Final drive weigth reduction

Discussion in 'Airheads' started by Dmaster, Jan 28, 2013.

  1. Dmaster

    Dmaster Been here awhile

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    I've searched the internet and this forum but couldn't find any info I'm looking for.
    Did anyone ever tryed to get some weigth out of the final drive?
    Does anyone know of someone doing it? Any picturs available?
    What could you take away, drill/machine/whatever?
    #1
  2. JonnyCash

    JonnyCash turd polisher

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    I've seen people put holes in the aluminum housing, but i think that's more for the look than anything else. I'd imagine that one could pare some weight from the ring gear, like you would with a flywheel. That said, when I pick up a BMW final drive, I feel like it is pretty light, for what it is. Go pick up one from a Guzzi, it's much heavier, and then you'll be happier with the weight of the BMW part!
    #2
  3. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

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    Jim Roche aka "Dr. Curve" did some lightening of his White Dog racer. Not a huge weight savings, but it is some... [​IMG]
    #3
  4. Dmaster

    Dmaster Been here awhile

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    The housing (is that the right name?) isn't the heavy part its the "gears"
    why not cut the red parts?:
    [​IMG]
    [​IMG]
    this isn't gonna help much but why is it here anyway?
    [​IMG]

    I'm sure I can get some material of the small gearing but how much will it be. :evil

    Someone must have tried this before.
    I know about "lightweight gearboxes" (drilled holes in anything) why not the final drive :ear
    #4
  5. chasbmw

    chasbmw Long timer

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    The later final drives look lighter.

    Just think of what would happen if your final drive locked up......declutching won't help.....
    #5
  6. chollo9

    chollo9 Screwed the Pooch

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    Like chasbmw says, transmissions are risky places to lighten.

    Weight savings is always about the sum of little bits (bites?), but in some places reliability and maintenance aren't good tradeoffs. I would want to talk to a rear end specialist prior to removing any metal.

    There's weight to be saved in the hub, I think.
    #6
  7. Airhead Wrangler

    Airhead Wrangler Adios Mexico

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    The gears are heavy, but out of a total weight of 17 pounds they only account fo about 6 pounds, so theres a lot of metal just in the housing.
    #7
  8. disston

    disston ShadeTreeExpert

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    Leave off every other nut, bolt or stud.

    Leave out the rear brake shoes and other parts of the brakes.

    Leave off every other spoke on the rear wheel.

    Buy a skinny tire.

    Of course you could also buy a Honda? :lol3
    #8
  9. RonZacapa

    RonZacapa Adventurer

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    The sum of parts is all in the unsprung weight. When I went from a tubed tyre to tubeless and junked the heavy duty tube on the rear wheel on my 1985 R80 monolever I threw away 3.65 lbs of weight. I would rather look at weight savings elsewhere on the bike, it can be done.
    R80 Monolever roadbike = 175kg dry with an empty tank (385lbs for you imperial guys) I got another 6kg to go - 169kg no fuel. However I will not be reverse engineering important mechanical bits & pieces I know not much about. If you are obsessed with weight reduction (so am I) lets start with the easy bits.
    #9
  10. Airhead Wrangler

    Airhead Wrangler Adios Mexico

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    The point here though is that it's not JUST weight reduction, but suspension performance as well.
    #10
  11. Prutser

    Prutser Long timer

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    I know that the suspension performance is his main purpose.
    #11
  12. supershaft

    supershaft because I can

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    I believe the later FD's are heavier. Dr. Curve's modification is about all you can do. The gears are too hard to work with. I would leave the internal oil baffling alone. If I know Dr. Curve, that's a magnesium wheel. THAT's the solution. I wish it wasn't such a pricey solution!
    #12
  13. Dmaster

    Dmaster Been here awhile

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    Later? twin shocks vs mono arms vs para levers?
    Tell me more, i wanna know all :evil
    I'm into offroad,. somehow I want spoke wheels in a offroad. Don't know why either.
    #13
  14. AliBaba

    AliBaba Been here awhile

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    #14
  15. jackass dave

    jackass dave Adventurer

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    how about the rider going on a diet ,that would lighten the overall weight !!!
    #15
  16. jings

    jings Been here awhile

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    hahahah thats a cracker :lol3
    #16
  17. Dmaster

    Dmaster Been here awhile

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    I'm 69 kg @ 1,89m tall... Not much to improve :evil.
    Its the unsprung mass that bothers me the most.
    #17
  18. supershaft

    supershaft because I can

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    Besides, I few pounds in unsprung weight loss is like losing 50lbs elsewhere. Going on a diet? The wheels are THE place to start! It makes a HUGE difference right off the batt.
    #18
  19. Paul_Rochdale

    Paul_Rochdale Been here awhile

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    Why does it 'bother you'? They are strong enough to regularly tackle RTW trips so that's good in my eyes. In fact I've followed Dogbytes/HPN tips and actually filleted the frame, just for a bit of piece of mind, as I'm sure the bike is strong enough just for road riding. If you want a lighter bike, there are plenty of lighter Japanese bikes to choose from without going for the dodgy business of drilling holes in the final drive IMO. However I may be wrong:wink:
    #19
  20. ME 109

    ME 109 Long timer

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    Plenty of unsprung weight has been taken outa blokes wallets.:wink:
    #20