Undoing R80 exhaust pipe nuts ?

[Jeff in W.C.]

We don't want no steenkin' dremel/chisel marks on the exhaust threads.

When I cut mine off, I used a dremel with two cutting disks stacked together. You need to go very slow when you get down to the threads and stop once the threads show. I then cut a similar gap 180 degrees apart. Once both were done, I used a small angled flat bar to spread them apart. The nut falls apart in two pieces with no damage to threads from the dremel or the flat bar.

[dougie]

I had to do mine Sibbo.

For the soak and hope approach use multiple applications of a proper penetrating oil such as Liquid Wrench and patience (overnight).
That didn't work for mine.

I then tried heat (propane torch).
That didn't work for mine.

So I cut them off carefully. It's a fiddly job.
I used Duane's trick for smoothing the threads. I had an old but still good nut so I put FINE valve grinding paste on it and the head and ran it on/off a few times until it felt smooth. Then clean clean clean!

Then two new nuts went on with lots of Never-seize using the proper spanner. Never regretted buying that spanner ($20).

[ME 109]

We don't want no steenkin' dremel/chisel marks on the exhaust threads.

When I cut mine off, I used a dremel with two cutting disks stacked together. You need to go very slow when you get down to the threads and stop once the threads show. I then cut a similar gap 180 degrees apart. Once both were done, I used a small angled flat bar to spread them apart. The nut falls apart in two pieces with no damage to threads from the dremel or the flat bar.

Very good technique Jeff, I like the forcing apart with the bar.

[Sibbo]

I had to do mine Sibbo.

For the soak and hope approach use multiple applications of a proper penetrating oil such as Liquid Wrench and patience (overnight).
That didn't work for mine.

I then tried heat (propane torch).
That didn't work for mine.

So I cut them off carefully. It's a fiddly job.
I used Duane's trick for smoothing the threads. I had an old but still good nut so I put FINE valve grinding paste on it and the head and ran it on/off a few times until it felt smooth. Then clean clean clean!

Then two new nuts went on with lots of Never-seize using the proper spanner. Never regretted buying that spanner ($20).

I wouldn't mind one of those spanners , in fact it's essential . Is this the right one ?

http://www.ebay.com.au/itm/BMW-exhaust- ... 1c420b9130

and I found my can of Penetrene , it goes on tomorrow.

[dougie]

I had to do mine Sibbo.

For the soak and hope approach use multiple applications of a proper penetrating oil such as Liquid Wrench and patience (overnight).
That didn't work for mine.

I then tried heat (propane torch).
That didn't work for mine.

So I cut them off carefully. It's a fiddly job.
I used Duane's trick for smoothing the threads. I had an old but still good nut so I put FINE valve grinding paste on it and the head and ran it on/off a few times until it felt smooth. Then clean clean clean!

Then two new nuts went on with lots of Never-seize using the proper spanner. Never regretted buying that spanner ($20).

I wouldn't mind one of those spanners , in fact it's essential . Is this the right one ?

http://www.ebay.com.au/itm/BMW-exhaust- ... 1c420b9130

and I found my can of Penetrene , it goes on tomorrow.

Looks correct, although I haven't seen that one before.
Motobins have them. I got mine from Bob's BMW in the U.S.
Perhaps a BMW shop in Aus. carries them as well.

[Airbear]

Peter, how are your fabricatin' skills? Pretty good, I would imagine, given the things I saw in your shed ...



A South African bloke who used to post here (Boertje) made his own exhaust spanner and posted the plan.



As an exercise, I drew a 3D model of it -



It looks simple enough to make. It doesn't need to be all that strong; you are only using it to crack the nut open and then to gently but firmly tighten it again. With good anti-seize the nut should just about spin off.

Or you could do what a succession of Previous Owners have done to the ones on Brunhilde and use a hammer and various screwdrivers, cold chisels, bits of steel bar, etc. It's called patina.

I have access to a proper tool and always clean the threads and re-apply some 'non-metallic' anti-seize (from SuperCheap Auto). It's great for spark plugs too.

[Sibbo]

Thanks Charlie, I looked at the idea of fabbing one but didn't have the specs . I can't quite make out the radius to the centre of the line of pins .... is it 33 mm ? The jpg is a bit blurry.

[Duane Ausherman]

Never tighten up to the book spec at first. I only go to at most 1/2 way. Then I start it up and tighten just to where it stops leaking. I think it very rare to go up to the spec. The tighter that you make it, the more chance of ruining the threads.

[barryh]

Thanks Charlie, I looked at the idea of fabbing one but didn't have the specs . I can't quite make out the radius to the centre of the line of pins .... is it 33 mm ? The jpg is a bit blurry.

The radius to the pins isn't shown but the dia of the pin circle is 63mm.

I have a better quality PDF of that drawing but it won't allow me to up load it. If anyone wants to PM me with an e-mail address I'll send it by return.

[SteveD]

I'm unsure where this was made Sibbo, but it has a very home made appearance. These were around in the '80's and this one was mine. It worked ok.