Exhaust nut woes

krullbeast

krullbeast

Joined
Apr 18, 2017
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Hello there,
Has anyone had any luck with gooping up your exhaust port threads with high-heat jb weld and tapping new threads with a 1 15/16 tap? I am at my wits end with my 74 850 exhaust nuts. I can't afford to take the head off and ship it to mass. for those brass inserts. Thank for any information.
 
I welded mine in place, BUT, it already had a previous repair.

www.accessnorton.com

Engineering compromises leading to exhaust threads stripped (2012)

Best I can see is, the exhaust threads being a problem area, is the result of multiple engineering EVOLUTION compromises. In the beginning, the head was cast iron and the threaded attachments probably worked just fine. Then the thread (head) material changed to softer aluminum... and they...
www.accessnorton.com www.accessnorton.com

This guy has given good results:

www.accessnorton.com

Norton Exhaust Port Repair

Two more Norton. Exhaust port repairs machined and shipped off to Alberta and British Columbia.
www.accessnorton.com www.accessnorton.com


Never tried JBWeld, but I grabbed a beer can outta the ditch, cut strips with my knife, and wrapped them around the nut to shim the O.D. bigger.
Tightened it back in to the wallowed out threads. Rode it home.
 
Last edited:
concours said:
I welded mine in place, BUT, it already had a previous repair.

www.accessnorton.com

Engineering compromises leading to exhaust threads stripped (2012)

Best I can see is, the exhaust threads being a problem area, is the result of multiple engineering EVOLUTION compromises. In the beginning, the head was cast iron and the threaded attachments probably worked just fine. Then the thread (head) material changed to softer aluminum... and they...
www.accessnorton.com www.accessnorton.com

This guy has given good results:

www.accessnorton.com

Norton Exhaust Port Repair

Two more Norton. Exhaust port repairs machined and shipped off to Alberta and British Columbia.
www.accessnorton.com www.accessnorton.com


Never tried JBWeld, but I grabbed a beer can outta the ditch, cut strips with my knife, and wrapped them around the nut to shim the O.D. bigger.
Tightened it back in to the wallowed out threads. Rode it home.
Click to expand...
What I would call a "quality bodge"!
 
concours said:
I welded mine in place, BUT, it already had a previous repair.

www.accessnorton.com

Engineering compromises leading to exhaust threads stripped (2012)

Best I can see is, the exhaust threads being a problem area, is the result of multiple engineering EVOLUTION compromises. In the beginning, the head was cast iron and the threaded attachments probably worked just fine. Then the thread (head) material changed to softer aluminum... and they...
www.accessnorton.com www.accessnorton.com

This guy has given good results:

www.accessnorton.com

Norton Exhaust Port Repair

Two more Norton. Exhaust port repairs machined and shipped off to Alberta and British Columbia.
www.accessnorton.com www.accessnorton.com


Never tried JBWeld, but I grabbed a beer can outta the ditch, cut strips with my knife, and wrapped them around the nut to shim the O.D. bigger.
Tightened it back in to the wallowed out threads. Rode it home.
Click to expand...
Thank you for sharing your story with me. mine are the original head threads that have finally crapped the tux. I think i'm going to try an insert, if i can figure out how to do it without taking the head off. Say you could go back and do the original repair on your's yourself, would you use a pressure fit or a thread in type?
www.classicbritishspares.com

Triumph / Norton Exhaust Pipe Spigot Thread Repair Inserts (1) - Choose Spigot Type

If you are working on a vintage Norton Commando cylinder head or a Triumph head, often times you might find that the exhaust spigot threads may be stripped. If so, they will need to be repaired.. In this listing you will find exhaust spigot repair inserts for sale; we have a few different...
www.classicbritishspares.com www.classicbritishspares.com
www.classicbikespares.com.au

Exhaust Port Repair Insert, Norton » Classic Bike Spares

Exhaust port repair insert. HE15 Dural - not a helicoil. Length- 25.1mm O/D-53.5mm I/D- 46.80mm 1 -3/4" BSP OUT SIDE THREAD 1- 15/16" X 14 TPI internal Thread For Norton Dominator and Commando. Made in England. 069383
www.classicbikespares.com.au www.classicbikespares.com.au

