Shimming Isolastics

In checking the clearance for the front iso's the workshop manual says take the measurement on the left side , with an ideal clearance of 0.010". However, this differs from the INOA Tech Digest notes which says the clearance on each side should be 0.010", with a combined total of 0.020". Which is correct?

I have removed the front ISO from the bike and am using Method 2 as per the workshop manual to adjust the shimming. With the shims removed and the unit mounted in the vice, this method suggests measuring the clearance at one side only. Howevrer, with the mounting tightened down to 25ft/lb I have clearance at both ends. It seems to me that I need to check the clearance at both ends and shim accordingly. If so do I look to obtain 0.010" on both sides?

Bazz

1970 Bonneville
1973 750 Commando
1993 Harley Dyna Wide Glide

Bazz said:

In checking the clearance for the front iso's the workshop manual says take the measurement on the left side , with an ideal clearance of 0.010".

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Before attempting to check the clearance, as the factory manual states, it is necessary to: "Push or lever the engine to the right until all slack is taken up" and to hold it there whilst checking.

Bazz said:

However, this differs from the INOA Tech Digest notes which says the clearance on each side should be 0.010", with a combined total of 0.020". Which is correct?

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That's not how I would interpret it?

The INOA Tech Digest says this:

4-5. 3.
"If the combined side play, as measured from both sides, is either greater or less than .010", shims of the proper thickness should either be added or removed from the unit"

Which to me, means that when both side play clearances are combined together the total play should ideally, be 0.010", not 0.020".

Personally, I try to get as little clearance as possible so that the thrust plate containing the shim is still free to rotate by hand. So therefore, anything up to .010" total. You will not get any more vibration by reducing the clearance, as long as it is free to move.


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Roadworks will start here 5th November for as long as possible.

Thanks for the clarification. The 0.010" play is what I always thought was the case.. The information that I quoted must be old data. It was in a copy of the tech digest that I have . The note suggests it was from "Norton Service Bulletin" and stated " When the mounting bolts are torqued to 25 ft.lbs., the clearance on each side should be 0.010" with a combined total of .0210".

Bazz