As folks know by now, I have a tendency to push the Blazer. 75mph....80...85. Yep, I may be guilty. Those darn aftermarket dumbo ears just can't stay put. And here's my next stab at fixing it.
So everybody knows there's a rubber insert and a metal clamp that cinches down on the stem/rubber to create the friction that holds them in place. Right? We also know the factory ones don't have the same problem.
Here's why. It's not the rubber insert that is the problem it's the clamp. The factory unit is painted with some kind of paint that has a noticeable coefficient of friction when compared to the bare metal of the aftermarket units. That's one friction surface solved. The other one is between the rubber insert and the mirror stem. I got that figured out too. Here we go:
I use this rubber stuff to wrap the stem with thin rubber. Wrap it tight and thin with not too much overlap.
I then put the rubber insert over the rubber wrap. Once you clamp things down, don't adjust the mirrors. This rubber does something over a period of a few minutes time where it really turns to rubber.
Then I insert it with a factory clamp. Perhaps you can paint the aftermarket clamp with some kind of self etching paint.
Don't forget the factory clamp screws because the aftermarket's are different.
Again, let it sit after clamping down on it. The rubber wrap material will bond with the rubber insert and really grip the stem. The factory painted clamp will provide the additional friction missing while still allowing some shear adjustment. Again this rubber tape is the lick:
http://www.allelectronics.com/item/s...er-tape/1.html