rod bearing question

[SuperHO]

so how would one know whether or not one would need to go with standard rod bearings or go with undersized? I don't really have ready access to a pair of calipers, so should I stick with standard and hope for the best or what?

 

[yamahaSHO]

It is very rare that you would find a journal from the factory that had to be undersized. If your crank hasn't been messed with by anyone, you're almost good to assume standard is what you need. You can plastigauge to double-check, but I'm willing to bet that standard is all you would need.

 

[Phoenix]

It is very rare that you would find a journal from the factory that had to be undersized. If your crank hasn't been messed with by anyone, you're almost good to assume standard is what you need. You can plastigauge to double-check, but I'm willing to bet that standard is all you would need.

what he said.

 

[Devin]

what he said.

When they fail its, 99% too late , so the regrinded cranks are rare.

Regrounds would require oversize bearings.

I'd plastigage while you are down there.

 

[Phoenix]

Edited, I thought he meant oversized bearings , nm. :thankyou:

 

[Devin]

NP. I don't think undersized is a very common occurrence around here!

 

[yamahaSHO]

Regrinds require UNDERSIZED bearings as the CRANK is what is undersized. Phoenix was correct.

 

[Devin]

SO the +.25 are undersized bearings? Wouldn't the crank journal be the part that is undersized?

 

[SuperHO]

what is this plastiguage stuff you speak of?

 

[ST 2 SHO]

Devin SO the +.25 are undersized bearings? Wouldn't the crank journal be the part that is undersized?

ahhh I see your point but your also missing the point
It's referring to the crank journal ( under-sized )
+ .25 is referring to the bearing from stock ( over-sized )

 

[93rev2sev]

Plastiguage is hair-thick plastic that deforms under pressure. You stick a thread of this stuff on your bearing, torque the puppy down and see how much the plastiguage deformed. It will tell you your current bearing clearance.

It comes with it's own chart. Take the smushed plastiguage and compare it to the chart. When you find the line that's the same width as the smushed plastiguage, that's your bearing clearance.

When I did my first rod bearing job, I measured my rod bearing clearance with plastiguage before AND after swapping the new bearings in. I was able to tell EXACTLY how sloppy my old bearings were compared to the new ones.

 

[yamahaSHO]

SO the +.25 are undersized bearings? Wouldn't the crank journal be the part that is undersized?

When buying bearings other than the "standard" size, you refer to the crank for bearing size. Therefore, an undersized crank needs an undersize bearing, even thoug the bearing itself is actually thicker.

If you don't believe me, it's on the bottom left of this page.

http://books.google.com/books?id=83...kYTgDg&sa=X&oi=book_result&ct=result&resnum=2

 

[Mr Anonymous]

When buying bearings other than the "standard" size, you refer to the crank for bearing size. Therefore, an undersized crank needs an undersize bearing, even thoug the bearing itself is actually thicker.

If you don't believe me, it's on the bottom left of this page.

http://books.google.com/books?id=83...kYTgDg&sa=X&oi=book_result&ct=result&resnum=2

So simple yet so complicated...

 

[Devin]

My bad! Sorry about that Phoenix.

Well, maybe I can still be useful. SuperHO, here's an example of plastigaging:

 

[Phoenix]

No worries , we're all about helping. :sun:

 

[SuperHO]

thanks ya'll. I'll just go with a standard size bearing then.