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TR2/3/3A Grounding problem

Guys, you have to remember that the starter pulls something upwards of 100 amps--even more if the engine is cold and "stiff." It doesn't take much to prevent the starter from cranking, and the random connections of bolts to the body, scratching through the paint with lockwashers, may not be good enough. Even if you have a decent connection from the battery ground to the body, the so-called "spreading resistance" in the thin sheet metal may be significant when you're dealing with such high currents.

The best practice, in my opinion, is to ground the battery directly to the engine block and to run straps from the engine to the frame and body for the other electrics. In the TR4/4A, there are lots of points where a nut is welded to the body, and those are good places to make body grounds, as the thread contact area is large enough to provide a good electrical contact.
 
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