And so it starts....the Original G/SPD assembly

Discussion in 'Airheads' started by Beemerguru, May 14, 2011.

  1. Beemerguru

    Beemerguru Beemerguru...G/S guy

    Joined:
    Nov 7, 2006
    Oddometer:
    1,205
    Location:
    Redwood City, CA
    http://gregsgssite.shutterfly.com/

    Tomorrow is engine, tranny, and main harness. Not the usual assembly process because the front forks aren't back from reassembly yet. Trying to get this one at least in running condition before Memorial Day.

    Body parts are at the painter..new custom Works shocks on order. Wheels off getting polished.

    Step at a time.

    Nothing like trying to do 3 builds at once..send more scotch :evil
    #1
  2. camgregus

    camgregus riding gently now

    Joined:
    Feb 24, 2006
    Oddometer:
    3,023
    Location:
    on the banks of the mighty mississippi, AR side
    Greggs drink scotch? We should have our own thread....

    Keep it coming...
    #2
  3. Beemerguru

    Beemerguru Beemerguru...G/S guy

    Joined:
    Nov 7, 2006
    Oddometer:
    1,205
    Location:
    Redwood City, CA
    After almost a year of trial and error, rewiring, reworking, rewelding, rebuilding, re just about everything..it almost ready to go to it's new home

    Attached Files:

    #3
  4. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

    Joined:
    Nov 16, 2006
    Oddometer:
    5,455
    Location:
    Bowling Green, Ky
    I hope that was your customer's request to do it all in white. besides that very interesting. Like the custom muffler job.
    #4
  5. Houseoffubar

    Houseoffubar HoFmetalworks.com

    Joined:
    Dec 4, 2010
    Oddometer:
    1,874
    Location:
    Bothell, Washington
    Very impressive work!
    I've been thinking of something similar for my exhaust. Looks very good on this bike!
    #5
  6. Beemerguru

    Beemerguru Beemerguru...G/S guy

    Joined:
    Nov 7, 2006
    Oddometer:
    1,205
    Location:
    Redwood City, CA
    I was something that came together when I looked at the space left back there by extending the swingarm, the increased height from the longer dual shocks, and the desire for the same size panniers..something the normal G/S exhaust system stymied. Then roaming through one of the bike boneyards out here, I saw the flat Ducati muffler and had an "AHA" moment.
    #6
  7. Beemerguru

    Beemerguru Beemerguru...G/S guy

    Joined:
    Nov 7, 2006
    Oddometer:
    1,205
    Location:
    Redwood City, CA
    Patterned more or less by the factory PD bikes..all had white frames
    #7
  8. Beemerguru

    Beemerguru Beemerguru...G/S guy

    Joined:
    Nov 7, 2006
    Oddometer:
    1,205
    Location:
    Redwood City, CA
    Another thing I noticed about the color..I started going to a gloss black for the powder coating a couple bike's ago instead of the usual 40% standard BMW black..I found the gloss was easier to keep clean than the 40% for some reason. I went with a gloss white instead of a refrigerator white for this one and found all I had to do was spray some WD40 and wipe - and all the greasy fingerprints went away not matter how grimy I got everything.
    #8
  9. bgoodsoil

    bgoodsoil Dare to be Stupid

    Joined:
    Jul 9, 2008
    Oddometer:
    4,674
    Location:
    Washington, DC, USA
    Nice! Can you tell us anything about the fairing/headlight? :lurk
    #9
  10. Airhead Wrangler

    Airhead Wrangler Long timer

    Joined:
    Mar 4, 2008
    Oddometer:
    6,831
    Location:
    Back in Seattle, FINALLY
    The way those shocks are mounted on the subframe still has me pretty worried. The lower frame tabs just weren't designed for that. While all the BMW road models of the 70's got by just fine like that, all the PD race bikes mounted the shocks to the main frame. While monolevers got by with a single m10 bolt for the shocks, it was in a clevis arrangement basically doubling its effective shear strength. Those lower M8 subframe bolts are in simple shear and can easily distort the tabs they bolt into. If this thing sees serious off roading and something breaks, I'm betting on those lower subframe bolts and/or the tabs on the main frame. It could start slowly with the holes getting ovalled and then knocking. Also, the lower leg of the subframe on the right side has a big bend in it to go around the stock shock on an r100gs. This side is not nearly as stiff in tension as it's corresponding member on the left and is prone to lengthening if the supension bottoms out and knocks hard. That will distort the subframe as well as the swingarm. Not trying to shit all over your work, and it is nice work, but as an engineer who spends all day fixing failed structural designs, I'm just expressing sincere concern - especially if you're building this for someone other than yourself.

