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rod bearings

Posted: Wed Feb 17, 2010 5:07 pm
by jobuddy
i have a 79 184 engine i plane on putting in my 53 cub.the 184 had broken the crank, but all else was fine.so i got a nice crank from ralgh,but it older crank.there are two types of rod bearings,68 up are narrow and 67 down are wide. the rods are the same, i had them checked.so can i just put 67 down bearing on the newer rod.the bearing fit or to me they do. help please

Re: rod bearings

Posted: Wed Feb 17, 2010 5:15 pm
by Jim Becker
I thought the rod bearigs had to be matched up to the correct rods, crankshaft didn't matter (other than the obvious undersize questions.

Re: rod bearings

Posted: Wed Feb 17, 2010 5:40 pm
by jobuddy
i have not seen a difference,is there a way to know for sure?

Re: rod bearings

Posted: Wed Feb 17, 2010 5:53 pm
by Hengy
Jim Becker wrote:I thought the rod bearigs had to be matched up to the correct rods, crankshaft didn't matter (other than the obvious undersize questions.


Jim is correct on this. It is a difference in rod and not crank that you are concerned with. Have you measured the rod and main journals on the crank to make sure they are round and to see whether they have been turned?

Mike in La Crosse, WI

Re: rod bearings

Posted: Wed Feb 17, 2010 6:10 pm
by Rick Prentice
If I'm reading things right, the parts manual shows the same rod bearing for Fcub eng ser 261718 and above as the 184 rod. Both rods are the same part number. It's the early rods that create the problems-251246R13

Rick

edit: seems the 527458R11 bearings for the 184 rod will fit the 353743R93 crank, which should be the crank number you received from Ralph. Check and see.

Re: rod bearings

Posted: Wed Feb 17, 2010 6:25 pm
by jobuddy
ok let's do it like this 79 model engine broke crank ....older crank to put in it...do i use 67 and older bearings or 68 and newer bearing

Re: rod bearings

Posted: Wed Feb 17, 2010 6:32 pm
by Rick Prentice
If you're using your 184 --527457R11 rod, you'll use the 527458R11(std) bearing, like Jim suggested.

Re: rod bearings

Posted: Wed Feb 17, 2010 6:39 pm
by bob in CT
The bearing follows the connecting rod, not the crank.

Service replacement rods for the earlier crank are the later rod. If you have the later rod, you need to use the later bearing.

These pages explain it. Read what they say about the crank and then see the rod listing. They only have one rod as service replacement so it is backward compatible with the old crank but you need the newer bearing.

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Re: rod bearings

Posted: Wed Feb 17, 2010 6:55 pm
by jobuddy
so there is no difference in the crank

Re: rod bearings

Posted: Wed Feb 17, 2010 7:05 pm
by bob in CT
jobuddy wrote:so there is no difference in the crank


Not according to the parts book. The crank changed too, but you can use the new rods & bearings with the old crank.

The main bearings did not change, so I assume that the cranks can be swapped. You may want to give Clark a call. See his ad for snow plow blocks in the for sale section. His phone number is posted.

Re: rod bearings

Posted: Wed Feb 17, 2010 7:08 pm
by Rick Prentice
Just check things quick with your calipers, that'll confirm things for sure, but according to the information given, should work. Are you doing the work or having it done? Bearing sizes will need to be determined, as you already know.

Rick

Re: rod bearings

Posted: Wed Feb 17, 2010 7:23 pm
by BigBill
I have a question :?: Did the block with the broken crank, was it still running and knocking when it was broken and did it spin any main bearings?? In my experiences with cracked or broken cranks is sometimes the engine will still run and being its way out of balance with the broken crank it will spin the main bearing were most of the vibration is.

Re: rod bearings

Posted: Wed Feb 17, 2010 7:52 pm
by Rick Prentice
Bob, the other thing I noticed was the center (std size)crank bearing. The manual for cub shows number 11 as a #357216R91. That should read number 12, Along with the .002 bearing should be number 12. Also that same bearing for the 184 as number 11 with #376625R91. Not sure if this will creat an issue swapping cranks.

Rick

Re: rod bearings

Posted: Wed Feb 17, 2010 7:59 pm
by bob in CT
Rick Prentice wrote:Bob, the other thing I noticed was the center (std size)crank bearing. The manual for cub shows number 11 as a #357216R91. That should read number 12, Along with the .002 bearing should be number 12. Also that same bearing for the 184 as number 11 with #376625R91. Not sure if this will creat an issue swapping cranks.

Rick


I see that in TC37F both the standard and .002 under are labeled as 11, not 12. I don't think this is anything other than an editing problem as the same crankshaft bearings are used for all C-60 engines. The part numbers are in alignment with the standard crank kit assemblies.

Re: rod bearings

Posted: Wed Feb 17, 2010 8:06 pm
by Rick Prentice
the same crankshaft bearings are used for all C-60 engines.
My C-60 184 manual calls for a different center bearing number than the reg cubs.