Disassembly of SRAM i-9.pdf

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Disassembly of SRAM i-Motion 9 Internal-gear hub, disc-brake version (hub kindly supplied by David Chase).

Document prepared by John S. Allen, version of March 2, 2014. Most photos are mine; some are by Aaron Goss,

http://rideyourbike.com.

Please read

http://sheldonbrown.com/i-motion-9.html

in connection with this document.

David is strong and weighs 220 pounds (100 kg). He had used the hub for about a year when it locked up so he could not

pedal, though he could coast. He gave me the hub already removed from the shell. The SRAM 2010 technical manual,

http://tinyurl.com/o7yxlta

, covers removal from and replacement in the shell for all versions of the hub. Disassembly as

shown in this document begins with the right side upwards and the left end of the axle chucked in a vise.

The plastic bearing retainers were broken. It is possible that the hub failed due to a bearing retainer, though another

problem revealed itself during disassembly. Keep track of small parts (especially pawls) when disassembling!

SRAM has never sold (or named) individual most internal parts for this hub, or to my knowledge, provided information

about rebuilding, so I am going to have to invent names for parts.

1 - Remove right-side locknut

2 - Remove washer. This will come off along with the pulley/ bearing cone assembly if not removed separately.

3 - Remove pulley/ bearing cone assembly

4 - View of right side of hub after pulley/bearing cone assembly has been removed. The driver is now exposed. The right-

side smaller bearing cup is visible, just inside the 3-lug fitting for the sprocket. David had already disassembled the hub

this far, and the bearing retainer which belongs here is absent.

5 - Remove driver. The cone race of the larger right bearing is on the underside of the driver, not visible in this photo.

The cup for that bearing is press-fit into the hub shell.

6 - Remove dog ring. The teeth on its inner face are a ratchet for pawls, not a ring gear. The lugs engage the planet cage

(see step 24).

7 - Remove right-side pawl ring. The four cylindrical protrusions mate with the driver, and the pawls engage the dog ring.

8 - Remove shifter cam. The right side of the cam engages the pulley of the pulley/bearing cone assembly. One of the

four lugs is cut away to make room for a small spring on the back of the pulley where lugs engage the cam. The left side

of the cam pushes parts inside the hub leftward to shift gears. Orientation of the cam matters. Make a note of it.

9 - Now I have turned the hub over and we are looking at the left side. A pawl and a pawl spring are missing, but one

pawl remains, oriented to drive the wheel by engaging the ratchet inside the left end of the hub shell. The two narrower

recesses at 90 degrees to the pawls probably engage the coaster brake mechanism in the coaster-brake version.

10 - Remove crush nut. This nut is deformed during assembly to prevent it from unscrewing. Replacements are available

from Aaron’s Bicycle Repair,

http://rideyourbike.com.

Or send your hub to Aaron, as he has a stock of hubs to

cannibalize and can do an expert repair.