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Alternator Grounding #1425039 04/24/13 08:42 PM 04/24/13 08:42 PM
Joined: Jan 2003 Posts: 1,018 Here and now J jeebis44 OP super stock
jeebis44 OP super stock J Joined: Jan 2003 Posts: 1,018 Here and now	Question: I just got a rebuilt 114 amp alternator for my '83 Plymouth Gran Fury cop car, and the rebuilt unit does not have a ground post installed, only a hole marked GRD. The old alt does have the post and was grounded to the pass. cylinder head. How do i fix this? Can I just thread a screw into the hole and run it like that? Ground the casing to the cylinder head?? I've attached a pic of my old alt. - the new one just has a hole where I circled in yellow...

Re: Alternator Grounding [Re: jeebis44] #1425040 04/24/13 08:43 PM 04/24/13 08:43 PM
Joined: Jan 2003 Posts: 1,018 Here and now J jeebis44 OP super stock
jeebis44 OP super stock J Joined: Jan 2003 Posts: 1,018 Here and now	A pic of the front - 114 amp cop car alternator

Re: Alternator Grounding [Re: jeebis44] #1425041 04/24/13 09:05 PM 04/24/13 09:05 PM
Joined: Jun 2005 Posts: 5,100 Western Md. skicker "The Champ"
skicker "The Champ" Joined: Jun 2005 Posts: 5,100 Western Md.	I'd try using the bolt that holds the case together?? ...FAFO...

Re: Alternator Grounding [Re: skicker] #1425042 04/24/13 09:31 PM 04/24/13 09:31 PM
Joined: Jan 2003 Posts: 1,018 Here and now J jeebis44 OP super stock
jeebis44 OP super stock J Joined: Jan 2003 Posts: 1,018 Here and now	Do I just need to ground the casing? Or is there something inside that needs to be grounded?

Re: Alternator Grounding [Re: jeebis44] #1425043 04/24/13 09:39 PM 04/24/13 09:39 PM
Joined: Nov 2007 Posts: 21,819 Kirkland, Washington Pacnorthcuda Too Many Posts
Pacnorthcuda Too Many Posts Joined: Nov 2007 Posts: 21,819 Kirkland, Washington	Quote: Do I just need to ground the casing? Or is there something inside that needs to be grounded? [/quote I would be willing to bet its just a case ground. The way to check? SIMPLE! Just put a continuity or ohmmeter on the stud and case and check for continuity!

Re: Alternator Grounding [Re: jeebis44] #1425044 04/24/13 10:36 PM 04/24/13 10:36 PM
Joined: Jul 2007 Posts: 1,526 North Carolina cjskotni pro stock
cjskotni pro stock Joined: Jul 2007 Posts: 1,526 North Carolina	The stud is simply a stud screwed into the casing. Normally, the bolt that holds the alternator to the brackets would be sufficient to ground but running a jumper wire from that ground stud to a bolt on the engine block wouldn't hurt. Don't overthink it. It's just an additional point where you can ground from. That's it. Not a bad idea to use it to make sure your grounds are 110% but not absolutely needed.

Re: Alternator Grounding [Re: cjskotni] #1425045 04/24/13 11:18 PM 04/24/13 11:18 PM
Joined: Jan 2003 Posts: 1,018 Here and now J jeebis44 OP super stock
jeebis44 OP super stock J Joined: Jan 2003 Posts: 1,018 Here and now	Thanks for the replies. So then, I should be able to check for continuity between the case and the engine block and if it's there, I'm good?

Re: Alternator Grounding [Re: cjskotni] #1425046 04/24/13 11:26 PM 04/24/13 11:26 PM
Joined: Jan 2003 Posts: 18,407 UPPER MICHIGAN, MARQUETTE COUN... N NITROUSN I Live Here
NITROUSN I Live Here N Joined: Jan 2003 Posts: 18,407 UPPER MICHIGAN, MARQUETTE COUN...	Quote: The stud is simply a stud screwed into the casing. Normally, the bolt that holds the alternator to the brackets would be sufficient to ground but running a jumper wire from that ground stud to a bolt on the engine block wouldn't hurt. Don't overthink it. It's just an additional point where you can ground from. That's it. Not a bad idea to use it to make sure your grounds are 110% but not absolutely needed. That is wrong. That alternator needs a hd ground. It has rubber isolators for mounts thats why there was a wire when the car was built.

Re: Alternator Grounding [Re: jeebis44] #1425047 04/24/13 11:30 PM 04/24/13 11:30 PM
Joined: Nov 2007 Posts: 21,819 Kirkland, Washington Pacnorthcuda Too Many Posts
Pacnorthcuda Too Many Posts Joined: Nov 2007 Posts: 21,819 Kirkland, Washington	Quote: Thanks for the replies. So then, I should be able to check for continuity between the case and the engine block and if it's there, I'm good? Yes, correct. Just as long as there is a good reliable metal to metal connection.

