Q on 1HZ BEB oil clearance specs from manual (1 Viewer)

[erics]

Can anyone clarify these specs from the 1HZ manual I have dowloaded? Why is it listing different ranges for "STD" vs "US 0.25 and 0.50"?

Is anything between 0.036-0.077mm acceptable??

 

[mudgudgeon]

My mostly uneducated interpretation . . .

Undersized bearings means the crank journal has been ground, and the bearing is going to be thicker.
Thicker bearing means a bit more thermal expansion & contraction.

If you have standard size bearings, stick to tolerances listed for them

 

[erics]

Thanks mudgudgeon, after coming back to your response again it just hit me that U/S in the manual snippet above stands for undersized vs United States (which I'd initially read it as, and was why that spec description was throwing me, duh!).

Makes more sense with that in mind thanks, however I'm still wondering what U/S 0.25 and U/S 0.50 refers to exactly? Is the number a percentage describing the bearings used as 25% or 50% the size of STD? Or a measurement of the bearings in mm?

 

[mudgudgeon]

It's a reference to the crank journal diameter being ground to 0.25mm or 0.50mm smaller then STD

 

[erics]

thnak you!