Exhaust nut securing

Am in the process of installing an all new exhaust. Am changing my '73 Hi-Rider 750 to roadster trim. As I mentioned previously, the PO had installed an aftermarket exhaust with large diameter turn out mufflers. Am returning to original style exhaust with "peashooter" mufflers. Have read a number of posts relating to in use and with time and miles being put on that is some cases, it's difficult to keep the exhaust nut tight. I am installing new sealing gasket/washers and new tabbed lock rings. If installed initially with the tabbed lock rings, and then the tabs are bent over to lock on to the cylinder fins on one side and on the exhaust nut fins on the opposite side, how can the exhaust nut back off, when they are prevented from doing so by the tabs bent over locking the nut in place?

quawk said:

Am in the process of installing an all new exhaust. Am changing my '73 Hi-Rider 750 to roadster trim. As I mentioned previously, the PO had installed an aftermarket exhaust with large diameter turn out mufflers. Am returning to original style exhaust with "peashooter" mufflers. Have read a number of posts relating to in use and with time and miles being put on that is some cases, it's difficult to keep the exhaust nut tight. I am installing new sealing gasket/washers and new tabbed lock rings. If installed initially with the tabbed lock rings, and then the tabs are bent over to lock on to the cylinder fins on one side and on the exhaust nut fins on the opposite side, how can the exhaust nut back off, when they are prevented from doing so by the tabs bent over locking the nut in place?

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Nuts do not only come loose by ‘backing off’.

Nuts, or any faster, can also become ‘loose’ when the joint it is clamping together compresses further. When this happens, the nut is now ‘loose’ even though it hasn’t moved.

This is what can happen with the exhaust nuts. It’s a big thread, a fine thread, into soft metal, in an area exposed to huge heat differential, clamping a soft crushable gasket and trying to hold a long rubber mounted exhaust pipe into a horribly vibrating engine… Frankly it’s a miracle they work at all !

And that is why many folk don’t like the tab washers as they prefer instead to perform frequent torque checks, especially in the first few hundred miles post installation, to ‘nip up’ any extra compression or movement that has occurred.

Having said all of that, some people use the tab washers and do so very successfully.

drill the large fins for lockwire, re tighten after a couple heat cycles, then lockwire to bottom rocker cover studs

acadian said:

drill the large fins for lockwire, re tighten after a couple heat cycles, then lockwire to bottom rocker cover studs

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Thanks for the response and info, but how does that accomplish anything different than what the tabbed lock rings do?

quawk said:

Thanks for the response and info, but how does that accomplish anything different than what the tabbed lock rings do?

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Lockwire doesn't rattle.

You can only unbend/rebend the tabs on the rings a couple of times before they break.

I went through a few heat cycles / tighten on mine, thought I'd got them tight, but hadn't. It took a couple more attempts, by which time the tabs were no more.

The washer rattle drove me mad. I didn't fancy removing the exhaust to ditch the washers. I now have them sealed to the exhaust rose with some RTV silicon. They're doing nothing, but they're not rattling. That was 3 years / 6,000 miles ago and I've not needed to retighten the exhausts. I just check occasionally.

So, if you use the tab washers, give it 1,000 miles of running without the nuts loosening, before turning the tabs over. Or just don't bother with them.

When everything is rubber mounted including the exhaust system things will move even when tighten, the tab washers didn't do their job to stop this, wasted time using them, I always had troubles keeping the exhaust rose tight when my Norton was Commando form when new till 1980 when I did the Featherbed conversion, everything is hard mounted now and I have never had a exhaust rose come lose in the 44+ years since, my header pipes were made for the conversion and I only use the flange gaskets with the exhaust rose, have no locking devices at all and only have one muffler mount bolt for each side muffler, so one muffler mount bolt and the header rose to remove my whole exhaust each side.
Movements in the exhaust system and motor is the rose thread down fall in the Commando design in my opinion.
I have seen so many boggy jobs on Commando's from people trying to fix this problem from holes drilled in the fins for safety wire, to welding studs in the head to use clamping flanges and all had the same problem, so no real answer to the problem but to keep checking the flanges regularly.

