R80 Final Drive...

Discussion in 'Airheads' started by Fred C. Dobbs, Jan 3, 2012.

  1. Fred C. Dobbs

    Fred C. Dobbs Adventurer

    Joined:
    Nov 23, 2008
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    Location:
    Winthrop, Wash.
    I've a 1983 R80RT and I have to pull the final drive for a thread repair. The four nuts holding the final drive to the driveshaft appear to be made to accept a twelve-point socket. A 12mm twelve-point socket seems to fit pretty well. Or is there a special type of socket made specifically for that type of nut? My Clymer manual doesn't address this.

    Also, what's the best type of thread repair system to fix the driveshaft fill/drain plug holes?

    Thanks for any help!
    #1
  2. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    12 point boxed end wrench as the socket won't reach all four. I don't remember exactly why, clearance issue on one....
    #2
  3. subagon

    subagon Hopelessly lost

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    If you can get a 12 point socket or a 12 point box end wrench on the nut(s), it's what to use. If there's a nut you can't get at with the socket, keep reading...

    I have a R80ST, so the final drive is a little different. One of the nuts on my ST is blocked by the lower shock mount, so I can't get a socket OR a box end wrench on it. I used the WRONG tool, an open end wrench, and ^$@*&! up the nut. I then made a special tool from a box end wrench, kind of like a flange wrench but with more "points" (all the flange wrenches I've seen have 6 points). I used a dremel tool with a cutoff disk to cut the box end wrench. I'd also suggest not to cut the opening as large as I did. Make it as small as you can and still get on the nut. You can always cut more off, but not add it back :D


    [​IMG]

    I was able to get this on the nut, but the open end wrench had done it's work and rounded off the corners making it so no wrench could get a good grip. Vise grips then trashed it some more, big fail. I ended up using a cold chisel to get ti off. Just make a notch with the cold chisel and then start tapping the nut at an angle to get it off. Super size picture here if you want to see the notch in the nut.

    [​IMG]
    #3
  4. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Do a search for the thread repair - this was all hashed over a few months ago. Perhaps someone knows where it is and can post a link. :wink:

    We need to have a thread with links to all of these repairs so we don't have to start a new one every time, or explain the same stuff over and over.
    #4
  5. boxerboy81

    boxerboy81 Stay Horizontal

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    The oem tool kit has the correct ring spanner to remove the four bolts. That's all that's needed.
    #5
  6. bikerfish

    bikerfish flyfishandride

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    yep,, 12mm box wrench.
    #6
  7. hardwaregrrl

    hardwaregrrl ignore list

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    This is in your BMW tool kit.

    [​IMG]

    You may have the grind the outside down a bit to get proper clearance.

    And while you're at it, look at this.
    #7
  8. subagon

    subagon Hopelessly lost

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    I can't speak to what will/won't work on the RT, but the R80ST and R80G/S has one nut that you can't remover with a socket or a box end wrench. The lower shock mount blocks the socket and the nut is too close to the drive shaft to allow fitting a box end wrench on. This is why i had to modify a box end wrench the way I did.

    This isn't the best picture to show this, but it's what I have...

    You can see the lower shock mount that blocks nut from a socket. This same nut doesn't allow a box end due to the clearance between the nut and the drive shaft housing. I cut out the back side of the box end to remedy the clearance problem.

    [​IMG]
    #8
  9. bikerfish

    bikerfish flyfishandride

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    I've had no problem using the factory supplied wrench on my G/S rear drive. might be some manufacturing tolerance issues.
    I've had the rear drive out of the damn thing more than I care to talk about.
    #9
  10. Airhead Wrangler

    Airhead Wrangler Long timer

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    Tolerances indeed. The weld on my swingarm behind those nuts is thicker than it's supposed to be and doesn't allow the factory wrench or any other box end 12mm that I've tried to fit well on all but one of them. I can just BARELY grip the nut by cocking the wrench on at a weird angle. Not ideal. The open 12 pointer is the way to go for me. They must have used something like that at the factory or they wouldn't have been able to assemble my bike.
    #10
  11. subagon

    subagon Hopelessly lost

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    Glad I'm not the only one with clearance issues. I never thought it might be a production issue, i.e. thick weld. I just couldn't figure out why it would be designed the way mine is :scratch
    #11
  12. Fred C. Dobbs

    Fred C. Dobbs Adventurer

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    Thanks for all the replies. I assumed the twelve-point wrench/socket was what I needed, but wanted to be sure--I have enough buggered stuff on my plate at the moment. No clearance issues on my bike either, which is a plus. And I searched the 'thread repair' posts and am going to have Time Serts installed to fix the damage properly.
    #12
  13. subagon

    subagon Hopelessly lost

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    Post your comments about the Time Serts repair when finished. I have a striped out drain plug on my final drive and I'm not sure to try a thread repair or tap it out one size larger.
    #13