Sidecar Design Formula - IMPORTANT!

Discussion in 'Hacks' started by Get Back, May 25, 2009.

  1. brstar

    brstar Long timer

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    Mine worked out to be 9 degrees apparently (i never did the maths) from horizontal. From the front pivot to the rear.
    Just used Nolathan suspension bushes that required the 2 points to be inline .
    Seemed to work quite well.
    Have recently added struts to make it ridgid.
  2. Hvymax

    Hvymax Been here awhile

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    I'm planning on a strut for winter riding.
  3. claude stanley

    claude stanley Claude

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    We used the clevis connections for a while but got away from them. Yes double shear has it's fans and of course the theory is correct but they can be a little harder to work with in ways. We used them to satify the ones who promoted them but in reality one is not going to shear off a grade 8 x 1/2 bolt. The ones we used as well as our eyenuts had /have all change of direction areas machined to a radius ( not squared corners to promote stress risers ) and the internal threaded body of them is a little longer than some to insure a good connection. We had some from another source that had the internal threaded hole drilled to deep into the unit and the tab broke off the end of the eyenit ...not good. Our eyenut is also locktited to the B7 grade 3/4 x 16 coated / threaded rod so it will not tend to thread out of the eyenot during any adjusting. This is important...... oh BTW have seen clevises from other sources where one side broke off ...why? Possibly the sides were too thin and due to tightening and untightening they developed stress cracks on the 90 degree transition surfaces that were not radiused at that point.
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  4. claude stanley

    claude stanley Claude

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    Didn;t read the link you posted but when viewed from the front or rear 45 degrees would be ideal....but this is not typically possible in many cases. We have added a verttical 'hoop' to the sidecar frame in some cases to get the struts at a better angle though. When viewed from the side opposing angles are best for better sypport fore and aft. At times we will add a third strut attached to one of the uppers to triangulate things better. This extra strut is removed when the main ones are adjusted then adjusted to fit the main ones. It's sole purpose is for triangulation.
  5. claude stanley

    claude stanley Claude

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    Note that none of my posts ( unless noted ) are related to leaners. Those are a different story in many ways. Just sayin'
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  6. Strong Bad

    Strong Bad Former World's Foremost Authority Supporter

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    Found out a long time ago that going with Grade 8 isn't always the best choice. I've seen from damaged front ends on off road race cars that a Grade 8 is more likely to fail in a brittle failure (snap) where a lower Grade 5 will deform (bend) allowing the race car to limp into the next pit.

    Also during the last big full built from scratch off road race car, the Arciero/Miller team VW Baja Rae Touareg, the shop was built up with zero supplies. The team manager found when ordering hardware that the market is saturated with "fake" or "forgery" nuts and bolts. The heads of the bolts are marked with the 6 radial lines indicating Grade 8 but when tested they barely came out to Grade 5. It was thought that buying hardware in bulk you could get them with the testing verification certifications (aka: "Certs") and eliminate the issue of fake hardware, but alas there was fake hardware with fake Certs!! Unfortunately, the forgery business also extends into the bulk material where alloys are miss-represented, that is phony 4130!! Most of the forged crap is coming out of China and India.
  7. DRONE

    DRONE Dog Chauffeur

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    Now THAT'S interesting. Can't even trust bolts anymore. I wonder what the phony Grade 5's would test out at?
  8. claude stanley

    claude stanley Claude

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    ..............................................................................................................................................................................................................................No debate there......Actually a grade 5 would do what we need done but would not be acceptable to most. BTW years ago many switched to grade 5 on things such as radius rod attachments on the sprint cars etc. Why? Well they would do the job of securing a 5/8 heim end and would bend in a crash rather than buggering up the spud through the frame of the car. Simple logic .... chasing weak spots can be a crazy thing.
  9. pagomichaelh

    pagomichaelh Been here awhile

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    At the salt mine, we've flogged off fasteners (and other stuff, of course) for over 40 years. We purchase many tons per year.

