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Classic/Antique Car Repair/Crankshaft bearing sizes

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Expert: - 6/25/2011


Question
I am very new to automotive repairs and hope you can enlighten me with some information. The first under-size bearings for most American and British engines is referred to as 0.010 in the repair manuals. Does this mean 0.010" will be ground off from the crankshaft journals plus a further clearance between the bearing shells and the crank pin journals? How will the machine shop operator know the amount of metal to be ground off the journals or do we have to provide him with the original dimension of the crank pin journals in the first place if the engine is new to him?

Answer
A good automotive machinist will have a complete list of specifications to go by. And yes a .010" specification means that the inside diameter of the bearing is .010" under size or less in diameter. If the engine is new to him and you have the manuals and specifications then provide him with them.

Classic/Antique Car Repair

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Brad Sears

Expertise

All automotive including antique and collectible. However if the car has been modified I can only answer in general terms and maybe get you pointed in the right direction.

Experience

Automotive tech instructor. Syndicated auto columnist 1970's though the early 1990's. Syndicated auto radio talk show, Ask Brad About cars, CBS Radio 70's through 90's TV Show "Last Chance Garage" 1980's PBS-TV syndicated. Auto instructor for the following companies: Fram Autolyte Holly Carter AMF Ford Motor University Of Conn Blue Hills Technical School Sugar River Technical Center Grew up in a family garage in Needham Mass and turned wrenches from the age of 14.

Publications
Manchester Union Leader, Nashua Telegraph, Motor Service Magazine, Yankee Magazine, Popular Mechanics (Saturday Mechanic early 80's), Los Angeles Times, New York Times, and lots more.

Education/Credentials
More than I care to remember. Basically Franklin Technical Institute in Boston, Northeastern University, Fitchburg State Teachers College, Tufts University, and a lot of factory schools along the way.

Awards and Honors
Moto Award winner. And much more.

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