While tightening the 13mm nut on the threaded post in the trunk that secures the battery's ground cable, I must have overtightened and the damn post sheared off -- half of it remains on the bare trunk, which isn't enough to keep the battery ground cable terminal from slipping off.

1. Can I connect the ground cable to another nearby post, or can it only be connected to that one post?
2. How would I repair the post? I don't even see how it can be removed since it's through the metal of the trunk, it must have to be accessed from under the car.
3. Am I that dumb to not know that these can shear off, or should that not happen?

Thank you!

 

You can connect it to another nearby metal post. I would try and stick with something similar in size to the post that broke. No need to repair the post that broke unless it left a hole where water could possibly get in.

 

Thank you. There is a nearby post but on it is a black plastic connector that secures the nearby wiring harness. There are three clips on the plastic connector so I am trying not to damage anything more -- it's another pain to remove!

 

I have a MY2017 coupe and will go out and check the trunk floor for possible ground studs and post photos.

 

Update: I moved the battery ground cable to an alternate post that was holding a retaining clip for the nearby wiring harness (the bare post pictured below).

2017 F-Type Coupe Luggage Compartment Battery Negative Ground Post

During my initial installation, the car did not complete the circuit. I reseated the cable and the car powered on the accessories, but upon starting, there was a ground fault and the car went dead. That led me to believe this new ground connection, fully tightened and as flat to the metal body as possible, would not work. I reattached to the factory post, and the car started as usual.

The difference between the factory post and the alternate post I tried is the washer-type nut that's connected to the bottom of the post, which creates a flat surface for the negative lead. There is another post just like this, except it's another inch or two beyond the cable's reach. See the post below with the metal surface surrounding it.


2017 F-Type Coupe Luggage Compartment Open Ground Post similar to factory ground post

So -- is it possible to get a longer ground cable and reattach to this post with the washer/nut? Or is it possible to get a new washer/nut, install it on the other bare post, and attach the cable as I had intended? Thanks for any and all help!

 

I would just clean and remove all paint from that stud? You can't get a good ground thru any coating?
Yes some star washers would also bite into the car body and would also be a good addition after cleaning the stud off.
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You could repair your original post with a threaded rod connector. See pic. Thread the connector onto the old post, then secure the battery with an appropriate bolt. FYI.

 

Hello,

So quick confession, I have done the same. A little disappointed that the post was quite so flimsy because I barely put any pressure onto it when tightening the nut back on.

Just wondering if you managed to fix the issue or what it was you did? I went with the connector nut as suggested lower in this tread but today I believe I had a grounding issue while driving and now I’m not sure I’ve fixed the issue as well as I thought.

 

Thank you to everyone here. @diablo2112 I did not know a threaded connector was a thing, will keep that in mind.




I did manage to make a new ground using the nearby post. My issue was that I didn't scrape the paint on the chassis to the bare metal, and since I did that and added a zinc flat washer to the bottom, boom -- perfect. At least I hope it is perfect. So far, after about a month it's been running and starting fine but the headlights did flicker once a couple days ago. The nut may need a quarter-turn to tighten, except I am nervous to even bring my socket wrench near the thing in case I break this stud!

 

A toothed washer AKA claw washer might provide a better, more long lasting connection?

 

I may need to try that. At Home Depot I could not find a tooth washer in the right size.

 

"Close" is good enough for toothed washers. It's the claws that make the connection.

 

You sure the washer you used is Zinc and not galvanized steel?
You are running electricity through that to aluminum, you may want to pull that apart and check for corrosion. It'll look like pitting and or a white powdery substance.
Not saying this is your problem, but I have seen it in marine applications.