Ground straps

projectheaven · December 31st, 2008, 11:33 PM

Why do you put a ground wire from the engine block to the chasis?

I seen a few people put as much as 2 or 3.

EKi · January 1st, 2009, 02:10 AM

I think it's supposed to cut down on radio interference, but I don't know why someone would put 2 or 3

Jamesbo · January 1st, 2009, 04:25 AM

I can tell you from personal experience many [years ago ] when my ground strap rusted into.The transmission cable welded itself in the Drive possission one rainy day.

joe_padavano · January 1st, 2009, 08:23 AM

You want all the metal parts of the car to be at the same voltage for the ground. Since a car is made up of parts that are bolted together, corrosion, paint, and other non-conductors can disrupt these ground paths, leading to bad grounds and electrical problems. The negative battery cable bolts directly to the engine, since the starter is the highest current draw. Some negative cables have a pigtail that bolts to the fender, some to not. Even if it's there, the pigtail may become corroded. A ground strap from the block to the body provides a redundant path to ensure a good electrical ground for the body. In addition, since the fenders bolt to the body shell, there may be paint of rust in the path from the pigtail to the body shell anyway. To be honest, you can't have too many ground straps. Gaskets, rubber motor mounts, paint, corrosion, can all disrupt the ground path.

Chumley · January 1st, 2009, 08:56 AM

I guess that's why my Chevy truck has 5 of them. More steel, more straps? Anyway, Joe , where are the straps located on a '72 Cutlass? Chumley

citcapp · January 1st, 2009, 10:13 AM

A lot of mystery electrical problems are caused by missing or rotted ground straps. I install a 9/16 bolt thru the fender adjacent to the battery and run the ground from the battery to the bolt and from the bolt to the starter. I then run a strap from the intake manifold to the body of the car. Completes the circuit. Never have any electrical mystery problems with this setup

Olds64 · January 1st, 2009, 10:15 AM

You can get ground strap material from the hardware store.

projectheaven · January 1st, 2009, 10:58 AM

All of that info helped alot.
I have the pigtail of my negative cable going to the body and one from the motor to the body.

December 31st, 2008, 11:33 PM	#1 (permalink)
projectheaven Registered User Join Date: Dec 2007 Location: San Francisco bay area Posts: 180	Ground straps Why do you put a ground wire from the engine block to the chasis? I seen a few people put as much as 2 or 3. __________________ ____________________ 96 Impala ss 96 Buick Rivera(supercharged) 00 Yamaha R1

January 1st, 2009, 04:25 AM	#3 (permalink)
Jamesbo Super Moderator Join Date: Jun 2008 Location: Atlanta, Georgia Posts: 2,862	I can tell you from personal experience many [years ago ] when my ground strap rusted into.The transmission cable welded itself in the Drive possission one rainy day. __________________ 69 H/O 69 442 convertible 69 Vista Cruiser 69 442 hardtop "Growing old is mandatory,Growing up is optional"

January 1st, 2009, 08:23 AM	#4 (permalink)
joe_padavano Super Moderator Join Date: Mar 2007 Location: Northern VA Posts: 4,402	You want all the metal parts of the car to be at the same voltage for the ground. Since a car is made up of parts that are bolted together, corrosion, paint, and other non-conductors can disrupt these ground paths, leading to bad grounds and electrical problems. The negative battery cable bolts directly to the engine, since the starter is the highest current draw. Some negative cables have a pigtail that bolts to the fender, some to not. Even if it's there, the pigtail may become corroded. A ground strap from the block to the body provides a redundant path to ensure a good electrical ground for the body. In addition, since the fenders bolt to the body shell, there may be paint of rust in the path from the pigtail to the body shell anyway. To be honest, you can't have too many ground straps. Gaskets, rubber motor mounts, paint, corrosion, can all disrupt the ground path. __________________ Joe Padavano 64 Jetstar 88 Conv 66 442 L-69 Conv 68 W-30 69 H/O 69 442 70 W-30 72 442 84 Custom Cruiser 86 Caprice wagon (w/307 Olds)

January 1st, 2009, 10:13 AM	#6 (permalink)
citcapp Super Moderator Join Date: Nov 2007 Location: Bothell, WA Posts: 3,455	A lot of mystery electrical problems are caused by missing or rotted ground straps. I install a 9/16 bolt thru the fender adjacent to the battery and run the ground from the battery to the bolt and from the bolt to the starter. I then run a strap from the intake manifold to the body of the car. Completes the circuit. Never have any electrical mystery problems with this setup __________________ Pat 1957 Super 88 with a 455 1948 2dr series 76 with a 455

January 1st, 2009, 10:15 AM	#7 (permalink)
Olds64 Landyacht Club President Join Date: Jul 2007 Location: Lawton, OK Posts: 4,286	You can get ground strap material from the hardware store. __________________ Ferris, my father loves this car more than life itself... Apparently, you don't understand! Ferris, he never drives it! He just rubs it with a diaper! Cameron Frye Ferris Bueller's Day Off 1986

January 1st, 2009, 02:10 AM	#2 (permalink)
EKi Registered User Join Date: Jan 2008 Location: Augusta, ME Posts: 28	I think it's supposed to cut down on radio interference, but I don't know why someone would put 2 or 3

January 1st, 2009, 08:56 AM	#5 (permalink)
Chumley Registered User Join Date: Dec 2005 Posts: 217	I guess that's why my Chevy truck has 5 of them. More steel, more straps? Anyway, Joe , where are the straps located on a '72 Cutlass? Chumley

January 1st, 2009, 10:58 AM	#8 (permalink)
projectheaven Registered User Join Date: Dec 2007 Location: San Francisco bay area Posts: 180	All of that info helped alot. I have the pigtail of my negative cable going to the body and one from the motor to the body. __________________ ____________________ 96 Impala ss 96 Buick Rivera(supercharged) 00 Yamaha R1

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