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Thread: 78 r80/7 drive shaft bolts wrench

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    78 r80/7 drive shaft bolts wrench

    Hi a few years ago I rehabbed a 86 r80, I am now doing a 78, when I did the drive shaft bolts last time I made the wrench and torqued them down , now I cant remember what to set the torque wrench to with the added length of the little wrench ala snowbaulm.Anyone know?
    Brian

    86 k100rt, 78 r80/7

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    Benchwrenching PGlaves's Avatar
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    Quote Originally Posted by yankeeone View Post
    Hi a few years ago I rehabbed a 86 r80, I am now doing a 78, when I did the drive shaft bolts last time I made the wrench and torqued them down , now I cant remember what to set the torque wrench to with the added length of the little wrench ala snowbaulm.Anyone know?
    You need a 10mm 12pt wrench on one end that will fit your torque wrench on the other end. Attach the wrench so it is at a 90 degree angle to the handle of the torque wrench, thus minimally lengthioning the effective torque arm. Then use the specified torque for the bolts.
    Paul Glaves - "Big Bend", Texas U.S.A
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    Thank you
    Brian

    86 k100rt, 78 r80/7

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    I think Snowbum has a section on special tools.

    Also, check this: http://www.northwoodsairheads.com/Tools.html

    About half way down the page, there is a pic of what you want to buy or make.
    Attached Images Attached Images
    "The difference between death and taxes is that death doesn't change every time congress meets." - Will Rogers

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    Quote Originally Posted by jimmylee View Post
    I think Snowbum has a section on special tools.

    Also, check this: http://www.northwoodsairheads.com/Tools.html

    About half way down the page, there is a pic of what you want to buy or make.
    *************************
    If you don't have one of the special tools, you can make one; buy something that works......or, use the 10/12 mm dual box-end wrench in the standard BMW tool kit, and give the wrench what we call a 'good grunt'. That Good Grunt works fine with the stock length 10mm/12mm dual box end wrench.
    Some have used that wrench and a 3/8" square drive torque wrench, calculating the lowering of the setting due to the wrench length. I have that calculation method in my torque wrench articles.
    The torque you want on the bolts is 29 footpounds, if using a torque measurement. If your bolts came with split lockwashers, remove them, do NOT! reuse them, do NOT replace them. Get the new SHORTER bolts. HEED MY WORDS!!
    Put ONE small drop of Loctite BLUE on the clean threads before torquing.
    The original factory tool is pictured in my tools article. It is nothing more than a square drive of a socket with an added slit, to which a 10 mm offset box portion (they cut the other end off!) was brazed or welded (have seen them pressed too) into the square drive slit.
    Three photos of the factory tool are located, and described, etc., in section 4 of my tools article...that means it is about 2/3 of the way down the tools article page.
    The article is number 65 on my website.
    http://bmwmotorcycletech.info/tools.htm
    snowbum

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    They are called torque wrench adapters and are widely available from the usual tool suppliers.

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    Benchwrenching PGlaves's Avatar
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    Quote Originally Posted by beemerphile View Post
    They are called torque wrench adapters and are widely available from the usual tool suppliers.
    Here is one:

    http://www.trident-supply.com/Armstr...069-64-710.htm
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://www.bigbend.net/users/glaves

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    Thanks for the help, on the last bike I rehabbed, I made a copy the factory wrench, I just couldn't remember the calculations for torque, when I checked the last bike 86 r80, the bolts were loose, and I replaced them, on this bike I put the wrench to them and they are tight, so I am going to leave them.
    The Max BMW parts shows the long bolts with washers, have they changed there minds? The bike has 65 thou on it so it should be ok?
    Brian

