Subject: | Service Information on Wheel Nut Torque Sticks used to Secure Wheel Nuts |
Purpose:
This bulletin provides technical information on wheel nut torque and the use
of a wheel nut torque stick, with air-powered impact wrenches to tighten wheel
nuts.
One of the causes of brake pulsation is the lack of uniform wheel nut torque.
Each wheel removal and installation cycle presents the opportunity for mistorqued
wheel nuts.
Saturn recommends that wheel nuts be torqued to 140 N·m (103 ft-lbs)
in a crisscross pattern using a hand-held torque wrench only. This method helps
prevent brake pulsation caused by incorrect and/or non-uniform wheel nut torque.
However, because air-impact wrenches are often used to secure wheel nuts,
Saturn recommends the use of the Saturn wheel nut torque stick SA9305NE ) or equivalent
wheel nut torque stick) to secure the wheel nuts. Once the wheel nuts are secure, use a hand-held torque wrench to tighten the wheel nuts to the
specified torque.
When using an-impact wrench with a wheel nut torque stick to secure wheel
nuts, follow the listed guidelines to reduce torque variation:
Caution: ALWAYS USE SAFETY GOGGLES WHEN USING A WHEEL NUT TORQUE STICK.
Caution: NEVER USE A WHEEL NUT TORQUE STICK TO REMOVE WHEEL NUTS. THE WHEEL NUT TORQUE
STICK COULD SHATTER AND MAY CAUSE PERSONAL INJURY.
• | Use the correct wheel nut torque stick to obtain 140 N·m (103 ft-lbs).
(Saturn's wheel nut torque stick SA9305NE is rated at 100 ft- lbs.). |
• | Do not hold the wheel nut torque stick with your hands when tightening
the wheel nuts. If the wheel nut torque stick is held while tightening the wheel nut,
it will cause the wheel nuts to be over tightened. Over tightened wheel nuts can also
make it very difficult to remove the tire should an emergency roadside tire change
be necessary. |
• | Do not use an air-powered impact wrench that exceeds 330 N·m
(250 ft-lbs) of maximum torque. |
• | Do not exceed 1034 kPa (150 psi) of air line pressure. |
• | Secure wheel nuts in a crisscross pattern. |
• | Use the wheel nut torque stick with an air-powered impact wrench only; do not
use a wheel nut torque stick with a breaker bar or ratchet. |
• | After the wheel nuts are snugged tot he wheel with an air-powered
impact wench and a wheel nut torque stick, tighten the wheel nuts, in a crisscross
pattern, to the specified torque of 140 N·m (103 ft-lbs). |