Safety Wiring Exhaust Nuts

Not open for further replies.
Sep 7, 2006
There seems to be two schools of thought concerning the exhaust nuts. The first camp is the "tighten only" camp, that believes you should never safety wire them. The second group is the 'safety wire" camp, that says if you don't safety wire, the nuts will loosen, vibrate and strip the threads. Within this group there is the subgroup that says if you do safety wire, do not drill a cooling fin to attached the wire, rather attach it to the rocker cover bolt. My bike came with a hole drilled in the fin for safety wiring, and I have seen bikes secured this way. Has anyone had a cooling fin fail if drilled and safety wired? Also, it appears safety wiring would prevent the hassle of always checking the nut to make sure it is tight. What is the reason for objecting to safety wireing the nuts? I know these are mundane questions, but I am a mundane type of guy.....
This might open a can of worms.
I would recommend using bronze nuts not steel because they have a similar expansion rate as aluminium alloy. Always reuse the exhaust joint so you don't have to crush it. Don't wire or lock them because if they work lose you can't tell and they will chatter away the thread. If they aren't locked they screw right out and the bike'll pop and back like hell.

Works for me, perhaps not others.

cash said:
Don't wire or lock them because if they work lose you can't tell and they will chatter away the thread.

Indeed that was my experience with the factory tab washers and balanced pipes. Maybe safety wire would work better.

My current philosophy is to run them without wire and keep an eye on them. Tightening the nuts hot helps, and some feel that running unbalanced pipes helps too.

My 750 has been good about keeping the nuts tight, but I mainly use if for local riding. My feeling is that those long rides, where you're out on the highway for hours on end, is where you're going to have problems.

tighten and retighten severel times hot and running. mine are saftey wired to the rocker cover nut and if you pay attinion to them you will know if they are loose. I ride mine on anywhere from 100 to 650 mile rides and 6 to 12 hour days with no worry's :D

In my 850 MK2A with xover exhaust I use the bronze nuts and tighten when hot using the proper tool. Never had them loosen off
Norvil lists the bronze nuts(lockrings) for all commandos except those with balanced pipes. Mine is the MK111 with balanced pipes so I am stuck using the standard chrome over steel nuts.
Roger at RGM says the Bronze nuts are not necessary, simply tighten the stock nuts with the proper exhaust tool when the bike is as hot as you will ever get it. Then safety wire and put a little tension on the wire.

One other method suggested to me is to use a long spring which hooks onto a fin (drill)at the bottom of one exhaust nut and runs up to the top fin(drill) of the other exhaust nut, the tension pulling each nut in a clockwise (tighten) direction.
I will use either the lock wire or the spring , since my exhaust lockrings came loose quite often on long runs and eventually destroyed the port threads. The head is out for exhaust port thread repair right now.
I have tried tightening the exhaust nuts when I have returned from a long run, but it seems they will loosen during a long run and will never stay tight without constant tightening.

I think the worse thing that can happen is for he nuts to loosen up and bank around in the threads, I have seen what this can do if left unattended. When I got the bike it had 850 exhaust nuts with 3 gaskets to make up for the short threads. tried keeping these tight without wiring them up since other people swore they would eventually "bed in". Unforntunately, I was constantly tightening them. I then ditched the 850 nuts and got proper 750 ones, and ditched the extra gaskets, but even the additional thread lenght and aggresive tightening, these worked loose after long runs. I am now convinced that I will need to safety wire them, but I am hesitant to wire them through the holes in the fins, since given the engines vibration, I'm afraid it may break a fin at some point. Of course, I could wire them on the valve cover nut, but this means I will have to re-wire when the valves are adjusted. I would rather wire them through the fins, if they would hold.

I have two bevel ducatis, and the standard practice is to safety wire the similar threaded exhaust nuts through a hole in the fin. The Ducati engine, however, is much smoother and has little vibration, so this is less of a problem......I feel so much better now that I have unburdened myself.........
This talk of wire and springs is going to mess up some nice stock heads for no reason. When you own a Commando you have something you need to learn about it's fun now drilling holes in a good head that's not fun.
Fixing something that is not broke... Norton was bad enough with the rattle rings . Stop this, it's mad.
The exhaust system is rigid mounted to a head that is floating around on little circles as it runs. Knowledge from any other bike does not apply here you need to rethink this and look at the whole system. The rubber Isos need to be good, you don't allow any strain to develop between the mufflers and the pipes that would tweak the Isos, You don't allow the pipes to twist from the nuts that hold them as you tighten them. The only way to get them tight is on a hot running bike it's a bit hard to hold the pipes fast when their hot you have to have a plan.
You have to have the whole thing built loose just hand tight on the whole system. You have to pull and push while it's all movable to get all the strain out of the system. You then start at the back of the system tightening the bolts that carry the weight of the mufflers, then snug the clamps ,then using wood shims with the bike running you tighten the pipe nuts into the head.
Now the worst thing you could do to a thread is to loosen it while it's under a load. It looses it's ability to protect it's self. The head being alum. always gets wowed out. If the retainers are loose you need to know because that's your head going away. Any thing that keeps you from knowing your bikes tune is bad. Let the things come loose you can stop and fix it. They make a real nice water jetted flange wrench that fit's in a bag carry one till you get the system tuned it takes some miles with a new system. But if they come loose you still have to check on the whole system and not just re-tighten them. JMO Don't get me started.
Greg hit the nail on the head. If you have trouble keeping your exhaust rings tight you either have something out of alignment or there is something wrong with the isolastic system.

