I'm trying to find the cause of the low charging rate on my 6 conversion. It's about 13.2V at speed which is enough to keep the battery alive but less than optimal. So I'm going through all the ground paths and found that the transmission to body strap was connected to the rear tramission mount via painted metal rather than the nice clean stud on the trunk floor. Then I disocvered the likely reason way - it appears to be an M7 thread. How bizarre. Will have to order some M7 nuts and lock washers.Click to view attachment

Sounds like that bolt is rusted down to M7. It is supposed to be M8x1.25

Mine has broken off completely. So I have a ground strap from the transmission case to the motor mount bolt on the chassis. I have a second ground strap from the right front head to the stud where the battery ground is located.


Hope that helps.

Clay

I once owned a 1979 Fiat X19.

This year/model is one of the most electrically challenged cars ever built.

During the engine/transmission rebuild (needed both!) I added extra grounds.

I went "Godzilla" on the grounds.

Probably put in 20 extra grounds for different things.

Under my ownership the car went 90k without a single down day or a single electrical problem...

My wife Paula was primary driver and we got rid of the car when she became pregnant with our first child. She's been "mini-van" since.

Having extra grounds is NEVER a bad idea!

It made a hideously un-reliable car reliable...

Edit: Those braided ground straps look bad-assed but can have serious corrosion after 10 years of use.
I prefer the "look" but they can be a source of trouble and not appear to be bad at all.

Often, for testing purposes, I'll add an extra ground temporarily with a set of jumper cables between the block and the neg post of battery to see if another ground solves my issues. Kia/Hyundias have a piss poor block to chassis ground and no block to battery ground. I get one of these with starter/charging system issues I ALWAYS add a 24" simple ground cable between an open bolt hole on tranny case and the negative terminal of battery. Fixes the problem 90% of the time...

Braided ground straps are used for the following reason:

Can handle more current with less voltage drop than typical large diameter stranded battery cable wire. Better heat dissipation when used in high current applications (I.e. stater current).

They are way more flexible, allowing for movement and vibration of the engine and trans without stress fatigue.

Agree with comment above that they can look good but be corroded and cause problems. Best to measure voltage drop across it while cranking or just replace with new as a preventative measure if there are questions about its integrity.