Crank endplay measurements

[athlete3344]

Good afternoon,

I am currently cleaning out a 6 bolt motor in preparation to finish a very long project, so I figured while cleaning it, I would check specs for everything before its back together.

That being said, I checked the crank end play using feeler gauges to measure the thrust clearance around the main bearing journal two different ways, one by pulling and pushing the crank, and the other by lightly prying on the crank. Below are the measurements I took down.

F = measurement in front of the bearing relative to the motor
R = measurement behind the bearing


Using the push/pull:
#1 TDC
F = 0.006"
R = 0.004"

Rotate 90 degrees ccw
F = 0.005"
R = 0.005"

#1 BDC
F = 0.005"
R = 0.004"

Rotate 90 degrees ccw
F = 0.006"
R = 0.004"


Using the lightly prying method:
#1 TDC
F = 0.006"
R = 0.006"

Rotate 90 degrees ccw
F = 0.006"
R = 0.006"

#1 BDC
F = 0.006" - but somewhat tight fitting, 0.005" is easily fit
R = 0.005"

Rotate 90 degrees ccw
F = 0.006"
R = 0.005"



Can anyone help me out and give me a bit of guidance to these values?

Also to note, I watched a video of jafro doing some of these measurements, and you can audibly hear the crank click back and forth. Mine does not seem like it has that much end play, but there is a film of oil.

 

[donniekak]

A feeler gauge is likely to scratch the bearing or thrust journal. I use a dial indicator, and magnetic base to check thrust.

 

[curt-s]

Feeler gauges, I'm also not entirely convinced are accurate, especially at the lower thicknesses. It also depends on the quality of the guage. Princess Auto (up here) or Harbor Freight (down there) I would be willing to bet can be not so accurate at the thousandths of an inch.

On the side of scratching, the damage you could possibly do with an oil soaked tip of a feeler gauge should be inconsequential, if anything at all. You not only do not have enough force to do damage, but one should be mindful of any burrs or imperfections on their gauge, and not use it if there are issues. If there are, then again, could be quality issue which would make accuracy very suspect.
Woo fun.


I've never heard a crank click back and forth when moving it unless the thrust surface is worn and the crank is about to take a stroll. Any oil/assembly lube should dampen any audible sounds, and 5-7 thousandths of an inch is not enough to build momentum to make a metallic click. Maybe something else is making that sound in the videos.

Top/bottom halves of the bearing (assuming saddle thrust bearing) are aligned properly, I assume? No point in taking measurements if the bearing isn't set properly.

 

[athlete3344]

Not sure, but Im pretty sure the motor was running for about 10-15 miles before I picked it up. I plan on getting the rest of the measurements from the engine this weekend. Micrometers are in the mail and should be here before Friday .

Oh, and the feeler gauges I picked up from Napa.