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Rebuilding the BSA 3-speed
Internal Hub Gear
Spoke Divider

From the 1954 "Cycling Book of Maintenance"

bsa 3-speed hub

bsa 3-speed hub

Spoke Divider

Spoke Divider

Dismantling a B.S.A. Three-speed Hub

Hold the spindle in a vise with the sprocket downwards and unscrew the adjusting cone A. It will come away complete with its cover, which is a tight press fit, and need not be separated. Then unscrew the end plate B, noting that this has a left-hand thread. Take out the ball-cage C carefully and place it on one side. Next unscrew the actuating nut D on the spindle, noting that this also has a left-hand thread.

The complete gear assembly comprising pinion carrier E and sliding carrier F can then be withdrawn from the hub shell. This can be followed by the spindle J which must be drawn out from the other side of the hub. It will come away with the sprocket and driving member K in position. The sprocket may be unscrewed from the driving member if desired, but do not attempt to separate the latter from the spindle unless this is absolutely necessary, as upon its adjustment depends the correct positioning of the gears, and the cone L is shimmed for end location and securely locked in position.

Ball cages M and N are, however, not accessible for replacement until the driving member is detached from the spindle, and if this work is necessary, proceed as follows:-

bsa hub

Cone cover P is a tight press fit on the cone, and is removed with Service Tools 61-3117 and 61-3118 (see diagram). The cone can then be unscrewed. Note that this screws on to the spindle shoulder, and shims are interposed. On old-type hubs a castellated cone and locking washer were used, whereas the present type of fixed cone is locked into position by the cone cover, which has two flats to engage with flats on the spindle. This cover is a drive fit on the cone. The new cone and cover are interchangeable with the old pattern cone and locking washer.

To separate the pinion carrier E from sliding carrier F, remove the carrier plate, or spring circlip G from its groove H by inserting a screwdriver under the narrow portion indicated by the arrow and prising it out. The pinion carrier can now be lifted out, and the planet pinions R can be removed if their spindles are pushed out. These are an easy fit, and may drop out if the assembly is handled carelessly. When the hub is assembled they are, of course, correctly located endwise and cannot move out of position.

The three sets of pawls and springs can be detached for replacement if necessary. Those on the end plate B operate on pins which are riveted into position, and replacement involves the Installation of new pins. Pawls S and T are held on loose spindles located by split pins, as seen in the illustration, and are, therefore, quickly detachable. The driving-member balls U remain in position in the hub shell when K is removed. They are sprung lightly into their groove, and can easily be pressed out if desired. The correct number of balls, which are 3/16-in. diameter, is 26, and the hub must not be run with less. The driving ratchet V screws into the hub shell with a right-hand thread. The actuating-rod assembly W which lies inside the hollow wheel spindle, is detached by unscrewing the slotted end X and withdrawing the two parts from their respective ends of the spindle. Take care not to overlook the small bush Y and the actuating pin Z. NB. there may also be a grub screw with a hole through the middle at the opposite end of the spring to the small bush Y. This does not screw into the axle, but appears to support the actuating rod in the center of the axle. ( I managed to get mine stuck right in the middle of the axle, which prevented me from reassembling the actuator rod correctly - until I spotted it and got it out - then I didn't know what it was for!)

Assembly

This will present no difficulty if the operations described above are repeated in the reverse order. Ball cages must be replaced the right way round, as shown in illustration, otherwise they will not function properly. If the fixed cone L has not been disturbed, its location will be unaffected, and adjustment, therefore, unnecessary. If it has been removed, any shims between it and the shoulder against which it is screwed must be replaced. They are arranged to provide a dimension of 0.915 in. between the end of the sun pinion at (a) and the end of the driving member at (b). Arrange the number and thickness of shims to ensure this dimension, if necessary, which applies, of course, when the spindle and driving member are in position in the hub shell. Dust cover I must be assembled between the sprocket and driving piece K before reInstallation spindle assembly into hub shell. When a gearcase is fitted the dust cover I is omitted.

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Spoke Divider

Spoke Divider

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Thanks to Jane Thomas, who originated these pages,
later revised © 2007 by Sheldon Brown

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