Characteristics created by Incorrectly adjusted ISO (Too tight & Too loose)

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Sergio said:
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:

Characteristics created by Incorrectly adjusted ISO (Too tight & Too loose)


  • 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''.
Again my concern is that the gaiter dimensions provided by AN are not adequate. I include pictures showing the difference between my worn gaiter(left) and the new front one (right) 1 1/8 inch vs 1 inch.
Characteristics created by Incorrectly adjusted ISO (Too tight & Too loose)


Characteristics created by Incorrectly adjusted ISO (Too tight & Too loose)



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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I replaced my Mk3's front and rear Isos and gaiters just under 18 months ago using AN parts and except for the gaiters being a little tight in the grooves then they were no real problem and haven't split or cracked so far.

Characteristics created by Incorrectly adjusted ISO (Too tight & Too loose)


Characteristics created by Incorrectly adjusted ISO (Too tight & Too loose)
 
Those gaiters have to be a tight fit and of stout material as they’re actually having to handle the movement between engine and frame.
 
Just completed re-gapping front and rear...and have a new hatred for those oem gators. I cannot see ever attempting this gap adjustment out on the road to fine tune...took me about 2.5 hours of messing around with various allen keys to get a bite on the adjustment collar holes, set of feelers, sockets, spanners, ratchet to slacken/tighten/slacken/tighten the through bolts, a rubber mallet to wedge 'tween frame and cradle to force gaps open, working on at various angles and orientations laying down next to bike. This in the relative "comfort" of my parkade cement floor on foam mats. Never gonna happen on the roadside, nope, not on my watch >:d
 
Tornado said:
took me about 2.5 hours
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It's hardly any wonder it has taken you hours because you are doing it completely wrong!

Tornado said:
sockets, spanners, ratchet to slacken/tighten/slacken/tighten the through bolts,
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No. Once the through-bolt/stud has been tightened then you don't touch it again.

Tornado said:
a rubber mallet to wedge 'tween frame and cradle to force gaps open,
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No. You should not be forcing the gap open and definitely not with the bolt/stud slackened.


First
"Fit nut, #16 (06-2443 or 06-3598) and torque to setting as Workshop Manual, (25 ft/lbs)."

After that, the bolt/stud/nut should not be loosened again as the adjustment is done with the bolt/stud/nut fully tightened.

Then:
"Screw down adjuster using feeler-gauges between adjuster and PTFE washer. SET TO .010"."


"After setting clearance, fit grub screw and tighten in the most convenient hold[hole]. It is not necessary remove this screw again, only to slacken and re-adjust if necessary."

All of which should have taken no more than a few minutes.
 
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I am a sunshine rider now and I don't have the gaiters on the rear isos. With Hemming's adjusters
adjustment is pretty easy. I do have the front gaiters installed they lead a less protected life on the lanes.
Maybe I am wrong but the rear iso seems to be more sensitive to adjustment than the front.
 
The simple method for me to get to the "sweet spot" for my bike is to tighten the vernier adjusters to "snug" then back off 2 holes (which I believe, for that threadform, should be 0.008"). I tried 1.5 up to 3 holes - 2 seems to be best (for my bike).
Messing around with feeler gauges, when there are so many possible contributors to measurement error, is folly (IMHO).
 
L.A.B. said:
I replaced my Mk3's front and rear Isos and gaiters just under 18 months ago using AN parts and except for the gaiters being a little tight in the grooves then they were no real problem and haven't split or cracked so far.

Characteristics created by Incorrectly adjusted ISO (Too tight & Too loose)


Characteristics created by Incorrectly adjusted ISO (Too tight & Too loose)
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Thank you for your input. Hope the new gaiters will survive as the previous ones I replace (20 years). Being a senior, in 20 years the Norton will be sitting in the garage or could be cared of by a grand son.:)
 
robs ss said:
The simple method for me to get to the "sweet spot" for my bike is to tighten the vernier adjusters to "snug" then back off 2 holes (which I believe, for that threadform, should be 0.008"). I tried 1.5 up to 3 holes - 2 seems to be best (for my bike).
Messing around with feeler gauges, when there are so many possible contributors to measurement error, is folly (IMHO).
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hi, do you have Mick Hemmings or the MK3 vernier ?
 
