kartracer55
Well-known member
- Joined
- Jun 21, 2005
- Messages
- 5,317
I just got one of my engines back from a new builder. He sent back the parts he replaced... See part number 30 on the diagram...
These are the two crank bearings. They see speeds as high as 15,000 RPM (occasionally higher when Im feeling lucky). These are crank bearings, so they are supporting the force of combustion on top of the speed.
So heres my question...
The norm seems to be a 6304 bearing, unsealed/shielded
Factory bearings were "koyo" Made in Japan 7 ball with a rivited metal cage
The next build around the engine had two Different types of bearings, which prompted the post.
On one side was an SKF 6304 "RSA" bearing. 7 ball with a PLASTIC race. The other side had a German Made RHP "130404" "Y.N" double row bearing with easily 20 smaller balls and a plastic cage. The kind where the inner race and cage move to gether and can "twist" so to speak in the outer race. (what are these called, and how do I read that number... is the 404 the bearing series? I thought 400 was supposed to use larger balls, not smaller)
Why would the builder use two different types of bearings like this? My one theory is that he wanted to crank to be sort of "self aligning" if you will. The current builder called and said the machine work was awful and nothing was sitting square to the bore. Was the one bearing used to possibly account for the inability to do the advanced machine work necessary? Or is it just what the guy had on hand at the time?
Im not sure what the latest builder used for bearings, Ill try to remember to ask when I call next week.
What type of race/cage would be Ideal for this situation? The builder that did this engine is apparantly one hell of a machinist so I know the crank is now square to the case. Would it be beneficial to use these double row bearings like this or should I go with traditional ball bearings? I am considering purchasing a set of high-end ceramic bearings to be used for the two main crank journals among other things on the rebuild for my main engine over the winter.
Also, What are the advantages to having 7 balls as opposed to 8? (listed as 304 series vs 204 series... and where does the "6" in front of the standard number come from???) Which would be better for me?
What are the advantages to having, say a 2 piece metal cage as opposed to a plastic cage that snaps in the bearing like the one SKF I pulled out?
Anyother info would be appreciated as well. Im trying to learn whatever I can so that I can start making decisions for myself instead of having to post my questions all over the internet.
Thanks
Jim
These are the two crank bearings. They see speeds as high as 15,000 RPM (occasionally higher when Im feeling lucky). These are crank bearings, so they are supporting the force of combustion on top of the speed.
So heres my question...
The norm seems to be a 6304 bearing, unsealed/shielded
Factory bearings were "koyo" Made in Japan 7 ball with a rivited metal cage
The next build around the engine had two Different types of bearings, which prompted the post.
On one side was an SKF 6304 "RSA" bearing. 7 ball with a PLASTIC race. The other side had a German Made RHP "130404" "Y.N" double row bearing with easily 20 smaller balls and a plastic cage. The kind where the inner race and cage move to gether and can "twist" so to speak in the outer race. (what are these called, and how do I read that number... is the 404 the bearing series? I thought 400 was supposed to use larger balls, not smaller)
Why would the builder use two different types of bearings like this? My one theory is that he wanted to crank to be sort of "self aligning" if you will. The current builder called and said the machine work was awful and nothing was sitting square to the bore. Was the one bearing used to possibly account for the inability to do the advanced machine work necessary? Or is it just what the guy had on hand at the time?
Im not sure what the latest builder used for bearings, Ill try to remember to ask when I call next week.
What type of race/cage would be Ideal for this situation? The builder that did this engine is apparantly one hell of a machinist so I know the crank is now square to the case. Would it be beneficial to use these double row bearings like this or should I go with traditional ball bearings? I am considering purchasing a set of high-end ceramic bearings to be used for the two main crank journals among other things on the rebuild for my main engine over the winter.
Also, What are the advantages to having 7 balls as opposed to 8? (listed as 304 series vs 204 series... and where does the "6" in front of the standard number come from???) Which would be better for me?
What are the advantages to having, say a 2 piece metal cage as opposed to a plastic cage that snaps in the bearing like the one SKF I pulled out?
Anyother info would be appreciated as well. Im trying to learn whatever I can so that I can start making decisions for myself instead of having to post my questions all over the internet.
Thanks
Jim