I like how you did yours and i'm happy that it has held up so well for you. if i can't do an insert repair, maybe i'll do the beer can strips.
thanks again
 
Couple of old threads floating around showing some sleeve fittings held together with either springs or clever bolts between head fins.
JB Weld in my opinion will not hold if no original thread left as all epoxies soften under heating.
 
krullbeast said:
Hello there,
Has anyone had any luck with gooping up your exhaust port threads with high-heat jb weld and tapping new threads with a 1 15/16 tap? I am at my wits end with my 74 850 exhaust nuts. I can't afford to take the head off and ship it to mass. for those brass inserts. Thank for any information.
Click to expand...
*IF* you have the short nuts used with collets, and if you still have some good threads in deep, and if you have a Roadster, you can get long thread exhaust nuts and flanged pipes and not need anything more except diligence in keep them tight. To help with that, you could use actual exhaust sealer (not JB weld). Would cost less and no need to remove the head.

Yes, that's a bunch of ifs but you said nothing about what you actually have!
 
marshg246 said:
*IF* you have the short nuts used with collets, and if you still have some good threads in deep, and if you have a Roadster, you can get long thread exhaust nuts and flanged pipes and not need anything more except diligence in keep them tight. To help with that, you could use actual exhaust sealer (not JB weld). Would cost less and no need to remove the head.

Yes, that's a bunch of ifs but you said nothing about what you actually have!
Click to expand...
my apologies. i have a 74 mkIIa 850. it was a hi-rider but i have the new peashooters on and a roadster tank. i'm pretty sure my exhaust nuts are the short ones, no crossover pipe. my mechanic (that i hire when i can't do stuff) tapped the old threads to try and clean them up, but it obviously didn't work very well, it spun off after two rides. i have it held together with a wire hanger right now. not usable. i'll skip the jb weld idea. when you say flanged pipes, do you mean headers? i'm pretty sure my headers are flanged. do you think the longer exhaust nuts might work? are you talking about the 750 exhaust nuts? thank you
 
krullbeast said:
my apologies. i have a 74 mkIIa 850. it was a hi-rider but i have the new peashooters on and a roadster tank. i'm pretty sure my exhaust nuts are the short ones, no crossover pipe. my mechanic (that i hire when i can't do stuff) tapped the old threads to try and clean them up, but it obviously didn't work very well, it spun off after two rides. i have it held together with a wire hanger right now. not usable. i'll skip the jb weld idea.
Click to expand...
Since your pipes were originally crossovers you probably still have the now un-needed collets and good threads in deep. So, you may only need the correct long threads for the flanged pipes you have. I would consider putting them in with exhaust pipe sealer, but in the bad area only (put on the threads of the nuts, not in the head and use plenty - be sure to follow the instructions and cleanup before starting.

If you have the good threads I think you do, pretend you are Hercules when you tighten. The threads are damaged when the nuts come loose and they do not come loose if fully tightened. A tiny bit of nickel anti-seize in the good threads of the head will help you tighten more.

The sealer may make it difficult to get them apart later, but you're already in a mess, so...
 
marshg246 said:
Since your pipes were originally crossovers you probably still have the now un-needed collets and good threads in deep. So, you may only need the correct long threads for the flanged pipes you have. I would consider putting them in with exhaust pipe sealer, but in the bad area only (put on the threads of the nuts, not in the head and use plenty - be sure to follow the instructions and cleanup before starting.

If you have the good threads I think you do, pretend you are Hercules when you tighten. The threads are damaged when the nuts come loose and they do not come loose if fully tightened. A tiny bit of nickel anti-seize in the good threads of the head will help you tighten more.

The sealer may make it difficult to get them apart later, but you're already in a mess, so...
Click to expand...
thank you, i will check. What part number are the longer exhaust nuts you speak of? are they from a different year? a 750 maybe?
 
gotcha, i'm gonna try this. thank you for your info. i appreciate it! i actually think i have some longer exhaust nuts around here somewhere...i KNOW i have beer cans though... so, hmmmmm?
 
