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Thread: Starter motor cable

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  1. #1 Starter motor cable 
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    I have a Triumph-based Roadster with a 2.5Ltr engine fitted with a Lucas M418G starter motor. Its maximum lock torque 17lbs/ft at 450amps. Should I use 345, 415 or 485 amp battery cable?
    Many thanks in advance. Barry
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  2. #2 Re: Starter motor cable 
    frequent forum contributor Club Member b_caswell's Avatar
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    As the maximum draw would be around 450amps then the 485amp cable will leave a margin for overload.

    If you are fitting the terminals your self then make sure you get a good connection.
    Ben Caswell probably not the last word on anything here!!
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  3. #3 Re: Starter motor cable 
    frequent forum contributor Club Member stevejgreen's Avatar
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    My opinion.

    The starter motor cable, from battery to motor, should never be different in size, or smaller, than the cable from the battery to the chassis.

    The maximum current drawn will be limited by the batteries CCA rating, usually marked clearly on the battery itself and the cable size should be selected accordingly, taking into consideration that the duty cycle of a starter motor is measured in seconds, far from continuous.
    MOC member since 05/97
    1984 Marlin Roadster SWB.
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    The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.

    Loads of Marlin Reference can be found documents here or there.
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  4. #4 Re: Starter motor cable 
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    Hi Ben
    Thanks for that, it was as I expected.+it was wired up with a smaller cable from battery to chassis so both of you have put my mind at rest.
    Barry
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  5. #5 Re: Starter motor cable 
    frequent forum contributor Club Member b_caswell's Avatar
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    I would also run a heavy negative direct from the battery to the engine as well as the engine being
    earthed to the chassis.
    Ben Caswell probably not the last word on anything here!!
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  6. #6 Re: Starter motor cable 
    frequent forum contributor Club Member stevejgreen's Avatar
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    Quote Originally Posted by b_caswell View Post
    I would also run a heavy negative direct from the battery to the engine as well as the engine being
    earthed to the chassis.
    I would echo that, bad earth connections are generally a nightmare on Kit cars throwing up multiple strange faults.
    MOC member since 05/97
    1984 Marlin Roadster SWB.
    1800TC, Unleaded ported head, stage 2 cam. Ford Type 9 gearbox, Dolomite Sprint rear axle fitted with MGF disc brakes.
    Three core radiator, Renault Clio vented front discs.
    The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.

    Loads of Marlin Reference can be found documents here or there.
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