MTFCA Forum

This past weekend I was tinkering with some battery problems on my 1983 Chevrolet C20 6.2 Detroit Diesel. I was experiencing some excessive corrosion on one of my batteries and while I was addressing that problem I observed that both batteries ground to the engine block.

It then occurred to me that every car I've ever had was negative ground to the block. Except my Model T, which is ground to the frame by a strap.

Automotive electrics have always been a bit of a mystery to me, but might there be some benefit to running a heavy gauge ground from the negative battery terminal to the engine?

The Model T engine mounts conduct electricity.

Major problem with ground straps from the T vendors are the battery end of the strap is not a good connection. They are generally always somewhat loose. They need to be re-worked before installing. Re-swedged in a press and/or soldered.

Sometimes the connection from the block to the chassis has corroded over the years. Originally it is grounded through the crankcase ears and through the driveshaft and springs and through the front engine mount. It sometimes helps to connect a ground strap to one of the crankcase bolts near the starter mount directly to the frame at the brake cross shaft connection. scrape the areas where the ends of the cable are fastened and clean completely from paint, grease or rust. That also includes the area where the strap from the battery is connected.
Norm

Adding a ground strap from the engine block to the frame on a Model T is not a bad idea. I would use an existing hole in the frame, even if it meant using a longer strap/cable. If the engine has a good electrical ground at the upper rear motor mount bolts, it is sufficient. However, wear, dirt, rust, paint, and vibration can cause high electrical resistance, even with the bolts tight. It's also possible that with a poor ground at the engine mounts, the starter current could ground through the U joint, bearings, U joint ball housing, spring shackles, etc, which could cause bearing damage. Adding a ground strap would insure against that possibility and assure full current reaching the starter. It would also help provide full current to the ignition when operating on battery. Starters work better and last longer with full available voltage under load.

AND if you had your frame (or whatever) powder coated then you need to ensure that there is proper continuity to everything. You can still use the frame by attaching grounding wires to it. But its not good enough to rely on a bolt making contact the edges of freshly drilled hole. Scrape the paint off, use a washer, make the connection and then seal it.

If the battery were located next to the engine, then yes, a ground to the block would be fine. However, the idea is to keep the cables as short as possible, so given the location of a T battery, ground to the frame is best.

We disassembled the entire frame, cleaned the pieces, welded metal back in to where rust once was, primed and painted it black, finally reassembling the frame. When I repaired the battery tray, I realized then that there would be a ground problem for the battery. I thought about doing some stainless steel welds all over and may still do that but for now am using the ground strap plus some other ground straps. I have wire to run a separate ground to the dash/instrument panel because right now the dash is off and will get painted too.

Any engine that has rubber engine mounts would be direct earth strapped, several times over many years have seen a failed earth and a melted choke cable or throttle linkage trying to compensate.

I saw a case where the choke wire glowed red hot when the starter was cranking. 1960 Chevrolet pickup 6 cylinder 4 speed. Yes, it was hard to start.

The usual ground strap for a T works as it should, IF................
* It is the correct size for a 6 volt set-up.
* The frame is stripped of paint and rust at the point of attachment.
* The cable terminal is shiny clean.
* The attaching bolt is clean and rust free.
* The bolt is really tightened down.
It also helps to use a star washer between the cable and frame
The same rules apply to the starter switch and the cables to the switch and to the starter.

If you must paint, do it after the above steps have been taken.
Hope this helps.
Allan from down under.

Agree with Allan and done this with a the short strap from Battery to Chassis as well as one from one of the Starter Motor
bolts to Chassis with both being the large gauge cable. Overkill !!
Alan in Western Australia

Years ago when I was spinning wrenches for a living, a Chevrolet was towed into our shop with a frozen gas pedal. We easily determined that it was the throttle cable that had frozen. We installed a new cable and for kicks and giggles we decided to look and see why the old cable had frozen. We found that the cable had welded itself to the casing. It turned out that the throttle cable was the only thing that was grounding the engine to the chassis, as neither of the two engine ground straps were connected; the heads were cleaner then the rest of the engine, we found that another shop had done a valve job on the engine and had forgotten to reconnect the ground straps. Conclusion? A throttle cable will not handle starter current.

I was lucky when I restored my '25. I found a NOS Ford ground strap. A model A used a similar one but since the post is larger, it won't clamp down on a Model T.

Modek Ts and Model As use the same battery, a series 1.

That would be right Darel but Larry's NOS model A earth strap would have bigger positive post clamp for + earth.