maylar
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Take a look again, it appears that the photos have been changed.
Characteristics created by Incorrectly adjusted ISO (Too tight & Too loose)
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Tornado
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I finally fit my Hemmings iso adjuster to the rear last week. Had the conversion vernier kit on the front, DT top with MK3 spring already.
Took the opportunity to adjust front and back from the book to be spec'd 10 thou with through bolts slack and engine cradle pushed full over to far side. After torquing through bolts back to 30 ft-lbs, book says gap should then be at 6 thou. I found front and back were not taking the feeler gauge. Went for a ride and am getting pretty harsh vibes 2200-3500 rpm, esp through foot pegs, tingling the feet.
Will be redoing the gaps, what should I be shooting for?
Took the opportunity to adjust front and back from the book to be spec'd 10 thou with through bolts slack and engine cradle pushed full over to far side. After torquing through bolts back to 30 ft-lbs, book says gap should then be at 6 thou. I found front and back were not taking the feeler gauge. Went for a ride and am getting pretty harsh vibes 2200-3500 rpm, esp through foot pegs, tingling the feet.
Will be redoing the gaps, what should I be shooting for?
Fast Eddie
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IMHO don’t shoot for a measurement.
Slacken them a little at a time, test ride each time, and find the sweet spot.
When you‘ve found the sweet spot, THEN measure it and make a note for future reference.
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No. Unlike the factory verniers, the Hemmings type must be set with the through-bolt/stud fully tightened.
"Fit nut, #16 (06-2443 or 06-3598) and torque to setting as Workshop Manual, (25 ft/lbs). Screw down adjuster using feeler-gauges between adjuster and PTFE washer. SET TO .010". This Clearance can be varied to suit individual preference with regard to vibrations (less clearance will provide more vibration, but better handling). Also, with this adjuster, it Is quite simple whilst out riding to easily vary the clearance to suit."
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kind of curious - what do you folks consider the sweet spot? upgraded mt 74 Mk2 to the 75 Mk3 vernier types. set my front and rear to .010. seems find, but then again, i have nothing to compare it to. is there any characteristics i should be looking for?
Fast Eddie
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I don’t think there is such a thing as a universal sweet spot. Vibration itself is a function of many things. Personal opinion of the trade off between acceptable vibration and desirable handling are just that, a personal opinion.
Generally speaking, the tighter the isos, the tighter the handling. The looser the isos, the looser the handling (ie the ‘hinge in the middle’ feeling). The sweet spot for you is wherever the bike feels best for you.
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Also;
Even with factory shimmed or vernier Isos. the gap needs to be checked with the through-bolt/stud tightened (which is what the gap would be under normal operating conditions) or the measurement may not be accurate because pushing or levering with a loose bolt/stud is likely to increase the gap (nothing in the factory manual about slackening the bolt or stud first before checking, only if adjustment is required).
Even with factory shimmed or vernier Isos. the gap needs to be checked with the through-bolt/stud tightened (which is what the gap would be under normal operating conditions) or the measurement may not be accurate because pushing or levering with a loose bolt/stud is likely to increase the gap (nothing in the factory manual about slackening the bolt or stud first before checking, only if adjustment is required).
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Reading all these interesting posts, one question showed up about the 25lbs torque applied to ISO nuts/bolts. On vernier adjustable type, what difference it makes to tigthen nuts and bolts more than 25lbs, as the threaded abutments prevent frame pinching? ( Sorry, is my question clear enough?) Thank you
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I don't have an answer but the torque was increased to 30 lbs. ft. in the 850 Mk3 factory manual (the model that had vernier Isos.).
milfordite
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The nice thing about the MKIII iso's is that you can tailor them to how you are riding at that time. While on a cross country trip, I played with the adjustments to make the bike dead smooth at 70-75mph, the speed I was mostly riding at. When I got back home, I set them for the normal back road riding I do.
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This is a good interesting point; Increasing torque from 25 lbs to 30 lbs. Does it demonstrate that that the threaded abutments keep the correct gap between ISO end cap, PTFE washer and abutment? If so, 1/2 inch fine thread stainless ISO bolts (usually between grade 2 and grade 5 tensile strength) could take from 45 to 78 lbs of torque as per standard torque chart??Let's see this forum feeds. Thank you.
