Car Stereos: Grounding of car speakers, odd phenomena, unforseen consequences

Question
I've just installed rear speakers in a ceiling mounted speaker box in a kombi van (VW bus you you over there).  After running the cable months ago and having since lining the roof with lots of fibreglass batts and an expensive velour lining, I find that one of the earth wires is grounding on the body, probably as a result of the drilling to mount the speaker box.  This is all just to paint the picture of how difficult it would be to run a replacement cable.
My question is; can I (safely) ground the speakers directly to the car body & not though the cassette player/radio?  I know it works because I've tried it but I wonder if it has any unforseen consequences.

Regards

Answer
Hi Andrew

Grounding the speakers to the body does work.  The consequences aren't usually catastrophic however there are certain things to look out for.  

First off, you would be subjecting yourself to an unsecured ground, meaning your signal is more vulnerable to distortion, sounds and other odd phenomena that happen in the electrical systems of a car.  

Also, depending on your car stereo, the chip (amp) that pushes your speaker signal may overheat depending on how that particular brand wired the internal workings.  I wouldn't know which brands would have an issue, my expertise doesn't run that deeply.

If running another line is not an option, then it seems that you have no choice.  I'd say the worst problem you could have is a blown channel on your stereo.  As far as something dreadful happening, I seriously doubt it.  Most likely you'll get some interference once in a while and that would be the extent of it.

Good luck !

Dave