Timken use to offer a lot of thier Timken tapered roller wheel bearings in many different quality of bearings with the same part number except the suffix. I complained once about the price of a set of wheel bearings on my small single engine airplane when I had the fisrt annual inspection done on it, the shop charged me around $38.00 for the bearing and race, the same part number at the local auto parts store was $8.00
![work work](/ubbthreads/images/graemlins/custom/work.gif)
The auto parts bearing had a A suffix and the airplane bearing had a G suffix on it
![shock shock](/ubbthreads/images/graemlins/custom/shock.gif)
The FBO shop mechanix explianed the difference was in how close the tolerances where between the two, .0010 compared to .0001
![work work](/ubbthreads/images/graemlins/custom/work.gif)
That airplane took off and landed at 85 MPH + and the tires where very small in diameter so the wheel bearings on landing would go from a dead stop to real fast in a very short period of time
![work work](/ubbthreads/images/graemlins/custom/work.gif)
I put a bunch of time in that airplane, 1100+ hours and a lot of take offs and landings in that time and never had another wheel bearing failure after the first annual, I did remove and repack them every 100 hours per the factory recommended servicing
![thumbs thumbs](/ubbthreads/images/graemlins/custom/thumbs.gif)
That airplane had sat in northern CA for in a hangar 18 months on the north end of San Fransisco bay area for 18 months before I bought it so the salty air moisture content up there may have cause the pitting on the bearings and races
![confused confused](/ubbthreads/images/graemlins/custom/confused.gif)
I now buy the recommended bearings from the manufacture for that specific application