Why do you measure crankshaft end play?
Crankshaft “end play” is measured as the clearance between the crankcase thrust washer and the axial mating surface of the crankshaft (see Figure 1). If crankshaft end play exceeds the limits shown in Table 2 on page 4, conditions exist which may propagate premature engine wear.
End float is the amount by which a shaft can move lengthwise. The lubricated grooves allow the hubs to shift if shafts are misaligned or subject to end float.
A dial indicator should be used to. measure endplay between .
Typically, it is desirable to measure the output torque from the crank near the main journal bearing at the flywheel end of the crankshaft. This usually is the main measurement to which all other measurements are correlated.
The best method of measurement is with a dial bore gage that measures the bearing inside iameter when the bearings are installed at the specified torque without the shaft in place. Measurements should be taken at front, center, and rear of each bearing position.
Crankshaft Deflection Gauge
A form of dial gauge specifically made to measure the crankshaft deflection of the marine engine.
Conclusion. Shaft measurement can be performed with a variety of metrology tools, from handheld devices such as micrometers and snap gages to high-end coordinate measuring machines (CMMs).
An in-service daily driver may slide by with up to 0.010 inch without problems. Anything over 0.015 is asking for trouble. Most current-day engines (including LS engines) call for much tighter endplay values than these, so always consult a factory service manual.
Crankshaft balancing can massively increase the performance of your vehicle and engine whilst also reducing vibrations that may come with stressed metal and an unbalanced engine.
The real goal of balancing a rotating assembly is to make sure that the crankshaft counterweights offset the rotating and reciprocating forces created by pistons and rods. With today's lightweight pistons and rods, accomplishing this usually involves removing mass from the crank counterweights.
What is the purpose of end play?
The end play allows room for the formation of an oil film, misalignment, and thermal expansion of the bearing components. End play is the total distance the shaft can move between the two thrust bearings and is sometimes called float, thrust bearing clearance or axial clearance.
End play in an electric motor is the amount of axial movement allowed by the motor's construction. This end play is limited by the motor's bearing design.
The throw is the measurement from the center of the crankshaft to the center of the crankpin journal, which is used to determine the stroke of an engine. The throw is equal to one-half the stroke. The longer the throw, the greater the stroke, or distance, a piston travels.
The traditional bearing clearance standard for street and most performance applications has been 0.001-inch of clearance for every one inch of crank journal diameter.
Since different rods and different pistons are different weights, it is impossible to make a crankshaft that is balanced "right out of the box" for any rod and piston combination. All crankshafts must be balanced to your specific rod and piston combination.
There are two main methods used for checking bearing clearance – Plastigage® or gauges.
Measuring the inside diameter of a main or rod bearing will require a dial bore gauge. The best ones to use are accurate down to 0.0001-inch. With these two tools you can quickly determine the clearances in any engine. Measuring bearing clearance is only valuable if the numbers are accurate so use quality tools.
To measure the outer diameter of a bearing, place the jaws of your vernier caliper around the outside of the bearing and close it until it meets the outer edge of the bearing. It should be a snug fit, but not tight. Now, you can read the value on the caliper to find the outer diameter measurement.
A measuring tool is anything used to take a count of quantitative data, such as weight, length, time or temperature. Rulers and scales are two common types of measuring tools. Measuring tools can be very precise, but low quality ones can lead to faulty measurements.
3.4 Fatigue life analysis
To draw the S-N curve of the shaft, stress value (σF) where fatigue failure cycle at 103 cycles occur, can be calculated as  σF = m. UTS (7) where m = 0.9 for bending. The stress value at Nf = 103 according Eq. (7) is 648 N/mm2.
How do you measure the shaft?
The boot shaft starts directly above the boot sole. You can run a measuring tape up the side of the boot from the top of the boot sole to the top of the shaft. This measurement is your boot shaft height.
Commonly crankshafts have a diameter tolerance 0.0005-0.001”.
- excessive heat (if the oil doesn't provide sufficient cooling)
- etching or corrosion due to exposure to chemicals or acid in contaminated oil.
- exposure to dirt or debris in the oil, which will scratch the bearings (in turn scratching the engine parts they contact)
Typical amounts removed are (Standard) 0.005”, 0.010”, 0.020” and 0.030”. A crank can be ground to as much as 0.050" as this is the biggest bearing sizes the OEM makes.
Without counterweights, a crankshaft would be unbalanced and cause a lot of wear and tear on the engine. In addition, an unbalanced crankshaft can lead to decreased performance and shorter engine life.