What Greg said, BUT If there aren't many threads left, playing Hercules may finish off the remaining threads. I prefer to snug the nuts down with the blue, 12" exhaust nut spanner with the head warm, not hot. Then lock-wire the nuts in place. In my experience of many years, they do not move. Of course you'll have to drill the nut for the lock wire but the other end can be wrapped round the valve cover nut in such a way that you don't have to remove the wire to get the valve cover off. I've probably done fifty like that over the years, though some owners didn't like holes drilled the the nuts or the non-factory look of the lock wire. I asked first.
 
krullbeast said:
Hello there,
Has anyone had any luck with gooping up your exhaust port threads with high-heat jb weld and tapping new threads with a 1 15/16 tap? I am at my wits end with my 74 850 exhaust nuts. I can't afford to take the head off and ship it to mass. for those brass inserts. Thank for any information.
Click to expand...
Is Jim Comstock still doing his repairs?
Many years ago while on my way wo Colorado for the National Rally in Durango, 87 I beleive. I pulled the treads in my head. I bought 6 large hose clamps and went around the head to hold the pipes in place. Once over the top and once below. I then used some safety wire to keep the clamps from spreading. A bit crude but it got me home.
 
How a small person who is NOT Hercules tightens exhaust nuts: (1) Verify threads are good (2) Spin on exhaust nuts with collets in place (pain in neck getting collets in place) (3) Find the purpose built exhaust nut wrench and tighten as much as possible (4) Start up bike and get it warmed up (5) Re-tighten, tapping on tool with copper mallet. Doing it this way has resulted in tight exhaust nuts for several hundred miles.

I like the idea of drilling a hole for lock wire and will do so if the nuts get loose or if I have to remove the exhaust for some reason.
 
I addressed the root cause of the problem, which is movement of the poorly supported pipe and silencer, by bodging brackets to tie each pipe to the front engine mounting to stop them rotating about the exh. ring nut axis. Problem solved.
 
nortonmargie said:
How a small person who is NOT Hercules tightens exhaust nuts: (1) Verify threads are good (2) Spin on exhaust nuts with collets in place (pain in neck getting collets in place) (3) Find the purpose built exhaust nut wrench and tighten as much as possible (4) Start up bike and get it warmed up (5) Re-tighten, tapping on tool with copper mallet. Doing it this way has resulted in tight exhaust nuts for several hundred miles.

I like the idea of drilling a hole for lock wire and will do so if the nuts get loose or if I have to remove the exhaust for some reason.
Click to expand...
Of course a hammer can replace Hercules - the point is getting the damned things tight :D

And yes, I should have said with the engine up to temp.
 
krullbeast said:
Hello there,
Has anyone had any luck with gooping up your exhaust port threads with high-heat jb weld and tapping new threads with a 1 15/16 tap? I am at my wits end with my 74 850 exhaust nuts. I can't afford to take the head off and ship it to mass. for those brass inserts. Thank for any information.
Click to expand...
I know I've posted this a few times before but here's my version of an exhaust clamp
It picks up on the outer and inner cylinder head bolts and goes between the fins
No alteration is made to head
It's not pretty but I don't care
 

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This was an earlier version of my clamp
And earlier than this over 40 years ago I used to weld two small bosses to the Norton exhaust rose with the same setup
It's never failed
 

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For saftey wiring, I did it without drilling holes. I wrapped one fin on exhaust rose nut and then to a single exhaust manifold type hooked spring, then anoher wire from spring to other rose nut fin. Wired fins chosen such that wire load prevented each rose turning counter clockwise. Worked well with spring in tension able to keep wire tight. Lasted until i got the alu/brass sleeves into head from Precision Machining in Ottawa, Ontario (see link in an earlier reply in this thread).

Several folks have had that work done there and all report excellent work and fast turn around for a reasonable price.
 
Pardon my ignorance, after the alu/brass sleeve job is done is problem completelt solved? Tighten up and done?
 
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