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01-14-09, 11:50 AM
Various bike forums members have posted information about working on this hub, but it is difficult to find the most informative of these postings because they are often hidden in threads with rather opaque names. So I thought it might be useful to start a thread collecting some of that information.
Sturmey Archer has a pdf manual (http://SA8%20manual) describing the process, complete with pictures. It also has a number of errors, which make life interesting.
There is also a description of the overhaul of an XRD8 hub, which is very similar: http://www.velovision.co.uk/cgi-bin/...l?storynum=715
1. Before you think about overhaul, try adjusting the cable and, if that doesn't work, try adjusting the left side cones, and then adjusting the cable again. Proper --perfect-- adjustment of the cable is crucial. If the shift cable is not adjusted perfectly, the hub will not shift well. When adjusting it, or when removing the shift cable from the hub, it is helpful to insert a small steel rod (such as a small hex wrench) into the hole on the back of the shift pulley. The hole points directly toward the rear of the bicycle. A rod into that hole provides the leverage to move the pulley easily.
2. To remove the wheel you need a 15 mm wrench.
3. Once the wheel is off the bike, check if the axle turns freely. If the axle does not turn freely, or if it is too loose, the hub will not shift correctly. You may be able to correct this by adjusting the cones on the left side. The locknuts fit a 17 mm wrench; the cone is 16 mm.
4. Removing the cog. To remove the cog, you do not need to remove the fulcrum lever. Pry up the large circlip that holds the cog, and you can slip that and the cog over the whole fulcrum lever.
5. Removing the fulcrum lever. A small C-clip holds the fulcrum lever to its base, which resembles a washer with a flattened hole. Removing the C-clip is a pain in the neck and is NOT ACTUALLY NECESSARY. You can pull the whole fulcrum lever assembly off the axle together with its C-clip, washer and base.
6. You can now remove the cable pulley together with its dust cap.
7. You can now remove the cone locknut (17 mm wrench).
8. You can now remove the cone anchor, which resembles a washer with a flattened hole, but it also has two protrusions on the left (inner) side, which keep the cone from rotating. Note the two "(" shaped holes in the cone; the studes sticking up through these are the shift actuator. There is a spring that keeps the shift actuator turned clockwise; when you lift up on the cone anchor (you can use pliers, or pry the edge up with a flat blade), you will release this spring, so now the whole cone and shift actuator will turn clockwise.
9. You can now remove the driver, but first I would check to see all the balls are correctly placed in the retainer on the inside of the driver. If any have become dislodged, place them correctly and proceed. Note that there is a large but very thin wire C-clip, not mentioned in the Sturmey Archer part list or manual, around the outside of the driver. It does not appear to hold anything, so I guess it's some sort of a dust seal, and rather fragile, but problems can be caused by
... the ring under the plastic seal.
10. You can now remove the plastic dust cap by prying gently upwards with a flat blade screw driver. I found it helpful to replace the shift actuator at this point so it could serve as a fulcrum for prying off the dust cap.
11. You can now remove the large ball cage. It should just lift out. Be careful with it, it is rather fragile. Make sure it has all its balls; if any of them are loose in the hub, find them and put them where they belong.
I did stopped here, but jur did not:
OK here goes...
1. ball ring spanner: I made one using a piece of rectangular alum. tubing into which I tapped and screwed 2 M5 machine screws. The screws go right through the material and stick out a few mm on the other end, and those ends engage the semi-circular cut-outs on the ball ring. In the middle of the alum tubing between the 2 screws, a hole is drilled to allow the axle to stick through when engaging the ring spanner. The hole is just large enough, and when I put the ball ring spanner on, I fasten it down with an axle nut so it stays put. Remember to back off the axle nut when unscrewing the ball ring.
IMPORTANT: The ball ring has LEFT HAND THREAD! The manual is wrong!
You could try tapping the ball ring out with a hammer and screw driver. I tried that; didn't work, mostly because I was tapping in the wrong direction. So I made a spanner, and the spanner showed that no amount of force was unscrewing it. So I tried the left hand way, and presto! it came out.
I re-used all parts.
Grease is a problem. I got the best results with something called cable grease which comes out very thin from a spray can, then turns into a gel when the solvent evaporates. Everything else I tried just ran out again.
Very important: Do not make the same mistake as I and deform the ball retainers! Doing so ruined them, and no amount of fiddling could get them right again.
For your service, assuming all is OK with the gear works, don't do anything to the inner works, just remove it and set aside, leave the gel on it. It may be that all you need are new balls; they are standard size. Get rust-proof ones. Carefully pop the old ones out of their retainers, clean the latter and pop in new balls. Grease with ordinary grease and re-assemble the lot.
Work carefully with the plastic seal as it is plastic and can break.
Good luck!
Reassembling the hub, note that Step 9 in the Sturmey Archer instructions is also wrong. Fit the cone as described, then put the cone anchor over the axle and slide it down almost to its final position. It will not go all the way down because it is not aligned right. Now, holding the axle in a wrench, turn the cone COUNTERclockwise until the indentations in its visible side come into alignment with the flat surfaces on the axle. Turning the cone takes some force, because of the spring, so use a tool that provides good leverage. When the cone is turned to the right spot, you can press the cone anchor into its seat with very little force; even so, a third hand is useful at this point.
Disclaimer: I am by no means an expert in internally geared hubs, so what I have written may be full of errors. I write them in hope that someone will correct them, and perhaps add more useful information, especially links to information already posted in Bike Forums. Anyone?
