FINALLY about to start: Making a "jig?"

Discussion in 'Hacks' started by ZappBranigan, Feb 7, 2018.

  1. ZappBranigan

    ZappBranigan Still Riding

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    Well, the last two parts I needed have arrived from Bill Cozzi so I now have zero excuses not to work on the hack I bought over a year ago (November 2016.)

    Question for the group: I know there is a formula that the car wheel needs to "toe in" in order to turn safely.

    What I was thinking of doing was making a kind of inexpensive "jig." The jig would consist of two long furring strips or 2 x 2 pieces of lumber, as straight as I could find them. One would be laid along the left (outside) of the bike wheels and the other would be laid along the outside of the chair wheel.

    The wood strips would be attached to each other by pieces of string. The string at the front would be slightly shorter than the string at the back so as to "toe in" the wheel on the car.

    My question to the group, then, would be how much, in degrees, should the toe-in be? And then how do I translate that angle into linear measurements for the strings? I'm assuming I'm not the first person who's thought of this so any help would be appreciated.

    FWIW the pusher is a 2002 Triumph Bonneville 790. As for the car, well, it looks exactly like a Kozy to me but according to Bill Cozzi, it's actually an Inder.

    As far as actually assembling, I will probably have some help as I assume I'll need to hold the bike vertically off the side stand in order to attach the brackets.

    Any input as to how tight to torque the bolts? Two of the four attachments are going to "wrap around" parts of the tubular frame (one on the front above the oil cooler and one on the rear next to the side cover.) The other two attachments (the low front and low rear) were custom made, one goes onto the flat bracket between the front frame rails and the other attaches to both center stand attachment points.
    #1
  2. High Octane

    High Octane Long timer

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    Forget the wood and strings. just use two fluorescent 8 ft bulbs. The bike one should only touch the rear wheel not both. Use a tape measure, shoot for 3/4 toe in, ride and adjust as needed.
    #2
  3. RockyMtnRoadRash

    RockyMtnRoadRash Useful and decorative

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    Yawp. Aluminum C-channel also works and is less fragile.
    #3
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  4. norton(kel)

    norton(kel) vintage

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    Long straight edge works fine, laser level works good to. As High Octane says, "ride and adjust". I'm in Berthoud, if you need a hand. PM me.
    #4
  5. RetiredandRiding

    RetiredandRiding Retired to Ride

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    EMT is cheaper, hard to bend accidentally, and won't create a hazmat situation if you drop it
    #5
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  6. High Octane

    High Octane Long timer

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    I actually use rectangle steel tube but most people wouldn’t like the weight. Or I use a laser level but it’s not quite as intuitive as a straight edge. I used to use fluorescent bulbs when I had 8 ft fixtures.
    #6
  7. claude

    claude Sidecar Jockey

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    Measure just in front of the front tire and just behind the rear Tire. 1/2" should be okay. Too much will only create more tire wear and toe out will cause a pull toward the sidecar .plus tire wear. Recheck toe in after playing with lean out. What did Bill Cozi suggest?
    #7
  8. claude

    claude Sidecar Jockey

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    Oh,,,and try and get the straight edge up as high as possible ... sit it on 2x4's or something. You may also want to get the sidecar wheel off the ground and spin it to check for run out before doing anything.
    #8
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  9. claude

    claude Sidecar Jockey

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    Here is a Cozy we did years back on a Triumph Trident. Yes we did a few simple mods to it to lower it down and of course built the mounts for it. It won quite a few trophies and was a daily rider until it was finally sold.

    Attached Files:

    #9
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  10. Pokie

    Pokie Just plain Pokie.

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    Sounds to me like you are fitting four individual mounts. I shy away from this practice as with individual mounts, they tend to move or stray from where you set them. If the mounts clamp to the frame tubes, be careful you don't accidently damage the frame tubes. Some mounts I have seen folks use are made with "U" bolts, "U" bolts WILL damage the frame when you tighten them up enough to withstand the pressures that side cars give. A more logical way to mount a sidecar is to either weld mounts to your frame or make a "sub frame" that uses several locations or points that are on the frame of the bike. That way the sidecar is held in one place and no one mount will be over stressed as well as allowing you to remove and replace the sidecar without losing any adjustments.
    #10
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  11. norton(kel)

    norton(kel) vintage

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    Pokie is right on! You WILL damage the frame tubes with u-bolts if you tighten them enough so they won't move.

    When I was younger with my first chair I proved this to myself:imaposer
    #11
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  12. Valk rider

    Valk rider Adventurer

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    Just out of curiosity I once worked out that my degree of toe in for my particular rig was about .5 degrees. And no, I didn't calculate it I drew it with a cheap CAD program. Tried to find a high resolution iPhone compass app to check it but all I could find only resolved full degrees.
    #12
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  13. DRONE

    DRONE Dog Chauffeur

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    That's interesting. Never occurred to me to try it, but I think it would be fairly easy to write down the measurements then do some simple geometry to solve for the angle at the end of a VERY long skinny triangle!
    #13
  14. Valk rider

    Valk rider Adventurer

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    Your correct about using math to figure the angle. But I flunked high school algebra so had to resort to using the CAD program. The idea to set toe in by degree occurred while using the iPhone to set lean out. Figured I could reference against the rear bike tire using a straightedge just long enough to span the bikes tire, then using the same short straightedge across the cars tire make adjustments without having to keep re measuring using a tape measure. Still think it's doable if one could find a better resolution compass app.
    It would be interesting to have many people measure their toe in using the traditional method of measuring front and back and then calculating what the degree equivalent was just to learn if there was a consistent degree toe in between different rigs. I guess the lean out affects how much toe in is needed so that data would be necessary to try and arrive an an ideal set of values. OTOH I may not know what I'm talking about:y0!
    #14
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  15. High Octane

    High Octane Long timer

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    I don’t think the Zapbragger gives a rip. No action since posing the question.
    #15
  16. ZappBranigan

    ZappBranigan Still Riding

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    No I’m still here. Haven’t started yet, had another project take priority. Will most likely start wrenching this coming weekend.


    Sent from my iPhone using Tapatalk
    #16
  17. High Octane

    High Octane Long timer

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    Good. Keep asking questions. It’s a lot easier than making all the mistakes the rest of us made.
    #17
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  18. kshansen

    kshansen kshansen

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    Well first things first, this would not involve "algebra" but would involve "Geometry"and a bit of "Trigonometry"!

    I think the real problem with trying to measure the actual degrees is finding a way to measure a very small change accurately. A fraction of a degree change would be difficult to repeatedly measure where on the other hand using the two straight edges and taking measurements about 8 feet apart would give you readings in fractions of an inch. Much easier to get repeatable readings.

    We are not trying to shoot a rocket to the moon and land on some exact point so if our measurements are repeatable and within 1/8 of an inch I would say that was good enough. I feel the most important thing is to use the same method each time and have some way to know which direction you are moving. Exact degrees or even inches of toe are not the important thing. Besides the many differences between and two outfits makes most of this unimportant.
    #18
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  19. Pokie

    Pokie Just plain Pokie.

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    It's really easy to over think things while preparing. The real thinking happens when you start to work.
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  20. ZappBranigan

    ZappBranigan Still Riding

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    Alright, so silly question maybe but how much distance should there be between, say, my right footpeg and the sidecar frame? I'm trying to mock things up in my garage but it seems like the frame on the car is coming awfully close to the footpeg.

    If anyone out there has the 4-piece mounts (i.e, not using a specific sub frame) for a Bonneville or similar bike, could you snap some photos of how your connecting brackets are attached? I'm just having difficulty trying to visualize how this goes together.
    #20