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Rebuilding the Sturmey-Archer S3C
Three Speed Coaster Brake Hub
Also see other versions of instructions with parts list etc.
and see Sheldon's comments on Sturmey-Archer 3-speed coaster brakes.
A new hub must be oiled before use through the lubricator on the hub shell. Afterwards add a few drops of oil every month. Use a medium-weight oil, such as Phil Wood Tenacious Oil. Do not use thick oil or grease. Do not use thin spray lubricants.
To disassemble the S3C Hub
- Place sprocket end of axle in a vise. Remove left-hand locknuts 26 and 27, lockwasher 28 and adjuster nut 29. Lift off brake arm and cone assembly 4. Take out ball retainer 8 and brake band 10 from hub shell.
- Unscrew right hand ball ring 20 from the hub shel l(use hammer and punch). Remove unit from vise and withdraw gear from hub shell.
- Remove the brake thrust plate 12 and planet cage pawl ring 13.
- Place left hand end of axle in a vise and remove right hand wheel nut 42, wheel washer, cone locknut 41. Unscrew cone 39.
- Lift off clutch spring cap 36, spring 35, driver assembly 21, ball ring 20. ratchet ring 19, gear ring pawl ring 18 and gear ring 17.
- Unscrew gear indicator coupling 43, lift off clutch 34 and remove axle key 33.
- Take out planet pinion pins 15 and remove planet pinions 14.
- Remove axle from vice, push off circlip 30 from left end of axle and lift off planet cage 16.
POINTS TO CHECK
- Axle for straightness.
- All gear teeth for wear.
- All races for wear.
- All pawls and ratchets for wear.
- Pinion pins, sliding clutch, driver and gear ring splines, planet cage dog (tabs) and brake actuator screw and cam surfaces - for wear.
- Check engagement areas of brake thrust plate and gear ring and ratchet ring.
- Eliminate all movement of brake arm in its recess in left cone - if either component is damaged ( i.e. chipped) replace with new part. NOTE - the brake arm is a press in fit and must remain tight in cone recess.
- All dust caps for damage in - left and right cones - right hand ball ring and driver.
TO ASSEMBLE THE S3C Hub
Prepare in advance the following sub-assemblies:-
GEAR RING Assembly (A)- Fit gear ring pawls, pins and springs. Rivet the pawl pins securely in position.
DRIVER Assembly (B)- Assemble brake operating pawls, springs, pins and circlip in driver. Assemble sprocket dust cap, spacing washers and sprocket in arrangement noted when dismantling the hub, and add circlip. Fit the ball retainer 37 into the driver 21 - (The ring of retainer facing outwards) and fit dust cap 38 - fill dust cap with Shell Alvania No. 3 grease.
PLANET CAGE Assembly (C)- Fit planet cage pawls, pins and springs. Rivet the pawl pins securely in position.
BALL RING Assembly - Fit 24 ( 3/16" diam) ball bearings in ball race of right hand ball ring 20. Fill the ball track with Shell Alvania No. 3 grease and press in the inner dust cap. Make sure the bearings revolve freely after dust cap has been fitted.
BRAKE ARM AND CONE Assembly - Place dust cap 6 over left hand cone 7, and press brake arm 5, tightly into cone slots NOTE- ''Sturmey-Archer'' name must face outwards. Smearhigh temperature grease in the ball track of the left hand cone - (inside the hub shell) .
- Hold the right-hand end of the axle in a vise - the slot for the axle key below the sun pinion - and fit the planet cage 16 - actuator thread uppermost - and push circlip 30 into axle groove. Reverse axle in vice, add the planet pinions 14, and pins 15, making sure than the D shape ends of the pins are facing downwards.
- Fit axle key 33 into axle slot (with the hole of the key facing upwards), slide clutch 34 over axle and key, and screw gear indicator rod 43 into key.
- Fit the gear ring 17 and the previously prepared gear ring assembly. Ensure that the heads of the pawl pins are facing upwards.
- Insert the ratchet ring 19 into the right hand ball ring 20 and place these over the gear ring assembly. (Ratchet ring dogs MUST engage gear ring).
- Fit the previously prepared driver assembly.
- Slide the clutch spring 35 over the axle and fit spring cap 36.
- Screw the right-hand cone 39 on to axle (finger tight), then Loosen half a turn (180°) and lock in position with the washer 40 and locknut 41. N.B. Do not unscrew cone more than 5/8 of a turn, as that would throw the gear mechanism out of adjustment.
- Reverse the assembled mechanism in the vice. Locate previously prepared planet cage assembly over the flats on the pinion pins.
- Fit the brake thrust plate 12 - IMPORTANT - ensure leg of brake actuating spring faces outwards, also the thrust plate must ENGAGE FULLY the dogs on planet cage pawl ring 13.
- Fit the brake band 10 - (the inner band projections must face uppermost) over brake thrust plate 12.
- Remove the assembled mechanism from the vice. Hold the cycle wheel horizontally - insert the assembled mechanism into hub shell from below and screw in the right hand ball ring 20. (Use hammer and punch to tighten ball ring).
- Fit ball retainer (with balls down) in left hand ball race. Fit the left - hand cone and brake arm assembly 4. NOTE- Make sure that the brake band projections and actuating spring leg fit into their respective slots in the cone - i.e. spring leg in narrow slot at 90° to large slot.
- Screw the adjuster nut 29 on to axle (finger tight) . Fit the lockwasher 28 and locknut 27 - (Adjust the hub bearing). A correctly adjusted wheel has a trace of side-play at the rim - none at the hub. [More sensitive test: try to rock the sprocket: in this way, you can get play at the rim down to zero, while the sprocket still turns freely] N.B. Secure adjuster nut 29 after adjustment - center punch lockwasher 28 over the slot in adjuster nut 29, in a new place is necessary. Tighten locknut 27.
- Replace the wheel in the cycle frame. Secure FIRMLY, the brake arm clip 2 on left-hand chainstay of cycle. (N.B. Strengthening Pad 1 is fitted on top of chainstay - Sports Machines). Do not twist the brake arm sideways when tightening clip. Adjust the gears.
[There is a better way to adjust the gears than the following official Sturmey-Archer method]
Place the gear control in No. 2 position. Screw the cable connection 3, until the end of the indicator rod is exactly level with the extreme end of the axle. This can be seen through the "window" in the right hand nut 1. Now tighten locknut 2. ALL GEARS ARE NOW SET.
NOTE - When the brake is applied in No. 3 (High) gear only - the gear indicator coupling will move outwards - slightly. This is caused by the clutch - to which the indicator is keyed - sliding backwards over the ramps on the planet cage. Immediately the brake is released, the clutch moves down the ramp again to drive forward.
Thanks to Jane Thomas, who originated these pages, later revised© 2007 by Sheldon Brown
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Last Updated: by Harriet Fell