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Stripped Drain Plug Woes - Second Update

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srankin
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Re: Stripped Drain Plug Woes

Post by srankin »

Butting in here with probably not much help, I imagine R80GS final drives are like hen's teeth.
The bike is enormously favored, highly desirable, and I bet most owners would restore rather than part out. Add to the limited number of years offered and perhaps overall number of bikes sold. That limits what is out there as spare used as what was described, high milage or suspect. That is not good news for you.

No, I don't think that is an option I would take. LOL, I live in NY and right now am ill (short term Thank God) and am peeved at the number of riding days wasted before winter sets in. I get your point, you sound like me. You don't do half assed repairs and are willing to do what ever is needed to do the repair right.

Find a good machine shop, take a day to take things apart if you have the tools to do so, and have the threads repaired properly. It may be possible to build up inside the hole and remake the whole thing. I say this as I had broken fins on my RS cylinders repaired by a highly expert local welder fabricator and honest to God, you can't tell they were ever broken. Contact with a machine shop may give you the name of a welder who could do such work.
Or, the machine shop may be able to repair the threads themselves, or insert a sleeve.

LOL, Yeah, I know, it is almost the same advice you have already got. Sorry, Good luck happy hunting St.
Owner of a 84, R80RT and 78, R100RS

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Slash2
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Re: Stripped Drain Plug Woes

Post by Slash2 »

malmac wrote:
Sat Oct 15, 2022 1:37 am
The tread is in the final drive housing - right.

Take the back wheel off.

Remove the final drive.

If you don't want to do it your self, take the final drive to a machinist who will insert a new thread.
There are several options. There is an option that inserts a metal sleeve and then three triangular pins are driven down to retain the insert.

https://www.nei.com.au/product/kipp-thr ... rts-k0398/

07660-1.jpg

There seems to be room for this approach and there are probably others that are as good or even better.

Clean out the swarf, new gasket probably. Its all back together in a a couple of days max if you can get your local machinist to do it straight off.

My two bob's worth.

Mal
Mal,

This looks like a good solution if I can find a qualified machinist to do the work. I live in a very rural area and don’t readily know of any local machinists. I have a contact in Pittsburgh (nearest city) who should be capable of performing the task. I’ll reach out to inquire.

Thanks!
Western Pennsylvanian - Airhead Extraordinaire

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Slash2
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Re: Stripped Drain Plug Woes

Post by Slash2 »

srankin wrote:
Sat Oct 15, 2022 9:35 am
Butting in here with probably not much help, I imagine R80GS final drives are like hen's teeth.
The bike is enormously favored, highly desirable, and I bet most owners would restore rather than part out. Add to the limited number of years offered and perhaps overall number of bikes sold. That limits what is out there as spare used as what was described, high milage or suspect. That is not good news for you.

No, I don't think that is an option I would take. LOL, I live in NY and right now am ill (short term Thank God) and am peeved at the number of riding days wasted before winter sets in. I get your point, you sound like me. You don't do half assed repairs and are willing to do what ever is needed to do the repair right.

Find a good machine shop, take a day to take things apart if you have the tools to do so, and have the threads repaired properly. It may be possible to build up inside the hole and remake the whole thing. I say this as I had broken fins on my RS cylinders repaired by a highly expert local welder fabricator and honest to God, you can't tell they were ever broken. Contact with a machine shop may give you the name of a welder who could do such work.
Or, the machine shop may be able to repair the threads themselves, or insert a sleeve.

LOL, Yeah, I know, it is almost the same advice you have already got. Sorry, Good luck happy hunting St.
Question is, are all early-mid 80’s 37/11 FD’s the same or was there something special about the G/S FD?

If I was familiar with a reputable machinist, I would be moving in this direction already, so I suppose it’s time to find one OR send it off to Barrington for a full rebuild to the tune of who knows how much.
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srankin
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Re: Stripped Drain Plug Woes

Post by srankin »

Forgive me, I can't read or remember where you listed mileage on the bike? Are you absolutely sure you need a major rebuild of the unit? LOL I can see your point, if it has to come apart rebuild but, does it really need rebuilt? Or, do you just need to have the threads fixed?

I would think Barrington's would be able to give you a quote on a price to fix the threads properly and would do so? I have never dealt with them.
The only place I ever contacted who said send us the unit, pay a lot of money and we will fix the whole thing is Palo Alto speedometers. LOL, that is why I never deal with them. I don't want a total rebuilt speedometer I only need the odometer set to a certain mileage.
I would think Barrington's could quote you the price to fix the stripped threads, and inspect the unit's guts. If things need replacement you could go from there.
LOL, you don't always need brand new, of course the installation of new parts does mean zero time for wear but realistically how many miles will you be putting on the bike? LOL, I just spent a lot of money to overhaul my RT and who knows if I will live long enough or ride enough miles to make it worth while.

