In the process of renewing bearings on the M20. The drive side lipped roller is the MRJA25 R325 TH3. The company that supplied an equivalent, offered the Koyo NF305 roller bearing that meets all dimensions but does not have the C3 class fit stamped ( after original requesting). They have declined to offer equivalent as C3 is no longer available from this supplier. There is a KOYO class C3 with a polyamide cage but AI says this is generally only good up to 120C ( which seems a low temperature to me) On further delving in the world of bearings I have found a NSK bearing with the model NF305WC3. This has correct dimensions , a C3 class and a steel cage ( W) - which sounds better for operating temperatures. Wonder if anyone can confirm if this approach is correct . NSK is a world rated company so , as a supplier I see no problems. Loads of 'generic' NF305 with C3 class available but all come from unknown suppliers in far east. Many thanks.
I would not worry about bearings made in China or anywhere else in the far east. There are many millions of cars and motorcycles on the road using them. Fifty years ago we were told to avoid bearings made in Japan as they were cheaply made crap. And before that everything made in Taiwan we were told to not use. The car you drove today regardless of where it was made probably has Chinese bearings in it. All the major bearing manufactures such as SKF have factories in China.
Any bearing of the correct spec is OK. And it does need to be C3 clearance. As for the polyamide cage bearing that is OK. If your M20 gets up to anywhere near 120 degrees C you have bigger problems.
I was replacing the wheel bearings on a Ford a few months ago. It had Timken tapered roller bearings made in China. When I went to the shop to buy new ones, they sold me NSK bearings with no country marked on the bearing but it said made in Thailand on the box.
China made 30 million cars last year, do you think they have bearings made in Europe or the USA? Quality of bearings today regardless of where they were made are far superior to what BSA could buy 80 years ago.
