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Chris_B

Chassis Ground Fail

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As I said in a different post, all of my electrical problems appear to have been caused by a poor chassis ground. As it seems obvious now look at the cable I was relying on for the chassis ground, I need a different approach. I believe that hole and screw clip were used to anchor one side of the battery tray before I removed it. One approach would be to remove the paint around that hole and put a bolt through it with a star washer. But, is that flat cable big enough to provide an adequate chassis ground? Any suggestions appreciated.

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I couldn't figure out how to include a pic in a "start a new topic" post. What is up with that? Here is a pic of my poor chassis ground installation. IMG_1228.thumb.jpg.1d0ef91012a3d896aca3b5373a00c22e.jpg

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Hi,

 

The cable looks sufficiently up to the task.  Is the bolt on a welded bracket?  If so, that's probably the issue as welds age and mild corrosion can set it.  That does not allow enough current to flow.  I attached mine to the steering box mount to the chassis.

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It is a clip. I am sure when I pull it apart I will find rust/corrosion between the clip and the (painted surface of) the chassis.

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Ah, a Tinnerman clip.  That's a problem for sure :)

 

Even if there isn't much corrosion, the puny threads of a self-tapper won't cut it, so to speak.

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10 hours ago, Healey3000 said:

I attached mine to the steering box mount to the chassis.

2 electrical interfaces involved.  1. Steering box is mounted to the subframe.  2. Chasis sits on the subframe.

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What happened to the original chassis ground bolt?  At least on roundies, the ground bolt is on the inner fender well, as the battery box is bolted to the car's body--not a good ground path, as has been pointed out.  You should be able to find a bolt that threads into something that's directly attached to the body shell that's within range of your ground strap.

 

mike

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1 hour ago, mike said:

At least on roundies, the ground bolt is on the inner fender well, as the battery box is bolted to the car's body--not a good ground path, as has been pointed out. 

 

I'm drawing a blank.  Where is the chassis ground on my roundie tii?  Our battery boxes are welded in.

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on my '76 SqUaRiE it shares a ground point on the fender with a bunch of other brown wires.  Guessing yours would be the same.

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I think mine is grounded by that body clip also. Thought it looked a little janky. Also just purchased a new AGM battery from Interstate Battery store and found out they will make you a custom battery cable at the store. 

 

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52 minutes ago, '76mintgrün'02 said:

a ground point on the fender with a bunch of other brown wires. 

 

Oh!  I'm all too familiar with that sheetmetal screw into the fender under the regulator.  That's the replacement for a ground strap?  Seems puny by comparison.

 

I actually changed that screw to a through-bolt with plenty of metal-to-metal contact.

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32 minutes ago, PaulTWinterton said:

Oh!  I'm all too familiar with that sheetmetal screw into the fender under the regulator.

 

No!  It sounds like the later cars do use a different location for the ground strap to fender. 

 

It is part of the bracket for the relays.  Here is a photo of mine.

 

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7 hours ago, jimk said:

2 electrical interfaces involved.  1. Steering box is mounted to the subframe.  2. Chasis sits on the subframe.

Good point!  I hadn't thought about the subframe.  So far so good, perhaps because of the beefy bolts.  If it acts up, I'll have to find another spot,

 

Thanks for that.

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8 hours ago, PaulTWinterton said:

 

I'm drawing a blank.  Where is the chassis ground on my roundie tii?  Our battery boxes are welded in.

 

Weld in battery tray has a hole with one of the large self tappers (similar to the radiator bolts) through one of its rear edges. Certainly that’s how mine is arranged. 

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