The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: Kwkevy on 17.08. 2025 11:20
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Hi does anyone know what the thread size is on the top fork nut , a7 1958
Thanks Kevin
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1 1/16 inch x 20tpi cycle.
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Thanks Julian
Am trying to make a tool to pull forks into there tapers , so I need 20 this cycle diameter with a 1 and one sixteenth thread ?
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No, you need an old fork top nut to modify with studding.. ;)
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Thanks Rex , any chance of a diagram please 🙏
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I'm sure I remember doing this on my old Sunbeam S8 with a length of broom handle or similar. The wood could be force-screwed into the stanchion and then used to pull the leg up far enough for the wood to be unscrewed replaced by the fork nut. Or am I reinventing my ancient past here? Anyone else tried this?
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BSA suggested something similar back in 1948.
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Lot of ways to skin this cat, regarding lengths of studding, spacers needed, washers etc, but as long as the thread to enter the stanchion is right . . .
Here are several (pic not diagram with measurements - I just used whatever scrap was to hand), for doing different legs. All the same idea.
Broom handles can work too!
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Thanks Goiley
The first one looks perfect for job . Is that made from a sacrificial top nut?
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Yup, top and bottom are from top nuts, middle one was summat else I had to cobble up a bit scrawnily, but it worked!
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BSA suggested something similar back in 1948.
Thanks, Julian! So I wasn't imagining things. Of course, I've got a kit that covers various size beezas now, but I think somehow more satisfying when the backwoods approach works. Mike
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OK thanks that's the one will go with . Did you grind / cut the hex bit to size or just cut the hex bit from the thread ?
Cheers Kevin
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Decapitated the hex heads carefully with a hacksaw I think. Wasn't looking for beauty!
Then drilled holes clean through and used nuts both sides in one case (turned down to go into the legs by the looks of) , or tapped the hole and screwed studding in directly and peened it, with locknut on upper side (other case). Very primitive, all of it.
On forks with damper rods you have to go on a fishing expedition to hook 'em back up. Good to leave nuts on the rods as something to grab if you have 2-way damping.