    Our wholesale supplier, who I think has been in business twice that long, after getting shafted a few times from asian manufacturers, now do their own independent testing, screw the mfg certs. They're more expensive than other suppliers, but we sleep soundly.
  10. Jack Grinder

    Jack Grinder Adventurer

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    love that crazy crash bar around the front of the bike. Is that home-made or over the counter
  11. High Octane

    High Octane Long timer Supporter

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    I’ll ask this question here rather than my build thread because it may be relevant to more than just my rig.
    As I ponder the best way to make the upper rear mount on my R1150GS I ask myself just how much it’s actually needed. The BM rear subframe is known for its weakness so just clamping a mount seems a bad idea. So to make it work I see making a exoskeleton steel frame to essentially keep the load off the BM rear frame is done. If you run the beam calculations it still going to deflect. So I see builders wrapping the exoskeleton frame round to the other side of the bike to support it better. But it all comes back to bolting into the engine or transmission. So the sidecar forces really are all just transferred to the engine area. So what is that high up rear mount providing? Why not put the effort into a very rigid center high mount, in line where the exoskeleton frame bolts anyway?
    Sorry if this all makes no sense. I think you’d have to have looked very closely at the 1150 mounts to have a clue to what I’m asking here. But I’ll ask anyway.

    edit: I found this pic from TripTeq. It’s very close to what I’m thinking of building. But it looks like they still have a rear upper mount of some sort.
    Any thoughts?

    332887AB-D565-48FB-B5EA-C78E39D1C352.jpeg
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  12. DRONE

    DRONE Dog Chauffeur

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    Using a single upper sure would make toe-in and lean-out adjustments easy. My first worry though is where would you put it so that it would not interfere with you right leg/butt cheek? On my DMC 1150GS the rear upper was placed just barely aft of where my hip bone connects to my leg bone. Could not possibly move it forward.
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  13. High Octane

    High Octane Long timer Supporter

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    I already have the front upper mount figured out so I’ll have at least 2 upper mounts. It just the rear upper that I can’t make sense of. Does DMC just clamp to the bike rear frame? It’s a known weak point on the 1150. Is the only reason to move the mount to the rear so it clears your leg? I seem to have plenty of room right around the brake reservoir. I’m planning to build a short upper sub frame to spread the load and keep the forces off the BM frame. But again I just don’t see the importance of moving the upper rear way far rearward, as long as it clears your leg. Seems to me the further rear the more leverage on the mounting points, which really come don’t just a few bolt points on the lump of cast cheesium.
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  14. GR8ADV

    GR8ADV Safety Second!

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    The DMC method. D4F969E6-9C14-4221-88BB-092688B42C87.jpeg
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  15. GR8ADV

    GR8ADV Safety Second!

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    Pure horizontal upper mount? Hmmm. I have no experience directly with sidecar structures. But I do know that for strength, triangles are your friend.

    with respect to my opinion, you get what you pay for...
  16. High Octane

    High Octane Long timer Supporter

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    So DMC just clamps to the BMW frame? What is the tab coming off the top do?
  17. GR8ADV

    GR8ADV Safety Second!

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    Don’t hate the player, I just have the pic. The tab appears to be the member that takes the load to stop the rotation of the clamped ‘mounting’ point on a round tube. Given the axial loads and moments on that strut it will try to rotate said connection. That connection without the tab would appear to rely solely on the friction of the clamp. DMC would know best as I am speculating based on what I see.

    2081F3F3-C72F-4505-9892-9327CA170215.jpeg
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  18. High Octane

    High Octane Long timer Supporter

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    No no don’t get me wrong, I don’t hate on anyone. Thank you for your info. I’m trying to avoid clamping to that frame but maybe it’s all for naught. Not to clutter this thread I’ll post into my build thread.

    Attached Files:

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  19. GR8ADV

    GR8ADV Safety Second!

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    I was kidding.... you never struck me as the hating type.
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  20. DRONE

    DRONE Dog Chauffeur

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    GR8 is correct. The rear upper DMC mount clamps to the subframe and the tab keeps the clamp from rotating. Sounds hokey, but when I crashed my 1150 rig the sidecar body was OK, the frame was OK, the DMC subframe was OK, the BMW rear subframe was OK, and 3 of the 4 struts were OK. The only sidecar damage was the rear upper but . . . wait for it . . . the subframe clamp never moved -- only the lower mounting point (on the sidecar chassis) for the upper strut got bent. The left side pannier got squashed too so obviously there was a big hit back there there when it rolled.



    bent here.png
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