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TR2/3/3A The engine ground strap?
- Thread starter karls59tr
- Start date
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Most definitely. If the ground strap isn't there, besides causing havoc to the starter circuit those electrons/protons are gonna find somewhere to go, and often it's a choke cable or such; that'll leave a mark! Be sure to get one on there!
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Yes, definitely. The starter pulls something like 125 amps; the actual value depends on a lot of things, like whether the engine is warm or cold; but at its least, it is a LOT of current. That's why the strap is a fairly heavy braided wire. (The braid is for flexibility, no electrical reason.)
CJD
Yoda
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The "circuit" to complete the start power flow is battery positive to firewall through the cable, body to the frame through the body mounting bolts, frame to the engine through the ground strap, and finally the engine to the starter. Without the ground strap you are sending a lot of amperage through something not intended to take it...like the fuel sender or wiper motor. I would not start it any more until the strap is installed.
Geo Hahn
Yoda
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While waiting you could try an experiment... clamp a jumper cable from the body to the engine block to simulate the missing cable.
Choke cable and speedo cable are other popular alternatives for a path to ground. The former will glow red and the latter may weaken the speedo hairspring with the heat.
Choke cable and speedo cable are other popular alternatives for a path to ground. The former will glow red and the latter may weaken the speedo hairspring with the heat.
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As above yes you need a robust connection engine to chassis typically bridging the engine mount.
I added a second longer cable from a rear engine gearbox bolt to the same battery earth point to the body. This way it’s engine chassis and engine body AND battery earth.
very easy.
I added a second longer cable from a rear engine gearbox bolt to the same battery earth point to the body. This way it’s engine chassis and engine body AND battery earth.
very easy.
Online
I think that makes a lot of sense. That battery-to-body ground connection is far from optimal. Carrying that high current through the thin body metal, then hoping it finds its way to the frame and ultimately the block, isn't the best practice.
When I restored my TR4A, I ran the battery negative cable directly to the engine block, then I have a 3/8" braided cable from the block to the frame. I wanted to run a similar cable from the frame to the body, but there was no good connection point on the body. Instead, I ran a #12 wire from the battery connection to the body at the battery's previous connection point. I think that covers all the bases.
When I restored my TR4A, I ran the battery negative cable directly to the engine block, then I have a 3/8" braided cable from the block to the frame. I wanted to run a similar cable from the frame to the body, but there was no good connection point on the body. Instead, I ran a #12 wire from the battery connection to the body at the battery's previous connection point. I think that covers all the bases.