ORIGINAL: gaRCfield
Apparently there is a short life span of OS rear bearings.
I have never heard of or seen such a problem. Nothing mechanical lasts forever but a good bearing should hold up for a long time so long as it is lubricated properly and not allowed to corrode. I suppose a bearing that is not up to the application could cause problems as well but, like I said, I have never heard of this problem.
Could it be that the noise you heard was the rod rubbing the crank case?
How is the crank pin to rod fit? Is it sloppy? Does the crank pin look bent?
Could a bad bearing have allowed the crank to wobble and caused the contact?
What is the lubricant content and type in your fuel?
Did you over speed the engine at any time?
I called Hobby Services and they said to send it in, that there must have been a machining error and that the rod should not touch the crank case. I think this is what I'll do - it's under warranty and I'd rather not remove material from the con rod, and plus I just got a
NEW VENUS 40 to play with while the VII is down for service
This sounds like the thing to do. They are absolutely right: no engine should have the rod contact any part of the crank case. I would be sure to send them your original bearing too.
I wouldn't sand or grind anything if you can avoid it. Hypothetically though, I would add clearance to the crank case if I had to rather than removing material from the rod. The rod needs to be as strong as possible.
ORIGINAL: Gray Beard
does the new Boca Bearing you got look exactly like the one you pulled from the engine?. I used Boca on my last rebuild and they were different and I had to pull the sheild off the front and the rear had no seals, Boca said these were correct but OS said no way?? I didn't worry about the rear bearing but the way the front bearing was sealed made the engine run real hot very fast until I opened up the engine again and removed the seal. Just wondering if your bearing looked just like the stock one you pulled?
I ordered a set from them too for a .46-AX. The rear bearing they sent was an exact match but their front bearing had a shield on both sides where the OS only had a shield on the front. I removed the shield from one side of the Boca bearing because I had concerns about oiling. Truth is, I could have re-used the original bearings but I had it apart so I figured I would replace them. The Boca bearings are great but I have found that I can get the from a local bearing supplier for the same or less money and no shipping costs.