Thread: chassis/block/body grounds

Tweet

after i raised my 27,s body 2" and installed spacers i noticed my throttle cable was welding itself to the firewall
i mentioned it to my mechanical geius guru and 1st thing out of his mouth was.
ground the engine to the frame and do the same to the body.
he gave me 2 of those copper braided straps.
ran one from the block to the frame a 12 inch strap.
and one from the body to the frame a 6 inch strap.
i cant believe i forgot the fact that almost every electrical gremlin i have ever chased was a ground problem.
i just figured i'd post this in case somebody gets brain damaged and forgets the importance of a good ground.

Yep----these days most fiberglass Cobra and other KIT cars with rear mounted batteries are grounded with braided AN hose which they use for double duty of suppling fuel to engine----------

Originally Posted by jerry clayton

Yep----these days most fiberglass Cobra and other KIT cars with rear mounted batteries are grounded with braided AN hose which they use for double duty of suppling fuel to engine----------

Jerry, I bet there are more out there like that than we can imagine, and that's scary!

Originally Posted by billy zz

after i raised my 27,s body 2" and installed spacers i noticed my throttle cable was welding itself to the firewall
i mentioned it to my mechanical genius guru and 1st thing out of his mouth was.
ground the engine to the frame and do the same to the body.
he gave me 2 of those copper braided straps.
ran one from the block to the frame a 12 inch strap.
and one from the body to the frame a 6 inch strap.
i cant believe i forgot the fact that almost every electrical gremlin i have ever chased was a ground problem.
i just figured i'd post this in case somebody gets brain damaged and forgets the importance of a good ground.

Billy,
When I was chasing some problems with my battery size and location I mentioned using one of the copper braided straps for grounding the body reinforcing steel (glass body) to the chassis and was advised not to use them for a primary ground, but to use a regular, insulated battery cable instead. As I recall the comment was that the woven straps absorb moisture and with the electrical flow corrode and fail over time? Seems they were intended to connect body panels, like hood to firewall, but not intended for carrying the full grounding current? Not 100% on that reasoning, but I removed the one I had and replaced it with a short cable. Just mentioning it for consideration, and maybe one of the electrical guru's will comment and correct any mis-conceptions I've posed.

What Roger said is true. A short piece of battery cable or welding cable works best.

there's also a problem area using an aluminum radiator that is isolated with rubber mounts---an electrolis? takes place between coolant and iron/aluminum?anymetal and since there isn't a path to discharge it , erosion of the radiator happens------

This can be made even worse with electric fans (and/or temp controller sensor) that might get grounded to the radiator mount---------

My car is all steel - but I have a 2 awg cable from the battery to the engine and three of the woven cables from the engine to the body, one very wide and 2 fairly narrow. Then there are the usual wiring grounds......... As far as the woven cable being a poor choice - current flows along the outside of each strand and there being many in that woven cable, will do as good a job. Quite frankly, the only ones I've ever seen corroded are those older, pre electronic cars that used them for battery grounds - and the other being often just as bad - and you can't say positive as Ford used a positive ground until they went to 12 volts in '56.

I have always thought of the braided flat straps as "bonding conductors", rather than grounds, and have always used extra flexible cable, usually welding cable, and up-sized a couple of gauges over the stock size, to #2 or #1 at the least for current carrying conductors that connect the frame, engine, and battery.

I've used the flat braided cable lots of times, never had any problem or seen one fail.
I usually run the heavy ground cable from the battery to the motor, then branch from the motor to the frame and body.
Works for me!

To do a bulletproof job of it, replace the positive and negative battery cables at the same time. I've seen them corrode down inside the insulation where you can't see it and they look fine from the outside.

Originally Posted by techinspector1

To do a bulletproof job of it, replace the positive and negative battery cables at the same time. I've seen them corrode down inside the insulation where you can't see it and they look fine from the outside.

since my car has only been running a couple years all that stuff is in good shape.

Corrosion can happen in DAYS! Let alone years, techinspector1 gave you SOLID advice!

I disagree with that statement-----------you don't just throw parts at things----with proper basic trouble shooting of problems, it ain't necessary to do that---------

a power cable is very simple to check out and analize and with todays prices of copper and junkasschinaimports your better off with your old stuff if its still usable

A lot of very good information here on grounding, but we're getting away from Billy's original intent. When he lifted the body on the truck for header clearance he lost his solid ground connection between the cab and the frame due to the insulating spacers. This meant that everything electrical in the cab was "searching" for the best ground it could get, and that happened to be his throttle cable which was "welding" itself together. Billy's problem is solved, and he offered a Public Service Announcement to remind us all that a good ground is critical, and that when making changes our ground path can get compromised and not be apparent.

Thanks, Billy, for the reminder!!

Originally Posted by jerry clayton

there's also a problem area using an aluminum radiator that is isolated with rubber mounts---an electrolis? takes place between coolant and iron/aluminum?anymetal and since there isn't a path to discharge it , erosion of the radiator happens------

This can be made even worse with electric fans (and/or temp controller sensor) that might get grounded to the radiator mount---------

mine has rubber mounts.
now you have me concerned