Front & Rear Sprockets Torque Values?

Discussion in 'Parallel Universe' started by Mtl_Biker, Aug 15, 2014.

  1. Mtl_Biker

    Mtl_Biker Long timer

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    Can anyone help me out with the torque values for the front and rear sprockets on a '13 F800GS?

    I've just returned from a 6,500 km trip around the TLH, then to Newfoundland, Nova Scotia, Prince Edward Island, New Brunswick, Maine, New Hampshire, Vermont and finally New York back to my home in Montreal.

    And my chain is toast! The sand and grit along the Trans-Lab really did a number on my chain and I'd been lubing it every 500 km. Luckily I have a new chain and sprockets waiting for me to install them.

    But I've never done this before. Any tips/tricks you might be able to share?

    I would particularly like to know the torque values of all the bolts, if you could share them with me.

    Thanks very much!

    Eldor
    #1
  2. Reaver

    Reaver How Did I Get Here?

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    The front sprocket is 50 NM. Use lots of anti-seize on the shaft and loc tite on the bolt.

    The rear bolts "technically" need to be replaced as they are a torque plus 90 degrees. Most re-use these bolts and just make them tight. I use 40 NM as a guess.
    #2
  3. Mtl_Biker

    Mtl_Biker Long timer

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    Thanks very much!

    I'm not quite sure what you mean by "...they are a torque plus 90 degrees." Could you please clarify that for me?

    Gonna do this Sunday morning (I work today).


    #3
  4. FredRydr

    FredRydr Danger: Keep Back 300 Ft.

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    Once you reach the torque value, continue a 1/4 turn (90 degrees).

    If Reaver offers to lend you his bike with the re-used bolts, politely decline.

    Fred
    #4
  5. Reaver

    Reaver How Did I Get Here?

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    I see you've got the "Woody Worry" disease. IIRC, I was right behind you at all times and nuthin' fell off my bike. We might head out that way on the 650's. My '08 hasn't had the chain recall done yet and may just break. :eek1

    But yes Mon Ami, torque to yield bolts get tightened a specified torque, then an additional amount of degrees. They are meant to be replaced when loosened.

    Meh.
    #5
  6. Mtl_Biker

    Mtl_Biker Long timer

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    Thanks guys.

    Are the bolts that should be replaced only the ones on the rear sprocket? Or the front one as well?

    I might be able to sneak out of work to make a quick run to the dealer to get what I need.
    #6
    dualsportrider2 likes this.
  7. Reaver

    Reaver How Did I Get Here?

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    Just the rear. You can re-use the nuts ok, just get the bolts if you want.

    The front bolt only holds the sprocket on and doesn't transmit power so it doesn't need to be replaced.
    #7
  8. Mtl_Biker

    Mtl_Biker Long timer

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    I'm frustrated with my dealer, who's supposedly the oldest and largest BMW Motorad dealer in Canada. I ran over there only to find that not only did they NOT have a service manual in stock, they also didn't have the bolts needed for the sprocket change. They said they don't stock the bolts because the sprocket they sell includes the bolts. (And that's at a higher price and lower quality than the DID chain and sprockets set I bought.)

    Gonna have to reuse the bolts after all. And hopefully there's nothing in the service manual that I'd need to know about how to change the chain and sprockets.
    #8
  9. YrianX

    YrianX Viking Adventurer

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    It's fine to re-use the bolts. Then I used normal new nylock nuts with flange. M8 if I recall correctly. Did that last time and it's been good for more than 10k km now and just checked all are still tight to at least 50Nm. I know it's not the way of the service manual..
    #9
  10. Reaver

    Reaver How Did I Get Here?

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    You're supposed to bring it in for service and not question the quality or price. :deal

    They don't make money on DIY guys buying aftermarket parts. But they can order it for you! :rofl
    #10
  11. FredRydr

    FredRydr Danger: Keep Back 300 Ft.

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    I reused mine, and even followed the torque+ instruction. Double stretched steel. Pray for me, but blame Reaver.

    Fred
    #11
  12. itsatdm

    itsatdm Long timer

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    Hello again.
    :wave

    I would probably just reuse them, with a dollop of lock tite. The fact your dealer does not have them in stock is a clue how they do it.

    I really don't think the specs are enough torque to actually stretch the bolts unless some BMW mechanic did the previous ones. Ask me how I know.

    The sprocket bolts are 10mm for your bike. I am guessing the threads are 1.25 fine. If you have good hardware store or a chain like Lowes, they will have them. If in doubt take an old one with you.

    The front sprocket bolt is a specialty item. Its purpose it so keep the sprocket from coming off, it doesn't carry much of a load. Between lock tite and the bolt it will stay on.

    When you take the front sprocket off, look at the flanges on it face. One side will be thicker than the other. Put it back on the way it came off.
    #12
  13. Mtl_Biker

    Mtl_Biker Long timer

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    Dumb question (again) time...

    The bolt holding on the front sprocket is stamped "LF" on the top. Could this possibly mean a left-hand thread instead of the normal right-hand? I'd hate to be cranking away at it trying to open it only to make it tighter and tighter.

    As soon as someone can answer this for me, I'm going to do it.
    #13
  14. Reaver

    Reaver How Did I Get Here?

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    No Dear, it's a standard thread. LF is the manufacturer stamp. The engine compression is enough that it will hold the sprocket in first gear so you can remove the bolt. No need to hold the brake.

    The water pump gear on the cam, now that's a lefty but you can't read the head for the seal it sits inside of!
    #14
  15. malloy

    malloy Been here awhile

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    If you are getting the nuts from a hardware store, make sure the flange is large enough to clamp the chain ring. Take an old one with you to be sure..
    #15
  16. Reaver

    Reaver How Did I Get Here?

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    Is the chain ring connected to the chain gang?
    #16
  17. jeff34

    jeff34 aventurier français

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    I do not have the same values ​​on dvd bmw europe
    for the front wheel, the torque is 30 Nm
    for rear wheel torque is 100 NM without adding 90 °, and without changing the nut
    #17
  18. Reaver

    Reaver How Did I Get Here?

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    Correct, but we mean the sprockets, not the wheels.
    #18
  19. Mtl_Biker

    Mtl_Biker Long timer

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    Mission accomplished!

    Thanks everyone for your help.

    I've got a new chain (DID 525 Gold), front and rear sprockets, and new brake pads. All done.

    The bolt holding the front sprocket was a standard right-hand thread and it was fairly easy to remove it. Only issue was that the threads were coated with a very hard blue stuff (loctite 243?) that I couldn't get off by scraping, soaking in kerosene or varsol. I ended up filling it gently with the file on my Leatherman, just enough so I could remove the two washers from the bolt. I used blue loctite on the front and rear bolts, for better or worse. Job done.

    Also washed the bike... first time in a year and a half. (A clean GS is a dirty shame!).

    Thanks for your help!
    #19
  20. 05Retro

    05Retro n00b

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    Does anyone have current specs for rear sprocket torque with 10mm/m10 nuts. Bike is a 2010 F800GS.

    I've seen 25nm, 40nm, 10nm +90 degrees. I'm good with either method but keep seeing contradictory values and searched quite a few forums. Found spec for older 8mm/M8 nuts but not the 10.
    #20