OK, I'm resurrecting this thread as I have finally set up my solution for car mounting.
To recap, I had a Droid RAZR with the Motorola dock that used the same 17mm ball that almost everything else uses. Griffin decided 14.7mm was the way to go. So, after a lot of searching, I found that the RAM Mount ball size A is the closest ball to what I need. It is 14.22mm (.56"), which is slightly smaller than needed. Also, I could not find this on an AMPs plate. As you can see from the first picture I have two AMPs mounts in my car. The top shows the hole pattern, and the bottom has a 17mm ball mounted to it. I temporarily used the adhesive disk on the top mount while I waited on the ball.
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Here is a close up of the diamond mount on the AMPs mount. Two of the holes lined up. So, I'm happy.
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Here is the Griffin mount installed on the ball. As a temporary solution, I put some plastic from a store bag in the cup on the mount to fill in the space created by the smaller ball. I read on the site I bought the ball from that someone used liquid plastic to make the ball larger. If the temporary solution doesn't hold, I'll do the same. I usually use my phone vertically as shown here. As you can see, I've chosen indrive as my car dock app. It is the default and it launches as soon as I put the phone in the dock. The home button solution in posts above did not work. Home still take me back to the launcher. So, I've gotten used to hitting back instead of home.
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Here it is horizontally, allowing access to the bottom mount.
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And here is the full solution with the GPS mounted as well.
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This solution does not interfere with the passenger much even though it looks like it does. I haven't done any cable management yet either. It also gives the passenger access to control my devices while I drive, which is nice on long trips when I want them to check something for me. The smaller ball is not as tight as the original, but it holds the dock securely enough. After going through this, I'll NEVER get another dock that does not use a 17mm ball.
Here is the link to the ball. RAM Mount Diamond Plate with A-Ball RAM-A-238U
I held off on ordering it for a while longer than planned because I really wanted a better solution, and I could not get a response form GPS City when I tried to ask questions. I got tired and ordered it anyway. I could not find anything else that was close enough to work.
In case you are wondering the mounts are Panavise vehicle specific mounts. Just Google "Panavise vehicle specific mount *Your car model here*" and you'll likely find it. It is designed to be used as a single mount. It uses the screws that hold your radio to secure it. I bought two and shifted one up and one down. So, they are less secure than intended, but considering this is the third cell phone I've mounted, It isn't a problem. The bottom one is a bit off because it was where my other two cells were mounted, and has had the most use. I decided to try out mounting this one on top to see if I like it better. I might move it down later. One last thing, if you want to do this, get METAL balls. I originally bought plastic balls, and the stems on both broke. I replaced them with metal, and have had no issues since.
Hey Chiplg, I've been waiting to hear your solution. I appreciate the info, but unable to see your attachments. I get a "if you used a valid link, please contact the administrator" error when trying to view. Not sure if it is something on my end. Maybe someone else can chime in on whether they can see your pics. Thanks for the info!