I wanted to get rid of this string at the root so it would never show up in the first place. BTW... this tip will work for the unit string of any parameter in a model, not only G_L. So... as posted in the Autodesk ® Discussion Forums, here is what I did to get rid of it.
In Inventor go to Open From Content Center, then select the family you want to change. Select any member of that family, it doesn't matter which one. I tend to select a medium sized one just so it's easier to play with. Open it "As Custom" and give it a length that you can see to work with. (.001 is usually the default!)
|Open From Content Center|
|Open As Custom|
Once you have the new custom part opened, go to Parameters. Find G_L, then hover over the Equation value for it, right click and select Custom Property Format:
Hit OK, then Done in the parameter window. Save the part. Remember where you saved it, this is important. Now go back to the Content Center and find that family again. (Manage\Editor) Right click on the family in the Editor window and select Replace Family Template.
|Replace Family Template|
A file window will open, navigate to the file you just modified and select it by double clicking it. Inventor will chew on it for a minute or two depending on the size of the Family, but SHOULD come back with a "Successful" replacement. The changes you made to that part are now propagated to the entire family, and any steel used from that family will no longer show the unit string when G_L is shown anywhere.
This process needs to be repeated for any families that you want to make this change to.
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