I have a Yamaha XVS 650 Silverado with 15,500 miles on it. About three weeks ago the final drive leaked oil and when we opened the drain plug metal pieces came out. We went to the local Yamaha dealer and they said they would call back and we’re still waiting for a call.
When I didn’t hear from them we assumed there wasn’t anything they could do so we went to work on the final drive. What we found was that the pinion gear bearing failed. We believe this was a design flaw. Most differentials that use a pinion gear to drive a ring gear uses conical bearings to counter the force that the pinion gear produced outward as it turns the ring gear. The bearing (Part #93306-30539-00) they used was a ball bearing with a soft metal retainer/spacer and a circular loading spring that held the bearing together after assembly. This retainer was held together by what looked like spot welds or rivets it was hard to tell for sure since it was so beat up. This type of bearing is designed to support forces up and down not to the side. So the pinion gear pushing out against the side of the bearing assembly, put a strain on this retainer/separator and was trying to take the bearing apart. Eventually the retainer broke, part of it went through the gears (lucky it was soft metal) and one part reached out and cut the seal (also lucky). This allowed oil to leak out so we noticed a problem before the hard bearings released into the drive case to tear up the ring and pinion gears. When we got a new OEM Yamaha bearing (Part #93306-30533-00), we found it was redesigned so they must be aware of the problem.
While this does not appear to be a safety issue, a design flaw such as this should be recalled especially since the bike had less than 16K miles on it. We also found on the internet that many others had this same problem. So far this didn’t seem to be a safety issue however, thinking about it; if one or more of those ball bearings make its way into the ring and pinion gear portion of the gear housing the rear wheel could lock up. If that happens at high speeds there could be a catastrophic result.
