Crank journal size math

[Doug 13]

So I understand that the std crank Journal size is 2.488. For easy math I used 3 decimal places to get a rough idea. My crank shells have a #'676 010. My crank measurements are 2.242 front, 2.242 middle, and 2.244 rear. I did the math but not sure if the numbers are correct for a .010 under crank. Thanks

 

[wore out]

(quoted from post at 11:03:09 10/06/22) So I understand that the std crank Journal size is 2.488. For easy math I used 3 decimal places to get a rough idea. My crank shells have a #'676 010. My crank measurements are 2.242 front, 2.242 middle, and 2.244 rear. I did the math but not sure if the numbers are correct for a .010 under crank. Thanks

2.488'' - 2.243'' (average of your measurements) = 0.245'' (just short of 1/4'') something wrong in the numbers somewhere!

 

[wore out]

I looked up the main journal size, should be 2.2485'', so 2.2485'' - 2.243'' = 0.0055.

IF I did the math correctly your journals are five and a half thousandths undersized.

Did did you measure at several different points in case the journals ore wore ''out of round''?

 

[John Deere D]

What instrument did you use to measure the Journals.?...Micrometer I hope...

Was the Instrument ZEROED....as in checked with precision standard gauge......or did you use a Micrometer that is
set for
ie.......2.000 > 3.000 and did not check to verify that Micrometer was Zeroed.?

Bob..

 

[TheOldHokie]

(quoted from post at 14:53:35 10/06/22)
I looked up the main journal size, should be 2.2485'', so 2.2485'' - 2.243'' = 0.0055.

IF I did the math correctly your journals are five and a half thousandths undersized.

Did did you measure at several different points in case the journals ore wore ''out of round''?

The main journal size I have is 2.248-2.249 so 2.2485 is the midpoint of the tolerances. Your arithmetic is right. The crank is .005 under and needs to he ground .010 under for .010 under shells.

TOH

 

[Doug 13]

(quoted from post at 14:15:20 10/06/22) What instrument did you use to measure the Journals.?...Micrometer I hope...

Was the Instrument ZEROED....as in checked with precision standard gauge......or did you use a Micrometer that is
set for
ie.......2.000 > 3.000 and did not check to verify that Micrometer was Zeroed.?

Bob..
<img src=https://www.yesterdaystractors.com/cvphotos/cvphoto137457.jpg>

<img src=https://www.yesterdaystractors.com/cvphotos/cvphoto137458.png>

Yes, my numbers are truly off. I used a old borrowed micrometer. After talking with the owner he confessed to dropping them several times. So I will buy my own.

 

[TheOldHokie]

Deleted

This post was edited by TheOldHokie on 10/07/2022 at 01:23 am.