Rod Bearing Questions

[Noah H]

Took a look at my bearings. No 2 is worn very badly .04 all the others read .0015 on the plastiguage 

 

I’ve heard 2 and 5 go bad the fastest due to an oiling design. So they were the first ones I checked.

 

my question is, are these standard bearings? I am not seeing STD anywhere.. 

 

i cannot get a good picture but I can read what they say. 
 

#2 2568B010N 

 

#5 13- OB 60M MG 

Any Ideas? 

 

next step.. mic the crank. 

[DJK]

I have a set of TRW .002 rod bearings if you are in need of them.

[Sniper]

my main bearings were not stamped with any size designation either, but there was shim stock underneath them.  I think that was common back then.

 

My rods were marked with .001.  Here a link to the thread on that tear down

 

 

 

[keithb7]

Mic the crank is the way to go. For some of us rookies, I find that taking 6 or so readings with a mic on the crank, remove and re-set the mic each time. Write down your 6 measurements. Add them all up and divide by 6 should get you a good average. A difference .002 to .004 can be easy to get a bad reading. If I recall main bearing is 2.5", rod bearing 2 ⅛".

 

What was your oil pressure?

Edited July 14, 2022 by keithb7

[kencombs]

8 minutes ago, keithb7 said:

Mic the crank is the way to go. For some of us rookies, I find that taking 6 or so readings with a mic on the crank, remove and re-set the mic each time. Write down your 6 measurements. Add them all up and divide by 6 should get you a good average. A difference .002 to .004 can be easy to get a bad reading. If I recall main bearing is 2.5", rod bearing 2 ⅛".

 

What was your oil pressure?

Excellent advice.   Crank measurement drives the bearing choice anyway.  And that's the only way to determine if it is out of round or tapered in addition to the basic size.

[keithb7]

If you used plasti-gauge, a long enough strip should give you a good visual on any tapered wear. 

[Noah H]

1 hour ago, Sniper said:

my main bearings were not stamped with any size designation either, but there was shim stock underneath them.  I think that was common back then.

 

My rods were marked with .001.  Here a link to the thread on that tear down

 

 

 

Very helpful thanks sniper..

[Noah H]

2 hours ago, DJK said:

I have a set of TRW .002 rod bearings if you are in need of them.

are these the bearings I would use if my crank is slightly worn?

[keithb7]

Figure out if you have taper wear. You likely do. How much taper?  Take good measurements then come up with a plan upon review.  The quick easy solution is not just popping-in 0.002 bearings on the crank as it sits now. 

[kencombs]

2 hours ago, keithb7 said:

If you used plasti-gauge, a long enough strip should give you a good visual on any tapered wear. 

Only if the taper is uniform.   Not unusual to find taper only on the portion of the crankpin that is up when the cylinder is on the power stroke.  Usually accompanied by overall wear though.  If that portion happens be under the rod cap with plasti-guage it will not show up.

[Noah H]

16 hours ago, Sniper said:

my main bearings were not stamped with any size designation either, but there was shim stock underneath them.  I think that was common back then.

 

My rods were marked with .001.  Here a link to the thread on that tear down

 

Did you end up keeping the bearings you had?

 

[Noah H]

13 hours ago, keithb7 said:

Figure out if you have taper wear. You likely do. How much taper?  Take good measurements then come up with a plan upon review.  The quick easy solution is not just popping-in 0.002 bearings on the crank as it sits now. 

What benefit would I gain polishing up the journal and throwing in .002 bearings? 
 

Common sense says to replace all bearings, even if the rest are within spec?  I have yet to find my mic. But if I have slight taper would the .002 bearings wear prematurely? 

[Sniper]

6 hours ago, Noah H said:

Did you end up keeping the bearings you had?

 

I haven't got that far, yet.  Odds are that even if everything checks out good and I don't need machine work or bearings I will be putting new ones in anyway.

[DJK]

On 7/14/2022 at 10:23 AM, Noah H said:

are these the bearings I would use if my crank is slightly worn?

Yes. As stated previously, after careful measurements.