The MkIII conical seats help to align the system to prevent strain on the headpipe, but careful rotation and loose fitting of the entire exhaust system before final tightening can be done with the flat flange pipes. They may need to be tweeked slightly on initial installation, but once done it should not take more than a couple adjustments as the crush washer seats in.

If this does not work, then you best look at isolastic buffers, shims, and any torn muffler mounts. If the muffler is doing a 6 inch orbit when idling the headpipes are not going to stay tight.

I have owned my MkV 750 for almost 35 years and had the headpipes off several times in that period, but have never had to re-tighten the exhaust rings more than once.

People have different opinions on this, and you certainly appear to be heavily invested in yours. I understand the dynamics with the Norton differs from the dynamics of a Ducati, and I realize we are not talking about simple engine vibration loosening a fastener, however fact still is many Norton owners do use safety wire and have their reasons for doing so, just as you have reasons for what you do. Within the Norton community one sees divisions where each side desperately clings to their belief systems concerning oil, ingnition systems, vendors, carburators, stock vs. stainless, 850 vs. 750.....etc.the list goes on...these are idiosyncratic and anachronistic machines and there is a large, diverse worldwide body of experience with its numerous foibles.
Well I just bought an 850 with a spare head and both heads have holes in the fins around the head for springs /wire. It's just not right. JMO The holes brake out cracking the fins, they just are not a good anchor for this. Please consider that I know of many high mileage riders who know how to make the system work so hopefully some will speak up here and further develop the tribal knowledges about how to cope with this. A bodge is a bodge not an opinion.

I think the most important aspect to keeping those pesky exhaust nuts from loosening is to really bear down, using a one-foot cheater, when tightening them. Never underestimate brute force!
Jason Curtiss said:

I think the most important aspect to keeping those pesky exhaust nuts from loosening is to really bear down, using a one-foot cheater, when tightening them. Never underestimate brute force!

Just don't use too much brute force! :shock: :lol:

I've seen some people recommend using a six foot length of pipe as a cheater bar for tightening the nuts. That's a recipe for trouble in my opinion.

I don't use a cheater bar at all, just the standard tool, and I'm just a weak little girly girl. 8) Yet the nuts on my 750 have been staying tight. I think RonL and norbsa were spot on with their comments. On my old 850 I had a lot of trouble with the nuts working loose, but back then I wasn't very good about doing the maintenance. I never even checked the iso clearances, much less adjust them :oops:

If you must wire the exhaust nuts why not wire one to the other, saves drilling the head, just a thought. And just to add a bit to NORBSA's advice; It might be a good idea to do the final complete tighten off the main stand (models with centre stand on the plates) to ensure all the stresses are removed. It's amazing how far the silencers move as the ISOs settle.
My old Mk3 has done over 160K and still has the original threads. I use a long tube and heave 'til she falls over :wink:

(no I don't)

A six-foot cheater - wow!

Being a wobbly old man, after all I ride a MK3, I find it easier to crush the gasket and pre-load the nut with the help of a cheater. No matter how well you adjust this and that, the exhaust nuts will absolutely loosen if they aren't good and tight.
hmmmm....using a one foot cheater on my exhaust nuts, then heaving until she falls over......
From some of the posts it sounds as though the Norton exhaust should not be problematic in any way, simply tighten things up and go.

The fact is though, these exhaust port threads have given huge amounts of trouble for many years. The fellow who is currently machining my exhaust ports first set up to do this work nearly 30 years ago when the bikes were still nearly new. No worn out parts or shoddy maintenance to blame back then, the bikes were mostly untouched by their owners, and the stripped exhaust port threads were the first big problem encountered.
Even then he was getting loads of work from this problem. Enough business showed up early on that he jigged up properly for the job. It was well worth doing as he has done hundreds of heads over the years
Colorado Norton Works, RGM, Norvil , British Italian and many others are very familiar with the Norton exhaust port repair and do it all of the time.

Personally I see no problem in securing one nut to the other, I will install a neatly done lock wire. Lock wires don't offend me, race bikes are covered in them and they work!
This only requires drilling of a fin on each lockring. The lockrings are easily replaceable should the next owner prefer to run without the safety wire and think that a tiny hole in one fin of each nut is unsightly.
worntorn said:
The fact is though, these exhaust port threads have given huge amounts of trouble for many years. The fellow who is currently machining my exhaust ports first set up to do this work nearly 30 years ago when the bikes were still nearly new.

One thing to keep in mind is that the factory did not go to all the effort described by norbsa and Ron. They just threw them together as fast as they could. Hence all the problems even back then. I think a lot of owners didn't realize how poor the build quality was. I know my dad and I assumed that because we bought the bike new, it had been put together properly by the factory and the dealer. We were so naive back then :lol:

That said, it's certainly one of the major flaws with the bike. i think it's a rare Norton owner indeed who never experiences stripped exhaust threads.

It's refreshing to read such a spirited post!

The threaded exhaust nut is definitely a flawed design. The moment arm created by the vertical length of exhaust pipe is simply too great. Forces, vibration and rocking, are amplified by this moment and the nut backs off; it's as simple as that.

This topic reminds me of the discussions we’ve had on wet sumping. Yes you can do this and that to the oil pump, leave the piston at TDC, etc., etc., but the engine will invariably wet sump. Another flawed design at work.

But it’s these flaws that attract us to the Norton. We love the challenge and think we can fix them through our meticulous tweaking and fiddling. After all, most Norton owners think they are more cleaver and meticulous than the next person. And by golly we manage to cleaver-away some of the flaws – at least for a while. But in the end, the Norton wins, warts and all.

By the way, there is an excellent article on Mr. Norton in the latest edition of Cycle World.
Not open for further replies.