    86 k100rt, 78 r80/7

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    Quote Originally Posted by yankeeone View Post
    Thanks for the help, on the last bike I rehabbed, I made a copy the factory wrench, I just couldn't remember the calculations for torque, when I checked the last bike 86 r80, the bolts were loose, and I replaced them, on this bike I put the wrench to them and they are tight, so I am going to leave them.
    The Max BMW parts shows the long bolts with washers, have they changed there minds? The bike has 65 thou on it so it should be ok?
    Max (Rusty) encouraged me to purchase the shorter bolts without washers, and as Snowbum suggested, DO NOT use the washers. Apparently they can break, and when that happens, the bolt goes loose. I actually had that happen on my R50/2 when I was on a trip. Happened exactly in front of the US Capitol building. I managed to nurse the bike over into the middle park, and practically tore the whole back end off to fix, right there on a 100 Deg. day. Got the new bolts up the road (had a friend on a Moto guzzi go get them for me) and installed by 2:00 PM that day. Got home back to NE Ohio that evening!

    Also, I was told that the torque wrench routine was not really necessary. Snowbum's "good grunt" would work fine with blue Loctite.
    "The difference between death and taxes is that death doesn't change every time congress meets." - Will Rogers

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    Quote Originally Posted by jimmylee View Post
    Also, I was told that the torque wrench routine was not really necessary. Snowbum's "good grunt" would work fine with blue Loctite.
    Torque wrenches are never "necessary" if you have a well calibrated grunt. If peoples' grunts were generally well calibrated, you would not find so many stripped out threads on motorcycles. Lots of untrained wrenchers tighten it "all the way plus a quarter-turn". Tell a seasoned M/C mechanic, a retired librarian, and a pro football player working on his first motorcycle to give it "a good grunt". Tabulate removal torque. Give each a torque wrench and a spec. Repeat and compare. Providing torque specs (either force or angular) is the only reliable way that a technical writer can communicate how tight a fastener is supposed to be. Sure, torque specs in manuals can be wrong and they should be tested against reality and a "common torque" chart. Conversions (torques listed both in N-m and ft.-lbs.) are always suspect for conversion errors. I normally use the writer's native dimensions or check the math.

    I have done driveshaft bolts by feel as well when I had to (or didn't know better) and never had one let go. However, with fasteners this critical I choose to use the tool and the spec whenever possible. It is my observation that seasoned mechanics use torque wrenches more often than rank amateurs. As I have gained experience, I find myself using them more often rather than less. Certainly I have a better calibrated "grunt" than I used to have, but I also have more knowledge, judgement, technical literature, and tools.

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    I ordered new short bolts, when I put the rear drive back on , do I just use dry gasket?
    Brian

    86 k100rt, 78 r80/7

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    Quote Originally Posted by yankeeone View Post
    I ordered new short bolts, when I put the rear drive back on , do I just use dry gasket?
    I use a thin film of Hylomar on both sides just for belts 'n' suspenders.

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    Quote Originally Posted by beemerphile View Post
    Torque wrenches are never "necessary" if you have a well calibrated grunt. If peoples' grunts were generally well calibrated, you would not find so many stripped out threads on motorcycles. ..........
    I think this is where a lot of us rural mechanics get in trouble as metric threads are generally much finer than our past experience with US Coarse threads. We get by with metric threads into steel, but fine threads into softer materials seem to generate a lot of forum thread-strip questions.
    Retired w 2005 K1200LT, 2000 R1100RT, & 1975 R90/6

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    Quote Originally Posted by yankeeone View Post
    I ordered new short bolts, when I put the rear drive back on , do I just use dry gasket?
    Where are you talking about using dry gasket? On the driveshaft boot? I can't think of anywhere else to use any gasket type material. I must be missing something here. Personally, on the driveshaft boot, I would use a real thin film of black silicon sealer available from any auto parts store.

    On the bolts, per above, use blue Loctite to secure them. Make sure they are first clean and free from oil.
    "The difference between death and taxes is that death doesn't change every time congress meets." - Will Rogers

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    I, too, was confused about sealant, but he did say his "rear drive", so this must have been more than just the four bolts at the back of the transmission. There are four bolts where the rear drive bolts on...hmmmm....
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
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