A little Sturmey-Archer info

[professor]

A video of SA 3speed hub disassembly and assembly on youtube gave me incentive to take mine apart.

I am using one as a jackshaft.

The jumping out and back in of high gear was bugging me.

Third gear is driven by a cross shaped (called a clutch) part that contacts 4 pins in the mechanisim. So, my first idea was to braise up the wear spots on the clutch. This helped eliminate the jumping out a lot, but it still did it some. I was thinking the wear was allowing the parts to "work themselves away" as I went down the road, since it took time for this to occur.

Today, I took the 4 pins out and found they were tapered from wear.
Ah ha. Culpret found I think, chucked them in a drill (clamped in my vise) - home made "Lathe" and put a reverse taper (with a file) of about five thousandths on both the pins and the clutch. I am thinking the taper will tend to lock the hub in 3rd gear with load. Letting off the throttle (like usual) takes the load away to shift.

It's dark and 20 degrees now, I'll post back after then next snow (predicted) is off the roads and I can test it out.
Then I can order some new parts to have in inventory.

I do like the hub, I like being able to switch gears at a standstill. Third gear jumping out is the only issue and the most likely to wear these engagement points. The hub did come off a 40 year old bike though.
I am amazed that this was designed a hundred years ago. Brilliant people.

 

[ibdennyak]

Ha, you beat me to it Prof. It's been in single digits for over a week or so here, so I stopped at the storage unit to pick up my bike with the SA and see what I could find. Frozen solid....moisture had condensed everywhere, and the recoil wouldn't even turn. Got to find a warm place to dry things off around here. Oh well, now I have your experience to draw from.

Was it very complicated to open up???ie springs and little parts flying all over? My big ole fingers are too cold and stiff to deal with that now.

 

[Esteban]

Here is a website for help.

http://www.users.globalnet.co.uk/~hadland/samaintind.htm

 

[professor]

Denny, it's not bad at all.

I have a small vise mounted on a steel block that I set on a clean bench (so if anything falls it doesn't go far). The flats on the axle lock nicely in the vise. It would be good to make a note of the distance from the end of the axle to the bearing or lock nut for the bearing, to be quickly able to put the axle back in the same location.

Note- when taking out the drive sprocket, it is not necessary to detach the sprocket itself. After the axle nuts are off that side, the spring pops up and you slide the sprocket up and out.

I put a layer of grease carefully on the row of ball bearings that become exposed- to keep them in place.
Those bearings sit in a housing that needs to come off.
I lock the spoke flange (no rim or spokes are on it) in the vise and wack the slots (like in the youtube video- check it out)- counter clockwise with a punch and hammer.

The hardest part of the whole thing is getting that housing back in and screwed down because the ratchet pawls stick out, but they can be flicked in place fron the inside with a small screwdrive if necessary, they are like a tetter- tauter, with a nub sticking toward the inside.

It is a seemingly balmy 30 something degrees now, so I will try for a ride before it is dark at a little after 5.
Hope the rain holds off.

 

[professor]

The good- once engaged in hi gear it does not skip.
The bad- skips once or twice upon engaging.
I guess the wear places were like ramps that eased engagement previously.
Now I am thinking that a little chamfer on the "Clutch" would help engagment but that will have to wait.

 

[professor]

Victory at last.
The little pull cable for the gears was not releasing enough (possibly the cold of winter buggers it up), so I added a tiny spring down by the pull chain and it is fine.
I did do a tiny chamfer to the "clutch" (cross shaped part that engages gears) but do not know if it helped engagement, may have though.

 

[ibdennyak]

Hmmmm, thanks Prof.tI never did trust the long cable I have on the pusher. I have slack at the shifter, but can't say for sure at the hub end. Does your chain just run around the bevel in the nut or does yours have the wheel?

 

[professor]

The chain has slack in the first gear position (no slack at the trigger shift).
When I was having trouble going into hi gear, I reached down and jerked the cable toward the hub and it went right into gear, thus telling me the problem was the cables' drag. Adding the little spring pulled the cable enough to let the chain slide into the 3rd gear position.
I'm pretty happy with the set-up now. Plus knowing, if the dropping out of gear returns that the fix is easy.

 

[curtisfox]

There is a little tool that you clamp on the cable to lube them, Check with small engine shops or motorcycle shops. Clamps on and it shoots fluid right down the cable.....Curt

 

[professor]

Thanks for the tip, I have heard of these!