Friction drive with the clutch

Discussion in 'Friction Drive' started by sojudave, Sep 25, 2008.

  1. sojudave

    sojudave Guest

    I've seached. I swear I have. I got three weed wacker motors, and I'm going to make friction drives out of them, but I want to keep the clutches on them. Is this possible? I know most folks take the clutches off.



  2. kerf

    kerf Guest

    From the weed wacker clutches I've seen, they're a little light to hold up to the torque required. Doesn't take very much to cut grass.
  3. Happy Valley

    Happy Valley Active Member

    What size weedwhackers do you have? There are a lot of small size whackers of 25-31ccs out there. There are also some larger models, sometimes called brushcutters, that use the larger engines popular with MBers as well.

    From what i've seen there are two common size clutches on small motors, 78mm and I believe 56mm on the common smaller weedwhackers and chainsaws.

    The commercially made friction drives use the larger clutch because they usually suggest motors larger than 31ccs where the 78mm clutch is used.

    One problem in engineering occurs after the clutch though. How will you mount the drive spindle so it aligns with the clutch and how will you support it with bearings? I think that's why many diy friction drives simply hang the motor over a wheel, bypass the clutch and direct drive the spindle off the motor shaft.
  4. kerf

    kerf Guest

    One other aspect of weed wacker engines is the 1/2 crank design. As a w/w has almost no radial loading on the crankshaft, many use only one crank bearing. If the crank is radially loaded with drive roller tension, it will fail.

    In addition to clutch diameter, rotor/drum width also is an issue.
  5. rkbonds

    rkbonds Member

    I'm running a 24cc weedeater engine on my bike with the clutch. I only have about 20 miles on it so far but, I like how it works. I am trying to figure out how to make a bearing mount on the other side for even pressure though.
  6. kerf

    kerf Guest

    I was going to do the same thing on my first bike but bought a Staton friction drive instead, glad I did. The unit has two bearings on the roller so the engine and clutch are not radially loaded. The 43CC - 2.2 HP TLE43 has plenty of torque and good top end, also very quiet.
  7. SirJakesus

    SirJakesus Guest

    Agreed the kit is really good and removes any need for backyard engineering. If you have around $450-500 and a bike this is the way to go with friction drive. If you don't have much money, lots of tools, several spare engines and other assorted hardware laying around and a bike to put it on a homebuilt would be the cheaper but not necessarily better way to go. I've heard the only things that "go" on a staton friction drive are the tires, spindels and engines, all after many hours on the road.

    If you're going to make your own please post pics. It's always cool to see how people converted old scrap metal into something cool.
  8. vegaspaddy

    vegaspaddy Member

    i third motion the above two guys, i just fitted a slightly used staton model to one of my bikes and i was very impressed, boy is that 43cc mits quiet compared to my 33cc tanaka its like a mouse but with plenty of power,

    have you looked into these kits

    at least you should be able to get some good ideas.

    good luck !!!!
  9. sparky

    sparky Active Member

    Interesting... I was curious how the 43cc Mitsu would sound compared to the 33cc Tanaka.

    So, in terms of sound dB... it goes:
    Mitsu << Subaru < Tanaka ?? (where the Subaru & Tanaka have nearly the same volume, but the Sub wins because of the lower pitch)
  10. Happy Valley

    Happy Valley Active Member

    Not in my experience. Can't speak about the Tanaka but I have a Robin and a Mitsu and there is no comparison, the Robin is the quieter of the two.
  11. SirJakesus

    SirJakesus Guest

    Well, I don't know if it's the different position of the exhaust and lack of transmission/chain noise but my newer TLE43 friction is whisper quiet. Whisper quiet not even comparing it to the one on my Nuvinci. It's so quiet I can hear other sounds perfectly with the purring of the engine in the background and it only gets kinda loud when I wind the thing out to 30+. 25 and below its incredibly quiet. It does have some visual changes compared to the older TLE43 so I'm figuring they improved on design.
  12. 5-7HEAVEN

    5-7HEAVEN Guest

    I second Happy Valey's observation. The Sub is quieter, especially at idle.

    And my red/black Mits with tuned pipe is quieter than the newer Mits with stock muffler. On my twin-engined bike, I hear both Mits engines running and idling simultaneously.
  13. Happy Valley

    Happy Valley Active Member

    To hijack this thread just as little further, I'd be interested in knowing more about that tuned pipe you speak of for the Mits. Link? thanx.
    Last edited: Sep 30, 2008
  14. 5-7HEAVEN

    5-7HEAVEN Guest

    This one, with silencer. However, the mounting bracket needs to be removed to clear the top of the engine and the friction drive housing. And the exhaust manifold's holes need reaming to fit.

    ADA Series 1 Chrome Rev Pipe - used by National and World Go-ped racing champions! Designed for midrange to top speed - adds 3-5 MPH top speed. Spring mounted, center bleed chamber. Fits Sport / X-Ped / Super X-Ped / Liquimatic / Bigfoot / Super Bigfoot / Go-Quad / Super Go-Quad / Homebuilders Kit. Does not fit GSR25 / GSR26R / GSR29R. Fits Zenoah G23LH / G2D / G230RC / G260RC engines. Also fits Chung Yang CY23RC / CY26RC / CY27RC / CY29RC / GP290 engines. Save $10 when purchasing a pipe and silencer together!
    Last edited by a moderator: Sep 30, 2008
  15. sparky

    sparky Active Member

    My friend bought one of those ADA pipes (tho it was a different one for a different CY motor)... but his added low-end & midrange speed. I figured all those ADA pipes woulda done the same.
  16. to bring this back to topic- friction drives are really easy to make and use....

    I used the clutch on my craftsman until I fubar'd it. The larger OLDER weed wackers have much sturdier clutches. THe clutch on the Ryobi I have was caro- I tossed it.

    Instead I made a "gravity" clutch, where I lift the engine up and down on the tire with a break lever and use a door spring to hole the engine to the tire. Works slick. I have a 1.5 inch drive spindle covered with JBWeld and sand mixed together. I can get a flat no pedal speed of 19mph and an easy 21 or 22 with pedaling. HOWEVER on the down hills it can power me to 30+mph. scary fast on my cheap bike.

    I built a simple frame out of aluminum angle and hung the engine off the side. works well for me.

    Anyway, I put a bad paint diagram of how my pulley and brake cable system work for the gravity clutch and a coupl of pictures of the bike. The engine only weighs 4 or 5 pounds so the balance of the bike isn't as bad as you'd expect.

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