|Creaking ping from hub||Kurt H|
Sep 29, 2002 12:14 PM
|During the last 5-10 miles of a ride the other day I started picking up a creaking ping in my driveline that I couldn't isolate. After pulling the cassette off, I can freewheel the hub backward, then turn it to engage the pawls. In some spots, the hub seems to slip forward VERY slightly and give an ugly ping. In other places, the pawls engage immediately and without noise. I used the grease ports on the freehub and injected grease until nothing but clean stuff came out, so everything should be lubricated with fresh grease, but I still get the noise. Any ideas as to what would cause this?
|Are you sure it's the hub?||Kerry|
Sep 29, 2002 4:01 PM
|There are a huge number of places for noises to come from. Are you doing this pawl engagement bare handed? That's a tiny amount of force on the freehub compared to pedaling. Are you saying that you can reproducibly induce engagement slipage and the same noise you hear when riding? And the pawls engage without any movement (reproducibly) at other points on the rotation? What brand and model hub? How old? How many miles? A lot more information (or at least clarity) would be helpful.|
|Yep, it's something in the hub.||Kurt H|
Sep 29, 2002 4:47 PM
|I can recreate the noise with the cassette and chain removed, with just the wheel sitting on the floor by grabbing the freehub and twisting with my hands. It's a (guessing here!) 97-98 Chorus 8 speed hub. When I grab it by hand, I can twist in some places with no apparent slippage or noise. However, I can freewheel it a "click" or two back and start forward. It start to get hard to turn, pings and pops forwards a tiny (tiny! not wholesale slippage) amount. When I first felt this while pedaling, it just felt like a click in the pedal stroke at a certain point. I had just changed cassettes that day and thought it might be the cassette coming loose. No dice.
I don't really know the mileage on the hub, although I doubt it's overly high. The bike served as a test bike for my LBS for a couple of years, then the owner sold it out to make room for a newer model. Was it probably ridden hard when loaned out? Sure, but it probably didn't see the miles of a bike that is owned and ridden multiple times a week, and it was maintained by the LBS.
If you have any more questions, please fire away. I'd really like to figure out what is causing this and get it taken care of.
|Open things up||Kerry|
Sep 30, 2002 5:04 PM
|Take the freehub apart. It sounds like maybe one of the springs got sprung. Disassembly, cleaning, inspecting, and lubing may solve everything. If a spring is broken or bent, you'll see it easily. An LBS can get replacement springs from Campy USA. Though mine had no symptoms that I noticed, one of my springs was broken after 30K miles or so (Record 98) - may have happened during an overhaul. Everything inside the hub is serviceable without much difficulty.|
Oct 1, 2002 3:26 PM
|It's very suspicious that it appears the same day you changed the cassette - this is no accident. Mechanical things don't suddenly go bad unless there's a catastrauphic failure and then it's pretty obvious. It could be that you've had an incremental progression in the freehub and the new cassette body is amplifying the noise OR it could just be that the new cassette is moving on the body. In any event you're dealing with worn parts. The simple thing to do is just swap in a new freehub body. Of course this is a bit more costly in the Campy world. Even if you pull apart the freehub body and find that things are messed up inside changing the pawls is only half of the picture - the other half is the notches that they fit in. Maybe you'll get lucky and they won't be damaged, but don't count on it. If it is repairable then you'll have a spare unit. However, it could be that the outside splines that the cassette engages on is all messed up - this is common also. In any event it's most likely that it's a combination of all of the above. I'd nicely ask the shop for a decent discount on a new freehub body since it appears the one you got from them is hammered - careful mention of the "internet" word should help push them over the edge if they're hesitant. |
BTW - You've heard the saying about the shoemakers children always being barefoot? Same situation with the LBS loaner bike. Where do you think the shop rats "borrow" parts from when they need them for a race and what do they replace them with? You'd be naive to think that this freehub body was only ridden on Sundays by little old ladies.