Engineering compromises leading to exhaust threads stripped (2012)

Re: Engineering compromises leading to exhaust threads strip

frankdamp said:
The number of "engineering" compromises made on the Commando, in favor of production cost-cutting, would start World War Three in the Norton Owners' Community if they were ever published. I don't know them all (maybe 20%), since I was in the R&D/Competition department at Marston Road and wouldn't even comment about those I do know!

Water under the bridge a long time ago.

No doubt. Many of them have been very succesfully worked around/remedied/solved/accepted. Thanks to this GREAT site, and the GREAT people who contribute!
 
Re: Engineering compromises leading to exhaust threads strip

4,000 miles, looks to be holding tight. Exhaust nuts have needed no re-tightening, (checked half dozen times)
 
Re: Engineering compromises leading to exhaust threads strip

I've been searching on and off for weeks to find this thread again. Specifically for re-examining this beautifully made header pipe support.

Jeandr said:
concours said:
R.H. side fitted with grade 8 bolts, 1-3/8" clamp
Engineering compromises leading to exhaust threads stripped (2012)

Very clever 8)

Jean

Of course I am at a disadvantage because I know nothing about welding. Neither do I have any expertise on the issues addressed by this
solution. I don't have the slightest hint of a problem with the exhaust nuts loosening on my Mk3 either. Not yet, anyway. What I would
like to address is the annoying rattle coming from the junction between the header pipes and mufflers. Before I go ahead and install a new
set of headers from Commando Specialties I was hoping for an inexpensive solution. Then I stumbled upon this idea for clamps:

Left side ...
Engineering compromises leading to exhaust threads stripped (2012)


Right side ...
Engineering compromises leading to exhaust threads stripped (2012)


There is enough play on the frame side to add a 1/8" rubber strip between the rail and the clamp. I would also use a longer center
screw with a nut on the end to hold them tight. But before I get into their original purpose and where I got them can someone tell me
why it is a bad idea, fastening a support to the frame rails?

I am all ears,
Peter
 
Re: Engineering compromises leading to exhaust threads strip

contours said:
I've been searching on and off for weeks to find this thread again. Specifically for re-examining this beautifully made header pipe support.

Jeandr said:
concours said:
R.H. side fitted with grade 8 bolts, 1-3/8" clamp
Engineering compromises leading to exhaust threads stripped (2012)

Very clever 8)

Jean

Of course I am at a disadvantage because I know nothing about welding. Neither do I have any expertise on the issues addressed by this
solution. I don't have the slightest hint of a problem with the exhaust nuts loosening on my Mk3 either. Not yet, anyway. What I would
like to address is the annoying rattle coming from the junction between the header pipes and mufflers. Before I go ahead and install a new
set of headers from Commando Specialties I was hoping for an inexpensive solution. Then I stumbled upon this idea for clamps:

Left side ...
Engineering compromises leading to exhaust threads stripped (2012)


Right side ...
Engineering compromises leading to exhaust threads stripped (2012)


There is enough play on the frame side to add a 1/8" rubber strip between the rail and the clamp. I would also use a longer center
screw with a nut on the end to hold them tight. But before I get into their original purpose and where I got them can someone tell me
why it is a bad idea, fastening a support to the frame rails?

I am all ears,
Peter
Hi contours, you don't want to clamp them to the frame... but rather the engine cradle
 
Re: Engineering compromises leading to exhaust threads strip

Okay, I trust your opinion. But why?
 
Re: Engineering compromises leading to exhaust threads strip

contours said:
Okay, I trust your opinion. But why?

The frame is stationary, the cradle moves with the engine.
 
Re: Engineering compromises leading to exhaust threads strip

Okay, so I'd be adding more stress to the pipes this way?
 
Re: Engineering compromises leading to exhaust threads strip

So I get the impression that the locking tabs are not acceptable, why would that be? Granted my bike only has 6k miles on it but 2k since I got it and the locking tabs seem to be the ticket for keeping things tight, and they are still tight after many many heat cycles and checks.

I'm not going to mess with anything at this point but just curious.
 
Re: Engineering compromises leading to exhaust threads strip

contours said:
Okay, so I'd be adding more stress to the pipes this way?
Correct.
 
Re: Engineering compromises leading to exhaust threads strip

lrutt said:
So I get the impression that the locking tabs are not acceptable, why would that be? Granted my bike only has 6k miles on it but 2k since I got it and the locking tabs seem to be the ticket for keeping things tight, and they are still tight after many many heat cycles and checks.

I'm not going to mess with anything at this point but just curious.

The locking tabs are agreed by most as a poor design solution. The fact that yours have remained tight is the exception rather than the rule. If they are genuinely tight, it will make sense not to mess with it, but do keep checking very regularly. If they loosen at all, get them out of there. Good wire locking is the racer's solution, always has been, works for road bikes too.

Once they are even slightly loose they allow the nut to chatter and damage threads, and mainly that will happen without being obvious to you until it is too late. Sounds like you are checking regularly, keep it up.
 
Re: Engineering compromises leading to exhaust threads strip

lrutt said:
So I get the impression that the locking tabs are not acceptable, why would that be? Granted my bike only has 6k miles on it but 2k since I got it and the locking tabs seem to be the ticket for keeping things tight, and they are still tight after many many heat cycles and checks.

I'm not going to mess with anything at this point but just curious.