Re: Alternator Grounding [Re: jeebis44] #1425048 04/24/13 11:30 PM 04/24/13 11:30 PM
Joined: Jan 2003 Posts: 18,407 UPPER MICHIGAN, MARQUETTE COUN... N NITROUSN I Live Here
NITROUSN I Live Here N Joined: Jan 2003 Posts: 18,407 UPPER MICHIGAN, MARQUETTE COUN...	Quote: Thanks for the replies. So then, I should be able to check for continuity between the case and the engine block and if it's there, I'm good? No.. You want to use a heavy guage wire from that stud to the engine. All the factory cars and trucks had a ground wire. You alternator is mounted with rubber isolators thats why there was a HD wire on the car. I would ask for another correct alternator.

Re: Alternator Grounding [Re: NITROUSN] #1425049 04/24/13 11:35 PM 04/24/13 11:35 PM
Joined: Nov 2007 Posts: 21,819 Kirkland, Washington Pacnorthcuda Too Many Posts
Pacnorthcuda Too Many Posts Joined: Nov 2007 Posts: 21,819 Kirkland, Washington	Quote: Quote: Thanks for the replies. So then, I should be able to check for continuity between the case and the engine block and if it's there, I'm good? No.. You want to use a heavy guage wire from that stud to the engine. All the factory cars and trucks had a ground wire. You alternator is mounted with rubber isolators thats why there was a HD wire on the car. I would ask for another correct alternator. "That stud" represents nothing more that an electrical connection to the case. As long as the the alternator is NOT isolated (electrically) he's fine. I did not read they the posts carefully, but I thought he is using this alt in a non stock application. I could be wrong.

Re: Alternator Grounding [Re: Pacnorthcuda] #1425050 04/24/13 11:39 PM 04/24/13 11:39 PM
Joined: Nov 2007 Posts: 21,819 Kirkland, Washington Pacnorthcuda Too Many Posts
Pacnorthcuda Too Many Posts Joined: Nov 2007 Posts: 21,819 Kirkland, Washington	Now I see. The alts mounting bosses are isolated. All that would be required would be to reliably defeat this isolation. That could be by using the ground stud as designed, or by defeating the isolation itself.

Re: Alternator Grounding [Re: Pacnorthcuda] #1425051 04/24/13 11:41 PM 04/24/13 11:41 PM
Joined: Jan 2003 Posts: 18,407 UPPER MICHIGAN, MARQUETTE COUN... N NITROUSN I Live Here
NITROUSN I Live Here N Joined: Jan 2003 Posts: 18,407 UPPER MICHIGAN, MARQUETTE COUN...	Quote: That stud" represents nothing more that an electrical connection to the case. As long as the the alternator is NOT isolated (electrically) he's fine. I did not read they the posts carefully, but I thought he is using this alt in a non stock application. I could be wrong. You are very wrong. His whole post is full of mis-information. That alternator is rubber isolated mounting. Look at the rubber mounts. The stud is there for a reason. That unit is very power full and needs a correct ground. Why do you think the factory used it and had about a 10 or 8 gauge wire on it??? Come on you guys smarten up.

Re: Alternator Grounding [Re: Pacnorthcuda] #1425052 04/24/13 11:44 PM 04/24/13 11:44 PM
Joined: Jan 2003 Posts: 18,407 UPPER MICHIGAN, MARQUETTE COUN... N NITROUSN I Live Here
NITROUSN I Live Here N Joined: Jan 2003 Posts: 18,407 UPPER MICHIGAN, MARQUETTE COUN...	Quote: Now I see. The alts mounting bosses are isolated. All that would be required would be to reliably defeat this isolation. That could be by using the ground stud as designed, or by defeating the isolation itself. You don't want to eliminate the mounts. They help make the alternator last longer, run cooler and from what I remember cut down on RFI as they were mainly used in police and taxi.

Re: Alternator Grounding [Re: NITROUSN] #1425053 04/24/13 11:53 PM 04/24/13 11:53 PM
Joined: Nov 2007 Posts: 21,819 Kirkland, Washington Pacnorthcuda Too Many Posts
Pacnorthcuda Too Many Posts Joined: Nov 2007 Posts: 21,819 Kirkland, Washington	Quote: Quote: Now I see. The alts mounting bosses are isolated. All that would be required would be to reliably defeat this isolation. That could be by using the ground stud as designed, or by defeating the isolation itself. You don't want to eliminate the mounts. They help make the alternator last longer, run cooler and from what I remember cut down on RFI as they were mainly used in police and taxi. So the millions of alternators that are solidly and electrically mounted are doomed? Not saying you're wrong, just saying you're being extreme. In The typical moparts fashion. Lighten up. If the OP doesn't want to do add any wiring, fine....if he doesn't care then do it!