Ashley

I unfortunately can't remember where I sourced these. You can see the grub screw (one on each side of the rose). I honk em down tight while hot and tighten the grub screws. I replace the screws every time the rose comes off. They have been on the bike for about 15 years, and on 2 different heads. Never come loose.

Post in thread 'Exhaust nut woes'
https://www.accessnorton.com/NortonCommando/exhaust-nut-woes.39008/post-663413

Mart UK said:

So, if you use the tab washers, give it 1,000 miles of running without the nuts loosening, before turning the tabs over. Or just don't bother with them.

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I don't use the tab washers anymore, but they work fine and do not rattle when installed properly. Unfortunately, they don't come with instructions. They are made flat - clearly they are not pinched so will rattle. So, before installing you reform (bend) them into an "S". Then, as you say you don't bend the tab until sure that the nuts are tight. In other words a couple of heat cycles and herculean tightening. Then you bend the tabs. That all works perfectly.

What works better is a small dab of nickel anti-seize which gets you and extra 1/4 to 1/2 turn of tightening. I damn near pick the bike up with the wrench when tightening the timing side and knock it over when tightening the drive side! I use nickel rather than copper anti-seize and only a small amount. Nickel is higher temp and if you use too much some can leak out and copper is uglier than nickel. On a new build, I tighten very well, go for a ride, and tighten with all the might that my 74-year-old arms will do, and they do not loosen.

Also, I use the steel seals, not copper ones. Heat anneals copper so it becomes softer, you tighten, you again heat and it becomes softer, ad infinitum.

marshg246 said:

What works better is a small dab of nickel anti-seize which gets you and extra 1/4 to 1/2 turn of tightening.

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I see this and another post recommending using nickel ant-seize for use on the exhaust nuts. I assume since you specifically refer to nickel anti-seize that it is different from the conventional (Permatex #80078) anti-seize you can pick up most anywhere including places like Menards.

quawk said:

I see this and another post recommending using nickel ant-seize for use on the exhaust nuts. I assume since you specifically refer to nickel anti-seize that it is different from the conventional (Permatex #80078) anti-seize you can pick up most anywhere including places like Menards.

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Permatex makes Copper and Nickel anti-seize (maybe more). The number specifies the product and the size/method sold (brush container, arosoll, tube, etc.). Whether Copper or Nickel was first - I have no clue and couldn't care less.

Paraphrased from Permatex:

Aluminum, Copper, and Graphite (1oz tube: 81343, 8oz bottle: 80078): Up to 1600 degrees Fahrenheit, primarily for marine use, Silver Metalic color.

Copper: (8oz bottle: 09128): Up to 1800 degrees Fahrenheit, Spark plug threads installed in aluminum, exhaust manifold bolts, engine bolts, oxygen sensors, knock sensors, thermostat housing bolts, fuel filter fittings, and battery cable connections

Nickel: (.5oz tube: 77134): Up to 2400 degrees Fahrenheit, for use with stainless steel, titanium and nickel alloys and where copper must be avoided. Some applications: Exhaust manifold bolts, exhaust system bolts, muffler clamps and tailpipe assemblies

Stainless in stainless, nickel is clearly specified. Steel in aluminum below 1800F, copper is clearly specified. High temp, nickel is clearly specified. IMHO, the only common things on a Commando not clearly specified: stainless in aluminum, stainless in steel and vice versa, and stainless in cast iron.

So, again IMHO, nickel is all around better.




Every auto parts store I've looked in, Amazon, and Walmart all sell Permatex Nickel in squeeze tubes. I quit using Copper long ago so I don't know where it's sold. I originally quit becuase if you get Copper anti-seize on clean aluminum, it's hard to get off and looks terrible. When I wanted to try it on exhaust I looked up the temperatures and realized the that nickel I already had was best.

I stopped using the lock washers or any other form of locking about 30 years ago after efter eventually getting the courage up to add an extension to the standard spanner to double the length of it and hauling the nuts up nice and hard. I've not stripped any more threads and never had a nut come loose. It's worth trying before spending money on anything else. You will not be able to strip the threads this way unless they are already damaged from having a loose nut rattling around in them.