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Sturmey Archer AW hub - skipping in first gear

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Sturmey Archer AW hub - skipping in first gear

Old 05-22-14, 07:12 PM
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markk900
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Sturmey Archer AW hub - skipping in first gear

Hi all: I normally hang out exclusively in the C&V forum, but had a question about a problem I am having with an AW hub that sounded more suitable for here.

I have a 1949 AW hub that is giving me some trouble. It skips every so often under load in 1st gear. I have some good experience with AW hubs so this is not my first rodeo, but I am stymied.

Only happens in low; does not happen all the time; I get about 1/2 crank rotation when it does happen.

I have replaced the low gear pawls, pawl springs, (all with brand new parts), inspected the left side ball cup and can see no signs of wear. The pawls move freely.

The one area I am suspicious of is the pawl installation:
the original pawls were almost symmetrical; newer replacements have a long side and a short side. Clearly the long side engages the ball cup, but the question is flat side up or side with the small bevel machined into it up? The SA manual says flat side up, but looking at the pieces it seems a better "catch" would happen the other way round. I've assembled based on the manual.

The other curious thing is I get no discernible ticking when in Normal or High gear (that should be the sound of the low gear pawls being overdriven) - some of my other hubs are very quiet but this one is silent.

Anyway, can anyone offer any suggestions of things to inspect or adjust? I should add that I have experimented with cable tension as well with no change.

Thanks, Mark
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Old 08-01-14, 10:56 AM
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Hmm. I have a 1948 AW hub that is doing the same thing. It has been almost 40 years since I have taken one of these apart, but I have a couple of newer, undated spares. I see you had no replies, how did you fare?
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Old 08-01-14, 11:19 AM
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AW hubs are driven by either of two ratchet (freewheel) units. 2nd and third share the high gear ratchet, and 1st uniquely uses the low gear ratchet, while the high gear side is neutralized.

Therefore the first suspect in low gear slipping is the low gear ratchet itself, whose pawls may be chipped, or kept from engaging solidly by dried grease in the ratchet ring. The ring itself could be chipped, but IME that's rare.

You can either open and inspect, or do a thorough flush with solvent (including riding a short while on the solvent) to dissolve or soften any dried grease, then drain, rinse, drain and relube. (do the work by backing off the left side cone (leave the right alone unless you know what you're doing. You never know this may save the hub, but it won't cure chipped pawls.
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Old 08-02-14, 07:48 PM
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Thanks for the response, FB.
I took my hub apart yesterday and soaked it overnight. It was very gummy, but is has been sitting for at least 50 years. I last time took one of these apart was 40 years ago and had forgotten how easy they were to deal with. After overnight in mineral spirits, I finished up with a brass brush and some brake clean. One pawl spring was distorted and that was likely the culprit. I had an extra wheel with a repair ticket on it from 40 years ago. It was a rim replacement job that was abandoned in the shop that I stashed away for my parts collection. The hub was greased (hardened) but like new. I decided to use those internals rather than chancing the spring and the worn pawls, so I cleaned that one up and it worked great. Next project for the BSA will be to make a decent Dynohub out of the two I have and perhaps look into modern magnets for it. The front hub I have is not correct and the Dynohub will at least get me to the right country of manufacture.
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Old 08-02-14, 08:57 PM
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Originally Posted by Time Trialer View Post
.... One pawl spring was distorted and that was likely the culprit. I had an extra wheel with a repair ticket on it from 40 years ago. ....
Save the parts from the dead hub. There's a chance you might be able to help the OP with what his needs.
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