Exhaust with Two Crush Washers?

Big_Jim59

Big_Jim59

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Today I got around to pulling the exhaust and noticed that two exhaust crush washers were in place behind the exhaust nut. I wouldn't be concerned except I know Debby assembled this and I trust her work. It made me wonder if there was a good reason for this. In the past I just used one and I see that some people opt to not use them at all.

This is for a stock exhaust system with no crossover.
 
Big_Jim59 said:
It made me wonder if there was a good reason for this.

This is for a stock exhaust system with no crossover.
Click to expand...

One possibility would be if it has '750' flanged pipes but short '850' lockrings.

Big_Jim59 said:
In the past I just used one and I see that some people opt to not use them at all.
Click to expand...

Crush washers aren't used with the 850 Mk3 type flared pipes, collets and spherical seatings.
 
L.A.B. said:
One possibility would be if it has '750' flanged pipes but short '850' lockrings.



Crush washers aren't used with the 850 Mk3 type flared pipes, collets and spherical seatings.
Click to expand...
That could be it. This bike is a bit of a bitsa but it doesn't have the split collets. (I am trying to remeber my MKIII lore.) The header pipe has a flare that fits into the head and it could be for a 750. Like I said it was built from part.
 
Big_Jim59 said:
The header pipe has a flare that fits into the head and it could be for a 750. Like I said it was built from part.
Click to expand...

Flared (850 Mk3)...
Exhaust with Two Crush Washers?


...or flanged (750)?
Exhaust with Two Crush Washers?


750 pipes would not have the flare.

Flared pipes need spherical seatings and collets.
andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
andover-norton.co.uk
andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
andover-norton.co.uk
 
Big_Jim59 said:
Today I got around to pulling the exhaust and noticed that two exhaust crush washers were in place behind the exhaust nut. I wouldn't be concerned except I know Debby assembled this and I trust her work. It made me wonder if there was a good reason for this. In the past I just used one and I see that some people opt to not use them at all.

This is for a stock exhaust system with no crossover.
Click to expand...
I use two on the timing side to get a bit of extra clearance from my Maney style pipe where it bends across the tach drive, so it may be a clearance issue somewhere. I have had welds inside the peashooters which have not been clean internally that cause the end of the header to hang up, for example.
 
In 1982 when getting headers made for my 850 for the Featherbed frame my left pipe has one crush washer and it tightens up but the right pipe I have to use 2 crush washers to tighten works good with no problems at all, the 850 flanges are shorter than the 750 flangers but I used what I had.
 
Just use what you need. No issue if there are two or whatever is required to tighten the exhaust properly.

It's interesting how in the old days we use to smooth out inlet and exhaust tracts to a polished surface but now people engineer in reverse cones and stepped headers to control reversion. Look at the exhaust ports of the new Fullauto type cylinder heads.

The most important thing is no leaks.
 
It was necessary to add another washer/ gasket to a 750 if you wanted to use 850 exhaust nuts. Finned 850 nuts were prettier than previous 750 rounded fins, but threaded area was shallower than 750. Really necessary if you wanted to use the lock rings.
 
Deckard said:
It was necessary to add another washer/ gasket to a 750 if you wanted to use 850 exhaust nuts. Finned 850 nuts were prettier than previous 750 rounded fins, but threaded area was shallower than 750. Really necessary if you wanted to use the lock rings.
Click to expand...
Yes, the shallower threads cause many issues.
However, for those that prefer the look of the 850 rose and want to run a 750 pipe, there is a factory, long thread rose.
It came on the 73, Mk V. Very nice.
andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
andover-norton.co.uk
 
Hi to all, reviving this thread with a question: I am using standard 850 rose nuts with the Emgo non-balanced header set. Fully tightened, without any washer, there is rocking and room. With a single washer, slightly tighter, but with two I think I can tighten fully. So:

= I assume two washers, flat sides back to back, dome side one towards head, one towards pipe, for maximum seal?
= Has anyone introduced RTV hi-temp coating on these washers? Would that help the seal?
= Where may I purchase half-width rubber supports 06-0622 to tuck my exhaust pipe closer to the mounting / Z plate? I have searched RGM and elsewhere but no luck

Thank you for your replies!
 
