CrankShaft Scissoring

[glider]

Now are you saying the crank weights or fly wheels are turning on the crank journal just a tad bit and throwing it out of balance ..or just starting to spread?

Not sure what your term "spread" means but they are running out of plane with each other (crank halves) on the crank pin where they are pressed together.

Take two paper dinner plates and drive a pencil (acting as the crank pin) through the two plates near the edge somewhere. Move the two plates (acting as the crank halves) in opposite directions with the pencil being the pivot point and that's scissoring.

 

[NEWHD74FAN]

Not sure what your term "spread" means but they are running out of plane with each other (crank halves) on the crank pin where they are pressed together.

Take two paper dinner plates and drive a pencil (acting as the crank pin) through the two plates near the edge somewhere. Move the two plates (acting as the crank halves) in opposite directions with the pencil being the pivot point and that's scissoring.

Understood, so used to one piece cranks, never thought of multi-piece would be used in an inherently "off balance" engine...racers always welded if multi-piece. :small3d019:

 

[Bud White]

Not sure what your term "spread" means but they are running out of plane with each other (crank halves) on the crank pin where they are pressed together.

Take two paper dinner plates and drive a pencil (acting as the crank pin) through the two plates near the edge somewhere. Move the two plates (acting as the crank halves) in opposite directions with the pencil being the pivot point and that's scissoring.

I got ya and that what i was thinking it was never heard it as Scissoring

Twisting a Crank though know that one well

Spreading i would say as moving outwards on the crank pin like opening or closing the door.. So simple put the the one half is twisting the opposite of the other

Bit different that what i am used to with a solid 1 piece crank ..

Ya would think in these days that they would have figured out how to keep that from happening .

 

[glider]

They probably have but it's cheaper to built them like this.

 

[Bud White]

They probably have but it's cheaper to built them like this.

For Sure just like in mine line of repair stuff cheaper to fix after the fact if someone complains than stop the line.