Servicing The Sturmey-Archer
ASC Three-Speed Fixed-Gear Hub
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by Sheldon "Coasting Is A Pernicious Habit" Brown
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Sturmey-Archer ASC Page

SunRace/Sturmey-Archer has now released a new 3-speed fixed-gear hub, the S3X. Given SunRace's track record with Sturmey-Archer, the new version can be expected to be more reliable than the original. The hub is now available at Harris Cyclery.

This page gives technical imformation about an earlier Sturmey-Archer fixed-gear hub.
ASC Hub cutaway

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ASC Hub exploded

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CODE No. DESCRIPTION
K831 Axle, 5 1/2" long
K805A Low Gear Dog
K806 Dog Sleeve
K402 Low Gear Key
K809A Secondary Sun Pinion
K811 Locating Plate
K 412 Locking Washer
K812 Locknut
K8l5A Secondary Planet Cage
K816A Secondary Planet Pinion
K8l0B Low Gear Spring
K808 Primary Sun Pinion
K715 Planet Cage
K16 Planet Pinion
N24 Pinion Pin
K716 Indicator
X8 Collar for
Compensator Spring
K8l3B Compensator Spring
K527 Clutch Sleeve
K505A Sliding Clutch
K526A Axle Key
K807ZA Coupling complete
K807Z Coupling complete,
quick-release type.
Not illustrated
K74OAZ Quick Release
Connection.
Not illustrated
K528A Thrust Ring
K411 Thrust Washer
K530B Clutch Spring
K529 Spring Cap
K511B Gear Ring
 
K228 R H. Ball Ring
K230Z Ball Cage with 3/16" balls
K462 Driver, 3-Lug
K657 Driver, 12-Spline
K67Z Ball Cage with 8 1/4" balls
LB405 Outer Dust Cap
K506Z Axle Cone with Dust Cap
K516 R.H. Cone Locking Washer
K718Z Shell, 40 holes, with Ball Cup
K7l8AZ Shell, 36 holes, with Ball Cup
K227 Connection Locknut
X42A Axle Spacing Washer
K47A Cone Locknut
K521 Axle Locking Washer
N190 L.H. Axle Nut
N200 R.H. Axle Nut
K229 Sprocket Dust Cap
K464 Sprocket, 14 teeth, 3-Lug
K465 Sprocket, 15 teeth, 3-Lug
K466 Sprocket, 16 teeth, 3-Lug
K467 Sprocket, 17 teeth, 3-Lug
K468 Sprocket, 18 teeth, 3-Lug
K469 Sprocket, 19 teeth, 3-Lug
K470 Sprocket, 20 teeth, 3-Lug
X49 Sprocket Spacing Washer
K463 Circlip
K214 Sprocket, 14 teeth, 12-Spline
K215 Sprocket, 15 teeth, 12-Spline
K216 Sprocket, 16 teeth, 12-Spline
K217 Sprocket, 17 teeth, 12-Spline
K218 Sprocket, 18 teeth, 12-Spline
K219 Sprocket, 19 teeth, 12-Spline
K220 Sprocket, 20 teeth, 12-Spline
K36 Sprocket Lock Ring

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TO RE-ASSEMBLE THE ASC HUB

Proceed as follows:

