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battery post connectors


Great Pumpkin
I've been checking how well my MG battery (only a few years old) charges.

Today by accident I discovered that both the battery post connectors are very loose. But it's a mystery to me how you tighten those connectors.

View attachment 49806

There's no screw or bolt, and the connector rotates easily around the battery post, and pulls off very easily.

How the heck do you tighten up these "old style" connectors?

Tom M.


Great Pumpkin - R.I.P
I believe there is supposed to be a screw that goes through the center hole and forces the connector down onto the battery post. The connector should be the right diameter to fit snugly onto the post before it bottoms on it. In your photo, it appears you have the wrong connector for that post (positive and negative are difference sizes, I forget offhand which is larger).

Here's a random image from the web

lucas helmet.jpg


Great Pumpkin
Thanks Randall. Obviously the MG TD is a positive ground car, and the battery is hooked up the way it was for several years before I got it.

Just wondering here, but what tells you it's the wrong connector on that battery post? Both of those caps do rotate, but there's no "wiggle". It's like they're the correct size, but just not tightened down.

Edit: Do those cap screws actually go down into the post? Wish I could find an image of the screws, and the connection with the cap off, to see if there's a hole drilled in the post.



Great Pumpkin
Update: I called Moss about their battery "helmet" screws, part 332 205. Mark said the screws are #8 3/4" sheet metal screws. No hole in the post needed, as they penetrate as screwed down.

Onward through the fog.
Tom M.


Great Pumpkin - R.I.P
Mating tapers on the post and inside the helmet. If it is loose enough to turn freely, then there should be some space between the top of the post and the bottom of the inside of the helmet, so the screw can pull it down farther and lock the tapers together. It's possible I am wrong, but in your photo it appears that the connector is already touching the top of the post.

Maybe it was the right connector, but has gotten worn from moving around? Again I am guessing, never been enough of a purist to mess with those Lucas helmets, but I think it should lock with only moderate force from your thumb on top of the connector. If not, there is something wrong. If all else fails, you could probably cut a piece of thin copper sheet (preferably coated with tin or lead solder) to make a shim.


Great Pumpkin
Thanks. I'll check those tapers next time I've got them off. The cables are likely original - at least the + one from battery to starter harness is woven in to the harness. They couldn't reach the posts if the battery were reversed, but I wonder if older batteries actually were made with pos and neg posts reversed so the post sizes were reversed also?

I also found that if I twist the helmets just a bit, they "lock" on to the post somehow, so I went ahead and added the helmet screws.

View attachment 49816

My learning curve is steepening.



Luke Skywalker
Country flag
As cool as they look, it's a poor design at best. We used to tap them down with a hammer and then tighten the screw. It worked for a few cycles, then was difficult to get them tight again. Cleaning them made it worse. Very limited success at shrinking them with grips but it might have added a cycle or two. Finally we would replace them with "universal" clamp on ends.
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