Spanking the Cow- The continuing saga of an R100GSPD at the Races

Discussion in 'Airheads' started by Stagehand, Jan 20, 2011.

  1. Airhead Wrangler

    Airhead Wrangler Long timer

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    It's heavier, but not THAT much heavier. Weight could be mitigated a bit by installing an excel tube type rim instead of the monster tubeless cross spoke rim. Also keep in mind that it's already quite a bit longer and the shorter stroke shock means that that weight of the shock is only "semi-unsprung", less effect of its inertia when trying to move the wheel. I added up all the weights of various rear end setups a while back based on the weights listed in the parts fiche which actually seem to be pretty accurate:

    R1100GS
    final drive 16.7
    paralever rod 1.3
    swingarm 7.8
    drive shaft 5.2
    rear wheel 14.7
    disc 2.0
    caliper 1.8
    shock 10.0

    59.5 lbs total


    R100GS or GSPD
    rear wheel 14.2
    swingarm w/ all bearings, pins, lower boot 6.2
    tie rod 1.0
    driveshaft 4.4
    final drive 17.8
    brake shoes, cam, lever 1.9
    shock 8.4

    53.9 total



    R80G/S, R80ST
    swingarm w/ bearings and pivot pins 7.3 lbs
    driveshaft 3.9
    final drive 16.2
    rear wheel 13.0
    brake pads, cam, lever 1.4
    shock 6.3

    48.1 total




    HP2
    final drive 17.4
    swingarm 9.6
    paralever tie rod .9
    rear wheel 11.3
    driveshaft 4.8
    rear disc 2.1
    rear caliper 2.1
    shock 4.9 (I find that very hard to believe)

    53.1 lbs total
  2. LoJack

    LoJack Long timer

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    Cool!

    Hp2 had an air shock, didn't it? That might explain the weight.
  3. Prutser

    Prutser Long timer

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  4. Airhead Wrangler

    Airhead Wrangler Long timer

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    How much travel are you looking for? I think once you factor in driveshaft angles and shaft clearance issues inside the swingarms, there's really no way to get any more travel without lengthening the swingarm beyond 100mm. Not to say that's not possible, but the longer you go the more likely you are to high center the engine on something - breakover angle and all that.
  5. Stagehand

    Stagehand Imperfectionist

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    I only cased the bike once that I am sure of. That was sort of an extreme circumstance, and one wouldnt bottom or case as long as the suspension is right. Rooney's front and rear wheels both had 300mm of travel.

    The slightly added weight of a late model rear end could be mitigated by the fact you dont have to extend both a swingarm and a driveshaft. Thats nice, all that work is done at least.

    One would want to lace an 18" rear on the rear anyway, so you'd probably put a lighter rim on anyway.


    Why do we think we are limited to 245 rear travel with the 1100? Is that the angle limit of the shaft? I seem to think it will do more than that if you hang the right shock on it. It will just a be a custom one, but then, you'd be making your own top mount anyway, so you will be anyway, right? Unless you just try and use the 1100 shock as well with a differnet spring, but then how you mount the shock might give you some different room, too... it really gets kinda mind blowing, quickly.
  6. Airhead Wrangler

    Airhead Wrangler Long timer

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    That was just an assumption on my part. HPN listed 245mm for their bike that uses the 1100 swingarm and it seems like they push everything as far as they possibly can. I haven't actually measured and assembled and tried to break it. Someone give me measurements and I'll CAD it up. Anybody have all these parts laying around?? :D
  7. the_babaji

    the_babaji Been here awhile

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    A cow grate, ah, how fitting.:D

    Sent from my GT-I9000 using Tapatalk 2
  8. Stagehand

    Stagehand Imperfectionist

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    I also did a down and dirty measurement of the R100 paralever and the GS1150 I have in the barn, and the 1150 was 2.5 inches longer. Pivot center to axle center.

    I'm saying if the rear is 100mm longer it can get more travel than if its 50mm longer.

