What makes a good Earth Point
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  1. #1
    1000+ Posts Shobbz's Avatar
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    Default What makes a good Earth Point

    I am looking at the earth points on my car, especially the alternator one. In the mean time I might have a look at the other earth points around the car.

    So my question what is the most effective earth point, or what is the best way to attach an earth wire to a car?

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    Is there any merit in having the one earth point?? I guess if it dies everythig goes which could be good and bad.

    thanks

    shobbz
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  2. #2
    Fellow Frogger!
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    The job of the earth is to provide a return path for voltage back to the battery. In the good old days there used to be two wires to every electrical fixture a supply wire and a return (earth) wire. When all metal bodies came along, manufacturers decided they could save money by using the metal of the body instead of running wires all over the place.

    Therefore, the best place to put an earth wire is anywhere directly onto the body. Make sure there is bare metal between the wire and the body, i.e. no paint or grease, and secure the wire with a screw or bolt and nut. To do a tidy job you could use a crimp terminal with a push on tag or an eyelet.

    You must make sure the earth cable between the battery and body is in good condition and has clean joints at both ends. Sometimes these leads can corrode inside and give a poor connection. Also make sure there is a cable between the engine and body which is also in good condition.

  3. #3
    1000+ Posts dino's Avatar
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    What on Earth is the Point of this?





























    cheeers


    dino




    .......yes I know.............................STUPID....but what the hell.................

  4. #4
    1000+ Posts CHRI'S16's Avatar
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    Quote Originally Posted by Shobbz
    I am looking at the earth points on my car, especially the alternator one. In the mean time I might have a look at the other earth points around the car.

    So my question what is the most effective earth point, or what is the best way to attach an earth wire to a car?

    Is there any merit in having the one earth point?? I guess if it dies everythig goes which could be good and bad.

    thanks

    shobbz
    As some of the lads have written the earth is the return path (conventional current) of the cars electrical system.
    The alternator will ground itself on the engine block on 90% of cars.
    I would buy 1 meter of decent 4 gauge cable, cable lugs (connectors) and bolts with nylock nuts to suit (all from Jaycar/Dicksmith). From the negative of the Battery run about 1/2 a meter (the shorter the better, but allow some slack) to the cars chassis rails or a meaty part of metal. Remove any oil, paint, grease and sand paper clean the hole you will bolt one end of the cable. Once bolted rub a light coat of marine grease over it or even a bit of motor oil, then wipe clean. You are aming for direct metal to metal contact of aleast 8mm square.

    The next run is from the chassis of the car (you can use the same point as the one above) and onto the engine itself. Most modern EFi cars already have this but they use minimal and cheap cable. Again choose carefully the bolt you want undo (i use a inlet mainfold bolt) and make sure the surfaces are clean and bolt up the cable. MAKE SURE YOU LEAVE ENOUGH SLACK FOR ENGINE MOVEMENT!!!. Also from Jaycar you can get split corrugated conduit (flexible plastic hose) to go over the cables so it gives them a bit more protection. You can tidy up other areas with any left over bits and pieces. Use cable ties and black electrical tape to make it real pretty.

    I used to do this to stop alternator whine in hi-end car audio competition installs. Its also makes the electrical just that little more realiable. - Chris
    ... ptui!

  5. #5
    Gone Fishin' Ray Bell's Avatar
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    The XN engine block has a dedicated bolt on the block for the main earth lead from the battery... down low and to the right of the fuel pump. Usually the earth line from the engine to the chassis is from the rear of the gearbox.

  6. #6
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    Mate just another tid bit of advice...

    I've done some high end speaker work (house stuff) & the thing thats emphasised is "Mechanical" connection over electrical...

    i.e. dont just solder a wire into a connector, buy a good connector which you can clamp to the wire, & clamp like hell!!! then solder...

  7. #7
    WLB
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    Quote Originally Posted by Ray Bell
    The XN engine block has a dedicated bolt on the block for the main earth lead from the battery... down low and to the right of the fuel pump. Usually the earth line from the engine to the chassis is from the rear of the gearbox.
    And keep an eye on the condition of the gearbox earth lead, and its connections, on rear-drive Pugs. It's not unusual for a failure or poor connection to eventually cause rear wheel bearing failure as these end up carrying the current and get eroded. It was certainly the case with 504 and 505. Can't remember about 404 and 403. Should be the same, but I never had a problem and it was a long time ago.

    Ray could probably comment.

  8. #8
    Gone Fishin' Ray Bell's Avatar
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    Shouldn't be a problem with 203, 403 and 404...

    The choke cable takes the earth current if the strap breaks on them!

  9. #9
    Budding Architect ???? pugrambo's Avatar
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    Quote Originally Posted by Ray Bell
    Shouldn't be a problem with 203, 403 and 404...

    The choke cable takes the earth current if the strap breaks on them!

    ever seen them glow ??

    i'll stick to having an extra earth somewhere just in case
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