As for finding a good machine shop, think hot rods or classic car guys, expand the scope beyond BMW motorcycles, talk to the Local Honda dealership. All gear heads have shops they go to. LOL, I found the guy who fixed my cylinder fins at a shooting match. He had never done cylinder fins before but was game to give it a try.

Lol, yeah I am waiting a lot, it happens when I am ill and can't ride, sorry, Good luck and good hunting. St.
Owner of a 84, R80RT and 78, R100RS

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Slash2
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Re: Stripped Drain Plug Woes

Post by Slash2 »

I just spoke with Scottie Sharpe and was given some useful information. He performs this fix with a jig and his drill press to insure a perfect perpendicular hole which is necessary to properly seal. (See attached photo)

He quoted me $90 labor plus the timesert ($10-$15) sounds great except he’s 2800 miles from me and it’ll cost damn near $200 for shipping both ways. He suggested finding a good local machinist. So…

As for mileage, the bike has 38k miles and there is a very minor tick of play in the rear wheel. BMW states .5mm is acceptable. Zero metal on the drain plug so it could be a shimming issue or the large bearing. I’m not an expert on these units but I’d guess it’s fine for another 30-40k miles and I intend on putting some real miles on this bike.
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sherman980
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Re: Stripped Drain Plug Woes

Post by sherman980 »

Chris,
A couple of thoughts... If you want to ship your drive to Scottie Sharpe, it will fit in a large Flat Rate USPS box. You may have to remove the shock stud and/or the brake cam, depending, but it will go. I double or triple box to reinforce, but have shipped quite a few rear drives this way over the years. About $24 each way plus insurance if you want it. Scottie does good work and will get you taken care of.

The above said, this is another case of "not rocket science". Yes you want the threads perpendicular to the sealing surface, but a few degrees off honestly won't mater here - that's one of the reasons you use a crush washer. Not saying you shouldn't aim for "perfection", but it's just not necessary in this specific application. It is easy enough to block up your drive in a drill press or a mill using the mating surface with the driveshaft housing and the machined surface on the inside edge of the drive as references for perpendicular. I use a Timesert for this application (done quite a few over the years) and put a little JB Weld on the threads before I install it - helps prevent any leakage around the Timesert. Between setup and Timesert installation, it shouldn't take you more than about an hour before you're ready to put things back together for the next 100k leak free miles :)

Hope that helps.
Thanks.
Chuck S

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Slash2
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Re: Stripped Drain Plug Woes

Post by Slash2 »

Photo credit Scottie Sharpe.
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3789E108-643C-490E-86E7-651AA2C29B26.jpeg
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sherman980
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Re: Stripped Drain Plug Woes

Post by sherman980 »

Yep, that's very similar to my set up. If you don't have a mounting plate that fits the four studs on the rear drive, you can also use a bolt through the axle hole to a metal plate that mounts in your vise (you only need to drill one non-precision hole that way) and bolts against the inside of the casting. To adjust the horizontal plane, use a screw jack under the drive about where the top fill hole is. This provides lots of support for your drilling effort. I've used both methods and both work.

A couple of other thoughts while we're at it. If you're still concerned about trueness, after you drill the hole for the Timesert, you can "face" the surface with a very quick skim cut using an end mill large enough to include the seating area of the crush washer. Adds about a minute to the whole process. Last, I start the tap with it mounted in the chuck and use a pin wrench to turn it until the first several threads are cut. That way you know the tap is started straight. It's easy to get it a bit "off" if you start it by hand. The aluminum is soft and if the tap starts crooked, it will continue crooked. I'd assume Scottie does the same.
Thanks.
Chuck S

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Slash2
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Re: Stripped Drain Plug Woes

Post by Slash2 »

Great info Chuck thanks for weighing in. Wish you were in my neck of the woods. Would love to come over and watch you work your magic on this thing. It sounds relatively straight-forward provided you've got the right equipment and tools. I guess it's time to start thinking seriously about finding a drill press and a small lathe would be a great addition to the shop as well. I hesitate to trust a local machinist for this job which is probably silly but I would feel more comfortable with it in the hands of an expert who has done this before.

Ah well. I go away for work for a few days and can think it over. These last few days have been gorgeous and I was aching not being able to ride but there wasn't much time left over with a toddler and an infant keeping me occupied anyway.
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malmac
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Re: Stripped Drain Plug Woes

Post by malmac »

If you talk with a person who has a milling machine of suitable size it will be unlikely that he/she cant do this job.
It is really a basic job.

TIG welding the hole up and recutting an original thread is in a different ball park.
Easy to get that wrong even when one has quite a lot of welding experience.
Welding it up is a much more tricky job with a bunch of variables.
Contamination by oil being not the only one, but certainly the most obvious.

It will work out OK.

Mal
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Toowoomba- Australia

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