Ground straps, Make me angry Options

[emerygt350]

Brand new ground strap, installed clean and brushed on both transmission and body. Completely failed me. Wire brushed the neg to body. Checked the cables and replaced the post to starter cable (it was questionable ). Car still wouldn't turn over. Added a new 6 gauge cable from the negative terminal to the spot where the coil attaches to the tin work, turns over like a new car. Even my gauges are working better. Wth. Could it just be the transmission case itself?

I remember an argument about additional ground straps a couple years ago, but can't find it. Any reason not to just keep my aftermarket ground strap?

[930cabman]

50 years of corrosion

It doesn't take much, but glad you found the fix

[emerygt350]

Corrosion where? I put a brand new strap on when I rebuilt the engine last year. Cleaned everything when the engine was out... Maybe the 50 year old metal (what's left on my car) just can't take it?

[brant]

Corrosion on the unit body and between the panels
Not getting a good ground at your chassis mount likely

[Luke M]

LOL... Funny how it's three Upstate NY guys here at the top talking about this first.

It must be the winter salt in the air that gets to our cars.. (IMG:style_emoticons/default/blink.gif)

Ok, seriously now. When I redid my brothers wiring on his 6 conversion I ran a new ground wire anywhere that I could. I would say the best one was from the battery neg to the drivers side ground wire portion. You know the one next to the relay board. has a bunch of grounds to chassis. Then all new ground straps from chassis to trans, battery to chassis, and IIRC I ran a new ground to the front truck to help with the new fuse panel that I install there. His car never had an issue. Lights on gauges, and headlights are bright as can be. Try running a wire from the battery to the relay board side and see how that goes. I can go look and see what size I used if need be.

[anderssj]

Thanks for the post! I would be interested to find out what size wire you used.

[Superhawk996]

Corrosion where? I put a brand new strap on when I rebuilt the engine last year. Cleaned everything when the engine was out... Maybe the 50 year old metal (what's left on my car) just can't take it?

Measure where it’s at. I keep posting how to do this but no one takes it seriously.

Stop guessing

https://www.fenderbender.com/running-a-shop...ircuits-part-11

If you’re unclear on how to do this I’ll gladly help.

[emerygt350]

Corrosion where? I put a brand new strap on when I rebuilt the engine last year. Cleaned everything when the engine was out... Maybe the 50 year old metal (what's left on my car) just can't take it?

Measure where it’s at. I keep posting how to do this but no one takes it seriously.

Stop guessing

I was measuring and it all looks good till you hit the key. My eyes glaze over when superhawk starts writing about all the ways you measure load. I had my Porsche guy use his magic amp measuring device. Not like I was throwing parts at it, just pissed a brand new strap on perfectly clean points didn't work for more than a year. And it's parked all salt season, so seriously, in the air apparently.

Another interesting outcome: I updated to all LED lights and my fog lamps (not led) kept on working. After I fixed the ground today... No more fog lamps.

[emerygt350]

Thanks for the post! I would be interested to find out what size wire you used.

I used a 6 gauge lawn tractor battery cable.

It's the freedom that comes from the chalon lifestyle.

[Superhawk996]

I was measuring and it all looks good till you hit the key.

You cannot measure the resistance. Hundredths of an ohm matter.

Please read link. Have to measure voltage drop while cranking.

[930cabman]

I was measuring and it all looks good till you hit the key.

You cannot measure the resistance. Hundredths of an ohm matter.

Please read link. Have to measure voltage drop while cranking.

"while cranking" is the key phrase here. When everything is at rest or near rest, the current path works, add a real load and (IMG:style_emoticons/default/WTF.gif)

[emerygt350]

I know, I actually do read your posts, but I went for amps instead. Neat tool.

[Superhawk996]

So to answer your original question, I would not depend on grounding through the engine tin as a long term fix.

[r_towle]

Last time I dealt with this I ran a new cable from the ground post to the upper bolt on the starter…that made it stfu and work.

Rich

[914_teener]

Soooooooo.....coil mounted to the tin. That's a solid grounding point.

(IMG:style_emoticons/default/av-943.gif)

[porschetub]

Soooooooo.....coil mounted to the tin. That's a solid grounding point.

(IMG:style_emoticons/default/av-943.gif)

Thought that also but I'm too polite ...anyway better to use one of the air pump mounting bosses on the fan housing or similar 8mm on there, much better ,cheers.

[Superhawk996]

Last time I dealt with this I ran a new cable from the ground post to the upper bolt on the starter…that made it stfu and work.

Rich

(IMG:style_emoticons/default/agree.gif)

Although I’m not a fan of multiple ground straps, Rich’s suggested location is a good one.

There are engineering design principles that guide where grounds are placed.

The main ground strap needs to be close to the starter. The starter is by far the largest current load in the vehicle. A starter is capable of drawing hundreds of amps. This is why the OEM ground strap goes to the transmission casting rather than the engine case.

You don’t want that starter ground having to be pulled though a fan shroud, through the engine case (potentially through bearings), and finally through to the transmission housing that the starter is attached to.

Other important design principles:

1) Braided ground strap can handle more current than an equivalent gauge stranded ground cable.

2) Ground straps are to be kept as short as possible to minimize voltage drop.

Ideally the OEM ground strap would go from the chassis / trunk area near the starter to the bolt Rich mentions. Post too long already without going into speculation on why they didn’t put it there.

[emerygt350]

Interesting, so the same stock place on the body, but to the starter bolt rather than the transmission case? That would imply the case is the issue?

Yeah, the tin doesn't make me comfortable either but it was convenient and apparently a way way better ground than a new strap on the transmission.

I might run a beefy cable from the battery post to the upper starter bolt in the engine compartment.

Not so sure I buy welding bearings and such, do transmission gears weld together because the case is the original ground? Now, using my oil pressure line as a route to ground, I worry about (copper).

[VaccaRabite]

I have an additional ground strap that goes from an alternator case bolt through a stout cable to the driver side ground stud. It helps! I was getting voltage drop through the doghouse - just enough to keep the battery from fully charging. You could not measure the drop at all when the car was off. When running, you could measure a 1.5 volt drop. Added the ground and the issue went away.

When I changed engines I kept the added ground cable.

Zach

[Superhawk996]

Not so sure I buy welding bearings and such, do transmission gears weld together because the case is the original ground? Now, using my oil pressure line as a route to ground, I worry about (copper).

Not highly likely but it all depends where the ground strap is, where electrons flow to, and how much current is drawn.

(IMG:style_emoticons/default/sheeplove.gif) Around and find out.

https://www.waukbearing.com/en/resources/be...al-pitting.html