Prepare the following preliminary sub-assemblies:
    • Fit the ball cage into the left-hand ball cup, with the ring of the ball-retainer facing outwards and the recess in the dust cap also facing outwards. If a new ball-retainer is being fitted, the dust cap also should be new.
    • Fit the ball cage into the driver, with the ring of the ball- retainer facing outwards and the recess in the dust cap also facing outwards. If a new ball-retainer is being fitted the dust cap also should be new. If the sprocket has been removed see No. 27 below.
    • Smear grease in the channels of the dust cap of the left-hand ball cup and the driver and in the recess of the right-hand ball ring. Do not use grease anywhere else.
  2. Hold the axle in a vise, with the smaller slot uppermost, and fit the low-gear clutch sleeve with its flange on top.
  3. Slip the small low-gear key through the holes of the low-gear clutch sleeve, making sure that the hole through the key is in line with the bore of the axle. Hold the key temporarily in position by dropping the indicator rod down the axle through the key.
  4. Holding the indicator rod in position with one finger, remove the axle from the vise and hold it the other way up. Fit the low-gear clutch on to the axle, with the four dogs pointing downwards.
  5. Fit the large low-gear spring and the primary sun pinion, with its four large legs pointing downwards and so engaging the low-gear clutch. (The low-gear spring, the compensating spring, and the clutch spring must be of the same series. If one has to be replaced, the other two must be.)
  6. Slip the indicator rod out of the axle (the low-gear clutch key will now stay in position) and put the axle back in the vise.
  7. Fit the primary planet cage complete.
  8. Drop the compensating spring down the axle, collar first.
  9. Fit the clutch sleeve (flange first) and the sliding clutch with the recess over the flange of the sleeve.
  10. Lift the clutch sleeve and the clutch up to the top of the long axle slot and insert axle key through the clutch sleeve, making sure That the two flats on The key are facing upwards.
  11. Fit the indicator coupling by passing the rod down the axle through the axle key and onto the compensator spring. Note that the indicator coupling must always be fitted before the indicator rod.
  12. Remove the axle from the vise and push the indicator rod into the left-hand end of the axle. Press the assembled mechanism down on a flat surface to force the indicator rod into the axle, at the same time pressing down on the sliding clutch. Then rotate the indicator chain to screw it to the indicator rod. When the chain is felt to be fully screwed home insert a small screwdriver into the slot of the indicator rod and exert a slight extra pressure on the chain, to make sure that the indicator and the rod are both fully screwed together, taking care not to twist off the small threaded end.
  13. Fix the axle in thc vise again and make sure that the clutch slides quite freely on the axle when the indicator chain is moved up and down.
  14. Fit the thrust collar, making sure that both slots fit over the flats of the axle key. Add the thrust washer.
  15. Fit the gear ring, the ball ring (with ball cage), the driver, the axle spring and the clutch spring cap in that order.
  16. Fit the right-hand cone and screw it up finger tight. Then slacken it back half a turn and lock it in that position with the special washer and locknut. On no account must the cone be unscrewed more than half a turn, as that would throw the gear mechanism out of adjustment.
  17. Remove the assembled mechanism from the vise and replace it the other way up.
  18. Fit the secondary planet cage, with the pins upwards and the slots engaging the limbs of the low-gear dog.
  19. Fit the secondary planet pinion.
  20. Fit the secondary sun pinion, with the recess downwards so that the sun pinion engages with the square flats on the axle.
  21. Fit the locating plate and tab washer and tighten the locknut. Turn over the edge of the washer on two opposite sides of the locknut.
  22. Remove the assembled mechanism from the vise, hold it vertically with the planet cage uppermost and pour about two teaspoonfuls of a good quality thin oil into the cage.
  23. Insert the assembled mechanism into the hub shell and screw up the right-hand ball ring finger-tight only.
  24. Make sure that the marks put on the ball ring and the hub flange before dismantling will register properly, and then screw up tightly.
  25. Fit the left-hand cone, washer and locknut in the arrangement noted when dismantling, and adjust the hub as described in The Fitting and Adjustment of Sturmey-Archer Hubs.
  26. Fit any special washers noted when dismantling the hub.
  27. If the sprocket has been removed from the driver, fit the outer dust cap over the driver before replacing the sprocket, and see that the dust cap is properly centered on the flange of the driver. Replace the sprocket and the spacing washers in the arrangement noted when dismantling, and add the circlip.
  28. Replace the wheel in the cycle frame and adjust the gear as described in The Fitting and Adjustment of Sturmey-Archer Hubs.

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