Re: Alternator Grounding [Re: Pacnorthcuda] #1425054 04/25/13 12:03 AM 04/25/13 12:03 AM
Joined: Jan 2003 Posts: 18,407 UPPER MICHIGAN, MARQUETTE COUN... N NITROUSN I Live Here
NITROUSN I Live Here N Joined: Jan 2003 Posts: 18,407 UPPER MICHIGAN, MARQUETTE COUN...	Quote: So the millions of alternators that are solidly and electrically mounted are doomed? Not saying you're wrong, just saying you're being extreme. I. The typically moparts fashion. Lighten up. If the OP doesn't want to do add any wiring, fine....if he doesn't care then do it! No they are not doomed. The problem here is you gave incorrect advice on a designed system that you clearly know nothing about. You should admit the incorrect advice and take a back seat and learn something. He needs to correctly ground that alternator. If not what that unit gets full fielded it will look for a ground and burn up what ever it can trying to find it. The op even states it was grounded by that stud to the head by a wire. Do it right and he wont have issues.

Re: Alternator Grounding [Re: Pacnorthcuda] #1425055 04/25/13 12:03 AM 04/25/13 12:03 AM
Joined: Jan 2007 Posts: 7,664 IN A ahy master
ahy master A Joined: Jan 2007 Posts: 7,664 IN	I run the "big Chrysler" alternator also. As posted, the alternator mounts are rubber isolated - unlike the typical round back or square back. The big alternator needs a heavy ground from the case to to engine head or block to function correctly. Good sized block to chassis grounds are needed also. The OE ground on my donor vehicle looked like 6 gauge so that's what I used. Same size for the power wire (+).

Re: Alternator Grounding [Re: ahy] #1425056 04/25/13 12:05 AM 04/25/13 12:05 AM
Joined: Jan 2003 Posts: 18,407 UPPER MICHIGAN, MARQUETTE COUN... N NITROUSN I Live Here
NITROUSN I Live Here N Joined: Jan 2003 Posts: 18,407 UPPER MICHIGAN, MARQUETTE COUN...	Quote: I run the "big Chrysler" alternator also. As posted, the alternator mounts are rubber isolated - unlike the typical round back or square back. The big alternator needs a heavy ground from the case to to engine head or block to function correctly. Good sized block to chassis grounds are needed also. The OE ground on my donor vehicle looked like 6 gauge so that's what I used. Same size for the power wire (+). Finally someone else that can tell it like it should be.

Re: Alternator Grounding [Re: Pacnorthcuda] #1425057 04/25/13 12:06 AM 04/25/13 12:06 AM
Joined: Jan 2003 Posts: 1,018 Here and now J jeebis44 OP super stock
jeebis44 OP super stock J Joined: Jan 2003 Posts: 1,018 Here and now	OK - This is in a relatively stock car, used for daily driving. Rubber mounts are intact, and using a multimeter, found continuity between the alt. case and engine in several points without the ground wire hooked up. That said, I did upgrade the ground wire years ago to about an 8 gauge wire... would like to keep it that way, if for no other reason than vibration may cause issues down the line ( i drive the thing like a a maniac...). Main point of my original question was to find out exactly WHAT needs to be grounded here, and from all posts to now, it's the case. Simple fix IMHO. Tap and screw into the original ground hole in the case and hook up my HD ground wire going right into the pass. side cyl. head. Am I wrong?

Re: Alternator Grounding [Re: NITROUSN] #1425058 04/25/13 12:08 AM 04/25/13 12:08 AM
Joined: Nov 2007 Posts: 21,819 Kirkland, Washington Pacnorthcuda Too Many Posts
Pacnorthcuda Too Many Posts Joined: Nov 2007 Posts: 21,819 Kirkland, Washington	Quote: Quote: So the millions of alternators that are solidly and electrically mounted are doomed? Not saying you're wrong, just saying you're being extreme. I. The typically moparts fashion. Lighten up. If the OP doesn't want to do add any wiring, fine....if he doesn't care then do it! No they are not doomed. The problem here is you gave incorrect advice on a designed system that you clearly know nothing about. You should admit the incorrect advice and take a back seat and learn something. He needs to correctly ground that alternator. If not what that unit gets full fielded it will look for a ground and burn up what ever it can trying to find it. The op even states it was grounded by that stud to the head by a wire. Do it right and he wont have issues. Please show me where I advised that it does not need to be reliably grounded? Clearly the ground stud is to facilitate isolation. Again...lighten up. Stay grounded.

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