Rear rack Greyhound mountain build

Discussion in 'Rack Mounted Engines' started by 4950cycle, Mar 24, 2011.

  1. 4950cycle

    4950cycle Member

    I have been gathering and being entertained by MB info & stories on this great site and 1 or 2 other MB sites for a long time now. I think its time I finally give something back. Not that what I am doing is more important than what you are doing or sooo clever. It is just the sharing of our MB experiences that make this site what it is. A heck of an archive of info that before this day in time was never available to the other MB enthuseist in the world.:bowdown: So walk with me and allow me to show you how I build my Mongoose full suspension frame rear rack HF 4 stroke Grayhound 2 1/2 hp build. I will say IMHO, it is not one of the easier build choices there are. At least the way I am going about it.:jester: Mind you I am far from a compuker geek so bare with me as I take great effort in posting pics and such.lol
     

  2. 4950cycle

    4950cycle Member

    This is the rear rack mount build in progress. I took advantage of the swingarm being ferrus metal (steel of some sort) to use welding as my connection method even though the bike is obviously an 26 inch aluminum alloy full suspension Mongoose except swingarm. The material for the rack is a steel subframe from a 26 inch girls Roadmaster MT sport. The front of mount connection to swingarm is a alum. with steel swivel peg front caster from an electric wheelchair. I will have more for you that are interested in a day or so. Thank you for your intrest. John
     

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    Last edited: Mar 25, 2011
  3. Wheres my dog

    Wheres my dog Banned

    Looking good so far... are you certain you have a solid weld on the swingarm there and it can handle the torque and weight?
     
  4. 4950cycle

    4950cycle Member

    Even though I am darn sure no pro welder,lol I made sure I got good pentration on the welds and am over doing it. Its welded on top and its welded on the bottom (upside down). And the two small tubes going down from rack are welded also so won't have a ton of twist when I twist. And as far as the actual pivot pin on that upright It is made for putting up with 400 lbs people in electric wheelchairs. That little motor isn't going to fitegue the pin to the point of breaking. But you are right, the weld will most likely be the weak link.
     
  5. lowracer

    lowracer Member

    Lookin good John.
    Looking forward to more pics as it goes.
    -Lowracer-
     
  6. 4950cycle

    4950cycle Member

    Thanks Lowracer. Oh yea I got the Whizzer wheel sheave in the pic and a lot of forward thinking ideas from Lowracer. He's helped with a lot of how things work and don't work in MBs in my planning.
     
  7. 4950cycle

    4950cycle Member

    Second stage or rear rack build

    I mean Second stage "OF" rear rack build. Here are some pics of what you might call a ruff sketch in physical form. Threw it together just enough so you can get an idea. Of course alum. flange bearing mounts will be trimed in, Alum jack shaft will be cut to length, Pulleys/sheaves will be ventilated (lots of holes drilled in them to lighten).
     

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    Last edited: Mar 27, 2011
  8. lowracer

    lowracer Member

    After seeing these pics I have a better idea about your build.
    As they say, 'a picture says a thousand words'...lol
    Keep'em coming...wanna see this rig rolling.
    -Lowracer-
     
  9. 4950cycle

    4950cycle Member

    Oh yea, Trimmed and painted the flange bearing plates last evening. Its all looking a bit better than I thought. And even better is everything looks like it will line up, so far anyway . As far as belt lines and weight "Not bad at all" . BTW, Everything that looks like it may be aluminum and/or aluminum alloy probably is. Except silver upside down bike subframe (rack). I managed to bolt the alum. plate flange bearing mounts on without compremiseing the rack dropouts. So this rack is very adaptible. I can get rid of the flange bearing plates an expose the drop outs again to mount a 3 speed hub jack shaft. Or I can cut the down tubes out and put Staton like adjustable slider rear mounts and go friction wheel. Remember the front of rack hindges, so with rear uprights cut out you could tension said friction roller. As you can see I don't like to get cornered.
     
  10. 4950cycle

    4950cycle Member

    Here is a couple pics of the near finished swingarm rack /jack shaft mount before I start reassembleing the bike for a cruise test (no power). I try to ride a bike peddle only with motor/drivetrain mounted to see how it peddles and how the weight is distributed to see if the design is worth spending the time and energy to tweak all the bugaboos out.
     