"Rattle rings"

Get the special spanner, and keep the nuts RFT. Common wisdom is to discard the rings.
 
Re: Engineering compromises leading to exhaust threads strip

lrutt said:
So I get the impression that the locking tabs are not acceptable, why would that be? Granted my bike only has 6k miles on it but 2k since I got it and the locking tabs seem to be the ticket for keeping things tight, and they are still tight after many many heat cycles and checks.
I'm not going to mess with anything at this point but just curious.

Best leave them be, then. If the lock rings are bowed slightly before fitting, and both pairs of tabs are pinched tight to the captive fin on both the head and nut, then they don't always rattle.
 
Re: Engineering compromises leading to exhaust threads strip

contours said:
Okay, I trust your opinion. But why?

It really is a bad idea to clamp the exhaust to the frame rail. clamping with rubber to the engine plate is a different story even if there is pretty good evidence however that most people (includig racers) don't have too much of a problem with that if the silencer rubbers are in good condition and the exhaust nuts are tight and stay tight.

But if you want evidence of how bad it might be to clamp to the frame rail, run the bike on the stand without those clamps, observe engine movement (up and down), fit clamps and run bike and observe again, that is observe reduced movement and vibration going staright into frame rail.....don't do it for long and don't ride it....neither the exhaust nor the frame rail is designed for that kind of stress.

By fitting those clamps you will have short cut all the rubber that Norton put into the exhaust AND the Commando frame design to islolate you from the vibrations, and to allow the exhaust system to have some flex as well.

Even on a rigidly mounted engine (Featherbed or my Rickman for example) you would use rubber (bobbins) in all of the mountings except the head joint. You would then put one mounting at the end of the down pipe and one to support the weight of the silencer (muffler), maximum. '70s style race exhaust with open megas would only have used one bobbin each pipe, but the rubbers would be changed often.

Flex is generally good for exhausts, its just that the Commando can take it to extremes.
 
Re: Engineering compromises leading to exhaust threads strip

Much thanks for the explanations! I guess the rattle is just something I/we need to live with. Maybe the new header pipes will make a tighter connection. :eek:
 
Re: Engineering compromises leading to exhaust threads strip

Rattle??? Commando should not rattle even on very rough surfaces and what ever is rattling may fracture too soon or already has. Factory muffler Lords mounts are like tires, must replace before blow outs. My longer term solution is getting Harley rubber mounts and waisting them to ease header motion and not tightening the muffler clamps to point it actually clamps header but allows slight sliding fit to take up even more isolactic motion front to back that only road load can apply so no apparent in shop testing/feeling of mounting security. May have to tweak the run of the header into muffler to relieve that level of strain. Most common reoccurring rattle on my Cdo's is the muffler internal tube attachments breaking up. IN shop most vibes are up&dn but on the road most is the forward/rearward shift of road load forces in line of drive. In shop reving up hard, front iso's hop up/dn about 1/16" off center but on road they move 1/8" or more off center - front to back.
 
Re: Engineering compromises leading to exhaust threads strip

Ruining ex threads only has to happen once to really piss you off.

Best solution is to remove the retaining flange on the pipe and fit a sleeve so the pipe is a snug fit (weld to pipe or use silicone to hold in place). You must use 2 washers so the nut will tighten down on something when the retaining flange is removed. Use one spring to hold in the pipe and another spring to keep the ex nut tight. With the retaining flange gone the pipe will no longer vibrate back and forth against the nut and try to loosen it. End of problem forever.
1-1/2" dia pipes in photo.

Engineering compromises leading to exhaust threads stripped (2012)
 
Re: Engineering compromises leading to exhaust threads strip

A better view of the LH side
Engineering compromises leading to exhaust threads stripped (2012)
 
Re: Engineering compromises leading to exhaust threads strip

Check out the exhaust nuts that Matt (CNW) is doing... I have a set they work well,also have a set that Doug macadam (Dougs Norton) provided that has a small
Set screw that.... When tightened puts a wee bit of pressure on the head to lock and stabilize the affair,the best advise I ever got was to re tension the nuts after a good ride,do this a couple of times and never worry again... Agree big time with the a antiseieze too.... I'm using a paste made by Wurth it's very good and does not migrate with heat... Stays where you put it... On the threads,I couldn't swear to it but these nuts with the set screw look
Like something jim Comstock might have concocted.... It's got that thought out look and application to match
 
Re: Engineering compromises leading to exhaust threads strip

concours said:
A better view of the LH side
Engineering compromises leading to exhaust threads stripped (2012)

That is one of the better exhaust bracket designs I've seen.
 
Re: Engineering compromises leading to exhaust threads strip

zefer said:
Check out the exhaust nuts that Matt (CNW) is doing... I have a set they work well,also have a set that Doug macadam (Dougs Norton) provided that has a small
Set screw that.... When tightened puts a wee bit of pressure on the head to lock and stabilize the affair,the best advise I ever got was to re tension the nuts after a good ride,do this a couple of times and never worry again... Agree big time with the a antiseieze too.... I'm using a paste made by Wurth it's very good and does not migrate with heat... Stays where you put it... On the threads,I couldn't swear to it but these nuts with the set screw look
Like something jim Comstock might have concocted.... It's got that thought out look and application to match


If you got them from Doug -they are probably Scholtz Tooling castings that were purchased unfinished after Mr. Scholtz passed. They would have been finish machined by me but the locking screw was in the Scholtz design. Jim
 
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