Crankshaft and Connecting Rods
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]
Mark here with a punch [B].
Fit micrometer pins into punch marks [D].
Apply a small amount of molybdenum disulfide oil solution
to the following.
Threads [A] of Nuts and Bolts
Seating Surfaces [B] 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
Connecting Rod Assy
(2) Rotation Angle Method
If you don't have a point micrometer, you may tighten the
nuts using the "Rotation Angle Method".
Be sure to clean the bolts and nuts thoroughly with a high
flash-point solvent, because the new bolts and nuts are
treated with an anti-rust solution.
Gasoline and low flash-point solvents can be
flammable and/or explosive and cause severe
burns. Clean the bolts and nuts in a well-ventilated
area, and take care that there are no sparks or flame
anywhere near the working area; this includes any
appliance with a pilot light. Do not use gasoline
or a low flash-point solvent to clean the bolts and
Immediately dry the bolts and nuts with com-
pressed air after cleaning.
Clean and dry the bolts and nuts completely.
Use the bolts attached
to new connecting rod.
Replace the bolts with
Usable Range of Connecting
Attached to new
Rod Bolt Stretch
0.24 ∼ 0.36 mm
(0.0094 ∼ 0.0142 in.)
0.20 ∼ 0.32 mm
(0.0079 ∼ 0.0126 in.)