Joined
·
4,404 Posts
Pictures of recent "preemptive" rebuild posted for the FD's owner and anyone else who might be interested.
This FD is off a 2001 with 56K miles. The owner had the FD off the bike to do other things, and decided to have me do a preemptive rebuild. Owner reported no metal flakes in the drive lube and no problems with the drive.
He is lucky, this drive was going to fail. And given the condition of the shims, I am very suspicious that this FD had a catatrophic failure sometime in the past and a new bearing was installed.
The bearing looked fine, but after removal from the crowngear a slight roughness could be felt when rotating by hand. Upon cutting the bearing open two significant areas of pitting on the inner race were readily visible. The outer race and balls looked okay, but my inspection of the balls was rather cursory; given the condition of the inner race, it was just a matter of time before total failure.
I don't know if the current owner is the original owner and I have no additional information regarding the FD history at this time. But I am curious. The shims looked like shims that have been through catastrophic failure which the current bearing did not experience. This makes me think that the FD was rebuilt at one time using the existing shims. The 0.60mm shim has the scoring around its circumference consistent with the bearing spinning in its seat, and there is a pitted area the 0.60mm shim where it got torn during spinning.
Likewise, the 0.15mm shim has an area that is shredded, again consistent with a spun bearing:
This FD is off a 2001 with 56K miles. The owner had the FD off the bike to do other things, and decided to have me do a preemptive rebuild. Owner reported no metal flakes in the drive lube and no problems with the drive.
He is lucky, this drive was going to fail. And given the condition of the shims, I am very suspicious that this FD had a catatrophic failure sometime in the past and a new bearing was installed.
The bearing looked fine, but after removal from the crowngear a slight roughness could be felt when rotating by hand. Upon cutting the bearing open two significant areas of pitting on the inner race were readily visible. The outer race and balls looked okay, but my inspection of the balls was rather cursory; given the condition of the inner race, it was just a matter of time before total failure.
I don't know if the current owner is the original owner and I have no additional information regarding the FD history at this time. But I am curious. The shims looked like shims that have been through catastrophic failure which the current bearing did not experience. This makes me think that the FD was rebuilt at one time using the existing shims. The 0.60mm shim has the scoring around its circumference consistent with the bearing spinning in its seat, and there is a pitted area the 0.60mm shim where it got torn during spinning.
Likewise, the 0.15mm shim has an area that is shredded, again consistent with a spun bearing:
Attachments
-
173.3 KB Views: 801
-
175.2 KB Views: 755
-
176.9 KB Views: 779
-
169.1 KB Views: 786