XT 775 Freehub Failure

The new 10 degree engagement oversize aluminum axles have arrived for Shimano XT in 2008. Great hub. Nice seals, quick engagement, light, and cheap. But what if these things aren't the workhorse we have been so used to.

What Happened?

Just at the end of a hike-a-bike section we were pushing up on our weekly Tuesday Night Ride a short pedal section put me back on the saddle. KLUNK, PING! WTF?

Push the bike the rest of the way to the top of the trail where it comes out to fire road to check out the problem. The freehub was frozen solid! Basically, the bike was now a fixed gear. Nothing we did could free it up. Amazingly, Ron had one of the best suggestions to try to fix this (WTF?). He said to drop the wheel onto the ground against the QR. Dana (a very good Porsche mechanic) and I both figured that this made a lot of sense. Sadly, it didn't work but it was worth a try.

Since any coasting would destroy a bunch of drivetrain parts, I had to break a brand new Dura-ace 10spd chain and coast the bike off the mountain while the group went up and had a great night ride without me. I drank one of my MGD 20's and scootered myself out for the next 20 minutes.

Real fun.

Freehub Failure

Forensic investigation showed that all 4 palls shattered and jammed the mechanism. Never seen this on a ride personally. Usually freehubs fail by skipping rather than seizing.

Dissasembly

Many people have never taken a freewheel or freehub apart. Here are some pics. Note that the new style shimano freehubs require a 14mm allen to remove (used to be 10mm). Buy one today if you don't have one.

14mm allen wrench.




The freehub body cup wrench.