<HTML><FONT FACE=arial,helvetica><FONT SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="0">In a message dated 8/5/03 4:18:50 AM Pacific Daylight Time, rcaerobob@cox.net writes:<BR>
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Assuming that OS doesn't offer a solution to lubrication of the rear bearing on the 1.40, what other options are available?</FONT><FONT COLOR="#000000" style="BACKGROUND-COLOR: #ffffff" SIZE=3 FAMILY="SANSSERIF" FACE="Arial" LANG="0"><BR>
</FONT><FONT COLOR="#000000" style="BACKGROUND-COLOR: #ffffff" SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="0"> What mods could be made to the crankcase to permit more oil flow back there?</FONT><FONT COLOR="#000000" style="BACKGROUND-COLOR: #ffffff" SIZE=3 FAMILY="SANSSERIF" FACE="Arial" LANG="0"><BR>
</FONT><FONT COLOR="#000000" style="BACKGROUND-COLOR: #ffffff" SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="0"> Would increasing oil content of fuel make any difference?</FONT><FONT COLOR="#000000" style="BACKGROUND-COLOR: #ffffff" SIZE=3 FAMILY="SANSSERIF" FACE="Arial" LANG="0"><BR>
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</FONT><FONT COLOR="#000000" style="BACKGROUND-COLOR: #ffffff" SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="0">If the real core problem is undersizing of the bearing for the load application the motor endures, then a real fix would be a redesign of the crankcase to use a larger and wider bearing. Pretty unlikely that would happen, I would guess.</FONT><FONT COLOR="#000000" style="BACKGROUND-COLOR: #ffffff" SIZE=3 FAMILY="SANSSERIF" FACE="Arial" LANG="0"><BR>
</FONT><FONT COLOR="#000000" style="BACKGROUND-COLOR: #ffffff" SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="0"> So what's the solution besides keeping the bearing suppliers well-funded??</FONT><FONT COLOR="#000000" style="BACKGROUND-COLOR: #ffffff" SIZE=3 FAMILY="SANSSERIF" FACE="Arial" LANG="0"><BR>
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Bob Pastorello, Oklahoma<BR>
NSRCA 199, AMA 46373<BR>
<A HREF="mailto:rcaerobob@cox.net">rcaerobob@cox.net</A><BR>
<A HREF="http://www.rcaerobats.net/">www.rcaerobats.net</A><BR>
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Continued - A larger bearing is a double edged sword, larger bearing means larger balls and larger diameter races and thus higher surface speed, between the balls and races at a given RPM. I'm not enough of a mechanical engineer to say where the trade off is, but I know in other engines larger bearings have not solved the problem (OS .61). The solution is a tapered/timpkin bearing, I've tried to find a match, but no success, the problem is that we are using a ball bearing in the wrong application, auto manufactures tried this for years on wheel bearings, tapered bearings solved the problem. I can get roller bearings that fit, but they will not stand the thrust load. Again, stainless has worked for me, several different engines and I have a lot of data/experience, many thousands of flights on mine and others engines, most recently the OS 140 and believe me I've tried all the "fixes" Interestingly I just changed the bearing in a new OS 140 RX, just because it had 140 flights and I was planning to go to a contest this weekend, bearing seemed fine. Turns out that it is a stainless bearing, with the seals removed (I've never found a stainless without seals). The bearing was fine, no corrosion, I jumped the gun. No for the rest of the story I had this engine apart for other reasons and it was a year or so back so it's possible that I just changed the bearing because I was in there, but I think I would remember and I keep pretty good records so that is a doubtful answer. It will be interesting to see it the new engines start showing up with stainless bearings or if this was a fluke, maybe they were out of bearings at the factory and used the bearing from the EFI or...<BR>
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Bob <BR>
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Bob</FONT></HTML>