L.A.B. said:
It's hardly any wonder it has taken you hours because you are doing it completely wrong!



No. Once the through-bolt/stud has been tightened then you don't touch it again.



No. You should not be forcing the gap open and definitely not with the bolt/stud slackened.


First
"Fit nut, #16 (06-2443 or 06-3598) and torque to setting as Workshop Manual, (25 ft/lbs)."

After that, the bolt/stud/nut should not be loosened again as the adjustment is done with the bolt/stud/nut fully tightened.

Then:
"Screw down adjuster using feeler-gauges between adjuster and PTFE washer. SET TO .010"."


"After setting clearance, fit grub screw and tighten in the most convenient hold[hole]. It is not necessary remove this screw again, only to slacken and re-adjust if necessary."

All of which should have taken no more than a few minutes.
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I ha v e hemmings on rear, MK3 retrofit kit on front. Perhaps there is some difference in how these are meant to work. But I found on Hemmings and on MK3 kit with the through bolt at the 25 or 30 ft-lb torque, there is no way the adjusters will turn. So it is necessary to slacken, make an adjustment and re torque to verify the gap. Repeat until its right.
 
Tornado said:
I ha v e hemmings on rear, MK3 retrofit kit on front. Perhaps there is some difference in how these are meant to work.
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Yes, they are adjusted differently (sorry, I thought it was also a Hemmings adjuster at the front), the pre-Mk3 front vernier conversion kit bolt must be slackened off. The Hemmings adjuster (either front or rear) must not.

Tornado said:
But I found on Hemmings and on MK3 kit with the through bolt at the 25 or 30 ft-lb torque, there is no way the adjusters will turn.
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I can't see how it can be the Hemmings vernier adjuster as that cannot be adjusted accurately with the bolt/stud slackened which is why the bolt/stud is tightened before the adjustment (see the Hemmings instructions) and having the bolt/stud tight shouldn't prevent the adjuster sleeve from turning as the purpose of the grub/set screw is to lock the adjuster to the threaded sleeve after adjustment.
Front and rear Hemmings adjusters (rear on the left)
Characteristics created by Incorrectly adjusted ISO (Too tight & Too loose)
 
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The only way I can think of for the Hemmings adjuster to be locked up with the stud tight (and the grub screw slackened) is if the adjuster collar was screwed out further than the end of the threaded sleeve. The threaded sleeve, therefore, should be wider than the collar. Edit: When the stud is tightened it clamps only the threaded sleeve between the inner Iso. tube and the frame leaving the narrower collar free to turn on the wider sleeve so it can be screwed in or out to adjust the gap.

Edit: Or, it's a short 'front' threaded sleeve and a long 'rear' collar.
 
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L.A.B. said:
The only way I can think of for the Hemmings adjuster to be locked up with the stud tight (and the grub screw slackened) is if the adjuster collar was screwed out further than the end of the threaded sleeve. The threaded sleeve, therefore, should be wider than the collar. Edit: When the stud is tightened it clamps only the threaded sleeve between the inner Iso. tube and the frame leaving the narrower collar free to turn on the wider sleeve so it can be screwed in or out to adjust the gap.

Edit: Or, it's a short 'front' threaded sleeve and a long 'rear' collar.
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Was sold to me by Mick himself as a rear adjuster. Could still be incorrect. Does look more like the one shown in your image at the left side. I compared it to the original rear flared piece it replaces and it was nearly the same width. There was nothing in the guidance about how far along the threaded section it should be placed when first fitting. I just got it threaded so it would easily slip into place 'tween frame and iso end cap, then winding it in/towards the iso from there. I may have started with it already too far inwards, making it way too tight against the ptfe washer.

