Why ground straps on a 73 rear deck lid?

[caproader]

I am sure that this is probably blindlingly obvious to everyone except me:

Why the ground straps (2!!) on the 73 rear deck lid? The rear license plate lights have their own dedicated ground wire in the wiring harness. The lights will work just fine when the lid is off of the car using a 12 volt battery. So what is there to ground that requires a braided ground strap from the hinge bolt up to the deck lid mounting bolts? And why is it that 2 are required? I realize that the 72/73 parts book calls for the two straps, but why? What happens if I leave the grounds straps off?

Thanks for the help

John, Member # 322
73 S with Sporto

[edmayo]

Now there ya go John, creating trouble, just accept the fact that Ferry wouldn't have put them on if they weren't needed Maybe its to ground the static electricity if you open your engine lid before pumping gas

[911pcars]

I am sure that this is probably blindlingly obvious to everyone except me:

Why the ground straps (2!!) on the 73 rear deck lid? The rear license plate lights have their own dedicated ground wire in the wiring harness. The lights will work just fine when the lid is off of the car using a 12 volt battery. So what is there to ground that requires a braided ground strap from the hinge bolt up to the deck lid mounting bolts? And why is it that 2 are required? I realize that the 72/73 parts book calls for the two straps, but why? What happens if I leave the grounds straps off?

Thanks for the help

John, Member # 322
73 S with Sporto

The factory offered an optional rear window wiper option back then. I don't know if that circuit had it's own ground wire, probably did, but redundancy is always good, yah?

If there's nothing electrical (requiring grounding) attached to the rear deck lid, the ground straps are superfluous.

Sherwood

[Tom F.]

I think that the ground straps were part of the radio prep package. You can find them in Table 0/9 of the spare parts catalog, part number 901.612.107.00.

[edmayo]

Hi Tom, since the straps were part of the radio package what do you suppose their function was? This may seem far fetched, but do you think they were trying to ground ignition wire static from a large metal surface, ie. engine lid? It seems that over the years, even back to 356's, they were always very concerned with static, or high frequency suppression, hence the number of capacitors they seemed to use on generators/alternators, and voltage regulators. Those all seemed to go away in the early eighties, maybe radios became less sensitive to that stuff ?

[caproader]

Ed,
I sat on the work bench in the garage trying to figure out why the factory needed an extra ground in addition to the ground already provided by the hardware in the hinge and deck lid hardware.

And all I could come up with was that the ground straps prevent intermittant reflectivity to the flux capacitor.

John

[davep]

The ground straps may be there to ensure the engine lid is part of the Faraday cage around the engine. The ignition is a major source of static, so the cage acts to contain the electrical fields. If you have a non-metallic lid, then there is no benefit.

[caproader]

So the Farady cage manages the inductive electric field farads produced by the ignition system.

I knew the flux capacitor figured in here somewhere!

Thanks to all who have provided the EE insight than an economics degree never provided. Looks like I'll keep the ground straps installed.

John

[davep]

Sort of; actually nothing to do with farads or capacitors.
A Faraday cage acts like an antenna to collect radio emissions and short them to ground. In this case it keeps the emissions from escaping, but in other cases it would keep them from entering. In this case it attenuates the emissions to a low level.

[72targa]

What's all this talk about the flux capacitor?