________________
Edit:
If the above links don't work, you might try these:
http://www.heliosrace.cz/dokumenty/navody/8spd-xrf8-techinfo.pdf
http://www.free-coaster.com/assets/applets/Sturmey_Archer_8-speed.pdf
Sturmey Archer has a pdf manual (http://SA8%20manual) describing the process, complete with pictures. It also has a number of errors, which make life interesting.
There is also a description of the overhaul of an XRD8 hub, which is very similar: http://www.velovision.co.uk/cgi-bin/...l?storynum=715
1. Before you think about overhaul, try adjusting the cable and, if that doesn't work, try adjusting the left side cones, and then adjusting the cable again. Proper --perfect-- adjustment of the cable is crucial. If the shift cable is not adjusted perfectly, the hub will not shift well. When adjusting it, or when removing the shift cable from the hub, it is helpful to insert a small steel rod (such as a small hex wrench) into the hole on the back of the shift pulley. The hole points directly toward the rear of the bicycle. A rod into that hole provides the leverage to move the pulley easily.
2. To remove the wheel you need a 15 mm wrench.
3. Once the wheel is off the bike, check if the axle turns freely. If the axle does not turn freely, or if it is too loose, the hub will not shift correctly. You may be able to correct this by adjusting the cones on the left side. The locknuts fit a 17 mm wrench; the cone is 16 mm.
4. Removing the cog. To remove the cog, you do not need to remove the fulcrum lever. Pry up the large circlip that holds the cog, and you can slip that and the cog over the whole fulcrum lever.
5. Removing the fulcrum lever. A small C-clip holds the fulcrum lever to its base, which resembles a washer with a flattened hole. Removing the C-clip is a pain in the neck and is NOT ACTUALLY NECESSARY. You can pull the whole fulcrum lever assembly off the axle together with its C-clip, washer and base.
6. You can now remove the cable pulley together with its dust cap.
7. You can now remove the cone locknut (17 mm wrench).
8. You can now remove the cone anchor, which resembles a washer with a flattened hole, but it also has two protrusions on the left (inner) side, which keep the cone from rotating. Note the two "(" shaped holes in the cone; the studes sticking up through these are the shift actuator. There is a spring that keeps the shift actuator turned clockwise; when you lift up on the cone anchor (you can use pliers, or pry the edge up with a flat blade), you will release this spring, so now the whole cone and shift actuator will turn clockwise.
9. You can now remove the driver, but first I would check to see all the balls are correctly placed in the retainer on the inside of the driver. If any have become dislodged, place them correctly and proceed. Note that there is a large but very thin wire C-clip, not mentioned in the Sturmey Archer part list or manual, around the outside of the driver. It does not appear to hold anything, so I guess it's some sort of a dust seal, and rather fragile, but problems can be caused by
... the ring under the plastic seal.
10. You can now remove the plastic dust cap by prying gently upwards with a flat blade screw driver. I found it helpful to replace the shift actuator at this point so it could serve as a fulcrum for prying off the dust cap.
11. You can now remove the large ball cage. It should just lift out. Be careful with it, it is rather fragile. Make sure it has all its balls; if any of them are loose in the hub, find them and put them where they belong.
I did stopped here, but jur did not:
OK here goes...
1. ball ring spanner: I made one using a piece of rectangular alum. tubing into which I tapped and screwed 2 M5 machine screws. The screws go right through the material and stick out a few mm on the other end, and those ends engage the semi-circular cut-outs on the ball ring. In the middle of the alum tubing between the 2 screws, a hole is drilled to allow the axle to stick through when engaging the ring spanner. The hole is just large enough, and when I put the ball ring spanner on, I fasten it down with an axle nut so it stays put. Remember to back off the axle nut when unscrewing the ball ring.
IMPORTANT: The ball ring has LEFT HAND THREAD! The manual is wrong!
You could try tapping the ball ring out with a hammer and screw driver. I tried that; didn't work, mostly because I was tapping in the wrong direction. So I made a spanner, and the spanner showed that no amount of force was unscrewing it. So I tried the left hand way, and presto! it came out.
I re-used all parts.
Grease is a problem. I got the best results with something called cable grease which comes out very thin from a spray can, then turns into a gel when the solvent evaporates. Everything else I tried just ran out again.
Very important: Do not make the same mistake as I and deform the ball retainers! Doing so ruined them, and no amount of fiddling could get them right again.
For your service, assuming all is OK with the gear works, don't do anything to the inner works, just remove it and set aside, leave the gel on it. It may be that all you need are new balls; they are standard size. Get rust-proof ones. Carefully pop the old ones out of their retainers, clean the latter and pop in new balls. Grease with ordinary grease and re-assemble the lot.
Work carefully with the plastic seal as it is plastic and can break.
Good luck!
Reassembling the hub, note that Step 9 in the Sturmey Archer instructions is also wrong. Fit the cone as described, then put the cone anchor over the axle and slide it down almost to its final position. It will not go all the way down because it is not aligned right. Now, holding the axle in a wrench, turn the cone COUNTERclockwise until the indentations in its visible side come into alignment with the flat surfaces on the axle. Turning the cone takes some force, because of the spring, so use a tool that provides good leverage. When the cone is turned to the right spot, you can press the cone anchor into its seat with very little force; even so, a third hand is useful at this point.
Disclaimer: I am by no means an expert in internally geared hubs, so what I have written may be full of errors. I write them in hope that someone will correct them, and perhaps add more useful information, especially links to information already posted in Bike Forums. Anyone?
________________
Edit:
If the above links don't work, you might try these:
http://www.heliosrace.cz/dokumenty/navody/8spd-xrf8-techinfo.pdf
http://www.free-coaster.com/assets/applets/Sturmey_Archer_8-speed.pdf