The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: ADP91 on 25.03. 2021 18:06
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Hello all,
I recently received my eBay purchased rear wheel setup for my A10 project. My frame date code shows the frame is a S/A 1957. However, when I tried to mount the rear wheel (starting by trying to pass the sprocket side stub shaft through the swing arm axle opening) I could not get the stub shaft to pass through the opening.
My question is: are there different rear axle diameter/sizes for different years of S/A frames?
I've considered gently filing/grinding the swingarm opening so it will accept the stub shaft but thought I'd check before doing something I may regret.
Cheers!
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Hello all,
I recently received my eBay purchased rear wheel setup for my A10 project. My frame date code shows the frame is a S/A 1957. However, when I tried to mount the rear wheel (starting by trying to pass the sprocket side stub shaft through the swing arm axle opening) I could not get the stub shaft to pass through the opening.
My question is: are there different rear axle diameter/sizes for different years of S/A frames?
I've considered gently filing/grinding the swingarm opening so it will accept the stub shaft but thought I'd check before doing something I may regret.
Cheers!
The s/a 56 and 57 model years have “ariel” hubs (brakes) so yes they are different and have different swing arms (definitely) and fork legs (probably) to other years.
What hubs have you have?
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G'day Angus.
Ditto what Kiwi said. What hubs were on it ?
May be cheaper to find a 58 swing arm.
Cheers
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Thanks for the replies.
No rear hub came with it (bought it as a frame and drivetrain). I've been trying to piece together a bike for a couple years...
Are the ariel rear hubs "single" sided? The ones that don't go the full width of the rim?
Are the swingarms drastically different or could I get away with modifying my swingarm slightly in order to accept the later rear hub?
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Single sided rear brake (drum and sprocket in one) are used on the early S/A models, brake pedal on left, brake rod linked directly to the brake drum. Swinging arm has open ended forks. Solid swinging arm spindle.
Ariel type are full width alloy hubs used from 1956 until 1958. Brake pedal on left, crossover shaft within the hollow swinging arm spindle, cable to rear drum brake lever on right hand side. From 1958, the alloy hubs are replaced by cast iron full width hubs, again with cross over shaft and cable to the rear drum. These later swinging arms have closed fork ends.
So, three basic variants of swinging arm. Some have mounts for a full chaincase, and lugs move to accommodate torque arms. Best to start with the hub assembly of choice and match the swinging arm. The wheel bearings are different on Early Single Sided, Ariel and Cast Iron hubs, as are the wheel spindles. So as you have found, variation in the size of the hole in the fork end.
Swinging arm has the same basic dimensions for all model years, so plenty of scope for mix'n match.
Model years and year of manufacture are not the same, and parts from earlier model years were fitted to later models to use up existing earlier type stock. Add to that the frame date is close to a major change in wheel type plus 60 odd years of other folks' mods and you can't assume any part is correct.
I measured a a late S/A, ( full width iron hub) and found slot width to be 17mm on chain (stub axle) side, 20mm on right hand side. Difference is to match the flat locating the stub axle. A further consideration is that while in theory swapping swing arms is a possible, doing it for real can involve major hassle. Plenty on this already on the Forum. Enlarging the slot is certainly possible, but because it affects the horizontal location of the spindle is not an angle grinder, hacksaw and file job. My view is that it is better to avoid modifying genuine OEM parts.
Swarfy.
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Single sided rear brake (drum and sprocket in one) are used on the early S/A models, brake pedal on left, brake rod linked directly to the brake drum. Swinging arm has open ended forks. Solid swinging arm spindle.
Ariel type are full width alloy hubs used from 1956 until 1958. Brake pedal on left, crossover shaft within the hollow swinging arm spindle, cable to rear drum brake lever on right hand side. From 1958, the alloy hubs are replaced by cast iron full width hubs, again with cross over shaft and cable to the rear drum. These later swinging arms have closed fork ends.
So, three basic variants of swinging arm. Some have mounts for a full chaincase, and lugs move to accommodate torque arms. Best to start with the hub assembly of choice and match the swinging arm. The wheel bearings are different on Early Single Sided, Ariel and Cast Iron hubs, as are the wheel spindles. So as you have found, variation in the size of the hole in the fork end.
Swinging arm has the same basic dimensions for all model years, so plenty of scope for mix'n match.
Model years and year of manufacture are not the same, and parts from earlier model years were fitted to later models to use up existing earlier type stock. Add to that the frame date is close to a major change in wheel type plus 60 odd years of other folks' mods and you can't assume any part is correct.
I measured a a late S/A, ( full width iron hub) and found slot width to be 17mm on chain (stub axle) side, 20mm on right hand side. Difference is to match the flat locating the stub axle. A further consideration is that while in theory swapping swing arms is a possible, doing it for real can involve major hassle. Plenty on this already on the Forum. Enlarging the slot is certainly possible, but because it affects the horizontal location of the spindle is not an angle grinder, hacksaw and file job. My view is that it is better to avoid modifying genuine OEM parts.
Swarfy.
Thanks Swarfy.
It definitely seems like I have a cast iron hub with a 1956-1958 swing arm. Do you (or anyone else) know what the swingarm fork opening is to accommodate the cast iron hub? Getting another swingarm may prove difficult and expensive so I may enlarge the fork openings on my swingarm to allow the axle shafts to fit.
Cheers
Cheers
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Looks like you missed my dimensions. The right side needs opening to the spindle diameter, the chainside lug opened to suit the flats on the stub axle. Equal amounts must be removed from the top and bottom of the lugs to maintain the spindle horizontal relative to the rest of the frame. In practice the amount will be small, and any error likely to be of little consequence. Not my ideal approach, but needs must.
Swarfy.
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I cleaned up the swingarm fork openings gently with a bit of sand paper and I was able to slide both the brake side shaft and the stub shaft up until the flat part. However, the sprocket side stub shaft appears too long? The gearbox sprocket and wheel sprocket are not aligned and the wheel is not centered in the 'U' of the swingarm.
Are there different stub shaft lengths for the different hubs as well?
Cheers
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all I know is I hastily got a stub axle and found a difference between my original and the new one. I was told the longer one I got was for an A65
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if you have a look at topic 51 plunger rear hub conundrum , on page 2 there is a drawing I did on the longer stub axle that I was told is A65 and I think about half an inch longer
https://www.a7a10.net/forum/index.php?topic=14218.msg118237#msg118237