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again, i have nothing to compare, and really can't complain about handling or vibration. it sure is a hell of lot smoother than my old paint shaker 70 triumph daytona 500. that thing shook so bad, that most times, the tach and speedometer readings were just a blur.
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My Daytona clocks just disintegrated...
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The fixed abutment screws onto the vernier Iso. tube until the tube bottoms out in the abutment so the fixed abutment cannot move (even without the grub/set screw locking the abutment to the tube).
Tightening the through-bolt/stud clamps the threaded adjuster tight to the frame lug at that end of the assembly so, theoretically, it shouldn't rotate.
I'm not sure I follow (ok, I don't)?
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Your description is in line with what I was wondering. My point is that 1/2 inch diameter bolt/stud could take a lot more torque than the proposed value of 30 lbs, without impairing the MK3 ISO set up to work properly. Sorry about my not very fluent English
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Ok, I think substantially increasing the torque could put the adjuster threads (Iso. tube external and adjuster internal) under unnecessary stress as they resist the clamping force of the through-bolt/stud.
Onder
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After a rather protracted overhaul, I got out on the 74 this afternoon. 2800 and below
it vibrates like a old BSA. Above 3k it is dead smooth. The isos were set at 10 thou.
But it really isn't 10 thou all the way around the iso no doubt the frame is not perfect.
So as FE says set them and then diddle to where you like it. Hemming's adjusters allow for
relatively easy changes.
Must say I am thinking about trying the RGM ultra soft isos . Anybody had a go?
it vibrates like a old BSA. Above 3k it is dead smooth. The isos were set at 10 thou.
But it really isn't 10 thou all the way around the iso no doubt the frame is not perfect.
So as FE says set them and then diddle to where you like it. Hemming's adjusters allow for
relatively easy changes.
Must say I am thinking about trying the RGM ultra soft isos . Anybody had a go?
Tornado
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Those that have the verniers or Hemmings setups, are you still using the iso gator rubbers? Seems these make the adjustment procedure much more difficult? Mine are hard to push out of hte way to access the ptfe washer for gapping and the adjustment piece turning holes. Would be much easier with gators removed. They seem to be used to keep the slding surfaces clean. Could a length of self-amalgamating "plumbers tape" wrapped around the adjuster following final adjustments provide same protection?
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"Gaiter, #27 (06-0773 or 06-3718) can be replaced with the MK3 type, (06-4674) or cut off the nose so that the grub screw and holes are exposed."
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I have concern about MK3 -AN 06-4674 and 06-4666 Gaiters fitment
Many years ago, I bought MK3 ISO conversion kits for my Commando. After all those years, gaiters needed replacement both front and rear. I have ordered Genuine AN replacement ones .
The problem comes when I try to fit them. I you look at the drawing submitted:
- On the left, I measured the groove of the abutment: 1 1/4''. At right,the front gaiter top hole should fit this groove, with some light tension. Actually, this hole is just 1'' and the gaiter have to stretch so much, that I suspect it could tear off very shortly.
- On the left, I measured the end cap: 2 1/4''.On the right the gaiter bottom hole is 1 7/8''. The gaiter has a lip that is supposed to overlap and clip over the end cap and slide on the 2'' front iso tube. So there is a 1/8'' interference fit between bottom gaiter and ISO tube. Despite it is less stretched than the top hole, I suspect that to much tension could tear it off or even make excessive drag when comes the time to adjust Isolastic.
- The rear ISO set up is the same for the abutment groove 1 1/4'' and the ISO tube is 1 3/4''.
So do you have any concern about trying to stretch a 1 inch gaiter over a 1 1/4 groove rather than a 1 1/8inch gaiter over the same groove? In my opinion, the 1 inch gaiter(right) needs considerable force to reach the groove, it does not even fit in , it will be over stretched and will tear off very shortly. Now, in your opinion, what is the solution? Do you have any other supplier in mind?
This is not a money concern for customers. Gaiters are normal priced. The real problem is that their replacement needs considerable and expensive work (engine /cradle removal). Providing every replacement Norton part with the right specs, should be Norton pledge.
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