The Premium of Small Transmissions... At Your Local Junkyard.

Discussion in 'General Questions' started by Blue Smoke, Jun 12, 2013.

  1. Blue Smoke

    Blue Smoke New Member

    I have long been on the search for a small multi-speed transmission more rugged than a 3 speed bicycle hub, yet affordable. Wading through all the Chinese junk and bad reviews led me nowhere. Seeing terribly misaligned, undersized, poorly machined, or poorly designed gearboxes made it seem hopeless. The only thing I could think of that I could afford was a well used transmission out of a riding lawnmower, but needless to say, was far too big.

    Then, I just so happened to get a job at a lawnmower repair shop. All of the self propelled ones had a common theme, that of a reduction drive that needed to be opened up and packed with grease at every service. Before too long, it came to me that these would make excellent reductions for bicycles. My only problem was that they were right angle drives using straight cut bevel gears and the output was perpendicular to the input. I would just about have to use a lawnmower engine with a vertical shaft to match it, and those were huge.

    Then came another great idea, that of mounting the engine transversely (a 2 stroke Tecumseh) and having the reduction bolted beneath it, with the output running to the back wheel via belt.

    That all sounded fine and dandy, until one day I came across one of the better Lawnboy mowers. It had a 3 speed transmission! Not only did it have 3 speeds at a fairly wide ratio, but it contained a reduction of 6:1 or so in the highest speed. It was self indexing inside of the transmission, so about anything push/pull would work for a shifter. The gears inside are about half an inch wide and are ALL made of steel. They have a steel pan that can have mounting lugs brazed on to it. On top of all that, they are fully rebuildable. All parts can be found for them new, so if you manage to find one and it doesn't work up to par the parts could be bought at the local Lawnboy dealer.

    These have to be fairly rugged. I have never seen one broken down. They run in the dirt for years on a vibrating lawn mower and don't show hardly any signs of wear when the rest of the mower is totally shot. The only common problems are that of the indexing cam getting worn and it won't shift well, but this isn't even all that common, and that part can be had fairly cheaply and is replaced easily. The other is that of the powder metal bearings on the mainshaft getting worn from dirt exposure, but they are also fairly cheap and easy to replace.

    My boss was nice enough to give me one out of a junker to experiment with. I have just started on a bike with the Tecumseh 3 horse and the Lawnboy transmission doing its job. I will report back as soon as I am done.

    So, stop by your local shop and see what you can find! It doesn't sound like it has been tried before, so we may have come by a gold mine here...

    Last edited: Jun 13, 2013

  2. BigBlue

    BigBlue Active Member

    Sounds like a great idea, but the video or link doesn't work.

    AKA: BigBlue
  3. Fabian

    Fabian Well-Known Member

    The video link does not work and the video description does not bring anything up on Youtube.
  4. bigoilbob

    bigoilbob Member

    What will transmission efficiency be like? I always assumed that such Xmissions had lower efficiency as a result of their rugged build. But I could be wrong - it was just my assumption - and even if I'm right, the trade off might well be worth it. I would be happy to be corrected here..........

    Separately, what are the "wide ratios"?
  5. Blue Smoke

    Blue Smoke New Member

    I just looked at the transmission. The high gear is a 5:1 reduction and the low gear is a 10:1 reduction. The middle gear is probably 7.5:1 reduction.

    I got rid of the link. Look up "Cleaveland Welding A2 Lightweight" if you want to find the video. You will know when you find it.

    I couldn't imagine the efficiency of this is any worse than that of a cheap shift kit or a pile of chains, sprocktes, and bearings. They don't exactly bog the mower down when the self propelled is used. To me anyway, the ability to choose different ratios for different riding situations would be well worth a bit of power loss. The engine could be in its power band at different speeds, so it is worth it for me. Living in the town, the low gear would be great for around the city and in alleys in most situations. Large roads and county roads would be where the "Highway Gears" are used instead of making the engine scream as it did in my last build.

    Also, I plan to use this to travel around the gravel and county roads of Iowa, so a bit more rugged of a transmission wouldn't hurt at all. Avoiding one time broken down in the middle of nowhere is enough to warrant a little power loss and weight.:helpsmilie:

    Thanks for the comments,
  6. BigBlue

    BigBlue Active Member

    Cleveland Welding A2 Lightweight not Cleaveland:)

    AKA: BigBlue
  7. LR Jerry

    LR Jerry Well-Known Member

    Small Lifan engines have multi speeds. However you must manually shift them. Which would become a legal issue in most states. Yes manually shifting gears through a shiftkit is illegal as well.

    So in order to have multiple gears and remain legal they must shift automatically. There's been a couple of people who've made 2 speed automatic transmissions. One could use a shiftkit, Kilduff shifter and a Shimano Nexus 3 speed hub.

    Here is my 5 speed automatic LandRider.

