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Old 04-03-2013, 12:14 PM   #31
Paul_Rochdale
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The easier solution is when the nuts won't budge, STOP, then use the 'Search' function at the top of the page. OK, OK, I won't mention this again, for a while at least
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Old 04-03-2013, 01:35 PM   #32
DK Dan
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Alternative repair technique

On a recent tech day a local airhead guru demonstrated an alternative repair technique developed by himself. Unfortunately I did'nt take any photos but the repair can be done with the heads still on the bike. I'm not sure that I got all the details correct but the repair involves the following:

- a special hollow fixing/guide bush is inserted in the exhaust port
- a small shaft with a cutting tool mounted is inserted in the hollow fixing/guide bush
- a hand held electric drilling machine is used to rotate the shaft w. cutting tool at high speed and the damaged thread is removed.
- a threaded pipe piece is made with the exact same thread type as the original exhaust thread and the threaded pipe piece is mounted on the exhaust port stub.
- the new thread pipe piece is locked on the exhaust port stub with two small screws and the screw heads are filed off.
- now you have a new thread installed

Hope my explanation makes sense. I will probably require this repair for one of my exhaust threads and will be sure to get some photos during the process.
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Old 04-03-2013, 01:49 PM   #33
GCCR OP
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Quote:
Originally Posted by Paul_Rochdale View Post
Reading about all of these wrecked threads irritates me no end. Why don't riders read up about such things before butchering their bikes? There's endless posts about seized exhaust nuts both here and elsewhere, even videos on YouTube about how to remove them. I've two BeeEms and never had a problem with the exhaust threads. Slice the old ones off if seized, clean up the threads, Copaslip then fit new nuts. Simple.
This is my 11th airhead, and I've never had one do this. Upon closer investigation it appears that it had a repair on it at one time and then someone botched up the replacement. Live and learn.
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Old 04-03-2013, 01:50 PM   #34
GCCR OP
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Originally Posted by isdt BMW View Post
Paul Sturges in Bend Oregon welds and machines for a perfect repair. been using him for 25 years.
Thanks for the lead. Do you have contact information by any chance.


Dan
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Old 04-03-2013, 01:54 PM   #35
GCCR OP
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Originally Posted by hensmen View Post
Hallo GCCR, from Germany i have an alternative, not originalbut it is repaired in a minute and best for adv used bikes. Mean when you travel, i try to put the link:
http://www.sternmutterersatz.de/
Don`t know if it is worth shipping but for travelling the eaysiest way.
Hans from Germany
Danke, Hans. I will definitely get a set as a backup, and to install for a cross country trip. Terrific product, augezeichnet!

Dan

P.S. I'm looking for a reasonably priceed Heinrich tank for a /2 frame. If you come by one that is in very good condition that is available please send me a PM.
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Old 04-03-2013, 02:02 PM   #36
GCCR OP
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Originally Posted by Stan_R80/7 View Post
The exhaust threads on one of my spare /5 heads are are M52x2. The thread dimensions can be calculated using a Machinery's handbook and there are some web pages with this dimensional information. I always wondered how to make a jig for the head to single point thread the exhaust threads in a lathe? I expect someone has figured out a way. I have seen dies for sale on Ebay from Germany for ~$100.00 + shipping.

Maybe an easier solution is to get a piece of 6061-T6 extruded rod, bore a hole ~42.5mm in diameter, single point thread the OD to make a threaded nipple, and then cut off the damaged threads on the head and TIG weld on the nipple? The welding raised portion of the new exhaust nipple ID could be line bored in a milling machine or hand filed smooth. Maybe one day I will try this with one of my spare heads, but my TIG welding has to improve first.

I'm truly amazed at the knowledge available here on this thread. I'm glad Chris at Boxer Metal referred me here. I'm grateful to all of you for contributing. Many thanks!

Dan
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Old 04-03-2013, 04:00 PM   #37
d mc gee
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I've got a question. Why didn't BMW make the nut "sacrificial"? I'm sure there is a reasonable answer. My basic metallurgy knowledge is less than remedial.

Here is a M52x2 die that sold for less than $100.

http://www.ebay.com/itm/Schneideisen...item257ad3a2fe
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Old 04-03-2013, 04:17 PM   #38
Plaka
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Quote:
Originally Posted by d mc gee View Post
I've got a question. Why didn't BMW make the nut "sacrificial"? I'm sure there is a reasonable answer. My basic metallurgy knowledge is less than remedial.

Here is a M52x2 die that sold for less than $100.

http://www.ebay.com/itm/Schneideisen...item257ad3a2fe
What's to sacrifice? Take care of them and you don't have issues with them. Don't take care of them and you sacrifice them with a hacksaw.
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Old 04-03-2013, 04:34 PM   #39
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Use the proper tool, smack it once or twice and undo those nuts by hand.
If they don't come loose, cut the nuts. Period.

Than clean threads, fit (new) nuts with anti-seize and repeat this annually, or with every valve-job.
A little maintenance goes a long way here.

As for repairing, weld up and re-thread is the proper way, all else is merely a bodge.

Paul.
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Old 04-03-2013, 05:30 PM   #40
danedg
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You guys are reinventing the wheel here....

Just send your worn and damaged heads to Randy Long. He's been doing it for years.
Randy Long
Long's Mechanical Services
R.D. 1, Box 685-K
74 Risbon Road
Honey Brook PA 19344
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Old 04-03-2013, 05:49 PM   #41
disston
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Quote:
Originally Posted by d mc gee View Post
Here is a M52x2 die that sold for less than $100.

http://www.ebay.com/itm/Schneideisen...item257ad3a2fe
That item has been relisted. It is in the Ukraine and says it will take 16-28 days for delivery. Seller has 380 reviews and all Positive. New item #


http://cgi.ebay.com/ws/eBayISAPI.dll...m=151012545349
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Old 04-03-2013, 06:13 PM   #42
garthg
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Cry Paranoia inducing

Quote:
Originally Posted by GCCR View Post
Hi Jim here are the pics you asked about. I'd be interested in anyone in CA that could repair this.


This got me so paranoid, I went out and re-anti-seized my exhaust nuts again.
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Old 04-03-2013, 06:54 PM   #43
Bill Harris
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Quote:
Originally Posted by danedg View Post
You guys are reinventing the wheel here....

Just send your worn and damaged heads to Randy Long. He's been doing it for years.
Randy Long
Long's Mechanical Services
R.D. 1, Box 685-K
74 Risbon Road
Honey Brook PA 19344
Seconded. A repair like that is as good as new. Too bad the OP's exhaust stub was bodged, but that happens. The annual ritual is to undo the nuts, clean off the threads with a BRASS wire brush, apply Anti-Seize generously and tighten them up. The Book say snug to 109 ft/lbs or so; I do them to a double-grunt.

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Old 04-04-2013, 01:08 AM   #44
Paul_Rochdale
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Screw the damned torque wrench, just do them up hand tight and then a gentle tweek with the correct spanner. Never had one come loose. Never had problems with the threads but once bodged like those images, an expensive and more thorough solution is required as has been explained.
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Old 04-04-2013, 02:53 AM   #45
DK Dan
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Quote:
Originally Posted by Paul_Rochdale View Post
Screw the damned torque wrench, just do them up hand tight and then a gentle tweek with the correct spanner. Never had one come loose. Never had problems with the threads but once bodged like those images, an expensive and more thorough solution is required as has been explained.
The repair method I tried to explain in my previous post above is a 1 hour job so not so expensive, but of course the special tools are required. Not sure that my explanation above is fully understandable but the new thread is put over the exhaust port stub as a loose sleeve which is easy to replace again later.
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