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Thread: 78 r80/7 drive shaft oil fill bolt/plug stripped

  1. #1
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    78 r80/7 drive shaft oil fill bolt/plug stripped

    Hi, putting the bike back together and when I tried to fill the drive shaft oil, the filler plug would not come out, just spins. I was able to remove it but now what?

    Thanks
    Brian

    86 k100rt, 78 r80/7

  2. #2
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    Brian -

    The only way to truly fix this is to remove the driveshaft and have the hole helicoiled or timeserted. Because of the internal shaft, there's not enough room to do it on the bike...not to mention all the swarf that you'll generate.

    Since there's no real pressure in the driveshaft, all you really need is something to securely seal and keep the environment out. A number of thoughts come to mind. A rubber plug of some kind with a hose clamp all the way around. An expanding rubber plug...I've seen these before use to seal holes in blocks...you tighten the central bolt and it expands the rubber plug. You could JB Weld a metal filler plug for the hole which has been drilled/tapped for another smaller bolt. Then just remove the smaller bolt to fill when needed.

    Just some thoughts...
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    I did remove the final drive again, and I am open to all suggestions, the new plug with smaller plug sounds good, thats how you can repair bleeders on brakes.
    Brian

    86 k100rt, 78 r80/7

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    If your swingarm is off, I would take it to a good local machine shop and have them weld the hole closed, then re-tap it to fit the existing correct filler plug. Most good shops have the proper tooling - tap size, etc. to do the job, or can get a single tap pretty easily

    If swing arm is off, you could do the above, but just tap to the size of your favorite plug or bolt that can be used as a plug. However, I think that you should try to get it back to factory specs to keep it like original.

    Also, most machine shops are knowledgeable on heli-coils. I have installed literally hundreds of them. The glitch here, is that if you want to go back to original plug size, the shop will probably have to purchase the heli-coil kit for that particular thread size - which will include a special oversize drill, and a helicoil tap, and then the helicoil itself, plus the insertion tool if the shop doesn't have one for that size heli-coil.

    Other options are to use other brands or styles of thread repairs. You can do any of these yourself if you have a good drill press and take your time. Key-insert is one brand. Still requires a special drill and tap, but doesn't stay in hole the same way heli-coil does.

    If you want to try yourself, check McMaster-Carr or Grainger for the various heli-coil or other brand prices.

    Local machine shops are pretty good at this kind of stuff.
    Last edited by jimmylee; 01-22-2014 at 11:08 AM.
    "The difference between death and taxes is that death doesn't change every time congress meets." - Will Rogers

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    Thanks, does anyone know just what size the factory bolt/plug is?
    Brian

    86 k100rt, 78 r80/7

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    Item #12 on this listing:

    http://www.realoem.com/bmw/showparts...19&hg=33&fg=76

    Looks like up to 1980, it's M18x1.5.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    I have a 1986 monoshock,but I suspect you could fix your filler plug the way I fixed mine. I made an aluminum replacement for the plug that was slightly oversized. I then drilled and tapped a hole (10mm I think) in the center of the plug. I used a small amount of epoxy near the base of the plug to permanently fix the plug in the stripped hole. I use a 10mm bolt as the new filler plug. Since I fill the drive shaft with a 100cc syringe, the small hole is not a problem.

    SI make my own insert since I have a metal working lathe, but you could probably just drill out an appropriately sized bolt and get similar results. Sorry about the lousy photo quality:

    Plug 1.jpgplug installed.jpgWith new plug.jpg
    BMW R bike rider, horizontally opposed to everything...

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    There are specialty shops that sell oversized plugs for any size plug and thread cut. I have an oversized, piggy-back drain plug in a transmission on a /5. A piggy back plug is a smaller plug inside an oversize plug. Maybe not a good application for a fill plug, but you get the idea.

  9. #9
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    Hi , thanks, I set the drive up in the drill press, had a endmill just the right size for a 1/2- 20 bolt. drilled and tapped it.


    Thanks
    Brian

    86 k100rt, 78 r80/7

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