Dampener for Universal Phone Mount

Looking for a cheap GPS solution for a Polaris Slingshot, I ordered a mount but found it chattered too much for comfort. I always felt like the phone was going to eject itself, given the right bumps. $12 for the mount via Amazon and $15 for the shocks at a local hobby shop ($10 on eBay).

I'd loved to have done dedicated GPS, but it would either be a magnet for theft or I'd have to remove it every time the vehicle was parked. This design isn't finished, but seems to work well with all the cra