H-D Big Twin round-tube swingarms 1958–72

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Re: H-D Big Twin round-tube swingarms 1958–72

#16

Post by hplhd »

eric, thanks so much for all your documentation. not just these swingarms but all of it.
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Re: H-D Big Twin round-tube swingarms 1958–72

#17

Post by Speeding Big Twin »

Cheers, Rich. Harley research seems never-ending. Two weeks ago I sent another letter to H-D but this time to the archives and I asked about model layout sheets. I have a couple from the 30s but I’d like some from the 40s–60s. And today on the State Library website I noticed another Harley book so I’ll request it soon. Often they don’t contain much good info but this one includes text by Herb Wagner so that’s a good sign. In the meantime I continue to work on a few things relating to SNs and BNs.
Eric
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Re: H-D Big Twin round-tube swingarms 1958–72

#18

Post by bigbox »

Eric, I find this post an appealing read, thanks for all your hard work. Mucho appreciated
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Re: H-D Big Twin round-tube swingarms 1958–72

#19

Post by cdndewey »

Great info. I'm on holidays right now but when I get home I'm going to check out the two that I have.
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Re: H-D Big Twin round-tube swingarms 1958–72

#20

Post by Speeding Big Twin »

Thanks, bigbox and Dewey.

Dewey, please let me know if your swingarms don’t fit in with the info I posted. If anything new and/or unusual crops up it can be added to this thread.
Eric
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Re: H-D Big Twin round-tube swingarms 1958–72

#21

Post by 58flh »

Eric-----Thanks for sharing all your info!!!----I have learned what certain hallmarks stand for now,& didnt have a clue before!/Also I always knew that HD would use parts on a new run of bikes that were left-over from previous runs./Atleast now I have a Timeframe for certain things & can account for originality to a bike when a customer asks!---Much thanks -(I know thats YEARS of research you have!).--Again much thanks----Respectfully---Richie
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Re: H-D Big Twin round-tube swingarms 1958–72

#22

Post by Speeding Big Twin »

Cheers, Richie. Yes, I’ve been studying round swingarms for several years and it’s interesting to follow the changes. Something I’d like to examine is an EXperimental version. I keep an eye on eBay but haven’t seen one yet.
Eric
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Re: H-D Big Twin round-tube swingarms 1958–72

#23

Post by Buddhahoodvatoloco »

Thanks, actually read the whole thread. Like the way you clarified the information.
Good job.
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Re: H-D Big Twin round-tube swingarms 1958–72

#24

Post by Buddhahoodvatoloco »

I reread this post again, alot to digest.
thanks
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Re: H-D Big Twin round-tube swingarms 1958–72

#25

Post by rudy »

Thank you. ..
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Re: H-D Big Twin round-tube swingarms 1958–72

#26

Post by Frazier »

The one thing i do know about round tube swingarms is that when i was building this bike out of the four swingarms i had in my stash only one fit the brake backing plate that i had , thanks to your info maybe i could research and see what year combo i have
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Re: H-D Big Twin round-tube swingarms 1958–72

#27

Post by Speeding Big Twin »

Cheers Frazier. According to my H-D parts catalogs, for 58–72 BT rear brakes there were two side plate (backing plate) assemblies: #41650-58 for 58–62; and #41650-63 for 63–72.

Re your swingarms, as a starting point you could check the forging number on the left axle clip. If you’re not sure what combo of parts you have, post photos anytime and I’ll help you figure it out.

And if you notice anything on any of your swingarms that isn’t mentioned in one of the above posts, please let me know so it can be added to this thread if necessary.
Eric
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Re: H-D Big Twin round-tube swingarms 1958–72

#28

Post by RUBONE »

Frazier, as you found out, due to the later backing plate being located closer to the swingarm there were clearance issues. When the brake assembly was widened in '63 the entire brake moved more to the left side of the bike. Early backing plates fit inside the drum recess and used a long left side spacer, '63 up backing plates have a lip over the outside of the drum (like automotive practice) and a short spacer putting them closer to the swingarm.
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Re: H-D Big Twin round-tube swingarms 1958–72

#29

Post by easykick »

Hello all,
The brown swing arm was listed on Craig's list many years ago, can't remember when, and the black swing arm pics are with a 1962 frame I bought back in the early spring.
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I hope the photos quality is good enough for information purposes.
Easykick
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Re: H-D Big Twin round-tube swingarms 1958–72

#30

Post by easykick »

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