Monday, July 20, 2015

The Answer

No one got it right.
Last Friday I posted this image and asked anyone that wanted to try and figure it out. Well, no one got it completely right, but that's okay. That wasn't the point anyway. The point, for me, was that this represents a victory in terms of fixing a problem. Here's the back story and the answer will become evident as we go along here.....

The ticket was for a Beargrease rear wheel which the customer had blown up the SRAM XD free hub body on. When I say "blown up", I mean as in the state of the freehub was that it was demolished. The bearings had even fallen out which caused the cassette, an XX-1 10-42T 11 speed one, to just wobble around. The lock ring teeth, which the tool needs to interface with to remove said cassette were 80% sheered off. Gone. It looked pretty grim.

So, after some thought, I decided the course of action here was to separate the free hub driver/cassette as a unit from the hub. Then the customer would have to buy a new XD driver and cassette, but hopefully the hub would be salvaged. I set out to disassemble the hub axle, hoping that I could pull the part off the drive side of the axle through the cassette. Conveniently, the sheered teeth, which would have allowed me to separate the cassette from the driver, actually helped here as that made the "hole" bigger so I could extract the axle end after unscrewing it. Then I used a mallet, pounding the non-driveside axle end, and in turn punching out the driveside bearing in the hubshell. This pushed everything off, including the cassette/XD driver, and then I could extricate the axle from the driver body. There! After reassembling the axle, the hub will be as good as gold with a new XD Driver and X-1 cassette.

So, the final bit was getting the inside bearing race for the XD driver off the axle shaft, which it was jammed on. (Yes, the XD driver had basically exploded into two bits- the main driver body and this race.) I opened the jaws of a vice just enough, covered them with a terry cloth, to avoid marring the axle, and carefully tapped the driveside of the axle, using the vice jaws as a bearing press, and drove the bearing, and subsequently the inner XD driver bearing race, off the axle shaft with no damage.

The image shows the axle, drive side bearing, and the separate XD inner bearing race.


james said...

What caused the self destruction, and is it just going to happen again?

Guitar Ted said...

@james: The customer was in a couple of events, one having pretty wet, muddy conditions, and this is what he believed put the end to the XD driver.

In my opinion, I feel it is the high torque/leverage generated by the largest cassette cogs in concert with how the cassette interfaces with the XD driver, the narrow stance of the bearings on the driver, and the poor conditions it was used in. That said- It is a mountain biking product and perhaps it should be able to survive that sort of an environment without imploding.

That's my opinion

james said...

I wonder if hub longevity/durability will be compromised with many manufacturers going to a 40+ rear cog? Hmmm