Muffler Mounts (2011)

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Well the couple of Nortons I had with open headers were quick enough police could not catch us but do worry farmer might shoot at me scaring weight off their cattle or waking them up. Peashooters weigh ~6.5 lb, not counting the hangers.
 
Nater_Potater said:
concours said:
Those bracket plates with an offset... did you custom make them?
Click to expand...
Nope, factory. This is an Interstate variant, if that has anything to do with it. The left side is straight/flat. I've always wondered about that myself, but the mufflers have always slid right on without any binding/misalignment noted.
Click to expand...


Service Release N.81 (March 1972)

p.3

Kickstart foul on right exhaust pipe.
1972 Commando, Interstate and Interpol models only.
063132 Muffler bracket (triangular).
Distributors only.
An alteration has been introduced onto the muffler bracket to provide adequate kickstart pedal operating clearance.
The new bracket, which should only be fitted to the right hand side pipe is supplied under part number 063579.

Alternatively the existing right hand bracket may be re-formed as indicated below.
Click to expand...

(Drawings of the modified bracket are included in the Service Release.)
 
L.A.B. said:
Kickstart foul on right exhaust pipe.
1972 Commando, Interstate and Interpol models only.
063132 Muffler bracket (triangular).
Distributors only.
An alteration has been introduced onto the muffler bracket to provide adequate kickstart pedal operating clearance.
The new bracket, which should only be fitted to the right hand side pipe is supplied under part number 063579.

Alternatively the existing right hand bracket may be re-formed as indicated below.
Click to expand...

(Drawings of the modified bracket are included in the Service Release.)
Click to expand...
Very interesting! I assume this was corrected from the factory after '72, as ours was like this "out of the crate". Thanks for the history lesson.

Nathan
 
Nater_Potater said:
I assume this was corrected from the factory after '72, as ours was like this "out of the crate".
Click to expand...

The service release is dated March 1972, so according to the wording, they were already fitting the modified RH bracket by then.
 
Picked up the set of isolastics ordered locally from ackland-grainger. 50 durometer, not sure what the originals are, but these are noticeably denser. As with the other post, the stud is a c-hair long and required trimming. Also noted something interesting when closely compared with the old ones, the stud on the iso's received from a regular commando supplier are not integral to the outer plate. On the new ones the thread and plate are one unit. According to the specs given by grainger, these are bonded to a solid (not hollow) piece of rubber. Will be interesting to see if they do outlast the mounts we seem to be stuck with from various suppliers these days

Muffler Mounts (2011)


Muffler Mounts (2011)
 
acadian said:
Picked up the set of isolastics ordered locally from ackland-grainger. 50 durometer, not sure what the originals are, but these are noticeably denser.
Click to expand...
Good call! As noted back on page 3, I used McMaster-Carr's 60A durometer, and am now thinking 50A would have been better. Let us know if you notice any change in isolastic action, as mine seems to transmit more vibration at low rpms, and the "smooth point" moved up from around 2500 to 2800 rpm. 'Very curious to hear about yours.
Don't forget the new hardware, as I see yours are also course thread. This would preclude their use as tank mounts.

Nathan
 
The common Harley variety is a bit more robust in density and width and back up plate similar to those shown above. I get more life out of these on head steady and silencers and header bends and rough surface isolation by 1/3 deep waist, expect for the ones that holds oil tank front mount and the under tank mounts. I gave up on resisting bouncing jouncing like strong but brittle tree in a storm for more flexible wealer palm trees in hurricanes.
 
I found some ones on eBay that have springs welded to the inside of the plates and the springs are encapsulated in rubber so they look just like the Norton ones. I was going to try these on my muffler mounts and see how they hold up. My current ones are fine so I haven't tried them yet. I also have found that I can buy the Harley ones, without the springs, dirt cheap at the local swap meet.

Dave
 
Did not hobot waist the spools at some point so there was more give? It isnt the life of the rubbers that matters but the life of headers and
exhaust ports.
 
Is there any feedback on the recommended durometer for these? Looks like the range is 30-60. Leaning towards 50, but wondering if i should go 40
 
pete.v said:
2. The exhaust needs to come together without (or at least as little as possible) stress points. Even the freshes rubber will fail if under constant pressure from a poorly fitted exhaust.
Click to expand...

What pete.v says above can't be over stated. Furthermore, when you have achieved a fitment that permits the pipes/silencers to fit without ANY stress check that the diamond shaped plates that fasten to the silencers make a flat fit to the rubber mounts; this may require reducing one of the two bosses or, alternatively, to add a shim to angle the diamond plate such that it achieves a flat fit to the rubber mounts. In either case I'd suggest that both silencer bosses be ground so that the resulting angle permits a good flat fitment compliments the grinding or shim method.

Best.
 
RoadScholar said:
Furthermore, when you have achieved a fitment that permits the pipes/silencers to fit without ANY stress check that the diamond shaped plates that fasten to the silencers make a flat fit to the rubber mounts; this may require reducing one of the two bosses or, alternatively, to add a shim to angle the diamond plate such that it achieves a flat fit to the rubber mounts. In either case I'd suggest that both silencer bosses be ground so that the resulting angle permits a good flat fitment compliments the grinding or shim method.
Click to expand...
I am probably overthinking but this begs the question: should this procedure be done with the weight of the rider on the bike with out the side stand or center stand deployed which is the orientation when the bike is ridden? OR with the bike on the side stand or center stand where is spends the majority of time? (except of course for those who average more than 12 hours a day riding their bike;))
 
oldbeezer said:
I am probably overthinking but this begs the question: should this procedure be done with the weight of the rider on the bike with out the side stand or center stand deployed which is the orientation when the bike is ridden? OR with the bike on the side stand or center stand where is spends the majority of time? (except of course for those who average more than 12 hours a day riding their bike;))
Click to expand...
Good question. I'm thinking that making a stress free fitment laden could be the better bet, but with good ISOs, a head steady that greatly limits port and starboard upper engine movement and employing the Mk3 head pre-loading spring may even the field; can't say. The down side is that anything that limits the drive line's movement would also increase the level of felt vibration to the rider; handling should benefit, but I would think each rider would have their own sense of where the balance of felt vibration and handling should be.

The rubber silencer mounts won't live forever, but, as mentioned by other posters in this thread, quality of the part and good fitment will go a long way to extending useful duty.

Best.
 
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