Overhauling An Atom Front-Wheel Hub, with Expander Brake

The overhaul instructions for disassembling and assembling this type of hub are divided into two sections---one for the brake components and the other for the internal parts of the hub.

If you are working on the hub to replace the brake shoes, only the procedures in the brake sections need to be followed. If the internal parts need attention, it is an indication the hub has had extensive use and, rarely, if ever, would the hub be reassembled without installing new brake shoes; therefore, all the procedures should be performed.

Removing The Wheel

1. Support the bicycle in an upright, position from a bracket, a set of hooks, or a rope attached to the garage ceiling, or secure it in an automobile rear carrier rack attached to the back of a car.

• Some bicycles may have heavy washers, serrated on one side, installed on the axle between the fork members on each side to prevent the forks from twisting when the axle nuts are tightened.

• If basket or fender supports are attached onto the axle, a thin washer may be installed between the outside fork member and the axle nut to prevent the supports from twisting when the axle nuts are tightened.

2. Back off the cable anchor bolt nut by turning it counterclockwise

3. Remove the cable from the anchor bolt.
   

4. Loosen the locknut on the adjusting sleeve, and remove the cable and housing from the sleeve.
   

5. Remove the two axle nuts.

6. Slide any basket or fender supports, along with any washers, off the axle
   

7. Remove the axle from the dropouts.

Diasassembly

1. Clamp the axle in a vise, with the brake lever side facing up.
   CAUTION: Protect the axle threads with soft vise jaws to keep from damaging them.

2. Remove the locknut and keyed lockwasher.

3. Lift off the complete brake shoe assembly. Remove the hub and axle assembly from the vise.

4. Clamp a support rod in the vise, and then slide the brake assembly onto the rod, with the brake shoes facing up and the brake lever free at one end of the vise.
   

5. Remove the spring on the stationary post side by grasping the spring firmly with a pair of needlenosed pliers and unhooking it from one of the knobs.

6. Hold one brake shoe in each hand, and then slide both shoes toward the center of the plate and off the brake cam. Remove the remaining spring from the brake shoes.
   

NOTE: If the only work to be performed is to replace the brake shoes, you can proceed directly to Step (9) and install a new set of shoes.

Disassembling the Internal Hub

1. Clamp the hub in the vise, with the jaws gripping the axle.

2. CAUTION: Protect the axle threads with soft vise jaws to keep from damaging them.
   

3. Remove the locknut, keyed lockwasher, and the cone.
   

4. Lift the hub up and off the axle.
   

5. Turn the axle end for end in the vise.
   

6. Remove the thin locknut

7. Remove the two keyed lockwashers

8. Remove the thick locknut

9. Remove two more keyed lockwashers

10. Remove the cone.

11. Remove the dust cap on the brake-shoe side by prying it up with a screwdriver, as shown. Work around the cap and it will pop out. Be careful not to crimp or damage it.
    

12. Count and remove the loose ball bearings from the bearing cup.
    

13. Turn the hub over, and then remove the dust cap on the other side by prying it up with a screwdriver as before.
    

14. Count and remove the loose ball bearings from the bearing cup. There should be nine (9) loose ball bearings on each side of the hub.

15. Loosen the locknut on the brake cam,
    

16. swing the brake lever away from the center of the brake plate, and then unhook the brake lever spring.
    

17. Remove the locknut, brake lever, and spring.
    

18. Remove the cable adjusting sleeve and locknut. Remove the cable anchor nut and bolt from the brake lever.

Clean and Inspect

1. Clean all parts, except the brake shoes, in solvent and blow them dry with compressed air, or wipe them dry with a lintless cloth. Keep all cleaned parts on paper towels to avoid contamination. Cover them with a clean towel to keep grit from entering the internal parts and bearings. A tiny piece of grit can do a tremendous amount of damage if allowed to work on a part over an extended period of time or while the wheel is turning at high speed.

2. Carefully inspect the ball bearings. If any of the ball bearings are pitted (pencil-point dots), show signs of excessive wear (dull spots), or are cracked, all the bearings in the set should be replaced. Replacing the complete set will ensure even distribution of the bearing surface load on all the ball bearings.
   

3. Inspect the bearing cups of the hub for scoring (scratchlike marks), pitting, or excessive wear. Inspect the cones for scored or pitted bearing surfaces and for stripped threads.
   

4. Check the axle and locknuts for signs of damage or stripped threads. Roll the axle slowly across a flat surface and check both ends for being out of-round, or watch the center of the axle to see if it rises off the surface. Either of these indications means the axle is bent and must be replaced.
   

5. Check the dust caps to be sure they were not crimped, bent, or damaged when they were removed.
   

6. Check the brake shoes for breaks or cracks and the linings for glaze and for excessive or uneven wear.
   

7. Check the brake shoe springs for damage, cracks, breaks, or weak tension. You should have had considerable difficulty unhooking the springs from the knobs, which shows that the spring tension is satisfactory. Inspect the brake lever spring for cracks or breaks.

Assembling the Brake Mechanism

1. Place the brake plate in a vise, with the stationary post and brake cam facing up. Set the two brake shoes on the brake plate so the brake-shoe cam ends will ride on the flats of the brake cam.
   

2. If the brake lever assembly was removed, install the brake cam through the brake plate so the brake cam and stationary post are on the same side of the plate. If the brake-lever assembly was not removed, reach under the plate and unhook the brake-lever spring to assist in assembly.
   

3. Turn the brake cam so the flats line up toward the center of the brake plate, allowing the brake shoes to come together as closely as possible.
   