    Your idea sounds good but in order to be legal in most places you'd have to figure out a way to make it shift automatically.
  8. professor

    professor Active Member

    I had one of those single speed gearboxes from a self-propelled mower, but I considered the load on it would be a lot more than its current use of spinning the front wheels on the mower. It also had only plain bearings on 1/2 inch shafts.
    In the mower application,they also had outboard bearings near the wheels, so the bearings on the gearbox actually carried very little load.
    Maybe your is better- hope it goes well for you.
  9. HeadSmess

    HeadSmess Well-Known Member

    another area coming into vogue is the 1:5 RC cars. i got the 2 speed transmission off of one, but still havent done anything with it. requires a mounting bracket, and if you want to clutch start, another one way bearing. also i shoulda saved my 150, bought the 120 dollar one my mate got, because it appears that I got the cheap one! his is made properly. mines got a gear bored at 5 degrees to true.

    remember, a chain runs up to 99% efficient. gear drives get to 95% or so, max. and thats high precision, ground, expensive gears.

    the gearbox is a nice idea. i know my mate has a small right angle drive ive always wanted for this exactly, its perfect, but he wont part with it. but convenience for lubrication and lack of adjustments...oh boy, who cares if you lose a bit of grunt? if the units sealed with a simple belt to the wheel.

    elctro-generator! petrol motor running a small genny wired directly to an electric hub!

    another thing to note with gear drives. the maximum power transfer goes up with rpm. high speed gears can be a lot more "delicate" than low speed gears. so you dont need anything too heavy on the engine itself, but by the time it hits the wheel, the loads are getting high, and speeds low.

    theres that nifty dog clutch twin speed someone designed and posted in the electrics section... the ideas workable into mutliple strands. i believe a certain car manufacturer tried that system years ago too :) possiblilty of adapting to auto with some braining.

    the scrap/junk yard is the place to go.
  10. Blue Smoke

    Blue Smoke New Member

    Motorized bicycles aren't legal in Iowa at all anyway, from what I can tell. If I am going to make it, I might as well make it how I want it to be...
    Got all kinds of parts and scrap, I plan on starting it soon....

  11. grinningremlin

    grinningremlin Active Member

    I love it, if it's a stupid law I break it, the common sense darkside.
  12. I've also thought of this! I have a small 4 speed tranny to a snapper that I thought of using because it is pretty small. But could it work? Cause you're right, the input is vertical.
    But now that there's two thinking the same, I'm with you on this one! What if you used a small vertical shaft motor. Like a 3 or 4hp, just made a frame to fit it. It would definately be one heck of a motorbike.. more of a motorcycle. Once I finish the build I'm on, I'm start fabbing a way to use that tranny. It'd be too cool with a suicide shifter!
  13. wheelbender6

    wheelbender6 Well-Known Member

    This idea has me very interested. It looks far less expensive than running a Briggs/Comet CVT setup.
  14. narley

    narley New Member

    I have put a 3 speed hub after a motor made 2 speed trans. 3 bike 3 years ago. narley

    If you want to put a 3 speed hub with a motor for a trans... will work I have done it works very good.. I fliped the hub over lost middle gear now it is nutal on gear.. So i removed the spoke flange farest from sprokit add sprokit to a short pice of pipe weld then bord it out to fit a round tne hub then I used a seres alan bolt zigzaged a round the pice of pipe to hold in place were the spokes would have been with the pipe you can move it over were you need it to be to the motor.. then the other sproket gos to the wheel... use a throlld shift works best.... nothing like it if you make a trans out of a hub you will love the gears...look at my bikes on
  15. professor

    professor Active Member

    I don't understand why you lost 2nd gear on the hub.
    I use a SA 3 speed with a 212 HF as a jackshaft and the center gear is one to one ratio (in / out).
    I do like the arrangement a lot. Click shift is great.
  16. narley

    narley New Member

    narley... I used a 3 speed hub flip it over welded a sprocket to the spock flange. It was a sturmey-archer hub old style steel, removed one of the spock flanges, the sprocket around the hub goes to the motor. and the drive sprocket of the hub goes to the back wheel. you get 2 of the gears and nutreal. works goods i have three bikes that way....
  17. narley

    narley New Member

    I fliped the hub over to fit in middle of bike. I used the hub as the jackshaft. you are right the center gear is 1to1 but it is not a gear it is a FREEWHEEL and when you flip a freewheel over it justs spins.. that is what i did to fit hub in the middle of the bike.. i put the motor in the center of the fram with the hub. I use the hub as the jackshaft depinding on how wide the back tire is.. I got motor in line with the trans then to the back wheel.. looks a lot like a can see my bikes at
  18. narley

    narley New Member

    I am going to try stumey archer 5 speed next i think it will work... highest speeds for down hill only, it will probely bog down other wise....