    I remember somebody saying that 100mm longer was a fair number to aim for, but it had no data backing it up. Just a number compromising additional travel and an over-long wheelbase.
  9. Stagehand

    Stagehand Imperfectionist

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    I thought that was pretty funny, also :lol
  10. Airhead Wrangler

    Airhead Wrangler Long timer

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    Another one from the guys at SWT:

    [​IMG]
  11. Koos

    Koos Wheeled Wanderer

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    I think that bike needs one of those maroon Husky tanks with the shiny spot on....
  12. Dmaster

    Dmaster Been here awhile

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    So, what happened to Stagehand?
    Secretly building his new Air-head rally bike?:ear
  13. Gone-Native

    Gone-Native XPLORER

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    Shhhhhhh......... It's a secret :D

    :deal
  14. Phreaky Phil

    Phreaky Phil Long timer

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    After riding the Rally Beemer in Ausie he just cant face gettin on the big old heavy GSPD anymore. :evil :D
  15. Stagehand

    Stagehand Imperfectionist

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    :shog

    Man there is some truth to that!

    I do love the old girl, though, and have finally gotten it back into road-running status... minus the bash plate, though....

    The poor thing is really bent so that even when I yanked on it the vice for a while and sort of straightened out the REALLY bent parts, it still doesnt quite line up with the holes in the new oil pan. Much tweaking will be required, but theoretically I could commute on it right now, if I wasnt such a wuss. Its only 35F.

    ANd I'm stupid busy at the thee ater.


    I also still need to take off the pannier frames and bend them out properly.. still kinda caved in from the CAnada crash. ANd I have no pannier system thats not just strapping the bent Zegas on. Its very Ghetto, but might be fine :lol3

    Motor still runs solid. Charging system is ok. Forks are awesome :thumb

    So I'm thinking about the lower shock mount bolt on the FD. Dont know how to make that bigger.


    Ok- here's the real issue facing the Airhead Rallye team. I would love to build a BM sort of like the Rooney special, and figure out how to race it in the MEx 1K and other events. Problem is I already have a project thats going to be fun, if I could ever get around to it. Its wrong for Rallye, in fact, I know its the wrong engine and frame for what I intended to do with it in the first place, but what the hell.

    I'd rather not make the same mistake with the new bike.

    What to do.. what to do.. .the New bike will budget out in the 15K region. Thats a years worth of racing, financially, sort of. Depending on teh racing schedule. And barely any love for any of the other bikes... it would eat everything for a long time.

    MAn thats tough love... I have to finish the bike I have and ditch it or keep it or whatever but get it in running condition and THEN look at maybe a rooney frame, and an R65/850 with cool forks and a long swingarm.

    R65 engine, R100cylinders machined down, and custom pistons: ANybody want to take a $$ Guess?

    then add a $1K shock, and maybe $1K in swingarm work, and $2K for powerdynamo igniton and maybe some DRZ front end. Need to mate a hub to an 18" wheel. Thats probably expensive.

    Lets not leave out frame. Long as I'm dreaming I might as well go all the way and get a Rooney frame.

    Thats a retarded amount of money for an old vintage brand new bike I plan on banging into the ground.




    woe is me but it sounds like a perfectly awesome idea.


    Sandblast Rally has moved the date a month back to first of March. Might take me that long to bend the bashplate straight again :D ah.. thanks for listening to the ramble.
  16. Rucksta

    Rucksta SS Blowhard

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    you know you want to

    how about a rolling chassis and become very good at engine swaps?
  17. AntonLargiader

    AntonLargiader Long timer

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    I have an R65 bottom end and I suspect I have some cylinders. I know I have iron ones to play around with. But is it worth giving up 130cc for?
  18. Beater

    Beater The Bavarian Butcher

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    I have an R65 bottom end as well ... and I know your address. Very tempted. :lol3
  19. Rucksta

    Rucksta SS Blowhard

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    The configuration has some advantages.
    - faster spin up
    - narower
    - lighter. a bit
    - maybe a bit more chuckable from side to side


    When I ran my mild 980 against an 860 in a similar chassis there was not a lot in it.
    The 980 was easier across the paddock in slow going .
    Once the revs were up to low 3000s there didn't seem to be much performance difference
    The 980 was stronger 5000 - 6500 but the 860 carried what power it had further into the rev band past 7200.
    Peak power was probably similar in the low 70s and the 980 clearly had more area under the curve.

    Lots of vibration from the 860.
    For a dirt race bike is probably a very good choice.
    AW certainly seemed to get some pretty credible performance out of the one he rode.

    Did you miss the grunt of the 980 under race conditions?
  20. Airhead Wrangler

    Airhead Wrangler Long timer

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    Is there another AW on here now? Do I have a doppleganger? It wasn't me. :huh