1970 Negative Battery Cable Bolt

[Mathew S.]

I went to put a battery in my car for the first time since I have owned it. Currently the bolt in the cable is a 5/16-18 thread while the positive cable has normal 3/18-16 thread size, and same head size. I recall years ago there was some discussion about battery bolt size, but not sure. This is on a serial number in 15,8xx range. I also have an adapter and not sure if that is normal as well. Attached are pictures of both.

I didn't see this in the new judging manual, but may have missed it.

[Gary B.]

Re: 1970 Negative Battery Cable Bolt

Page 35, under batteries addresses this. Probably not to the detail you have, but it does mention different size threads and change of hex sizes. One of the 70's I used as a reference, is 14,544. It is similar to yours, but both had 3/8" threads, different hex size.
If you send me some of the pictures, or all the pictures, I'll make sure the next revision shows this in much more detail.
We, I, keep learning more, and we should document it.
Gary Bosselman
gbozz08@gmail.com

[Joe L.]

Re: 1970 Negative Battery Cable Bolt

I went to put a battery in my car for the first time since I have owned it. Currently the bolt in the cable is a 5/16-18 thread while the positive cable has normal 3/18-16 thread size, and same head size. I recall years ago there was some discussion about battery bolt size, but not sure. This is on a serial number in 15,8xx range. I also have an adapter and not sure if that is normal as well. Attached are pictures of both.

I didn't see this in the new judging manual, but may have missed it.

Mathew------

1969's with side terminal batteries used 2 different thread sizes for the side terminal battery. The positive terminal was 3/8-16 and the negative terminal was 5/16-18. Vaguely, I seem to recall that the hex size was also different. I was not aware that 1970 was the same in this regard but it looks like it was.

When I replaced the original battery in my 1969, I found that no batteries were then available with the different thread size lugs. So, I had to remove the negative battery bolt and install a replacement with 3/8-16 thread.

[Terry M.]

Re: 1970 Negative Battery Cable Bolt

Mathew------

1969's with side terminal batteries used 2 different thread sizes for the side terminal battery. The positive terminal was 3/8-16 and the negative terminal was 5/16-18. Vaguely, I seem to recall that the hex size was also different. I was not aware that 1970 was the same in this regard but it looks like it was.

When I replaced the original battery in my 1969, I found that no batteries were then available with the different thread size lugs. So, I had to remove the negative battery bolt and install a replacement with 3/8-16 thread.

Joe,

The hex size for both positive and negative was the same, in spite of the thread size being different. I would have to go to the garage to find the hex size for the earlier bolts with certainty, but 7/16 comes to mind.

The later bolts with both terminals the same size (3/8-16) used 5/16 hex heads.

The smaller hex size that we are now so familiar with was so that a shorter wrench would be used in order to lessen the chance of over torquing the battery connection bolts in the field.

Until recently I wasn't aware that the different thread sizes went through most of 1970 production, but my end of January built 1970 had the two different size threads. I went through the same process you did when it came time to replace the battery for the first time. I have one of those batteries with the different threads (R-79S) in my collection (as you know, not for sale). It is dry charge, so it could be put in service at any time; but I won't. I know pictures of it are in line for a future revision of the 1970 TIM&JG.

[Terry M.]

Re: 1970 Negative Battery Cable Bolt

I went to put a battery in my car for the first time since I have owned it. Currently the bolt in the cable is a 5/16-18 thread while the positive cable has normal 3/18-16 thread size, and same head size. I recall years ago there was some discussion about battery bolt size, but not sure. This is on a serial number in 15,8xx range. I also have an adapter and not sure if that is normal as well. Attached are pictures of both.

I didn't see this in the new judging manual, but may have missed it.

Matt

What are the last two pictures? I take it the last one is one of the battery terminal bolts in an end view, but that is a bit of a guess on my part. Photo #4 is a mystery to me. Please explain a little more about those two pictures.

[Joe L.]

