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Canadian Vintage Motorcycle Group

L'Association Canadienne de Motos Anciennes


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california friendship on a BMW R80RT 1985

  • 30 Jul 2023 12:15 PM
    Message # 13234132

    Hello sidecar buddies,

    I mounted this sidecar on my bike, it runs on dirt roads up to 85km/h wobbled a little bit when slowing down, but as soon as I go on the ''normal'' roads, it wobbles. Untenable  under 60km and impossible to go quicker.

    I did the following: Lean out and tow-in , distance between center side car wheel and center rear wheel , used Velorex and Friendship guide, they give the same dimensions.

    From the Friendship, I replaced the VW  torsion suspension by helicoidal spring and shock absorber. The side car suspension is now rather smooth. The VW suspension was very hard, I first thought this was the problem

    What can I do more? Damper?  Stronger springs on the front suspension? I do not know if one can get them for this bike.

    Thicker fork oil?

    How do you mount this VW damper?

    Thanks for your help or suggestions


    4 files
  • 06 Aug 2023 1:06 PM
    Reply # 13237216 on 13234132

    Unless the geometry is changed the wheel is trying to rotate backwards as in caster on a shopping cart. The std sort of fix is to add a damper. a real fix is to change the geometry (think car) approx 1/2" negative trail. way back, you went to the Triumph, BSA dealer and bought new sidecar tripple trees, along with stiffer fork springs and lower gearing. I seem to remember some one in Cal making conversions long ago. Alternate method is to drop the tele forks in favour of a Earls fork set up.

    Line through steering head mark where it touches the ground at normal load, vertical line through the Axle should be approx 1/2 to 3/4" behind the line from the steering head.    Paul.

  • 11 Aug 2023 7:56 AM
    Reply # 13239593 on 13234132

    From my first chair at 16 years, and backed by Bernie Knickolson's small do's and dont's for sidecars. Chair wheel lead 10" give or take an inch. toe in 1" over 6ft and also lean the bike out a few degrees.

    Modern bikes for the most part are way too flimsy for sidecars, even BMW many frames are either alloy cast or lightweight chrome moly. Pock Chop (on Prince Edward county) recommend sub frames to try and spread the load. There was a fad for while in Europe of fitting small chairs on Vespa Lambretta scooters.......... because you can, for a short while. Paul.

    PS may have been Doug Bingham of "Side Strider" sidecars, who made the tripple trees.

  • 11 Aug 2023 9:49 AM
    Reply # 13239650 on 13234132

    Hello Paul and Al,

    Thank you so much for your answers, I will check again and a damper is on the way from Germany. You will hear more from me after it is installed.

    My wife translates my french to english, she hopes it is ok. I look at your answers in the french translation of CVMG down this page, sometimes real funny. Thanks a lot again


  • 11 Aug 2023 8:56 PM
    Reply # 13239935 on 13234132

    As a school boy in the UK I went on a school trip to France, Luxembourg, and Switzerland. maybe a short stop in Belgium. long and short was the mandatory basic French and German. Needless to say on return with neither of those in use in the UK all was soon lost. I regret that now. 

The Canadian Vintage Motorcycle Group (CVMG) is a not-for-profit organization aimed at promoting the use, restoration and interest in older motorcycles and those of historic interest.

The Canadian Vintage Motorcycle Group (CVMG) is a not-for-profit organization aimed at promoting the use, restoration and interest in older motorcycles and those of historic interest.

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