I just got back from a test ride with where it was all set at lastnight, likely still too tight. Much improved from first attempt's previous test ride where strong vibes up through foot pegs 2200-3500. Now it's much less vibs around 2500-2800 (peak) and very smooth above 3000. Will have another crack at it soon.
 
Tornado said:
Was sold to me by Mick himself as a rear adjuster. Could still be incorrect. Does look more like the one shown in your image at the left side.
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Ok, sounds as if it is the correct adjuster.:)

Tornado said:
There was nothing in the guidance about how far along the threaded section it should be placed when first fitting. I just got it threaded so it would easily slip into place 'tween frame and iso end cap, then winding it in/towards the iso from there. I may have started with it already too far inwards, making it way too tight against the ptfe washer.
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If the adjuster had been screwed in too far on the sleeve to begin with, then it would have clamped the feeler or, the Iso. assembly would have had zero clearance with the stud tightened so the subsequent loosening and tightening should have resulted in the adjuster being backed off until it was free to turn with the stud tight.

Tornado said:
I ha v e hemmings on rear, MK3 retrofit kit on front.
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Regarding the front factory type vernier (where the bolt must be loosened) with the necessary tools to hand it took just under 6 minutes to loosen, mess up the setting, readjust and retighten my Mk3's front Iso.

I prefer to use a feeler gauge rather than backing the adjuster off by a set number of holes as tightening the bolt/stud can reduce the gap which can be felt on the feeler if it becomes clamped as the bolt/stud is tightened.
 
Ok just to follow up on my rear Hemmings Iso adjuster, after another faffing with it today I confirmed it is the correct taller one for the rear. Reason it was binding solid once through bolt tightened was I had it set too far along the threaded piece. I slackened through bolt to permit unwinding adjuster to nearly all the way even with inner threaded bit, then torqued through bolt and voila, could easily turn adjuster back towards the iso disc. Got it to a 10 thou feeler sliding fit. I did that with the cradle push away from frame using a rubber mallet handle against SA and Z plate. This opened up the gap at adjuster and set it from there.
LAB: I know you said not to do this hold over, as does the guidance on OldBritts sheet, but the stock vernier adjust guidance does say to do it. Takes up any slack on far side so you measure total slack, not just what happens to be present at the one side you are measuring. Why not do same for Hemmings setup?

After a test ride things seem pretty good but may need more dialing in.
 
Tornado said:
LAB: I know you said not to do this hold over, as does the guidance on OldBritts sheet, but the stock vernier adjust guidance does say to do it. Takes up any slack on far side so you measure total slack, not just what happens to be present at the one side you are measuring. Why not do same for Hemmings setup?
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What you originally said was:
Tornado said:
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.
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Pushing/levering the cradle "with the through bolt/stud slack" can increase the gap as the threaded sleeve the adjuster turns on has to be tight between the frame and the inner Iso tube.
You can lever the cradle to check the gap but the through-bolt/stud must be tight or you are likely to get an inaccurate gap measurement with the bolt/stud slack which is why the Hemmings instructions say to tighten the bolt/stud first.

The same goes for the factory vernier as you can lever the cradle to check the gap but the bolt/stud should be tight as the procedure in the Mk3 manual states in sections F13(front) and F14 (rear). First, lever the cradle to check the gap. Then if adjustment is required, slacken the bolt...etc.
 
Also...

Tightening the adjuster collar of either the Hemmings (bolt tight) or factory (bolt loose) should close the gap at the opposite end of the Iso. so, theoretically, there should be no need to lever the cradle, only insert the feeler and screw the adjuster against the feeler and (for Hemmings) lock the adjuster with the grub/set screw and could be why the Hemmings instructions don't mention anything about levering the cradle.
 
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