Ground your alternators ! Esp if they have a painted case
Thread Starter
Race Director
Joined: Sep 2001
Posts: 14,674
Likes: 751
From: NEwhere Ohio
Ground your alternators ! Esp if they have a painted case
1993 Corvette #2 never seemed like the battery fully charged. Engine would seem labored during starting. Key on, digital volts would always be 10.x something
the digital volt gage was erratic. 13.2v one second and 14.6v the next. Strangely the analog voltmeter gage stayed steady…
slight whine thru the radio.
ive had the stock alternator rear brace removed to fit tall valve covers…
not an issue on corvette #1 and its unpainted alternator which must get a solid
ground thru the engine/frame.
but adding a welding cable to the frame on the back of corvette 2’s alternator case (the 3/8-16 threaded hole) fixed all these problems.
the digital volt gage was erratic. 13.2v one second and 14.6v the next. Strangely the analog voltmeter gage stayed steady…
slight whine thru the radio.
ive had the stock alternator rear brace removed to fit tall valve covers…
not an issue on corvette #1 and its unpainted alternator which must get a solid
ground thru the engine/frame.
but adding a welding cable to the frame on the back of corvette 2’s alternator case (the 3/8-16 threaded hole) fixed all these problems.
Racer
Joined: Mar 2025
Posts: 492
Likes: 241
This is a good point. Recently on some other older vehicles where the voltage regulator was separate from the alternator, that the VR was not properly pulsing the field ground as it should. Long story short it turned out that the newer VR replacements were powder coated which made it more difficult to properly ground through their chassis mounting.
I suppose they are trying to reduce corrosion with these replacement parts but many of them are case grounded and it creates a problem.
Did you have the rear brace removed on both Vettes or just the one with the bad ground? Did your test light light up on the alternator housing before you ran the new wire?
I suppose they are trying to reduce corrosion with these replacement parts but many of them are case grounded and it creates a problem.
Did you have the rear brace removed on both Vettes or just the one with the bad ground? Did your test light light up on the alternator housing before you ran the new wire?
Burning Brakes
Joined: Aug 2008
Posts: 861
Likes: 220
From: Tampa, FL
1993 Corvette #2 never seemed like the battery fully charged. Engine would seem labored during starting. Key on, digital volts would always be 10.x something
the digital volt gage was erratic. 13.2v one second and 14.6v the next. Strangely the analog voltmeter gage stayed steady…
slight whine thru the radio.
ive had the stock alternator rear brace removed to fit tall valve covers…
not an issue on corvette #1 and its unpainted alternator which must get a solid
ground thru the engine/frame.
but adding a welding cable to the frame on the back of corvette 2’s alternator case (the 3/8-16 threaded hole) fixed all these problems.
the digital volt gage was erratic. 13.2v one second and 14.6v the next. Strangely the analog voltmeter gage stayed steady…
slight whine thru the radio.
ive had the stock alternator rear brace removed to fit tall valve covers…
not an issue on corvette #1 and its unpainted alternator which must get a solid
ground thru the engine/frame.
but adding a welding cable to the frame on the back of corvette 2’s alternator case (the 3/8-16 threaded hole) fixed all these problems.
Race Director
Joined: Oct 2012
Posts: 17,334
Likes: 6,509
From: Melbourne, FL
The alternator grounds through the threads, not the case. Your issue was because you removed the factory ground brace. Your fix was adding a replacement ground. None of this is surprising to me.
That said, I'm a big fan of doing the "big 3" wore upgrades. It's big in car audio circles and it's useful on most cars. OEMs spec the bare minimum wire size they can, adding an extra 8, 4, or 1/0 cable to the big 3 connections helps a lot IME.
That said, I'm a big fan of doing the "big 3" wore upgrades. It's big in car audio circles and it's useful on most cars. OEMs spec the bare minimum wire size they can, adding an extra 8, 4, or 1/0 cable to the big 3 connections helps a lot IME.
