Big Three Upgrade

Stringer · Jan 26, 2022

Hey, I have searched but did not find this topic. I did this upgrade on my gmt800 and noticed a difference all around, bc i think the factory put bare minimal effort in grounding these trucks.

So i've got this 1/0 wire, 1/0 - 3/8 copper lugs, heatshrink, a 300 ANL fuse, wire cutter, and hammer crimper. I plan on cleaning up factory grounds too ... a little grinding/sanding, dieclectric, and spray with black tractor paint. Anyone have knowledge or tips for doing the big three upgrade in a gmt400 before i get started? Thanks!

kennythewelder · Jan 26, 2022

Yes, when I did my big 3, I added 2 more grounds. I used #2 welding lead. I am a welder after all, and that was easy for me to get. So, here is what I did.
1 added a wire from the alternator charging lug on the back of the alternator to the battery positive side. This wire is fused with a big 125 amp fuse, 8n a fuse holder, and I have 2 spair fuses in the glove box.
2 added a ground wire from the alternator case to the negitive post on the battery.
3 added a ground from the negative post to the engine block, next to the hormonic balancer, on the engine block, where the OE ground is.
4 added a ground from the battery to the frame of the truck by the upper control arm on the passengers side and
5 added a ground from the battery negative to the cab of the truck where the radiator overflow bottle is bolter to the fire wall.
All of this did help. The first thing I noticed, was how much faster my windshield wipers were. I did the upgrade because I did an electric fan swap. I wanted the alternator to charge quicker at low RPMs. All of my connections are copper lugs that are smashed to pinch the welding lead. For the battery, I welded 2- 3/8 blots, back to back, so I could screw this into the side post, and have a stud sticking out to add extra wires to the connections. I have seen these for sale on e-bay I think. My truck has been like this for a long time with no issues. I have since, replaced that overflow bottle, and moved that extra ground wire, to the other bolt on the fender side of the bottle.

Stringer · Jan 26, 2022

Great info and pictures, thanks a lot!! I plan on doing the same.

kennythewelder · Jan 26, 2022

If you have any questions, just hit me up.

Caman96 · Jan 26, 2022

kennythewelder said:
If you have any questions, just hit me up.

Kenny isn’t a member selling this kit on the forum?

Dnytro · Jan 26, 2022

The kit on here looks really well put together too. But if u have the time and the tools, you can easily do it yourself

PlayingWithTBI · Jan 26, 2022

Caman96 said:
isn’t a member selling this kit on the forum?

Yep, @5vortec7

Big 3 and Dual Battery Kits

All set up to make kits!! Red and Black 1/0 gauge cable hex crimped with 5 ton crimper and soldered, then marine grade shrink wrapped. Here’s my first Dual battery kit I made for my 98 5.7

www.gmt400.com

kennythewelder · Jan 26, 2022

Caman96 said:
Kenny isn’t a member selling this kit on the forum?

Yes, @5vortec7 sales them, and they are very well done. I'm sure he can make you some extra grounds if you ask. If he need any info on what I've done, he, or you can me.

Caman96 · Jan 26, 2022

Yeah I could easily do it. “Sometimes” in the end it’s cheaper and just easier to just buy. Probably not in this case BUT these type of things are always more involved and expensive than you first expect!

kennythewelder · Jan 26, 2022

It was easy for me. I have access to what I need to get something like this done. For the connectors, you can buy them on e-bay, although I did make mine.

Big Three Upgrade

Stringer

I'm Awesome

kennythewelder

Officially Retired, B31-3 (6-G) certified welder.

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Stringer

I'm Awesome

kennythewelder

Officially Retired, B31-3 (6-G) certified welder.

Caman96

OEM Baby!

Dnytro

OBS Enthusiast

PlayingWithTBI

2022 Truck of the Year

Big 3 and Dual Battery Kits

kennythewelder

Officially Retired, B31-3 (6-G) certified welder.

Caman96

OEM Baby!

kennythewelder

Officially Retired, B31-3 (6-G) certified welder.

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