    That muffler idea is pretty cool. Good way of saving luggage width without having to go low with it. Nice.
    #10
  11. Toyanvil

    Toyanvil Adventurer

    Joined:
    Feb 8, 2004
    Oddometer:
    1,766
    Location:
    Bakersfield CA
    Congratulations :clap That is AWESOME I like the white.
    Is the rear tire backward?
    #11
  12. hardwaregrrl

    hardwaregrrl ignore list

    Joined:
    Jan 26, 2006
    Oddometer:
    8,170
    Location:
    Atlanta
    #12
  13. Beemerguru

    Beemerguru Beemerguru...G/S guy

    Joined:
    Nov 7, 2006
    Oddometer:
    1,205
    Location:
    Redwood City, CA
    Actually have some of the same concerns and have another GS subframe being modified to address those issues.

    One of those things that when you finally hang it all together for the first time, something looks odd or could have been done better. Kept debating on if it would work or not..normal riding shouldn't be an issue...but that's not the goal here so back to tweaking.

    Fortunately,,about 15 bolts and it's all apart and the new one on...couple hours work.




    #13
  14. Airhead Wrangler

    Airhead Wrangler Long timer

    Joined:
    Mar 4, 2008
    Oddometer:
    6,831
    Location:
    Back in Seattle, FINALLY
    If it were mine, I'd go for this arrangement:

    [​IMG]

    Mount both shocks to the swingarm (not the final drive on one side). Supershaft can tell you how (not) strong a mount that is on the final drive. :hide

    Then again, people successfully ran the dakar on BMWs before BMW ever tried. This guy did it on basically the same setup you've got, but I'm not sure what (if any) modifications he made to the frame.

    [​IMG]

    All the other twin shock BMWs that followed that I've seen have used the first arrangement pictured above though or a slight variation thereof.
    #14
  15. Beemerguru

    Beemerguru Beemerguru...G/S guy

    Joined:
    Nov 7, 2006
    Oddometer:
    1,205
    Location:
    Redwood City, CA
    Nothing like fabrication to test your patience. No matter how much you plan, there is always something you find later that can be done better.

    First ride impression: This thing is TALL..but that feeling goes away as soon as you get over 5 mph. Then it handles like a much smaller bike..at 20 mph,fingertip control..smooth and solid. Hands off at 70 and no shakes and tracks straight as an arrow. Suspension needs to be adjusted...little hard in the rear. Brakes are great but the rear needs tweaking.

    Got back to the shop and did a walk around a decided to tear the rear apart and rebuild some of the attachment points like this group suggested. Got rid of some curved downtubes and replaced/repositioned the shock mounts with something twice as thick. Reinforced the rear bag mounts and cleaned up some small things.

    Off to the powder coater and should all be back together next week for the final shakedown ride.

    Attached Files:

    #15
  16. Beemerguru

    Beemerguru Beemerguru...G/S guy

    Joined:
    Nov 7, 2006
    Oddometer:
    1,205
    Location:
    Redwood City, CA
    Took most of your advice...see post above. Went for more strength and repositioned the muffler mounts so the stress goes into the frame and not as a shear force. The shock now sits about a mm about the frame which should minimize the ovaling potential a bit. No more bend either. The bike will be for world traveling not the PD race so I made the decision that this suspension setup should hold up well within those kind of parameters...or course time will tell :rofl

    The muffler is actually pretty quiet at speed...less than the Staintunes I usually mount. That is until you romp on it and THEN you get this authoritative bark that means business.:eek1:eek1



    #16