I needed a way to hear my cheap a$$ GPS under the helmet on my motorcycle and didn't wanna fork over 2x the price for a "motorcycle ready" GPS device so I made it myself.
This may be interesting to bikers a well!
You can also find it here:
GPS + bluetooth
Step 1: Open it...
Step 2: Radio shack bluetooth adapter
Buy a bluetooth adapter for non-bluetooth cell phones like this one from RadioShack ($30) that even comes with an adapter for nokia phones with a tiny receptacle 2.5mm headphone jack!
Step 3: Drill a hole...
Drill a hole in the bottom of the back really close to the back wall. You have about 12mm to the battery so be real careful.
Step 4: Connect...
You can do this by using a new two pin molex connector. Just attach two more wires to it.