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  11. lowracer

    lowracer Member

    Looks good...
    Now to get that motor up on there.
    -Lowracer-
     
  12. 4950cycle

    4950cycle Member

    :detective:I just noticed, Your 43 sucker. Geeese, the way you called me old man I thought you were 32 or something Alex.:shout: Yea, I should have her assembled in a day or two. Maybe a day or so more to get her riding under power. Have fuel supply and throttle to get solved and sorted.:-/
     
  13. lowracer

    lowracer Member

    HaHa...
    I feel like I'm 18...
    These rain days put me in the garage to build.
    Looking forward to seeing your contraption rolling along...
    -Lowracer-
     
  14. 4950cycle

    4950cycle Member

    Yea, I do know what you mean about the rain and the garage. I had to clean the darn thing so I could actually get to the bench to work on my contraption. Believe it or not, I am excited just at the thought of getting her back together so I can install all motor drivetrain conponents and ride her in bicycle form just to see how the layout worked out for ridability. The being able to go under motor power a little later is just an added bonus.
     
  15. 4950cycle

    4950cycle Member

    third stage of build well under way

    As any of you might know that have stripped down a Greyhound to its almost bare cylinder state will know that now you must find a place to mount your on/off switch,must seccure a new place to anchor your throttle linkage/cable back at the carb.(weld bracket for cable on engine valve cover),make a new version of the exhaust that will work with a rack mount MB layout. Not to mention haveing to weld the mounting brackets on the factory gas tank in totally different places then they came so I can get the gas tank higher than the engine carb. I choose on the handlebars. These are some of the things besides life happening way to much for my likeing that have been keeping me from being done already with this rack mount build. Will post a couple pics tomorrow.:-/
     
    Last edited: Apr 11, 2011
  16. 4950cycle

    4950cycle Member

    BTW, I had engine mounted and pulleys and shaft in place and took her for a peddle. Much more balanced and lighter than I thought she would be. I will deffinately go foward with this build to stage four of build. Designing and fabricating functional motor mounts was a real trip on this upside down bike subframe rack.:rolleyes7:
     
  17. ibdennyak

    ibdennyak Guest

    Lookin good 4950. One suggestion....I ran a 97cc Lifan on that frame for about 11,000 miles. It had enough torque that it took out the swingarm bushings. Nothing horrible, just kind of a funny crabbing sideways sort of feeling under hard acceleration. Don't know where you can buy them, so I robbed them from another frame. Always planned on making some out of brass or something, but you know how that goes. Just something to keep in mind for down the road.

    Lowracer, The double JBWeld rim idea that I stole from you is curing as I type. Finally got to it. Mine will stay where I mount it though. :grin5: I don't have near the ambition that you do as far as moving things around I guess. :jester:
     
  18. 4950cycle

    4950cycle Member

    Yea Ibdennyak, Lowracer Alex dosen't have the patience to follow along with a slow *** builder like me:dunce:. He can change the whole configuration of his MB in less than one day when I would have to fiddle with it for a week or more:ack2: Ibdennyak, was your motor rack part of the swingarm or was it remote (comeing off the seat area or main frame) ? To try to avoid some of those type of problems like torqueing issues I made the powertrain all one solid unit/all part of the steel swingarm. Where nothing was/is pulling and tugging on something else. The one drawback to this as far as proffessional motorcycle designing goes is what they call extra unsprung weight. But scooters have a **** load of it with their entire drivetrains before the shocks/suspension and its working for them :eek: !
     
    Last edited: Apr 12, 2011
  19. ibdennyak

    ibdennyak Guest

    Totally supported on the swingarm. The engine isn't all that heavy, but it still more than doubled the unsprung weight I'm sure. My theory was that I was building a bike with a motor, not a limo, so I would deal with it.

    The bushing problem was most apparent when starting from a dead stop and turning while the throttle was open. I could feel a flexing that got worse until I replaced the plastic bushings. I still can't complain about the bike though, the frame is indestructable, and the bushings hung in there pretty well for what they were subjected to.
     
  20. 4950cycle

    4950cycle Member

    Was a bike like this Mongoose ? And if it was, was it aluminum alloy like this one ?
     
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