Crankshaft and Connecting Rods
(1) Bolt Length Measurement Method
Be sure to clean the bolts, nuts, and connecting rods
thoroughly with a high-flash point solvent, because the
new connecting rods, bolts, and nuts are treated with an
Clean the bolts, nuts, and connecting rods in a well
-ventilated area, and take care that there is no spark
or flame anywhere near the working area. This in-
cludes any appliance with a pilot light. Because of
the danger of highly flammable liquids, do not use
gasoline or low-flash point solvents to clean them.
Immediately dry the bolts and nuts with com-
pressed air after cleaning. Clean and dry the bolts
and nuts completely.
Install new bolts in reused connecting rods.
Dent both bolt head and bolt tip with a punch as shown.
Before tightening, use a point micrometer to measure the
length of new connecting rod bolts and record the values
to find the bolt stretch.
Connecting Rod [A]
Dent here with a punch [B].
Fit micrometer pins into dents [D].
Apply a small amount of molybdenum disulfide oil solution
to the following.
Threads of Nuts and Bolts
Seating Surfaces of Nuts and Connecting rods
Tighten the big end nuts until the bolt elongation reaches
the length specified in the table.
Check the length of the connecting rod bolts.
If the stretch is more than the usable range, the bolt has
stretched too much. An overelongated bolt may break in
Bolt Length after
Usable Range of Connecting Rod Bolt Stretch
0.28 ∼ 0.38 mm (0.0110 ∼ 0.0150 in.)
Bolt Length before