Grubee 4stroke - in/out box reversal

Discussion in '4-Stroke Engines' started by HoughMade, Mar 17, 2008.

  1. HoughMade

    HoughMade Guest

    As it comes, the Grubee 4 stroke gearbox requires you to squeeze the left handle to engage and release the handle to disengage. I have a couple of problems with that:

    1- It just seems wrong. It is not a clutch, but an in/out engagement, but if you've ridden a motorcycle, you are used to squeezing to disengage, not to engage.

    2- In a "panic" stop, do I really want to have to remember to open my left hand and close the right hand simultaneoulsy? Try that without concentrating some time.

    Solution? Reverse the operation of the handle. I did this over the weekend and it was simple as anything I've done on this bike.

    There is a "Z" shaped bracket which holds the cable in place which is attached to the bike side of the gearbox at the in/out lever. It is attached with 2- 7mm .8 pitch screws. The photos below show the stock Z bracket location. They are photos taken for another purpose, but I think you can see it OK.

    I loosened the cable and removed it (keeping track of the spring), then I removed the Z bracket. After fiddling around, I found that if the Z bracket was bent a bit, reversed and attached to the gearbox cover, it would allow the cable to come in the opposite side of the lever and the spring would hold the lever in the "on" position instead of the "off" position. In this case, "on" is towards the middle of the bike, "off" is to the left, outside as the gearbox is on the left side of the bike. I tapped 2 holes into the gearbok cover to hold the bracket (it only located the cable, there is very little stress on the bracket). The Z bracket was attached with the 2 original screws (which are short enough not to touch the gears, blue loctite wouldn't hurt). The bracket is attached to not stick out the left side, but to extend over the cover back towards the lever. If you do not the reverse the bracket in this way, it sticks out 2 inches to the left of the cover- in the way- and the spring will not be long enough. As it is now, the spring works, but is a bit long. The last thing to do is to get a piece of stainless tubing to put the cable in so that I can make a 90 degree bend so that the cable does not come out to the left so far that it hits my leg. Because it must have a radius that enables the cable to move, it sticks out a little- but not much.

    I thought this solution was better than using levers and introducing additional complexity.

    Now, if I squeeze the left handle, it disengages. For safety, it has the locking button, so it can be locked "off" to start. For added safety, my bike has a stand that lifts the back wheel off the ground and I will start it with wheel off the ground.

    Photos of mod to follow (maybe tonight).

    As an aside, over the weekend, I also made a new bracket to hold the back of the seat up using one piece of steel instead of turnbuckles and I finished my tank cover. I fabricated a fiberglass cover to go over the stock tank to simulate the angular tank used on the Excelsior 1919 racer- that will have its own thread with pictures of each step and several "learn from my mistakes" tips- soon. next- a leaf spring to simulate the look of the springer on the Excelsior front- this is kind of fun.
     

    Attached Files:

    Last edited by a moderator: Mar 17, 2008

  2. azbill

    azbill Active Member

    nice idea !!!
    pics will clarify a lot (visuals help)
    thanks for this !!!
    you have explained the most with these kits, of any other poster
     
  3. I always thought those kits had centrifical clutches. So does that mean you can bump start that like a Happy Time? Wait. That rear sprocket isn't fixed,huh.
     
  4. HoughMade

    HoughMade Guest

    They do have cetrifugal clutches. That is why I refer to it as an in/out box. The gearbox can be disengaged so that when you are pedaling, you do not have to drive the the gears. No, it cannot be bump started because of the centrifugal clutch.
     
  5. HoughMade

    HoughMade Guest

    Pics of the new setup

    In these photos, you can see the new setup. The cable now comes from the left, outside, instead of from the right under the frame. This simple change if you have a tap set) allows the gearbox to disengage when squezing the handle instead of engaging when squeezed. I just have to add place some stainless tubing (copper would work too) over the last few inches so that I can place a bend in the cable to keep it out of the way of my leg.
     

    Attached Files:

    Last edited by a moderator: Mar 17, 2008
  6. mickey

    mickey Guest

    Pulling in to disengage makes so much more sense. Could you fabricate a turning block, like LF did for the HT, so that the cable could still come from the inside so as not to get in the way of your leg?
     
  7. HoughMade

    HoughMade Guest

    I thought of that- and that is a good idea, but I wanted simplicity over all....however, tinkering is the name of the game.
     
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