Re: 1970 Negative Battery Cable Bolt

Joe,

The hex size for both positive and negative was the same, in spite of the thread size being different. I would have to go to the garage to find the hex size for the earlier bolts with certainty, but 7/16 comes to mind.

The later bolts with both terminals the same size (3/8-16) used 5/16 hex heads.

The smaller hex size that we are now so familiar with was so that a shorter wrench would be used in order to lessen the chance of over torquing the battery connection bolts in the field.

Until recently I wasn't aware that the different thread sizes went through most of 1970 production, but my end of January built 1970 had the two different size threads. I went through the same process you did when it came time to replace the battery for the first time. I have one of those batteries with the different threads (R-79S) in my collection (as you know, not for sale). It is dry charge, so it could be put in service at any time; but I won't. I know pictures of it are in line for a future revision of the 1970 TIM&JG.

Terry------


Yes, I just checked. The positive terminal bolt and negative terminal bolt were both 7/16" hex. So, the difference in hex size was between 69-70 (and, maybe 71, 72) and later which used 5/16" for both hex heads.

[Terry M.]

Re: 1970 Negative Battery Cable Bolt

Terry------


Yes, I just checked. The positive terminal bolt and negative terminal bolt were both 7/16" hex. So, the difference in hex size was between 69-70 (and, maybe 71, 72) and later which used 5/16" for both hex heads.

Thanks for the confirmation. I am gratified that at least some parts of my memory still function. Thanks again for the effort.

[Joe L.]

Re: 1970 Negative Battery Cable Bolt

Matt

What are the last two pictures? I take it the last one is one of the battery terminal bolts in an end view, but that is a bit of a guess on my part. Photo #4 is a mystery to me. Please explain a little more about those two pictures.

Terry------


I think it's an adapter which converts the 5/16-18 negative terminal bolt to 3/8-16 size to work with batteries having 3/8-16 lugs at both positive and negative. I don't have any information that this was ever a GM item but it's possible it was.

[Terry M.]

Re: 1970 Negative Battery Cable Bolt

Terry------


I think it's an adapter which converts the 5/16-18 negative terminal bolt to 3/8-16 size to work with batteries having 3/8-16 lugs at both positive and negative. I don't have any information that this was ever a GM item but it's possible it was.

I have several GM kits to replace battery cable ends that came with bolts of 5/16 & 3/8 thread with the 7/16 hex as well as cable ends that can be installed in the field. But that adapter is a new one on me. I would like to see more if it. I can't quite get an image of how it works.

[Mathew S.]

Re: 1970 Negative Battery Cable Bolt

The last two pictures are the adapter that was on the cable when I got the car. I am not sure if the adapter was something from GM, JC Whitney or where it came from. Next time I am over where the car is I can get some more photos of it. I could not find any identifying marks on the adapter in the little bit that I looked.

[Terry M.]

Re: 1970 Negative Battery Cable Bolt

The last two pictures are the adapter that was on the cable when I got the car. I am not sure if the adapter was something from GM, JC Whitney or where it came from. Next time I am over where the car is I can get some more photos of it. I could not find any identifying marks on the adapter in the little bit that I looked.

I think I have an idea how it works, but a side view would confirm my imagination. It is an interesting piece (at least to me) whether it is GM or of other manufacture.

[Mathew S.]

Re: 1970 Negative Battery Cable Bolt

I found this photo on my phone, if it attaches.

If I can get the car running with some miles on it, may drive it down to San Antonio convention for the day. This is the one that I was working on while at Bloomington last year. Dads LT-1 was next to yours there, and is same colors.

[Mathew S.]

Re: 1970 Negative Battery Cable Bolt

Photo didn't upload initially and won't attach through. Editing.

[Terry M.]

Re: 1970 Negative Battery Cable Bolt

Photo didn't upload initially and won't attach through. Editing.

Matt
I see now how it works. Interesting piece. I hope you can make it to San Antonio with that 1970. I would very much like to see that car and you again. This time we will be closer to you. More fun times in store.