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Nut and Bolt Torque Values

The importance of correct torque application cannot be overemphasized. Undertorque can result in unnecessary wear of nuts and bolts, as well as the parts they secure. Overtorque can cause failure of a bolt or nut from over-stressing the threaded areas. Uneven or additional loads that are applied to the assembly may result in wear or premature failure. The following are a few simple, but important procedures, that should be followed to ensure that correct torque is applied.

Be sure that the torque applied is for the size of the bolt shank not the wrench size.

Use a calibrated torque wrench.

Be sure the bolt and nut threads are clean and dry.

Apply a smooth even pull when applying torque pressure.
Whenever possible torque the nut, not the bolt.

When applying torque to a bolt be sure to have a washer under the bolt head and lubricate the bolt shank.

The chart below is for most of the fasteners used on RVís. Note that on the smaller bolts the torque is quite low and is in inch pounds. Do not try and use a foot pound torque wrench on these bolts. Get one calibrated in inch pounds.

The propeller manufacturer and the engine manufacturer have specific torque requirements for their equipment. Consult the appropriate manual for that information.


AN Bolt size Bolt size - Threads per inch Standard nuts AN3IO, AN315,AN365
INCH Pounds FOOT Pounds
AN3 #10-32 20-25 1.6-2.0
AN4 1/4-28 50-70 4.2-5.8
AN5 5/16-24 100-140 8.3-11.6
AN6 3/8-24 160-190 13.3-15.8
AN7 7/16-20 450-500 37.5-41.7
AN8 1/2-20 480-690 40.0-57.5
AN9 9/16-18 800-1000 66.6-83.3
AN1O 5/8-18 1100-1500 91.6-125.0
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