Ground straps, Make me angry Options

[914_teener]

All well and good, BUT, how is the connection between the aluminum shroud and the case and the case with the chassis?

The electrical connection from the fan shroud to the engine case, and the engine case to the transmission case should be excellent, much better than the chassis itself. That is how the alternator is grounded to the chassis in all 914's.

There was some talk of current through bearings and gears, but IMHO that is totally insignificant. The fan housing bridges the two engine case halves and the case bolts do the same. If you keep the battery and transmission ground straps in place, then I see no possibility of problems

I agree. The German engineers knew what they were doing. The strap width and design takes into account any anodic activity and is the reason it is designed as it is. After 50 years of salt, rain or snow, the reason it should be replaced every 50 years or so. Mag is the most reactive metal, but light and strong.

[930cabman]

All well and good, BUT, how is the connection between the aluminum shroud and the case and the case with the chassis?

The electrical connection from the fan shroud to the engine case, and the engine case to the transmission case should be excellent, much better than the chassis itself. That is how the alternator is grounded to the chassis in all 914's.

There was some talk of current through bearings and gears, but IMHO that is totally insignificant. The fan housing bridges the two engine case halves and the case bolts do the same. If you keep the battery and transmission ground straps in place, then I see no possibility of problems

I agree. The German engineers knew what they were doing. The strap width and design takes into account any anodic activity and is the reason it is designed as it is. After 50 years of salt, rain or snow, the reason it should be replaced every 50 years or so. Mag is the most reactive metal, but light and strong.

Key phrase is "Mag is the most reactive" mix that in with a bit of salt spray our Northeastern cars get and (IMG:style_emoticons/default/idea.gif)

[emerygt350]

It is interesting that on all of my other projects over the years very few ground strap issues have arisen. I have had grounding issues for particular sensors and such but nothing like a clutch or throttle turning into a ground strap. I wonder why it's such a common issue on the 914. Maybe the location exposes it to too much road crap and acidic oil blow off? Just saw the 50 years of salt post. Mine was 1 year old... Of course the case and body are not.

[Spoke]

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?

@emerygt350

Wow. There's a lot to unpack with your ground issue. Some questions:

When did this issue start? Did you change anything?

Added a new 6 gauge cable from the negative terminal

Is this wire from the battery NEG to engine case in addition to the normal battery NEG to chassis?

In this case, you've paralleled the new wire with the OEM current path. The OEM current path is battery NEG to chassis lug, then panel to panel to panel to the lug above the trans to the trans strap. If there's some issues panel to panel then you still have an issue with chassis ground as the entire chassis should be at ground. All electrical components use chassis as ground. If your chassis isn't a good ground, the issue is still there. The added cable helped the starter current loop but may mask the real issue.

Do you have the OEM voltmeter in the cabin? If so it would be interesting to see if it changed.

Even my gauges are working better.

This may indicate a better ground at the gauges now. Question is what is that path? From battery NEG to engine case. Then where? Either through the accelerator cable, or the engine case to trans case to trans lug. If you were to connect your new cable from battery NEG to trans case bolt I bet it would work just as well. There might be something going on with the lug behind the battery or that panel.

I remember an argument about additional ground straps

@VaccaRabite

One of those discussions was for Zach's alternator issues. Turns out powder coating the fan shroud inhibited the ground return for the alternator. A ground strap from alternator case to chassis solved the issue.

[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?

@emerygt350

Wow. There's a lot to unpack with your ground issue. Some questions:

When did this issue start? Did you change anything?

Added a new 6 gauge cable from the negative terminal

Is this wire from the battery NEG to engine case in addition to the normal battery NEG to chassis?

In this case, you've paralleled the new wire with the OEM current path. The OEM current path is battery NEG to chassis lug, then panel to panel to panel to the lug above the trans to the trans strap. If there's some issues panel to panel then you still have an issue with chassis ground as the entire chassis should be at ground. All electrical components use chassis as ground. If your chassis isn't a good ground, the issue is still there. The added cable helped the starter current loop but may mask the real issue.

Do you have the OEM voltmeter in the cabin? If so it would be interesting to see if it changed.

Even my gauges are working better.

This may indicate a better ground at the gauges now. Question is what is that path? From battery NEG to engine case. Then where? Either through the accelerator cable, or the engine case to trans case to trans lug. If you were to connect your new cable from battery NEG to trans case bolt I bet it would work just as well. There might be something going on with the lug behind the battery or that panel.

I remember an argument about additional ground straps

@VaccaRabite

One of those discussions was for Zach's alternator issues. Turns out powder coating the fan shroud inhibited the ground return for the alternator. A ground strap from alternator case to chassis solved the issue.

Interesting! Yes, I kept the post to body ground. Just added my new one to the existing. Ground strap is still there. I ran my multi all over the place from grounds to body, to battery etc and all was fine (except the POS to starter cable, that was good but variable so I replaced it). It really was only when heavy draw was happening. As soon as I get a free moment (college just started back up, so my time is precious for a couple weeks) I will pull that ground strap and get a good look at the contacts and the strap itself.

The issue was over night. One day everything was normal (but nothing like now, I didn't know my starter could spin an engine like that) and then it would hardly turn over. I was noticing some oddness though. Backfiring through the TB when having fun kicking it at 3k (she really loves 2.5 to 5k) I would randomly get light rattle can backfires through the TB. That became a major thing after I lost my ground got it started and took it for a drive. So it seems like I was losing all ground at that point. That was the day I figured it out.