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I believe that 3/4 refers to the wrench size for the hex head.

Wheel bolts used from 1935 (and possibly earlier) to 1955 had a 9/16-18 thread and hex head 3/4" across flats.
Threaded length approx. 1" and overall length 1-1/2"

Big difference!

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Indeed, a classic Mopar "feature".

Really no need for snide remarks here.

Unfortunately the parts book doesn't specify the dimensions, so I would address your concern by taking off a drum with the wheel bolted to it and checking the depth of penetration of your bolts. However, I think those are blind holes so that won't work. An alternative is to stick a piece of wire or something into the hole to measure the depth. Your concerns are well founded as for the earlier cars Packard had a multitude of part numbers for those bolts.

If you want to size a fastener you can fit the open end of a wrench over the thread to determine your specification. For example if a 9/16 wrench fits the threaded portion that is a 9/16 bolt. If you have a thread gauge or a thread file you can then determine the thread pitch. On a thread gauge it is a number, say 21, or if you take it to a hardware or auto store that has open fastener stock you can find out that way.

Metric works the same way. A 6mm X 1.mm metric fits a 6mm wrench on the shank and, say, a 10mm wrench on the hex.

1/4-20 will take a 1/4 inch open end wrench on the shank and a 7/16 wrench on the hex. The 20 is the number of threads per inch which you can also count with a ruler. I miss the old USS/SAE systems where everything is in 16ths of an inch. Metric always bugs me because I hate French imperialism.

"Metric always bugs me because I hate French imperialism".

Hmmmm, is this a snide remark?

Thanks for the info. Will bring a bolt to the shop and ask the size of the thread. I do know its only bolted in about 1.1/4 inch (i checked the depth) in the brake drum. And yes the size i mentioned is the size of the wrench to take of the bolts.

I had 4 loose bolt over different wheels after 2000 miles of driving since i did them last time at 80ftlb.

Now i pulled them at 100 and drove 600 miles over the past weekend and they are still all tight.

I use a proper snap on for torque. So 80 clearly wasnt enough.

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LOL!!!


Actually, we missed out on the French Imperialism. Our number system is base 10, and most of us came with 10 fingers.


But, it is what it is, and it ain't what it ain't.

It sure is, but they deserve it. After all Vietnam was a French rubber colony. And that is putting it kindly.