CRADLE 9T4132 - Caterpillar

Length of The Connecting Rod
The connecting rod length (CRL) is the length of the connecting rod. Refer to Table 1 for each grade of length of connecting rod.In order to ensure that the piston height above the cylinder block is correct, three grades of connecting rods "R" to "B" are used during manufacture at the factory. Replacement connecting rods are available in three grades. These grades of connecting rod are "R" to "B". The grade of length is identified by a letter or a color which is marked on the side of the connecting rod. The longest grade is marked with the letter "R". The shortest grade is marked with the letter "B". The difference in length between each grade of connecting rods is the following value: 0.076 mm (0.0030 inch)The grade of length of a connecting rod is determined in the factory by machining an eccentric hole in a semi-finished piston pin bushing. Therefore, the grade of length is determined by the position of the center of the hole in the piston pin bearing. If the connecting rod must be replaced, a new connecting rod assembly must be purchased and installed. Refer to Table 1 for more information. A new piston pin bearing is installed in the new connecting rod at the factory. The bore of the piston pin bearing is reamed to the correct eccentricity.Piston Pin Bearings
Note: This procedure requires personnel with the correct training and the use of specialized equipment for machining.If the piston pin bearing requires replacement but the original connecting rod is not replaced, the following procedures must be performed:
Determine the grade of length of the connecting rod. Use one of the following characteristics:
The mark
The color
Measuring the length
Ensure that the connecting rod is aligned parallel and that the connecting rod is not distorted. Refer to "Distortion of The Connecting Rod" in this service module.
Remove the piston pin bearing from the connecting rod. Install a new bearing in the connecting rod. The new bearing is partially finished. The new bearing must be bored off-center to the correct diameter. This off-center position is determined by the grade of length of the connecting rod. Refer to Table 1. The correct diameter of the bore in the piston pin bearing is given in Specifications , "Connecting Rod". Surface finish of the bored hole in the piston pin bearing ... Ra 0.8 micrometers
Machine the ends of the piston pin bearing to the correct length. Remove any sharp edges. Refer to Specifications, "Connecting Rod".
If the grade of length of the connecting rod is changed, the letter that is stamped on the connecting rod must be removed. Etch a letter that is for the new grade of length on the side of the connecting rod. Note: Do not stamp a new letter on the connecting rod. The force of stamping may damage the connecting rod.Table 1 references the following information: Grade of letter of the connecting rod, the color code of the connecting rods and the lengths of the connecting