[ChevyBelly]

I just replaced my worn out ground cable and was wondering where would be the best place to put the ground cable. I see most people ground their cars on the alternator bracket. Does the alternator require the ground? There is also a secondary ground wire that comes off the cable that was originally attached to the firewall. Can I attach the primary ground cable to the subframe? I used a wire wheel and cleaned off the frame surface to expose fresh metal and attached ground to a bolt. Now I think of it, the cable will be a pain to replace once my front clip is back on. Is accessibility the reason its out on the bracket or does it ground the alternator and chassis?


Gary

 

[69LT1Nova]

Grounds

You need 4 grounds:

1. Battery to engine - factory location goes to the alternator bracket, but it can go straight to the block.
2. Battery to chassis
3. Engine to chassis
4. Engine to subframe

Some people even put in a 5th ground: subframe to chassis.

 

[ChevyBelly]

I'm not sure if I'm covered but ill just return the cable to the alternator and keep the secondary ground on the fire wall. This should cover me right?

 

[Custom Jim]

To ground the alternator and starter, run the big negative cable from the battery negative post to either the alternator, it's bracket, or a large bolt on the engine. This cable now will ground the alternator and starter to the battery. Make this connection to a clean paint free surface and ideally add some star lock washers to make a good connection and it would be better with a nut and bolt connection and not a self tapping type of bolt or screw.
Since there is no good electrical ground connection between the engine and the body of the car you need to tie the body of the car to either the battery negative terminal or the engine to the body of the car. On some GM's there was a small cable off of the battery negative terminal to the fender and this served to tie the body of the car to the battery while other's I've seen may or may not have this but instead a cable from the firewall to the engine.
If you have things requiring a ground that are bolted to the frame, then you need a connection between the frame and the engine as well. Most of the cars with subframes without turn signals mounted in the bumper do not require this connection. The reason it was needed on cars with turn signals mounted in the bumpers was that the subframes are on rubber body mounts.

Jim

 

[69LT1Nova]

I'm not sure if I'm covered but ill just return the cable to the alternator and keep the secondary ground on the fire wall. This should cover me right?

No. :no:

You still need the ground from the battery to the fender (part of the battery cable). You can get away with not grounding the subframe, but I'd do it anyway for insurance. The frame mount bushings do a real good job acting as isolators - keeping the frame electrically isolated from everything else.

Just speaking from experience! Grounds can be a bee-hotch if they aren't working correctly.

 

[69LT1Nova]

To ground the alternator and starter, run the big negative cable from the battery negative post to either the alternator, it's bracket, or a large bolt on the engine. This cable now will ground the alternator and starter to the battery. Make this connection to a clean paint free surface and ideally add some star lock washers to make a good connection and it would be better with a nut and bolt connection and not a self tapping type of bolt or screw.
Since there is no good electrical ground connection between the engine and the body of the car you need to tie the body of the car to either the battery negative terminal or the engine to the body of the car. On some GM's there was a small cable off of the battery negative terminal to the fender and this served to tie the body of the car to the battery while other's I've seen may or may not have this but instead a cable from the firewall to the engine.
If you have things requiring a ground that are bolted to the frame, then you need a connection between the frame and the engine as well. Most of the cars with subframes without turn signals mounted in the bumper do not require this connection. The reason it was needed on cars with turn signals mounted in the bumpers was that the subframes are on rubber body mounts.

Jim

Yep, what I was trying to say, just not so many words.

 

[6NOVA4]

yes all those ground straps everybody takes off are there for a reason!

 

[ChevyBelly]

So it sounds like you can't have too many grounds. Ill start running the wires and ill make sure to clean the surface to bare metal. The chrome alternator and bracket is what started my questioning of my ground.

 

[Custom Jim]

Look at the backside of your alternator and there may be a threaded hole in the alternators case you can use. Some of the high output alternators I have installed want you to use this point to go directly to the battery negative terminal.
Chrome brackets will probably give a better electrical path to other things it's bolted to compared to a heavily painted part.
If your new alternator is a higher output than the original one you may have to upgrade the wire on the output of the alternator. GM is not going to over build the wiring harness and if they can get by with a 10 gauge wire hopefully that is what they used but if a person later adds a high output alternator and goes from let's say an original 60A output alternator to a 200A output alternator then the original wiring will not be enough.

Jim