Nankai Hub Maintenance

ORIGINAL JAPANESE PAGE -- http://yottaka3.infoseek.livedoor.com/nankai.htm

Yottaka3's BMXFAN WEBSITE -- http://yottaka3.infoseek.livedoor.com/

Photos and diagrams are reproduced courtesy of Yottaka3


1.0 Tools
Tools from left to right: 1. Techno Nankai cone wrench (24mm) 2. Adjustable wrench 30mm 3. Grease 4. Parts cleaner or oil 5. Needle nose pliers (not shown)
1.1 Freecoaster Hub Structure
1. Locknut 2. Arm nut 3. Arm washer 4. Left cover 5. Ball Retainer (large) 6. Brake cone 7. Clutch spring 8. Arm brake washer 9. Clutch screw cone 10. Driver 11. Ball retainer (large) 12. Ball retainer (small) 13. Cone 14. Locknut
This photo -- all parts after complete dismantling.
1.2 Removal -- Dismantling
Dismantling begins from the driver's side of the shaft. Part 13 -- The right side cone is the part that controls the rotation of the hub. Adjustment of the cone and the locknut position will be detailed in a later section. The locknut holds the cone in the correct position. As shown in the picture at the right, use the 24mm cone wrench on the cone and the adjustable wrench on the locknut. Rotate the 24mm cone wrench clockwise while moving the adjustable wrench counterclockwise to loosen the locknut.
Right-side locknut in loosened position.
Continue and remove the locknut from the shaft as shown.
1.2.2 Removal of Ball Retainer(small), Driver, Ball Retainer(large) #10,11,12.
Begin removing parts from the right side of shaft. Photo -- ball retainer (small).
Photo -- Driver and ball retainer (large).
1.2.3 Removal of Shaft from Hub body.
At this point all the right-side parts have been removed from the shaft. The shaft can now be removed from the Hub itself by pulling it from the left.
The removed shaft.
1.2.4 Left Side Parts Removal
Remove the clutch screw cone (part 9), the brake washer (part 8), the ball retainer (large)(part 5), and the clutch spring (part 7). Clutch spring (part 7) is located inside the brake cone. Needle nose pliers can be used to remove it. For normal maintenance the remaining parts on the shaft do not need to be removed.
If you are replacing the shaft, however, you will need to remove the remaining left-side parts shown in the photos at the right.

If you have removed everything from the shaft, it should look like the photo at the right.
1.2.5 Parts Inspection
Parts that tend to wear should be examined. First, remove all the old grease using parts cleaner or regular oil. Examine the parts. The small and large ball retainers (part 5, 11, and 12) should be examined closely. The clutch spring (part 7) should be examined for any deformation of shape or defects. if there are any problems with these parts they should be replaced. They can be bought seperately and are not expensive. If you find any damage or deformation of the hub body you should buy a new FREECOASTER HUB.
1.3 Rebuild
Rebuilding is primarily accomplished by working in reverse order. Please note the following. NOTE: If you find the brake cone (part 6), arm nut (part 2), or locknut (part 1) are loose, they must be tightened as shown in the photo at right.
Do not confuse the direction of the clutch spring (part 7) or the three ball retainers (part 5, 11, and 12). The tapering side of the retainers should be directed towards the center of the shaft as shown in the photo.
You must grease the three ball retainers (part 5, 11, and 12) and the clutch spring (part 7).
1.4 Adjustment
After rebuilding, you must check the motion of the hub. Rotation is adjusted by tightening the cone. Just how much tightening is needed is best learned through experience and is therefore difficult to judge. The following section describes a method for checking the action of the hub.
1.4.1 Method for Checking the Action / Rotation of the Hub
After making an adjustment of the cone and locking its position with the locknut, the hub and wheel must be put back onto the bike frame. Then check the wheel for any movement in the direction of the shaft axis. If there is any movement, the wheel and hub must be removed once more, and the cone and locknut assembly must be tightened. Once the locknut has been adjusted to a point where the hub has no undesired side-to-side play, the hub adjustment is complete. Finally, the wheel must be adjusted. The standard or optimal condition is a point where the bulb's weight automatically causes the wheel to turn. This adjustment is time-consuming and difficult to perfect for the beginner. After some effort and experience, this adjustment will become easier.