Installing vernier ISOs

I am installing the vernier ISO front and rear in a 73 750 frame. I have the 06.7337 and 06.7117 conversion kits from AN. The bike is disassembled so I am doing the fitting on the bench with the mounts secured in my vise.

The problem I am having is that when I tighten the mounting bolt after setting the proper gap with it loose, the gap is significantly smaller than what I set it to. I expected that the threaded sleeve and screw on ends would hold the gap constant. I reviewed this thread:


which seems to indicate that the gap can change with tightening.

Is this "normal" and if so, how does one get the desired gap after torqueing? Trial & error?

I am using 30 ft-lb torque as the instructions call for and I am simulating the engine/frame being "levered" using a clamp or bearing puller when measuring with feeler gauges.

NickZ said:

which seems to indicate that the gap can change with tightening.

Is this "normal" and if so, how does one get the desired gap after torqueing? Trial & error?

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Yes, it is normal due to the play in the adjuster thread the gap closes up as the through-bolt (or rear stud) is tightened so there's literally no point trying to set the vernier Iso. clearance with the unit 'on the bench'.

L.A.B. said:

Yes, it is normal due to the play in the adjuster thread the gap closes up as the through-bolt (or rear stud) is tightened so there's literally no point trying to set the vernier Iso. clearance with the unit 'on the bench'.

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Why wouldn't the same thing happen when adjusting on the bike?

I found the (Not AN) RGM verniers to be around one division, want two divisions set three.

If you torque check them in the vice as per your photo and can hold that adjusted to position getting them in place it should be fine.
The cradle Isolastic should be no different based off your post.

Doing that will also give you a better view to check how the set gap is in multiple locations.
It is hard to see but you would need large diameter heavy spacers under the head and nut to simulate the frame lugs.

NickZ said:

Why wouldn't the same thing happen when adjusting on the bike?

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Yes, it will and that's why attempting to set the vernier clearance on the bench is a pointless exercise because there are no shims to change and why the bench setting instructions aren't in the Mk3 manual and setting the vernier with the Iso. mount in position is basically a '5-minute job', so remove all clearance, fit the front Iso., set the clearance with a feeler gauge and continue to check as you tighten the bolt/nut, if the clearance reduces so it clamps the feeler then loosen the bolt and increase the clearance, repeat until you have the required clearance with the bolt fully tightened.
Same procedure for the rear Iso.

NickZ said:

Why wouldn't the same thing happen when adjusting on the bike?

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It will as posted.
If you do as you have done and mark things to maintain that end positions it will work perfectly.
The catch is getting the cradle and front Isolastic housing especially in between the frame lugs in an adjusted position (overall outer width) is near impossible.

It is much easier to find the lost clearance on the bench than in the bike (obviously) as you have done, the trick is to mark things so you replicate that setting needed (CCW rotation) once in the frame locations.
If the front Isolastic housing is installed with the engine/gearbox and cradle already in the frame it will be near impossible from my experience if the both caps are in place which comes back to precise markings.

Its that or use the bench test to find the reduction which was one division (iirc) with the RGM Isolastics in my cases (four of)

L.A.B. said:

Yes, it will and that's why attempting to set the vernier clearance on the bench is a pointless exercise because there are no shims to change and why the bench setting instructions aren't in the Mk3 manual and setting the vernier with the Iso. mount in position is basically a '5-minute job', so remove all clearance, fit the front Iso., set the clearance with a feeler gauge and continue to check as you tighten the bolt/nut, if the clearance reduces so it clamps the feeler then loosen the bolt and increase the clearance, repeat until you have the required clearance with the bolt fully tightened.
Same procedure for the rear Iso.

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I see your point. I would re-check the clearance after installing on the bike, so not really saving any time doing it on the bench anyway.

NickZ said:

I see your point. I would re-check the clearance after installing on the bike, so not really saving any time doing it on the bench anyway.

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Yes, you'd just be doing the same job twice in my opinion.

NickZ said:

I see your point. I would re-check the clearance after installing on the bike, so not really saving any time doing it on the bench anyway.

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The torqued setting (crush or take up of the thread clearance) is not going to change from the bench to in the bike, it is mechanical principle not internet wish wash.
Would you check with a feeler gauge in the bike, of course but if you did your homework it will be the same and a two minute job if that (throw the rubber bellows away and even quicker)

Remember the bane of old people is to follow the crowd over thinking out of the box.
A fiddly job checked in the vice with no obstructions or in the bike with many.
That operation is probably a fraction of time within the total of a bikes reconstruction so why not make it easy. (as I found)

Time Warp said:

The torqued setting (crush or take up of the thread clearance) is not going to change from the bench to in the bike, it is mechanical principle not internet wish wash.

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Unless something moves between untorquing on bench and torquing after installing on bike. My vernier turns very easily when not tightened. Must have means to prevent that.

Time Warp said:

Remember the bane of old people is to follow the crowd over thinking out of the box.
A fiddly job checked in the vice with no obstructions or in the bike with many.
That operation is probably a fraction of time within the total of a bikes reconstruction so why not make it easy. (as I found)

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I have adjusted (and replaced) shimmed ISOs on the bike. Extremely difficult and time consuming job, especially if you haven't yet learned the tricks. That experience motivated me to do this job on the bench first, although maybe it does not provide the time savings that doing shimmed ISOs on the bench would.

NickZ said:

I have adjusted (and replaced) shimmed ISOs on the bike. Extremely difficult and time consuming job, especially if you haven't yet learned the tricks. That experience motivated me to do this job on the bench first, although maybe it does not provide the time savings that doing shimmed ISOs on the bench would.

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Precisely, as the vernier kit doesn't involve partially dismantling the assembly to replace shims so reduces the time it takes to do the adjustment and presumably why that method of Iso. adjustment was removed from the Mk3 manual.

Nothing particularly "fiddly" or "many" obstructions, when adjusted in position in my opinion and moving the gaiter out of the way to insert the feeler is no problem.