BMW 1100GS vs 1150GS final drive gear set swap ?

Discussion in 'Hacks' started by rg sw wa., Mar 8, 2013.

  1. rg sw wa.

    rg sw wa. Been here awhile

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    What is the down side / problems in replacing the 1150GS gear set with the gear set from a 1100GS ?
    Special tools needed ?
    Are the splines on the bevel gears the same ?
    #1
  2. DRONE

    DRONE Dog Chauffeur

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    It's a straight swap.

    There's a HOW article on this -- HERE.

    After reading the HOW article, and some threads about it, I opted to have my dealer (SSBMW) do it. Hopefully, your mechanical abilities are better than mine. :1drink
    #2
  3. twintwin

    twintwin Been here awhile

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    As Drone says it is a straight swap, all the 1100 and 1150 FD are interchangeable on all the bikes of these 2 seies. You may play longer than needed the first time, but you will get and feel better the following one's:clap. The procedure step by step, can be found also in the Haynes and the Clymer manuals.

    Now the question I'm still struggle with, is what would be the best FD on a R1150GS hacked. There is 3 different transmissions for the R1150GS, the standard, the enduro and the sport, and of course countless different FD ratio. The one's that reduce the gearing for the R1150GS are the 33/11 R1100GS, the 37/11 R850R, and the 32/10 R850RT, R850GS.

    So, let's say for a 04 R1150GSA enduro transmission (my rig), what would be the best choice?

    The article of Mr Largiader gives some clues, but I'm still confused.
    http://www.largiader.com/articles/gearing/
    #3
  4. DRONE

    DRONE Dog Chauffeur

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    Don't forget the ever-famous 34/11 from the R1100RS!

    You have a 31/11 now that gives you a final drive ratio of 2.82. There are lots of 33/11's (FD ratio 3.00) that come up on eBay but that's only a 6% change for you. Worth the money? A 32/10 is a 13% change and that should be pretty noticeable. But it does seem like the most serious guys search out that elusive 37/11 to give them the most low end grunt as possible.

    Do you know that you can simply order a new set of crown gears from BMW (about $600) and install them into you existing FD? There's a great You Tube vid on how to do that with simple tools--

    <iframe src="http://www.youtube.com/embed/f8_4lpAFLqk" allowfullscreen="" frameborder="0" height="315" width="560"></iframe>
    #4
  5. twintwin

    twintwin Been here awhile

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    Thanks Drone for the explainations, but still I do not get how the gearing of the transmission (standard, sport or enduro) comes in play when choosing the best FD for sidecar use.
    The earlier R1100RS (34/11 FD) have a different rear ABS sensor and the ABS housing on the FD are also different, so no swap possible with the other 11XX models, except if you do not want ABS
    #5
  6. RAZ1

    RAZ1 Airhead fan

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    Because what counts is the TOTAL demultiplication, which is made up of the gearbox selected ratio and of the final drive gearing.

    So, for example, on a 1100GS in 5th gear: 1.45 x 3 (assuming a 33/11 FD) = 4.35.
    IOW, it takes 4.35 revolutions of the engine crank to turn the rear wheel by 1 turn.

    Capisce?

    #6
  7. davebig

    davebig Another Angry Hun !

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    Oh my dog ! They're all right, the stock gs,r,rt rs 1150 tranny has a higher more wide ratio setuo than the GSsport or GSadv, Drone I and possibly twintwin have 1150gsadv with lower first and 6th I currently have a 33/11(65mph 4250 rpm) but will probably go to a 34/11, I am also the much poorer owner of a just rebuilt new cogs new bearing and seals 37/11 for my next project with possibly a 1150gs (higher 1-6th) of all these trannies 2-3-4-5 are all the same.With an R1100gs and 5 spd your only real change is the 37/11.
    The trouble with that video and I've never looked at it, will be that when your changing a big jump say 31 to 34 or 37 its a bear to shim pinion depth (shims behind both gears) one would be extremely lucky to get it right in 2 tries (one assembles and checks gear patterns with machinists blue between gears) real BMW techs hate this it requires a jig and patience I think BMW's flat rate is 3.5 hrs, In the last decade I fooled with lots of experiments, my hot rod GS saw 125mph on gps easy sitting up last fall they'll pull really hard if you gear down a bit.DB
    I watched the video, only enough info to make one dangerous, here's another that again only covers part of the job.DB

    http://youtu.be/bQddqKw8Lr8
    #7
  8. davebig

    davebig Another Angry Hun !

