Exhaust nut question

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rgla

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Been searching in the forums for a bit more info
My exhaust nut has loosened up a couple times. The threads are still "good" so I'm not ready to pull the head and send it off.

Has anyone tried Hot Lock - it's a high heat (2000 degree) threadlocker? The company says it's equivalent to loctite blue but heat resistant
Also, is anti-seize preferred over threadlock?
One more - What's preferred - Copper or steel exhaust crush washers?

thanks
 
rgla said:
Been searching in the forums for a bit more info
My exhaust nut has loosened up a couple times. The threads are still "good" so I'm not ready to pull the head and send it off.

Has anyone tried Hot Lock - it's a high heat (2000 degree) threadlocker? The company says it's equivalent to loctite blue but heat resistant
Also, is anti-seize preferred over threadlock?
One more - What's preferred - Copper or steel exhaust crush washers?

thanks
Click to expand...
You need to tighten the nut while it's it's hot
Even better tighten it with the engine running , several times
Copper gaskets are fine IMO
 
I use the standard laminated exhaust gaskets.

I also use bronze exhaust nuts with a bit of anti-sieze - tighten them, warm the engine and tighten again - never come loose. I tap the wrench tight with a rubber mallet (and good judgement).

FWIW
 
Last edited:
Is there a concern about using the lock tabs to secure the exhaust nuts? When I did my recent exhaust change I screwed up the nuts nice and tight and then lock tabbed them, as a mechanical lock surely that’s enough?
 
I've just fitted these aluminium ones from Andy Molnar. They are half the weight of the chromed brass ones I had on before. They should expand and contract the same as the head. I was instructed to use copper grease.
Exhaust nut question

We'll see how they perform!
 
Landspeedracer said:
Is there a concern about using the lock tabs to secure the exhaust nuts?
Click to expand...
Tabs are an accident waiting to happen, they loosen off just enough to destroy the threads but not enough to notice until its too late. I have 2 in a box somewhere to remind me never to use them. A good tighten after the first couple of runs and you are good to go, I use bronze nuts with copper grease.
 
Sooner or later, you will have to redo the threads. Many years ago a machinist, located in USA would offer beautiful OS (2inches) stainless nuts. I bought a pair for a friend I had to rebuild the engine. They featured a lock allen screw to prevent unscrewing. Unfortunately, I forgot the supplier's name. May be someone in this forum knows who I'm talking about.
 
I have the tab locks on mine and have been unconcerned but will continue watching this thread. Had no idea they were so frowned upon. :oops::oops:
 
998cc said:
I have the tab locks on mine and have been unconcerned but will continue watching this thread. Had no idea they were so frowned upon. :oops::oops:
Click to expand...
I used them too, up until the exhaust port threads got chewed up and I had to have sleeves welded in. That was 40 years ago.
 
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998cc said:
I have the tab locks on mine and have been unconcerned but will continue watching this thread. Had no idea they were so frowned upon. :oops::oops:
Click to expand...
Very simple; When nuts start to loosen, they do not unscrew completly, because the lock tabs. Instead, under vibration they move from one tab to the other and wear out the aluminum threads of the head. Then at the most unexpected moment...pouf! You then have a rattling exhaust nut sliding down on your exhaust pipe. Your nice sunny Sunday ride is over and hope finding some wires hanging from a farmland fence:eek:o_O
 
If you opt for the bronze ones , make sure the tooth on the C spanner engages the fin on the exhaust rose at the root . If it doesn’t , grind it ( the C spanner ) so that it does. Otherwise you run the risk of breaking a fin . Ask me how I know ...
 
I use hi temp rtv on the exhaust threads. Tighten them and then retighten a couple of times when hot.

Always stayed tight.
 
i also think the use of the steel non compressable sealing washers (RGM) help
 
I have always used Ludwigs tip to get the engine warm and bring it up to about 2500 rpm when you use your spanner. I also use the hi-temp RTV sealant
Mike
 
please no flames, but i'm using the stock factory style tab locks from AN. 2+ years and about 3K miles, and so far they seem to work just fine. i give them a visual inspection periodically to check for looseness, and so far no problems. with one set of tabs locked into the cylinder head fins, and the opposite side tabs locked into the exhaust nuts, i personally can't see the exhaust nuts can loosen and back out - unless i'm using something different than what you folks are talking about - ?????
 
joe czech said:
please no flames, but i'm using the stock factory style tab locks from AN. 2+ years and about 3K miles, and so far they seem to work just fine. i give them a visual inspection periodically to check for looseness, and so far no problems. with one set of tabs locked into the cylinder head fins, and the opposite side tabs locked into the exhaust nuts, i personally can't see the exhaust nuts can loosen and back out - unless i'm using something different than what you folks are talking about - ?????
Click to expand...
The first warning about these I saw was in the NOC Commando Notes written in the 80's, these notes have been superseded by later updated mods and equipment but they still stand as good indicators of what does not work. They were written by high mileage riders with input from John Hudson ex Norton service and the NOC model experts. You may have a working set and have the nuts nice and tight but years of experience and advice is to bin them.

From the NOC notes

EXHAUST THREADS: The exhaust threads in the cylinder head cannot be stripped using the standard nuts and the large service C ring-the fins on the nuts bend first. If the nuts aren't tightened enough, an pre-delivery, they will loosen and the lock rings enable you to carry on like this so that the threads wear, and will subsequently strip.
 
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