Exhaust finned nut won't budge...

[disco51]

Managed to remove the right exhaust nut with a wrench from Northwood's Airheads.  Can't seem to get the left one to budge.  This is just for preventative maintenance and my first time doing the job.  I have no idea if it's been done in the past.  Couple of questions...
How hard should I try before I break out the dremmel and cut the thing out using the chisel technique?  I've been banging the wrench a few times with a wood block, but with no movement.  Should I keep spraying PB blaster and giving it a go?

[Luca]

Heat will help things move along.  Heat the nut with a propane torch and then spray with oil or try to melt some parafin ion the threads.  The heat will help draw the lubricant in and also expand the nut.

I whacked on my wrench with a rubber mallet to get things moving.  The left nut still would not thread off by hand, but I made a judgement call and used the wrench to back it off without damaging the port threads.  I still replaced it, they're only about $20 from the dealer

Breaking the nut free might take some good persuasion, but as long as it isn't actually fighting you while spinning I don't think you'll damage the threads.


P.S. Not sure how much merit there is to it, but a "study" was done on penetrating oils.  It found homemade acetone/atf mix, kano kroil, and liquid wrench penetrating oil to be the best three.  When I was taking my steering head apart, PB wasn't working.  Switched to liquid wrench and things broke free.

[Bob_Roller]

If the nut refuses to move, your best route then, is to cut the nut off .

You risk stripping the threads on the cylinder head, the threads on the nut are harder and they always win .

If you have no sucess removing it, you may want to leave it alone until you are doing maintenance that requires it's removal and then deal with it then .

[k_enn]

Did you try the old trick of first trying to tighten the nut before you loosen it?  I don't know if it will work on the exhaust nut, but I have used it with success on other stuck nuts.  Also, I second Luca's comment about using heat.  The expansion and contraction from heating and cooling can often break the nut from being stuck.

k_enn

[Luca]

I thought the nut had aluminium threads and the cylinder had a threaded steel sleeve

[Bob_Roller]

The cylinder is SOFT aluminum compared to the exhaust nut .

There should be no steel sleeve, unless a previous owner had it installed after stripping the cylinder threads .

[nhmaf]

I had to battle one of mine - it would turn a bit, then bind up... I turned it back, applied more magic mixture, heat, etc. and gave it another go.   It did come off in the end, but the threads on that cylinder have been compromised... they will still hold, etc. but there is a thread or two that have been galled.   I've cleaned it with a thread file, etc but it irks me that I've partly bodged up the threads myself.  I should have just cut it off to begin with.  

[Rob Valdez 79 R65]

cut Cut CUT!!!

[steve hawkins]

I agree with the cut method.  If you do not know the history of the bike - i.e. the last time the nut was removed, then cut it off if you get any issues at all.

What you can do is seriously pre soak and heat and cool in the days running up to attempted removal, but if you still have any issues rotating that nut after that, then cut it of.

The nuts are cheap, removing your head and sending it away to have a new thread installed is a real pain in the arse, not to mention far more expensive.  Downtime on your bike might also be inconvenient.  Its not something to be rushed into lightly.  The nuts might not have been removed in decades!

When you come to re-install your new nuts, make sure you put some copper grease in there, so that next time it won't be an issue.

Cheers

Rev Light

[Rob Valdez 79 R65]

Probably a good place for this:

[montmil]

Cut it off and stop rolling the dice, hoping against hope that you won't totally f**k up the stub's threads.

A trashed stub can be welded up and re-threaded but the service is terribly expensive and you'll likely miss the summer's riding season while waiting.

I had to saw off one butterfly nut on my '81 R65 and upon inspecting the stub, found some PO's excessive force had left some damaged threads. If I had forced the issue, I would have been up creek without a paddle.

Ain't worth the risk and damage. Use anti-seize goop on the threads annually.

[disco51]

Cut it off it is...
Hopefully I won't go too deep.
Thanks as always.

[Glen]

Yup
I cut mine with a dremel..
Actually I made one real good cut pretty close to the threads and one half cut a quarter of the way on other side of nut.. Just for S&G I gave it a tap with a rubber mallet and wrench and she budged.. So it came off that way..
Good luck

[montmil]

Cut it off it is...Hopefully I won't go too deep.

Couple tips for sawing off the butterfly nut...

Tape over the exhaust header so as not to scratch up the chrome, blued metal, rust or whatever. Do it before you begin sawing, not when you get that first scratch and then remember this tip.

Consider buying a hack saw blade holder as seen in the photo. Install the blade so that it cuts on the pull stroke, not  on the push, as you'll bend/break the blade. Use short strokes and watch not to scratch the aluminum head either. Slow and steady will git 'er done.

See the exhaust stub threads in the photo? Stop sawing and try the wrench. Tension may have been released and the nut will come off fairly easily. Maybe. If it's still tight, split the butterfly with a fat chisel; a slim one will drive right into the stub's threads. D'oh!

[Luca]

Disco, since you're going to cut the nut off, why not order the new one first?  That way you can see how thick the aluminium is and be a little more confident that you don't go too deep.


Do you folks think it would be possible to split the nut, once cut, by wedging the two fins on either side of the cut apart?  Might break the fins, but that won't really make things worse and I reckon it's worth a shot before taking a chisel near the head.