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R50 exhaust nut replacement

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Logan246
Posts: 1
Joined: Sun Aug 07, 2022 1:40 pm

R50 exhaust nut replacement

Post by Logan246 »

I cut the round, perforated exhaust nuts off my 1960 R50 to avoid damage to the exhaust port threads. That worked fine and preserved the threads. I assume I will have to replace the header because new exhaust nuts can't be slipped on either from the front or the rear. However, I see that some suppliers sell the perforated exhaust nuts separate from the headers. Does that mean there is some way to replace the exhaust nuts on the header that I haven't been able to figure out? Does anyone have a suggestion? Thanks.

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therealkennyboy
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Re: R50 exhaust nut replacement

Post by therealkennyboy »

Ken Walker
Scottsdale, AZ, USA
1960 R60 (currently), 1974 R75/6 (past), 1981 R100CS (currently), 1984 R100RS (past), 1989 K100RS (past)

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monson2765
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Joined: Fri Oct 27, 2006 3:00 am

Re: R50 exhaust nut replacement

Post by monson2765 »

Several years ago, I was assembling a 61 R50S. I had chrome pipes but decided to go with a stainless steel. It had a R50-60 nut on it. I cut the pipe at the spot where the strap covers the pipe when the motor mount holds the exhaust pipe. The R50S has a R69S type nut. If welded with a TIG welder, it might not mess up the chrome much and should work out. That was why I chose stainless as it welded and can be polished. Of course, the welding would cost. If you do the cut route, make sure you make a couple of lines on the pipes so the welding doesn't mate it together so the so the pipes will not line as before you cut them. D Monson

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jwonder
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Re: R50 exhaust nut replacement

Post by jwonder »

I went a different route for my R 50 S. I basically made a female flange that I was able to slip inside the nut and seat on a small lip on the exhaust. This allows me to remove the nut whenever I wish and seals great! Many miles and still great.

Here is what I did:

1) I ground the flange down just enough to remove the original finned nuts. This left about 1/2 the flange height that was there originally.
2) I then got a thrust ring from an R 69 S https://bmwclassicmotorcycles.com/index ... 8114090254
3) I machined the outside down to where it was within about .020" of fitting into the nut (I forget the exact measurement but it was close to that)
4) I then made an angle cut in the thrust ring to allow me to squeeze the ring and slide it in the nut.
5) I wanted it to fit quite tight on the pipe when compressed, in order to get a good grip on the leftover flange, so I needed to play with the outside diameter and the angle cut width to get the best fit.
6) Once this was done and I verified it would work, I had the exhaust chromed.
7) The copper gasket crushes to fill any small gaps that might be there, but it is quite a good seal.

One other thing I was able to do with this setup is machine a spacer to go between the nut and the ring in order to space the nut a bit away from the head. It really allowed me to tune both sides to fit exactly and be exactly the same distance from the head side to side.

I have original pipes, original nuts and I am able to take them off if I need to do that! :D
James Wonder
Vice President, Vintage BMW Motorcycle Owners
2022 BMW Friend Of the Marque
Long Island, New York

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