So after shaking the Internet tree for all the info I could about replacing dry side bearings on my quiet drive MP40s, I realized there was some confusion regarding the bearings on the QD version of the MP40s.
So this post is to put that to rest.
They’re standard, cheaply made, skateboard bearings. Both of them. You can pick up an 8 pack at any skate shop. The ones that were originally in the pump were Chinese knockoffs of Japanese bearing manufacture Nippon Bearing. I wanted to see if I could get a little longer life (both my units started making noise after 2.5 years of <50% power), so I installed some semi-decent quality ceramic bearings; $85 for a set of eight from a local skate shop. (You can get decent bearings for a lot cheaper, or a lot more expensive. These fit the price point I was looking for). Factory Pre-lubed and sealed, with plastic cages. There’s a LOT of stupid marketing gimmicks around bearings in the skate industry. Just pick any major brand and you’ll certainly get good enough for this purpose. I wouldn’t even bother with ceramic, really. I was just curious about how they would perform.
I’ve had them running for about six days now. They’re actually ever so slightly louder than the old bearings were when new. Certainly due to the hardness of the ceramic balls, which should slowly polish the races over time. (My tank is extremely quiet, with a remote sump in the garage. The MPs are the only moving parts in the display room. You wouldn’t be able to hear them at all otherwise.) So I’m pleased. We shall see how the new bearings hold out.
Honestly, there’s almost no load on these bearings. The little spring (the wavy-shaped washer) at one end actually is the most critical part of the rotating assembly. That spring puts an axial load on the bearings to ensure the balls don’t skid. All the thrust generated by the wet side pump is absorbed by your aquarium wall. Bearings need to be loaded, and the rotor by itself doesn’t really provide any appreciable load. So don’t lose your spring! If my dry sides don’t quiet down in a month or so, I’m going to drop a couple more spacers behind the spring to increase the axial load a bit more.
So this post is to put that to rest.
They’re standard, cheaply made, skateboard bearings. Both of them. You can pick up an 8 pack at any skate shop. The ones that were originally in the pump were Chinese knockoffs of Japanese bearing manufacture Nippon Bearing. I wanted to see if I could get a little longer life (both my units started making noise after 2.5 years of <50% power), so I installed some semi-decent quality ceramic bearings; $85 for a set of eight from a local skate shop. (You can get decent bearings for a lot cheaper, or a lot more expensive. These fit the price point I was looking for). Factory Pre-lubed and sealed, with plastic cages. There’s a LOT of stupid marketing gimmicks around bearings in the skate industry. Just pick any major brand and you’ll certainly get good enough for this purpose. I wouldn’t even bother with ceramic, really. I was just curious about how they would perform.
I’ve had them running for about six days now. They’re actually ever so slightly louder than the old bearings were when new. Certainly due to the hardness of the ceramic balls, which should slowly polish the races over time. (My tank is extremely quiet, with a remote sump in the garage. The MPs are the only moving parts in the display room. You wouldn’t be able to hear them at all otherwise.) So I’m pleased. We shall see how the new bearings hold out.
Honestly, there’s almost no load on these bearings. The little spring (the wavy-shaped washer) at one end actually is the most critical part of the rotating assembly. That spring puts an axial load on the bearings to ensure the balls don’t skid. All the thrust generated by the wet side pump is absorbed by your aquarium wall. Bearings need to be loaded, and the rotor by itself doesn’t really provide any appreciable load. So don’t lose your spring! If my dry sides don’t quiet down in a month or so, I’m going to drop a couple more spacers behind the spring to increase the axial load a bit more.
