BEARING CRUSH



BEARING CRUSH

Postby grumpyvette » February 25th, 2014, 10:39 am

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AS USUAL THERES A GREAT DEAL OF INFO IN THE LINKS AND SUB LINKS

http://underthehood.mahleclevite.com/?p=706

http://stealth316.com/misc/clevite-77-r ... arings.pdf

http://www.bobistheoilguy.com/bearingwe ... alysis.htm

viewtopic.php?f=44&t=10923

http://www.youtube.com/watch?v=TX-eFEqAKaY

http://www.youtube.com/watch?v=mR-f8E-CxfI

http://www.nb-cofrisa.com/docs/web_fallos_ing.PDF

http://www.precisionenginetech.com/tech ... ch-part-1/

Crush

The term "crush" refers to the outward force created by the portion of the bearing which extends above the housing bore when the bearing halves are set into place. This "extra" material holds the outside diameter of the bearings firmly against the housing bore when the assembly is torqued to specification. By increasing the surface contact between the bearing and it's bore, crush minimizes bearing movement, helps to compensate for bore distortion and aids in heat transfer. Federal-Mogul's performance bearings have additional crush built into the design for enhanced heat transfer and bearing retention.
Eccentricity

"Eccentricity" refers to the variation in the inside diameter of a bearing assembly when it is measured at different points around its bore. A properly designed engine bearing is not truly "round" when it is installed in the connecting rod or engine block. Under operating loads, a rod or main housing bore will distort, pulling inward at the parting line between the upper and lower halves. To keep the bearing from contacting the crankshaft in these areas, our designs include additional clearance at each parting end of the bearing. As engine loads increase, so does the amount of distortion, thus race bearings require greater eccentricity than do passenger car bearings.


Clearance
Vertical bearing clearance is best measured by assembling the bearing into its bore, measuring the inside diameter with a dial bore gauge and subtracting the actual crankshaft journal diameter. Clearance specifications shown in this catalog are the arithmetic ranges possible with parts that meet factory specifications, not clearance recommendations. Always use the engine manufacturer's clearance specifications. Clearance should be measured vertically – 90 degrees from the housing parting line. The eccentricity designed into bearings will cause clearance measurements to vary at different points around the bearing's inside bore.

Plastigage can be used as a quick way to check clearance. To use plastigage correctly, first assemble the upper bearing shell into the housing, then install the crankshaft. Lay a strip of plastigage lengthwise across the center of the bearing journal. Install the lower bearing shell and cap and tighten the fasteners to the specified torque. Loosen the bolts and remove the bearing cap and lower shell, being careful not to rotate the crankshaft. Compare the thickness of the now compressed plastigage strip to the chart on its package to determine the bearing clearance. Carefully remove all traces of plastigage from both the crankshaft journal and the bearing before final assembly.

High performance applications may require different bearing clearances than unmodified engines. Many engine builders target a clearance range between .0022" and .0027". Clearances greater than .003" are not normally recommended. Some engine builders like higher oil pressures than a standard oil pump can provide, particularly at lower engine speeds. Large bearing clearances will lower oil pressure, and may require a high volume oil pump. An engine should maintain a minimum oil pressure of 10 lbs. per 1000 RPM.

Plastigage


Plastigage is a quick and easy device for checking bearing clearances. Available in four ranges to cover most applications. Twelve strips per package with a measurement gauge printed on each wrapper.



SPG-1 (green) .001 – .003 (.025MM – .075MM) range
SPR-1 (red) .002 – .006 (.050MM – .15MM) range
SPB-1 (blue) .004 – .009 (.10MM – .23MM) range
SPY-1 (yellow) .009 – .020 (.23MM – .50MM) range
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READ LINKS AND SUB LINKS
viewtopic.php?f=53&t=2726&p=7077&hilit=plastigauge#p7077

viewtopic.php?f=44&t=5531&p=39484&hilit=plastigauge#p39484

viewtopic.php?f=53&t=9955&p=38385&hilit=plastigauge#p38385
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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