With the amount of outsourcing going on these days getting good roller, tapered roller or Torrington style bearings is a crap shoot. The problem with Chinese bearings of those variety is hardness and base material content. They tend to be too hard and self destruct easily.
Case in point. I try to avoid anything from China for my engines but purchased was sent a set of PRW full roller rocker arms for the last engine build for my GTO. The engine is pretty "high end", about $12,000 worth of parts and machine work, but I topped it with a set of stainless steel full roller rockers supplied by the shop who CNC'd my cylinder heads and supplied the custom ground roller camshaft. Never gave it a second thought just figured they had good success with those items as they supplied them.
Engine goes into service, makes great power, car runs the numbers, all good to go....WRONG!
At the first oil change, apprx 200 miles my magnetic drain plug has about a teaspoon of metal "toothpaste" on it. Hum, where is all that coming from? No negative symptoms other hat a tiny bit of rocker noise, so I lash the valves and run it some more. Next oil change same deal. Re-lash the valves again as it's clattering just a tad more than I think it should and I keep driving and racing the car.
Within about 100 miles it starts clattering again in the valve train so I remove some rockers and low and behold the rollers are pretty loose on the pins, some worn out to .017" clearance. Turns out the pins for the rollers are simply too hard and getting all ground down. PRW gets them back, identifies the issue, says the corrected it (2009) but to this day we still see the same problems with them. I replaced mine with Crower Enduro rockers (USA made and very expensive, no more issues).
For bearings we see the same issues, parts that mate and ride on each other inconsistent in Rockwell hardness and "brittle" materials so they typically do NOT hold up in long term service. Buy Chinese drill bits if you want to see how brittle those materials can be.
We install a good many wheel bearings in the shop and absolutely REFUSE to use the cheap crap they sell at the auto parts stores or on-line. If you are buying $30 bearings you'll be lucky if they last 6 months. Get the $150-200 a piece versions or OEM replacements and they will go the distance every single time.
The problem with small replacement bearings is that outsourcing and re-boxing often makes it difficult if not near impossible to know what you are getting inside the package. Sometimes you can tell by the price, or by visual inspection (most cheap Chinese or other offshore crap is often dark in color on the rollers) but not always.
I've been burned enough times with this sort of thing to be very particular with parts. One last quick story of how this works. A few years ago my Kohler 12 HP engine in the JD-212 takes a dump. Turns out a mouse decided to build a nest on the engine cooling fins and it got hot and melted the ring lands on the piston in that area and the piston failed.
I just to go NAPA and order a piston/rod, hone the cylinder and put the engine back in service. It very quickly develops a double "knock" and ends up getting so loud I have to remove it. I can't find the issue anyplace, piston skirt mics fine, rod bearing to crank oil clearance OK, I'm stumped. So I'm very slowly rotating the engine and when the piston gets to BDC and TDC I see it "rock" in the bore as it changes direction. So I mic the top of the piston and it's like .030" SMALLER than the skirt....WTF???
I pay 20 times as much and source out genuine Kohler parts, reassemble and now quite a few years and hundreds of hours later flawless!
Just some things to ponder on when sourcing out parts. The NAPA Kohler piston did NOT easily identify the Country of origin for the part, I just figured it was a suitable replacement, measured the skirt clearance, ran with it and got bit in the backside pretty hard. Doubled the labor and frustration on a very simple job simply because I used junk parts from offshore........FWIW.......Cliff