Jdub said:
Hi to all, reviving this thread with a question: I am using standard 850 rose nuts with the Emgo non-balanced header set. Fully tightened, without any washer, there is rocking and room. With a single washer, slightly tighter, but with two I think I can tighten fully. So:

= I assume two washers, flat sides back to back, dome side one towards head, one towards pipe, for maximum seal?
= Has anyone introduced RTV hi-temp coating on these washers? Would that help the seal?
= Where may I purchase half-width rubber supports 06-0622 to tuck my exhaust pipe closer to the mounting / Z plate? I have searched RGM and elsewhere but no luck

Thank you for your replies!
Click to expand...
These work for tuckin’ your pipes in nicely:

andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
andover-norton.co.uk
 
MichaelB said:
Yes, the shallower threads cause many issues.
However, for those that prefer the look of the 850 rose and want to run a 750 pipe, there is a factory, long thread rose.
It came on the 73, Mk V. Very nice.
andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
andover-norton.co.uk
Click to expand...
Really? My '73 750 Mk V came with standard 750 style exhaust rose nuts. The parts books do not show a P/N 06-3555. Perhaps it was a replacement part only?
 
Jdub said:
Hi to all, reviving this thread with a question: I am using standard 850 rose nuts with the Emgo non-balanced header set. Fully tightened, without any washer, there is rocking and room. With a single washer, slightly tighter, but with two I think I can tighten fully. So:

= I assume two washers, flat sides back to back, dome side one towards head, one towards pipe, for maximum seal?
= Has anyone introduced RTV hi-temp coating on these washers? Would that help the seal?
= Where may I purchase half-width rubber supports 06-0622 to tuck my exhaust pipe closer to the mounting / Z plate? I have searched RGM and elsewhere but no luck

Thank you for your replies!
Click to expand...
Use the nuts with longer threads, as mentioned.
The non-crossover pipes have a flange that is much thinner than the flange and collet used on the crossover pipes.
You WANT those extra threads engaged.

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
 
Last edited:
Fast Eddie said:
These work for tuckin’ your pipes in nicely:

andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
andover-norton.co.uk
Click to expand...
The first commandos had stepped silencer brackets as standard. Have we gone in a full circle?
 
Ron L said:
Really? My '73 750 Mk V came with standard 750 style exhaust rose nuts. The parts books do not show a P/N 06-3555. Perhaps it was a replacement part only?
Click to expand...
Good catch Ron. I know you're the original purchaser of yours.
You're probably correct as it appears Andover is the one who lists the longer thread for the MkV.
Do you still have your orginal header pipes?
Thinking back the 750's came out of the head angling towards the front and then followed the downtubes tighter than the 850's.
This angle at the head would interfere with the bigger fins.
The newer pipes all come straight out of the head, allowing the bigger fins.
However, all these pipes don't tuck as close and have less ground and kicker clearance..
 
Wish that would work for me. AN pipes and silencers and the least stressed alignment leaves the
system pointing out. So a thick washer is required. It does work if a bit cobby.
 

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Fast Eddie said:
Didn’t know that.

I fitted them to both sides on mine and they really help to tuck things in nicely. Makes the stock set up look ‘clumsy’ by comparison, well to my eye at least.
Click to expand...
I've been making do ten years by reducing the height of the mounting lugs. Gained precious kicker clearance.

1702715414585.png
 
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My kicker is no problem. Use the later kicker and I have a TTI box so the dimensions are a bit different.
10k on this setup and so far all I do is replace the rubber mounts a bit sooner than most. Usually relieve
them as per hobot's old method. I didn't this time on the bottom, likely was in a hurry. :)
 
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