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> How common is the clutch cable becoming the ground?, My present clutch cable malady may be this issue....
second wind
post Nov 16 2023, 10:50 PM
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Hello all....I have been tackling a clutch cable problem and finally closing in on a solution....but my existing failed cable is so stubborn upon removal that it seems that the inner cable is welded to the outer housing....I have heard about the clutch cable becoming the ground for the car and I wonder how often this occurs and what are the symptoms?? I would like to prevent this from occurring while I am in clutch cable repair mode....thank you very much!!
gg
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yellowporky
post Nov 16 2023, 11:45 PM
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Make sure the trans to body ground is clean and good and if you switched from fuel injection to carbs make sure that you add a engine to body ground. There is a good place on the fan shroud to put a bolt on top
Electricity will take the path of least resistance
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Dave_Darling
post Nov 17 2023, 12:24 AM
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Yup, it usually doesn't provide a ground unless the regular chassis grounds are f***ed. Say, if someone doesn't remember to reconnect the transmission ground strap. Or there's significant corrosion in the strap or the grounding stud.

--DD
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Mikey914
post Nov 17 2023, 01:20 PM
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Common, it happened to me. Just make sure your ground strap is making good contact, and replace it if it looks crappy.

Easy simple solution that should be part of your spring ritual to check before the drive season.
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dr914@autoatlanta.com
post Nov 17 2023, 01:46 PM
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I was very good at replacing the clutch assembly in a 914 years ago. I had a 75 nepal orange car sold (this was 1979) and told the customer I would install a new clutch. Had the job done in less than an hour. The engine was slow to crank, so I put a battery charger booster on it, was still slow and then I noticed smoke coming from the cockpit! Forgot to attach the rear trans ground strap, the engine sought the accelerator cable as the ground and melted it in the center tunnel accelerator tube.

Well for the rest of the weekend I was busy cutting the tube out of the center tunnel and replacing it. Learned a very good lesson
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second wind
post Nov 17 2023, 04:06 PM
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Thank you all...it is all making sense to me....my clutch cable seems to be JB Welded in place....I am sure loving my borescope as it provides so much info instead of guessing...plus my hands are like catcher's mitts so getting in tight places is not so easy. I will inspect the ground cable when I install the clutch cable. Do all of the other brown wire grounds do enough grounding or is the tranny ground the big daddy? Thank you guys,
gg
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technicalninja
post Nov 17 2023, 04:16 PM
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I'm a huge believer in excess grounds.

I've never seen too many grounds do anything bad.

I once had a 79 Fiat X19 that went 80K without electrical issues.

I bet I added 20 different grounds to that vehicle...

Overkill, but it worked great!

Lots of cars have extra ground cables to the hood/engine cover.

As there is no electrical devices on these body panels, I've always wondered what the real reason is. I'm guessing stray voltage from electrical devices in the engine compartment but am not completely sure.

Extra, un-necessary grounds are a good thing in my book...
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Superhawk996
post Nov 17 2023, 04:29 PM
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QUOTE(technicalninja @ Nov 17 2023, 06:16 PM) *

Lots of cars have extra ground cables to the hood/engine cover.


As there is no electrical devices on these body panels, I've always wondered what the real reason is. I'm guessing stray voltage from electrical devices in the engine compartment but am not completely sure.


@technicalninja

Yup - needed to meet EMC / EMI regulations. Good educated guess!
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second wind
post Nov 19 2023, 11:23 AM
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Thank you all....so is there a way to test the ground strap to see if it is any good? What makes it deteriorate anyway? Why and how does this negative phenomenon occur anyhow? Thank you again...
gg
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Superhawk996
post Nov 19 2023, 11:46 AM
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QUOTE(second wind @ Nov 19 2023, 01:23 PM) *

Thank you all....so is there a way to test the ground strap to see if it is any good? What makes it deteriorate anyway? Why and how does this negative phenomenon occur anyhow? Thank you again...
gg

Test ground strap by measuring voltage drop across the strap while cranking the engine. Should be very near to 0 volts - like 0.1 - 0.2 volts.

This can be done with a remote start switch or the help of a friend. I prefer to use a remote start switch and to have the DMM visible so I don’t have to be under the car. Something about not trusting other people when I am under a car. (IMG:style_emoticons/default/huh.gif)

Trying to measure the resistance directly usually won’t work due to limited resistance sensitivity of cheap meters. I have a couple that will read 0.1 ohms measuring just the resistance of the meter leads when shorted together.

Here’s the quick math per ohms law
Voltage = current draw x resistance

We want resistance in the ground strap = 0 ohms, therefore even when drawing lots of starting current, the voltage drop across the ground strap is 0 volts.

Example:

Let’s say we actually have 0.02 ohms of resistance in the degraded ground strap. Doesn’t seem like much. (IMG:style_emoticons/default/confused24.gif) using a cheap DMM - you likely can’t even discern this from the resistance of the meter itself.

Most DMM’s cannot directly measure this low of a resistance accurately.

But by measuring voltage drop across it when cranking, we can measure small voltages accurately - even with an El’ Cheapo meter.

So let’s say the starter motor draws 50 amps (could easily be higher).

Now voltage drop across the ground strap is:
Voltage = 50 amps x 0.02 ohms = 1 volt (easily read by any cheap DMM)

This is a lot of voltage to drop across a ground strap and would not be a good thing. It would not be good for the dreaded hot start issue. Likewise, if the resistance in the ground strap gets high enough (missing strap or severely degraded) the starter will try to pull current though a lower resistance path if one is available - which can be the clutch cable or sometimes the accelerator pedal cable as the Doctor alluded to.
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mb911
post Nov 19 2023, 01:14 PM
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I think along with hood straps the metal that it attaches to need a to be clean. Stainless wire brush is a good way to ensure this. You can even use something like corrosion x as a way to preserve the connection
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worn
post Nov 19 2023, 06:06 PM
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QUOTE(dr914@autoatlanta.com @ Nov 17 2023, 11:46 AM) *

I was very good at replacing the clutch assembly in a 914 years ago. I had a 75 nepal orange car sold (this was 1979) and told the customer I would install a new clutch. Had the job done in less than an hour. The engine was slow to crank, so I put a battery charger booster on it, was still slow and then I noticed smoke coming from the cockpit! Forgot to attach the rear trans ground strap, the engine sought the accelerator cable as the ground and melted it in the center tunnel accelerator tube.

Well for the rest of the weekend I was busy cutting the tube out of the center tunnel and replacing it. Learned a very good lesson

But, did it start?
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second wind
post Nov 24 2023, 12:19 PM
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Hello fellow clutch cable grounders.....do you think the old tranny ground strap had anything to do with my clutch cable freezing up? I can't wait to put the new one on today !! Does anyone suggest using copper washers and/or nuts? Serrated washers? How about battery terminal spray on the studs? Thank you all and Happy Thanksgiving !
gg


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