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    I was so wordy I missed that it was you Ron it would be nice to get you at least a 34/11 but anything is a step in the right direction.DB
    #8
  9. DirtyDR

    DirtyDR Dana

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    Here are the transmission gears for the 1150 GS's but remember the Sport was only made one year, 2003, and was a non ABS bike. The engine and transmission case on the Sport was also powder coated black.

    Gear Ratios (ABS)
    1st: 2.045:1
    2nd 1.600:1
    3rd 1.267:1
    4th 1.038:1
    5th 0.900:1
    6th 0.679:1

    Gear Ratios (Sport)
    1st: 2.045:1
    2nd 1.600:1
    3rd 1.267:1
    4th 1.038:1
    5th 0.900:1
    6th 0.800:1

    Gear Ratios (Adventure)
    1st: 2.375:1
    2nd 1.600:1
    3rd 1.267:1
    4th 1.038:1
    5th 0.900:1
    6th 0.800:1
    #9
  10. davebig

    davebig Another Angry Hun !

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    thanks Diirty !
    I believe there may have been one more option a super low in the Adv trans but very few got to the US.DB
    #10
  11. DirtyDR

    DirtyDR Dana

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    I know a lot of people that think the 1150 GS Adventure and the 1150 GS Sport had the same gearing but the Sport only had the lower Adventure sixth gear and still retained the standard GS first. These gear ratios came from the 2003 U.S. sales brochure so I can't really verify anything but that.

    I have a little over 40,000 miles on my Sport with the hack on it and I think the stock gearing works real well on and off road for me. Then again I have 100,000 miles on the bike and I have not changed anything except the starter. I like the stock steering and still have the factory shocks.
    #11
  12. eastbloc

    eastbloc comprador bourgeois

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    The standard gearing on my '01 R1150GS was definitely too high for hack duty, especially when laden down with passengers and gear when I'd have to slip the clutch to get rolling.

    IMO the 37/11 is the way to go, and R850R's still get scrapped on eBay with fair regularity. I even got a spare one squirreled away for the inevitable.
    #12
  13. Mr. Cob

    Mr. Cob Howling "Mad", Adventurer

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    Howdy All,

    My bike is a 2001, R1150GS, NOT a GSA, I am running the R850, 37:11 final drive in my rig now that it is hacked and love it.
    #13
  14. Melrone

    Melrone Long timer

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    I just had mine rebuilt by Rubber Chicken racing Garage.From the time I sent it in To getting it back in a little over 3weeks for a total price of $638...I'm still using my stock GSA FD with no complaints...
    #14
  15. rg sw wa.

    rg sw wa. Been here awhile

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    Southwest Washington
    For those into song lyrics,

    Well I will save my pennies and I save my dimes
    (giddy up giddy up 409)
    For I knew there would be a time
    (giddy up giddy up 409)
    When I would buy a brand new or used 3.36 / 37/11 final drive
    (Beach Boys)

    Thanks guys for all your comments and good information,
    DRONE, Twintwin, Raz1, bigdave, DirtyDR, Mr. Cob and Melrone,
    Appreciate it !
    #15
  16. DRONE

    DRONE Dog Chauffeur

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    :lol3
    #16
  17. rohdster

    rohdster The Leaping Wombat

    Joined:
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    Location:
    Gladstone, Queensland, Australia
    I did this very same modification last week.

    I had a allen-key (socket drive) and a heat gun that pumps out enough heat to make the screwed in axles come out easily.

    Found the change very easy and rewarding.

    My only concern is that I am not absolutely certain that I got the uni joints 100% aligned ... may be one or two splines out

    The bike certainly runs OK but I am eager to learn what the consequences will be with such misalignment ... any experience out there?

    rohdster
    #17
  18. davebig

    davebig Another Angry Hun !

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    Check the G-spot forum but the if the shaft is out of sync (joints out of line) it'll take more power and wear the ujoints out quicker, if it picks up an odd vibration better take it apart.DB
    #18