#1 connecting rod bearing

[Kenk]

Finally got time to pull the 48 cub engine. #1 connecting rod bearing is toast. This pic is of the #4 bearing. Is it standard size or 20 over? Thanks for your help.

[k hutchins]

Ixm no expert, but l just replaced all of my bearings and they were all stamped STD. I would guess it is an oversized.

[Glen]

Hi,
The .020 on the bearing means it is .020" undersize.
Below is a page from the Cub parts manual showing the bearings. Your part number is almost the same as it shows for a .020" undersize bearing, except they added another 1 at the end of the number.
I don't know what the change was, it could be because the parts manual is newer than the bearings you have, but I don't know.

There are 2 different part number bearing for each size because IH changed the connecting rods in newer engines.

http://www.farmallcub.info/manuals/cub_ ... 012-04.jpg

I would measure the crankshaft while it is apart, and check for wear.

[Nelson 634]

Your both saying the same thing. It's a glass half full vs. half empty thing. The bearing is made .020 thicker for a crank which .020 worn away. Glen is calling it a bearing for a .020 under sized crank. The bearing is .020 over in size.

[Jim Becker]

Standard terminology is to call that undersized. The crankshaft has been reground to .020 smaller than standard. The hole through the middle of the bearing insert is also .020 undersize. By the way, having #4 .020 undersize is no guarantee that #1 is .020 undersize. Check each rod journal separately.

[Kenk]

Thanks for the replies. I will check all the Bearings and measure. Damage on #1 could be an issue. Thank you again.

[Glen]

Hi,
Nelson 634, I wasn't trying to disagree with k hutchins about what to call the bearing, if that's what you thought, I was simply using the term I normally use, to tell Kenk that it isn't a standard size bearing.

I know people on here use either term for the bearings.
The Cub parts manual calls them U/S after each listing for the undersize bearings, meaning undersize, I suppose.

[Magnum]

So this may be a silly question , but here it is anyways , what tipped you off to do the inspection of the bearings ? Knocking ? Low oil psi ? All the above ?

[Jim Becker]

So this may be a silly question , but here it is anyways , what tipped you off to do the inspection of the bearings ? Knocking ? Low oil psi ? All the above ?

This is kind of a part two to a story from before you joined.
viewtopic.php?f=1&t=108333&p=859473

[Magnum]

Ok thanks all caught up now

[Eugene]

So this may be a silly question , but here it is anyways , what tipped you off to do the inspection of the bearings ? Knocking ? Low oil psi ? All the above ?

This is kind of a part two to a story from before you joined.
http://www.farmallcub.com/phpBB2/viewto ... 3&p=859473

And a lack of good compression and/or poor engine performance. I think most would be found during the inspection in preparation for an engine overhaul.

[tst]

low oil pressure is more likely main bearings, knock is most likely rod bearing

[Kenk]

Sorry for the slow reply. Weather here is nice so building an equipment shelter.
Main bearings look great. Rod bearings are good but number 1 is toast. I will not be able to remove the crank as the pully is welded on. Guess they needed to make sure it stayed in place. Go figure. Have started to clean up the journal to see if it’s possible to use it. Otherwise I will cut it up and get a new one. Thanks for the replies.

[k hutchins]

I just replaced all 3 journal bearings, and all 4 piston arm bearings and never removed the crankshaft.
I Plastiguaged the old bearings to see where l stood, and found that none were that far out of tollerance. So l replaced with new STD bearings. For the top half of the journal bearings, l was able to "drive" them out using a piece of strapping. Then just slipped the new one in lightly tapping if it was tight.
I was working with the block upside down on a stand, it might be more difficult working from underneath.

Good luck

[tst]

An easy trick to replace bearings in the motor while you are doing it from underneath it, use a screw or nail, low profile head, put it in the oil hole of the crankshaft, turn crank and it will walk the bearing right out, same to install once it is started