isospastic

I am convering my shim iso units to vernier (the french guy). I dutifully removed metal off the front mount to give .250" protruding from both sides. But I now think I had the latter style vernier kit that does not require mount modification. Opps!

instead of admitting defeat and buying a secondhand mount off eba, could I just turn up some nice stainless spacers, to mount between frame lugs and adjusters?
If this would be okay and without compromising the mount, could anybody assist with the original dimensions,(protrusions) of the pipe thru the mount, as I remember they were not equal. Should have measured before cutting, I know?

Cheers Richard

I cannot remember the exact dimensions when I added 'Verniers' but it was about 0.41 LH and and 0.72 RH , which I reduced to 0.66 to match the 0.25 rear offset. I then added an 0.060 spacer to the LH. Really you need to match to the rear (if you have it out?). Failing that the RH needs to be 0.25 appx greater than LH. What I would do is assemble to the engine and frame with the frame rails on supports and find out where the front mount wants to settle. It will be difficult with the weight of the engine, transmission, swingarm and wheel but you may find a happy point where it wants to sit. Then shim the end caps to to frame tabs (you may need to do both sides if it doesn't want to sit to one side.

Thanx Keith for your comprehensive answer. If I have to do all that working out, so be it. But if somebody on the forum has a spare unmodified front engine mount on the shelf, could they assist by measuring how far the pipe protrudes from each plate?
If I can get these dimensions, I reckon I can add the appropriate amount over the .250" I have left on my pipes, to the outside of the vernier between the frame and that should get me back in the game.

Please can anyone measure the left and right pipe protrusions on their front mount.

Cheers Richard

I'll look in my spares box tonight. If I have a front mount I'll post the dimension you're looking for.

Hey ho Richard. Commando or marriage = live learn the hard way.
Short cuts and substitutions come back to haunt ya.
Your experiment of extra ~1/4" steel spacer in front mount has been done
by me and Wesley on his '71 which had worn that much easy slack.
Made his lovely handling and smooth rider - vibe bad up to 40 in 3rd
or 50 mph in 4th and judders front tire/forks in mid leans marked
35-45 mph turns just flowing with traffic. Its the Commando
i don't want to ride again but to test a new iso install.

Prior to placing the big steel washer, I followed him on my
past Peel and then also tested his in flnging zig zags to mild
sweepers for new level of Commando physics. It handling
quick lane changes just fine by a single mild twitch takeing
up the slack yet was delightfully smooth by 20' mph, no tach.
Did see the rear tire patch lever road texture thru rear iso as pivot to
slap the front iso gap sideways either side, which tweetersforks
to wobble front tire aim. Only became an issue when
I held some lean and steady power in 60 mph sweepers
that gave some some for the oscillations to build up.

So my conclusion is if not trying to be boy racer, leave
the iso's set slack and can be- or spend time - money
to dial vibration out yet still handle sweepers with some
zest.

hobot




hobot

If ya don't find a front mount to work with I may have a spare front
mount laying about. I fudged on factory Trixie Combat by putting
in adjustable iso's but think it was kit that didn't need front trimmed.
I had very hard time traveling 100 miles around taking front mount
to machinist and asking if they could trim one end off and square
both ends. Found a tool die shop in near me in the woods that
now get about all my special build business.
Abandoned Norton stuff on Peel with this alloy mount and iso adjusters.

Measured from the plates to the end of tube, and I get 0.590" on the left and 0.340" on the right.
HTH

Hehe, thanks for goofing up for an opportunity to learn something.
Might try the SS spacers and see how it feels.
If not so good then can still replace front mount and start again.
Sorry I can't help with measures but seems you got that down
to decide what might do it.

Its a rare event anything Commando goes as smooth as it should
first time around. Best wishes enduring the journey.

hobot

Thanx Dave for the details, now I can work out if it is feasible to add a spacer between frame lugs and vernier, or alternatively make up thicker abutments between the tube and vernier.
Also thannx everyone elese for answering.

Best regards Richard