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« on: March 11, 2012, 02:22:10 PM »
On the cleaence related to fit or preload I entered them into a woork book for comparison. I will futher entr data and expand the book.
What I though Honda was doing may not be the case. and futher investagation and discussion is warrented. I will call a bearing company I did some work for which schooled me in bearings a while back and get there opion. I I read the info collected correcty than theres a issue. Since engine are runnig fine I have to be wrong. I need to understand this better.
Looking at the pics and pic of the work book see it backward when it come to propper choice.
I have used bearing that came from a factory sealed engine that are what to be an unmarked or CN bering which in the case of the pilot is a prloaded press fit on both sides. Then a rebiuld factroy set that has the C3 on it which is also a press fit.
Looking at the chart with the clearences the CN and C3 has about the same amount of clearence built in to them comparing min and max. Comparing the minium clearence numbers uninstalled the CN or what I think is the factory bearing Has a tighter tolerence by.008 over the C3. So why did honda change this, if this is the case. I assume they did it to allow for more room for things to move or be out of alignment and still run within a given tolerence. This is fine and and I would say good in a tight engine for our application.
Now lets look at a what if. As Live wire has mentioned on the 350 cases and I have seen in pilot engines the fitment of the bearings is what we call Loose push inand crank slide on. Knowing the preload is less would the CN be a better choice for the use of a locking agent and still maintaing a good tolerence or amount of clearence. I look at it as if the C3 was used there would a greater chance of failure based on the lack of preload at higher load. This would indeed change the temapture balance to higher number. This is where a higher grade at a given amount of two clycle oil plays a part in the bearing survival rate. It can cussion the load or transfer it without break down at a higher temp.