Instrument Gauge Insurance

[Kingman]

Disclaimer – I am not vouching for the veracity of the following information. I am simply sharing.

Background: I was speaking to a neighbor’s retired friend this past weekend whose main career was repairing failed electrical gauges (starting years ago with the Japanese gauges). I’ve been lucky to date and have not experienced this problem, but I did share that the FGT has had an inordinate amount of failures.

The very first thing he said was, “usually it’s because of a voltage spike or condensation, but usually a bad ground”. We chatted about the FGT’s setup and he suggested the following;

Use a Stainless Steel serrated lock washer like this - http://www.uboltit.com/lock-washers.html?_vsrefdom=ppcgoogle&ex=dfhyxt-eep549-ihjbfc&gclid=CKPLmMXe9r0CFe99Ogodm0gAYA

and some dielectric grease such as;

http://www.permatex.com/products-2/product-categories/specialized-maintenance-repair/electrical-system-maintenance/permatex-dielectric-tune-up-grease-detail
http://www.sanchem.com/aSpecialE.html
http://www.cool-amp.com/conducto_lube.html?gclid=CP74zprh9r0CFeMSOgodZRoAUA

………on the battery ground strap in front…………. AND………… the starter motor ground in back.

He also suggested putting one or more additional ground straps on different areas of the car as further preventative measures.

To me, this seems like pretty cheap insurance when considering the price of the gauges.

 

[bonehead]

Good info! Can't hurt, right?

 

[Howard]

I installed a redundant ground strap from the battery terminal to the chassis. There is an empty threaded hole near the OEM chassis ground connection.

Howard

 

[Kingman]

I installed a redundant ground strap from the battery terminal to the chassis. There is an empty threaded hole near the OEM chassis ground connection.

Howard

Do you remember the thread size?

 

[Howard]

I found some photos of the extra ground installation.......

 

[mmlcobra]

Thank you Howard!
Best,
Mark

 

[junior]

Anyone knows why there's an empty threaded hole near the OEM chassis ground connection ? Curious as well to know what bolt to use (size, thread pitch and length)-Thanks.

 

[Howard]

Junior, now that I've seen my own photos, that "empty" threaded hole may not have been empty. I simply co-opted it to connect the new ground.

Howard

 

[Xcentric]

and some dielectric grease such as;[/SIZE][/COLOR][/FONT]

http://www.permatex.com/products-2/product-categories/specialized-maintenance-repair/electrical-system-maintenance/permatex-dielectric-tune-up-grease-detail
http://www.sanchem.com/aSpecialE.html
http://www.cool-amp.com/conducto_lube.html?gclid=CP74zprh9r0CFeMSOgodZRoAUA

………on the battery ground strap in front…………. AND………… the starter motor ground in back.

Dielectric grease is an insulator. You don't want that to get between the ground strap and the frame. It will reduce conductivity.

 

[Indy GT]

Gary, I believe you would apply the dielectric grease on the bolted connections after torquing up the ground strap bolt. This acts as a sealant to external influences such as water.

I remember seeing this practice frequently used by Johnson/Evinrude/Mercury on their spark plug boots. The dielectric gel would be placed into the bottom of the boot before the plug wire boot was attached to the tip of the spark plug. Worked well and kept any moisture out of the connection area of the wire to the spark plug tip.

 

[cobra498]

I doubt any of these "fixes" will prevent gauge failures, the failure mode is within the basic design of the gauge, that is why they redesigned the gauge electronics. Having the air motor coils connected directly to the microprocessor with no apparent protection for the microprocessor drivers seems like a problem waiting to happen.

 

[Xcentric]

Gary, I believe you would apply the dielectric grease on the bolted connections after torquing up the ground strap bolt. This acts as a sealant to external influences such as water.

I remember seeing this practice frequently used by Johnson/Evinrude/Mercury on their spark plug boots. The dielectric gel would be placed into the bottom of the boot before the plug wire boot was attached to the tip of the spark plug. Worked well and kept any moisture out of the connection area of the wire to the spark plug tip.

Yes, agree Bill. The links the OP provided actually link to a dielectric (Permatex) and a couple of other greases that are supposed to be conductive. Don't want anybody coating the contact parts of the circuit with dielectric grease.

 

[maxemus]

I guess I've been lucky with my car. I have had the speedometer not read once or twice but it went away by itself.

 

[Kingman]

Yes, agree Bill. The links the OP provided actually link to a dielectric (Permatex) and a couple of other greases that are supposed to be conductive. Don't want anybody coating the contact parts of the circuit with dielectric grease.

I apologize if I wasn't thoroughly specific. The Permatex is the only dielectric grease, and as Indy GT states, acts as a sealant - and I too use it on my spark plugs.

I did my own additional research that I thought the Forum might find interesting and included the other two potential solutions because they PROMOTE conductivity (the premise of this note) and prevent rust and corrosion (an enemy to conductivity). I thought the two provided links were very specific regarding the function they perform.