you have a larger engine.

    I ran into the same shifting symptoms as you, but it becomes second nature to ease into the throttle until you are moving. If you ever drove a Mack with a quadraplex trans, the upshifting procedure comes quickly too. Mine sounds almost like an automatic now. The best part is that it has been so troublefree. One thing I did notice is that under sustained hard pulling (up a long steep hill) it will skip and reengage. I read up on the hubs, and that does seem to be a characteristic of the SA three speeds. Doesn't seem to hurt anything so far.

    Good luck on your creation.
  5. professor

    professor Active Member

    Thanks Denny! I did experience that skipping. So I backed off a little on the adjusting chain. I figured maybe the teeth were not engaging far enough. Have to put a heavy load on it to test fully, but it seemed to help.
  6. motorpsycho

    motorpsycho Active Member

    That's a very good idea you have there. you essentially made a 3 speed transmisson with that hub.
  7. blckwlfny1

    blckwlfny1 Member

    ****! you beat me to it!
    i was planing almost the exct same thing...just trying to work out bump starting the engine
    how is the hub working for you? is it holding up to the vibrations?
  8. professor

    professor Active Member

    I have gotten the hang of shifting seamlessly.
    I do get a skipping in 3rd gear at high engine loads and low rpm, but it doesn't seem to bother it.
    Ist and second gear are fine. Remember to put some oil in the little cap (mine is plastic and seals very well).
    Having gears is great, probably put a hundred miles on it so far.
    I am a little disappointed that the milage only gained a little with gears- up to about 120 mpg.
    I ride mostly bike speed (15- 20mph) with bursts up to 25 (on the governor- set low) if needed.
    I see no way to bump start this deal. The hub will freewheel.
  9. blckwlfny1

    blckwlfny1 Member

    Thank you sir :)
    What about a NuVinci? Does anyone know if that will work in reverse or just freewheel?
  10. SimpleSimon

    SimpleSimon Active Member

    The only NuVinci I have been exposed to was a very early production model, and it freewheels. Looking at the design of that transmission, I cannot see anyway to make it work in reverse mode at all.
  11. blckwlfny1

    blckwlfny1 Member

    So how do you start your bike?
  12. SimpleSimon

    SimpleSimon Active Member

    I did start my trike with a pull start - that is, until it got backed over while parked and smashed.

    The new rig I am building will also be pull start, at least at first. If I go ahead with my contemplated "shift on the fly" system for the GEBE drive, I will likely inccorporate an electric starter, since I plan on using two 55 watt headlights along with taillights and turn signals. Battery power for all of that will be a primary concern, especially if I can get healthy enough to do some of the touring I would like to do.
  13. ibdennyak

    ibdennyak Guest

    Hey professor...glad to hear it is hanging in there for you. I have been riding the stretch with the Nu Vinci mostly lately, so I barely put 100 miles on my SA rig, but it still works fine too. Curious as to what oil you use. I added some ATF to clean it out and then used 30 wt motor oil. Wondering if something else would work better. I also notice that if overfilled it tends to *mark its territory*. Yours too?
  14. blckwlfny1

    blckwlfny1 Member

  15. professor

    professor Active Member

    Denny- yep, it will leave some oil- nothing like the old Harleys though. I use some old synthetic hyd. that was in my squirt can.
    Well, there are no seals in the hub, so too much will seep out the bearings. Probably a good thing to over-fill occasionally.
    This hub sat for years, wouldn't shift at all, I oiled it and rode around the pedal bike it was on until it worked. I doubt the type of oil is critical.
  16. ibdennyak

    ibdennyak Guest

    Kind of what I was thinking. Oh, a little tip for mounting sprockets.....I used an 18 tooth sprocket and a 44 tooth kit sprocket for a drive. If you use 3 5/16 bolts to bolt them together with washers for spacers (leaving room for the circlip), it will self center every time. snug up the bolts and turn the sprockets until they push against the teeth of the 18 tooth sprocket and tighten down. Did that on 3 of them, and they run very true.