Vibration Experiences

maylar · Jun 26, 2020

Norton used Nylock nuts on the tank studs and a few other places - I've never had one come loose. Pretty much all other fasteners have lock washers of some sort, either split locks or internal tooth and they shouldn't come loose either. The only recurring item that comes loose on my bike are the long mirror stalks, which have a chrome lock nut. I'm hesitant to tighten them with the Fear-Of-God because I stripped one and needed a Helicoil long ago, and no Loctite because I need to move the mirrors when maneuvering in narrow spaces. I carry a short 9/16 wrench in my jacket pocket and deal with them as required.

ILLF8ED · Jun 26, 2020

Scout63 said:
Thanks for the feedback. I’ll keep watching everything. The bike feels pretty smooth now that I loosened the isolastics a bit. I’m hoping that earlier iso tightness caused the engine bolt problem, and the loose fasteners are in the rear view. I’m using nylock nuts where possible and blue loctitie. I’ll report back in a few hundred miles.

Last time out riding at Interstate speed, my horn fell off. Use areolock nuts for your gas tank mount. My horn...just added a new star lock washer and I’m back in business. I’ve owned and ridden my bike for 22 years and 38,000 miles. Most of what will fall of has.

DogT · Jun 26, 2020

The S pipes are notorious for loosing stuff. I think I lost the first shields at about 4K. But you really shouldn't be loosing stuff. But you do need to check stuff regularly. And things do wear out.

acotrel · Jun 26, 2020

You will probably find that somewhere the engine / gearbox assembly is mounted rigidly to the main frame. It might only be that your exhausts are not flexibly mounted at the rear. With a rigidly mounted motor and gearbox, the crank balance factor is adjusted to give smooth running at race speed. With a normal Commando the system is designed to be smooth at low speed, so when the revs are high, the engine / gearbox assembly vibrates at a much higher frequency. Even on a race bike with the high balance factor, most things need to be rubber mounted.

baz · Jun 26, 2020

No it's not normal to vibrate that much
Once you are above 2500 rpm your commando should be smooth
I don't ever remember losing a bolt from a commando
I'd check the ISOs first
Maybe you have the rock hard rubber bushings that some vendors sell?
The exhaust system/mountings take a beating on a commando,it's the nature of the beast
But generally a commando is pretty smooth compared to others

MexicoMike · Jun 27, 2020

New Commando rider (me, many years ago): "Do I need to safety wire any of the fasteners?"

Former president of INOA (and now a personal friend): "Only the fasteners on parts you want to keep."

Peter R · Jun 27, 2020

baz said:
No it's not normal to vibrate that much
Once you are above 2500 rpm your commando should be smooth
I don't ever remember losing a bolt from a commando
I'd check the ISOs first

Taking a closer look at the iso's makes a lot of sense, I replaced my iso's a couple of years ago, and noticed that the bike vibrated more, and at higher rpm than before.
There were tales that the iso's would smooth out over time, this is BS in my opinion.
Replaced the front iso's again, and noticed that the new rubbers were not only softer, but the dimentions were differeent too (narrower).
Vibration level returned to the normal rumble at low rpm.

cliffa · Jun 27, 2020

Peter R said:
Taking a closer look at the iso's makes a lot of sense, I replaced my iso's a couple of years ago, and noticed that the bike vibrated more, and at higher rpm than before.
There were tales that the iso's would smooth out over time, this is BS in my opinion.
Replaced the front iso's again, and noticed that the new rubbers were not only softer, but the dimentions were differeent too (narrower).
Vibration level returned to the normal rumble at low rpm.

Peter, mind sharing where you got the softer ISO's from ?

Cheers,

cliffa.

acotrel · Jun 27, 2020

Isolastics only ever were a bodge job. Norton Atlas was a good motorcycle - it's problem was it felt like one when you rode it.

acotrel · Jun 27, 2020

My Seeley 850 has a rigidly mounted motor with a re-balanced crank. When you ride it, it is the best, most exciting thing on the planet - the feel of it is superb. -In traffic it would be a bastard would get booked.

joe czech · Jun 27, 2020

installed new iso mounts earlier this year. don't have a clue what vibration is supposed to be like since I have no previous experience with the bike. is there a norm, or are most bikes in general, unique? I seem to have a noticeable vibration around the 2000-2500 RPM range, but only during decreasing speeds and RPM's. other than that, things seem relatively smooth, but again, nothing to compare it to. I know it's a whole lot smoother than what I remember my 70 triumph Daytona 500 was back on the day. that sucker shook so much, the speedo/tach readings were pretty much a blur. to date, nothing's shook loose or fallen off - knock on wood....

Peter R · Jun 27, 2020

cliffa said:
Peter, mind sharing where you got the softer ISO's from ?

Cheers,

cliffa.

Got the softer iso's from RGM.

jbruney · Jun 27, 2020

Mine are RGM and I can't complain after opening the clearance. About as silky as an old 850 gets I guess.

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