Presentation on theme: "Pedal Depot: Overhauling the Sturmey Archer AW 3 speed hub."— Presentation transcript:
Pedal Depot: Overhauling the Sturmey Archer AW 3 speed hub
Pedal Depot: 25 June 2012/cbm rev.8 A short guide to overhauling the Sturmey Archer AW 3 speed hub Sturmey Archer invented the three speed hub in 1902. The improved AW model has been in continuous production from 1938-present (except WW2), millions made in Nottingham, UK; the most successful 3 speed hub in the World. Very robust, many are 50 years old and still in good shape. A version with improvements (S-RF3) is still in production in 2011, in Taiwan where the SunRace Sturmey Archer factory is now based. Gear ratios are 0.75 – 1.0 – 1.33 For removing old grease and oil, use kerosene or chain cleaner.For greasing the three ball bearings, use Parker Polylube green grease. For oiling the epicyclic gear and pawls, use ‘3-in- One’ SAE 20 Electric Motor Oil or ATF fluid. For pre 1984 units with the oil cap 20, add a few drops of oil monthly in service. For later sealed units, use white lithium grease on rebuild, or add oil though the shift chain hole in service for lower friction. Two excellent websites for advice: http://www.sheldonbrown.com/sturmey-archer.html http://vancruisers.ca/
Exploded view – these numbers are used in the text.
Disassembly 1. Remove sprocket circlip 31 with small screwdriver. Remove sprocket 29, two spacers 30 (note the spacer order, sprocket orientation) and dustcover 28. 2. Unscrew left hand bearing cone locknut 1, remove spacer 2 and cone 3. 3. Loosen large right hand ball ring 24 with hammer and drift (RH thread), unscrew and remove. Remove entire cluster from hub 4. Clamp left hand axle flat in vice, remove right hand cone locknut 34, special lockwasher 33, cone 32, clutch spring 22 and cap 23. 5. Lift off driver 26 and gear ring 14. 6. Lift off thrust ring 21 and poke out axle key 13. Remove cruciform clutch 12 and clutch sleeve 11. 7. Lift off planet cage 8, remove axle from vice. 8.Clean sticky old oil off all surfaces, check all 4 pawls 6,16 in planet cage and gear ring. If any are slow to return, dismantle one at a time (watch out for hairspring 17 ) - clean pins 18,7, pawl hubs and faces, clean surrounding area of glop, then oil and reinstall (pawl 6 edge out), pointed end of pin down. Rotate the 4 planets 9 by hand: if sticky to turn, remove pins 10 and clean hubs/pins, reinstall with fresh oil, ensure stepped ends of pins face upwards. 9. Remove old grease on the 3 bearings 4,25,27 and cones/seats (two small, one large bearing). Large bearing has 24 x 3/16” balls only (gap is normal). 10. Inspect race seats and gear assemblies for obvious damage/wear, replace where needed.
Typical trouble areas after huge mileages Pitted small ball race, especially sprocket side. Have a few spares on hand. Soggy pawls (old oil or rusted) that are slow to return after being pushed in – leads to missed gear changes. Carefully remove (hairspring!), clean, reoil and reinstall. Note that the pawl hairsprings can break, if the pawls are left unlubricated. Have a few spare springs on hand. Sticky planet gears that won’t spin freely on pinion by hand, leads to a draggy hub. Pull out planet pinions and gears, clean, reoil and reinstall. Broken small bearing cage (rare) if allowed to run badly out of adjustment, crunching noise. Replace bearing. Missing or misassembled parts inside, some owner had good intentions and panicked (gear now won’t shift at all). Compare to exploded view on Slide 3. Lack of oil inside leading to stiff/dry operation, owner never added those precious drops/year of oil. Add thin oil through oiler and hollow axle. Sun gear slightly loose on axle. Use hammer and punch to ‘rerivet’, being careful to support and not damage hardened axle. Spare axles are now one-piece. The two 1/16” spacer rings 30 adjoining the chain sprocket are very hard, and crack easily. Handle gently, replace if cracked. When not used for long periods, the clutch sleeve 11 sometimes ‘glues’ itself to the axle with dried-up oil, giving a hub that will not shift. Scrape clean and relube.
Reassembly 11. Regrease all 3 bearings 4,25,27, cups, cones, and pack bearing dustcaps (labyrinth seals) inside with grease. 12. Clamp left hand axle flat in vice 13. Install planet assembly 8 (pawls towards left hand axle end) 14. Fit clutch sleeve 11 and cruciform clutch 12 over axle, poke axle key 13 through sleeve/clutch with flat tips upwards. Install thrust sleeve 21 on top. 15. Fit gear ring 14 over planet assembly 8. 16. Add 2 teaspoons of SAE 20 thin oil to planet assembly gears and clutch. 17. Fit large ball ring 24 over axle, also driver 26 (ensure driver dogs seat with cruciform clutch). Insert clutch spring 22 and cap 23. 18. Fit rh bearing cone 32 by hand and finger tighten. Back off approx. 1/2 turn and lock with special lockwasher 33 and locknut 34. No more than 5/8 backed off for bearing cone. This needs to done carefully for long gear life. 19. Remove assembly from vice, keeping upright. Offer up hub shell 19 to assembly from below. Rotate hub shell anti-clockwise to seat low gear pawls 6 easily and totally engage assembly in hub. 20. Screw large ball ring 24 into hub 19 by hand fingertight, then tighten with hammer and drift. Note double start thread for rapid assembly. 21. Clamp right hand axle flat in vice, fit left hand cone 3 and adjust for almost no play, smooth turning. Add spacer 2 and tighten lock nut 1, while holding bearing cone.
On bike – adjusting the indicator chain This is an easy though important step. Symptoms of a maladjusted indicator chain are slipping gears (especially 2 nd ) or inability to get 1 st. With the hub installed on the bike and the handlebar shift trigger hooked up, thread the indicator chain finger-tight in the hub through the rh open axle end. Back the chain off up to 1 turn to thread the shift cable end on easily (don’t forget the knurled locking nut). With handlebar trigger set to gear 2 (or N on an older shifter), twiddle the shift cable end until the indicator solid rod just begins to appear out the axle end (looking through the round hole in flared nut). Ride around the block, shifting all gears up & down. Adjust cable end again in 2 nd as above if needed (cable stretch). Lock with the knurled nut. Solid rod just appearing at axle end Solid rod on indicator chain, 2 styles
Thanks for using this, please get any feedback to Pedal Depot, 1830 Ontario St, Vancouver - so we can finesse the procedure (rev.8, 25 June 2012) Original 1936 blueprint