7/16 x 24 thread bolts

[belmont]

I found these in an undiscovered bolt bin this weekend. They are 7/16" - 24 thread and 1 and 1/8" long with a 1/4" thick 5/8" hex head. They are parkerized and have an unmarked head.

Any help in identifying there use will be much appreciated. I have not found this unusual thread pitch before.

Belmont

[duffeycycles]

0131 nut is same thread but I don't see those bolts in my parts book.Sometimes the bolt has a special HD part number

[belmont]

Thanks, I have some of those nuts. I checked them against these oddballs and they are a no go. Apparently the minor on the threads of these bolts is too large to even start one of the 0131 nuts.

The mystery continues, the minor thread diameter, as near I can measure is .412" and the major is .435" and they fit my 24 thread gauge.

belmont

[Rubone]

Thanks, I have some of those nuts. I checked them against these oddballs and they are a no go. Apparently the minor on the threads of these bolts is too large to even start one of the 0131 nuts.

The mystery continues, the minor thread diameter, as near I can measure is .412" and the major is .435" and they fit my 24 thread gauge.

belmont

Are you sure they are not 26TPI.? That would make them English which would explain the thread pitch difference. 7/16-26 BSC.

[Tommo]

This publication was put out in 1920 and contains 4 references of 7/16 x 24 tpi bolts but none are as short as you describe.
This book is 48 pages so is too large for me to copy and post here but maybe the AMCA library may have one you can download. HD nuts and bolts.jpg

[Tommo]

I should have said that it wouldn't surprise me to find that that bolt was used by Harley sometime after this book was published.
3 of the bolts listed were used to attach the springs to the sidecar chassis and the other one was the clamping bolt to hold the seat post into the frame on pre 1920 HD bikes.
Hope this helps but it doesn't answer your question as to where your bolt was used.

[Steve Swan]

Joe Drociuk in British Columbia sells copies of the booklet Tommo refers to

https://www.ebay.com/itm/27576136864...Bk9SR-yh2YPmYQ

[Steve Slocombe]

It might just be a 1937-39 Harley 45 triple clamp pinch bolt. It's not listed in my 1930-40 parts book, but it doesn't make sense to use the earlier long stud meant to support the 1929-36 dash panel. Part number would then be 2655-37.

[belmont]

First thanks to all of you that have helped with this mystery.
Rubone, yes I am certain this 24 TPI.
Tommo, very good suggestions. I agree that these would have to be something for a sidecar, the front fork, or maybe a rear brake. I will check the library here to see if the 1920 book you mention is available.
Steve Swan's lead is a good one. Always nice to have reference material like this one and I can get one for $35 on ebay if the library doesn't have it.
Steve Slocombe, I found the 2655-37 listed in my 1941 parts book but not in my 1939 parts book. Unfortunately there is no depiction in the fork group in either of those books.

[Steve Slocombe]

The 2655-32 pinch bolt for the VL is also 7/16 x 24 tpi, and the 1937-39 45 triple clamp is essentially the same as the VL one but without the tapped holes for the dash base fixings, so that sounds like 2655-37 to me. No wonder there were left over nos ones with such modest usage.

[belmont]

Steve Swan, I just got my copy of the 1920 list of bolts, nuts, washers, and other hardware from Joe Drociuk in British Columbia. Very high quality reprint and extensive usage information. I would say it is a must have for someone working on most any 1920 and earlier Harley model. Nothing that nails down this particular bolt. The four 7/16-24 bolts listed are all longer. Thanks for mentioning it, I always appreciate a great research find like this, too bad there isn't one for later bolts and such. I can only imagine the undertaking as monumental in compiling all the places things got used on the 20's and 30's models.

[belmont]

Steve Slocombe, I would think you got it right. These are only 1 and 1/8" long, which is how long the Panhead/ Shovelhead lower tree pinch bolts are but 7/16-20 TPI. So I will go with 2655-37 and hope to find someone that needs some, I have 7 of them.

Once again thanks for the insights and help.

Karel