4. Hook one end of either spring over a hook on one side of the cam post.
   

5. Grasp the spring firmly with a pair of needle-nosed pliers, and then stretch it enough to hook it over the other brake-shoe hook.
   Install the other spring in a like manner.
   

6. Remove the assembly from the vise. Hook the brake-lever spring over the inside edge of the lever. If the brake lever and spring were not removed, you can proceed directly to Step 1, Assembling the Hub.
   

7. If the brake lever and spring were removed, place the spring over the brake-cam threaded end, with the small ear of the spring through the small hole in the plate.

8. Install the brake lever on the brake cam so the lever is approximately at a right-angle to the flats on the cam and the lever offset is up away from the surface of the brake plate.
   

9. Thread the locknut onto the brake cam and tighten it against the brake lever.
   

10. Hook the brake lever spring over the inside edge of the brake lever.
    

11. Install the adjusting sleeve and locknut with approximately the same number of sleeve threads visible on either side of the flange. Install the cable anchor bolt and nut on the brake lever.

Assembling the Hub

1. Apply a generous amount of multipurpose lubricant to the bearing cup of the hub opposite the brake shoe side.

2. Place nine (9) ball bearings into the lubricated bearing cup. The nine bearings should fill the cup with just a very small amount of clearance.

3. Position the dust cap over the ball bearings, with the flat side facing up, and then tap it into place with a hammer until the cap is fully seated in the hub shell.

4. Install one of the cones on either end of the axle and turn it to the end of the axle threads.
   

5. Slide two keyed lockwashers onto the axle, with the keys of the lockwashers indexing with the keyway in the axle.
   

6. thread a thick locknut onto the axle snugly against the lockwashers.
   

7. Slide two more keyed lock-washers onto the axle with the keys indexing with the keyway in the axle, and then thread on a thin locknut.
   

8. Tighten the locknut snugly against the lockwashers. Install the completed axle assembly through the hub shell from the side opposite the brake-shoe drum.

9. Clamp the axle in a vise, with the jaws gripping the axle locknuts and with the brake-drum side of the hub facing up.
   

10. Apply a generous amount of multipurpose lubricant to the bearing cup.
    

11. Place nine (9) ball bearings into the lubricated bearing cup. The nine bearings should fill the cup with just a very small amount of clearance as it did on the other end of the hub.

12. Slide the dust cap over the axle and ball bearings, and then tap it into place with a deep socket and hammer.

13. Install the cone on the axle with the bearing race facing down, and then tighten it until there is just a little drag when you turn the hub shell.
    

14. Now back the cone off 1 turn. NOTE: This is the only cone adjustment possible for this side because the cone is covered by the brake-shoe plate.

15. Place a keyed lockwasher onto the axle, with the key indexing with the keyway in the axle. Thread a thin locknut onto the axle. Hold the cone with a thin wrench or cone pliers, and then tighten the locknut snugly.

Installing the Brake Mechanism

1. Install the assembled brake-shoe mechanism. The springs will hold the brake shoes in the retracted position, and this should allow the assembly to slide easily into the hub shell.

2. Install a keyed lockwasher, with the key indexed with the keyway in the axle.
   

3. Thread a locknut onto the axle, and tighten it against the lockwasher and brake plate.
   

4. Clamp the assembly in a vise, with the jaws gripping the locknut on the brake-lever side.
   

5. Grasp the rim of the wheel and try to move it up and down---this is referred to as side play. Remove all but a trace of side play by backing off the locknuts and then tightening or loosening the cone.
   

6. Retighten the locknuts, and then remove the assembly from the vise.

7. Hold each end of the axle with your fingers. Slowly twist the axle with your thumbs and forefingers---the wheel should not turn. If it does turn, the cones are too tight and must be loosened slightly. Only the exposed cone on the side opposite the brake lever can be adjusted. 

8. Back off the locknuts, loosen the cone approximately 1/2 to 1 turn, hold the cone in position with a thin wrench or cone pliers, then retighten the locknuts.<><>
   
   CAUTION: If the cones are adjusted too tight, it will cause binding and scoring of the hub. If the cones are adjusted too loose, it will cause fatigue, which can result in a damaged hub or broken axle.

Installing the Wheel

1. Install the assembled hub and wheel in the front fork dropouts and secure it with the axle nuts.
   

• If the brake plate is anchored to the fork with a stud through the fork and indexing in a channel on the brake plate, rotate the wheel so the stud will slide into the channel as you move the wheel into the dropouts.
  
• If you are working on a bicycle with basket or front fender supports that attach on the axle, slide them and the proper washers onto the axle in the sequence indicated in the accompanying illustration.
  
• Be sure the serrated sides of the washers face toward the hub, as shown.
  

2. Hold the cone locknut on the inside of the fork with a thin wrench when tightening the axle nuts to prevent movement of the cone and loss of adjustment.
   

• After the axle nuts are tight, check to be sure the wheel still turns freely with a minimum amount of side play.
  
• If the cone adjustment was disturbed while tightening the axle nuts, loosen the locknuts on the cone side opposite the brake plate just enough to allow movement of the cone, adjust the cone, and then retighten the locknuts while holding the cone in position.
  
•  If the brake plate is anchored to the fork with a brake strap, position the axle in the forks with the brake plate on the right side of the fork.
  

3. Secure the brake arm to the strap with a mounting screw and nut.
   

4. Guide the cable and housing into the adjusting sleeve. Insert the brake cable in the brake-lever anchor bolt.
   

5. Pull the cable taunt with a pair of pliers, and then secure it with the nut.
   

6. Adjust the brakes by turning the wheel while you tighten the adjusting sleeve until the brake shoes just begin to rub on the drum. Back the adjusting sleeve off 1 turn, and then lock it in place by tightening the locknut.