How common is the clutch cable becoming the ground?, My present clutch cable malady may be this issue.... |
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How common is the clutch cable becoming the ground?, My present clutch cable malady may be this issue.... |
second wind |
Nov 16 2023, 10:50 PM
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#1
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Senior Member Group: Members Posts: 862 Joined: 30-December 10 From: Los Angeles, California Member No.: 12,543 Region Association: Southern California |
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 |
yellowporky |
Nov 16 2023, 11:45 PM
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#2
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Member Group: Members Posts: 427 Joined: 18-October 09 From: Martinez, Ca. Member No.: 10,948 Region Association: Northern California |
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 |
Dave_Darling |
Nov 17 2023, 12:24 AM
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#3
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914 Idiot Group: Members Posts: 15,048 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California |
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 |
Mikey914 |
Nov 17 2023, 01:20 PM
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#4
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The rubber man Group: Members Posts: 12,716 Joined: 27-December 04 From: Hillsboro, OR Member No.: 3,348 Region Association: None |
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. |
dr914@autoatlanta.com |
Nov 17 2023, 01:46 PM
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#5
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914 Guru Group: Members Posts: 8,066 Joined: 3-January 07 From: atlanta georgia Member No.: 7,418 Region Association: None |
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 |
second wind |
Nov 17 2023, 04:06 PM
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#6
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Senior Member Group: Members Posts: 862 Joined: 30-December 10 From: Los Angeles, California Member No.: 12,543 Region Association: Southern California |
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 |
technicalninja |
Nov 17 2023, 04:16 PM
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#7
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Senior Member Group: Members Posts: 1,890 Joined: 31-January 23 From: Granbury Texas Member No.: 27,135 Region Association: Southwest Region |
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... |
Superhawk996 |
Nov 17 2023, 04:29 PM
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#8
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914 Guru Group: Members Posts: 6,469 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch |
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! |
second wind |
Nov 19 2023, 11:23 AM
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#9
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Senior Member Group: Members Posts: 862 Joined: 30-December 10 From: Los Angeles, California Member No.: 12,543 Region Association: Southern California |
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 |
Superhawk996 |
Nov 19 2023, 11:46 AM
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#10
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914 Guru Group: Members Posts: 6,469 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch |
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. |
mb911 |
Nov 19 2023, 01:14 PM
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#11
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914 Guru Group: Members Posts: 7,168 Joined: 2-January 09 From: Burlington wi Member No.: 9,892 Region Association: Upper MidWest |
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 |
Nov 19 2023, 06:06 PM
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#12
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can't remember Group: Members Posts: 3,304 Joined: 3-June 11 From: Madison, WI Member No.: 13,152 Region Association: Upper MidWest |
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? |
second wind |
Nov 24 2023, 12:19 PM
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#13
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Senior Member Group: Members Posts: 862 Joined: 30-December 10 From: Los Angeles, California Member No.: 12,543 Region Association: Southern California |
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 Attached image(s) |
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