Ask Sarah, Problems with Nuts


penetrating oil
Penetrating oil often helps get rusty bolts out.  If they can soak overnight, even better.

The factory service manual is the only source to know exactly what torque spec is recommended for each nut/bolt on your car and using a torque wrench will ensure they are tightened properly in the future.  The two most common types of torque wrenches are the “beam” and the “clicker” types.  A beam torque wrench is the simplest and least expensive type.  It uses a calibrated scale to move the indicator arm that measures the force being applied in torque units, usually Newton meters, inch pounds, or foot pounds.  It stops applying force once the desired torque setting is reached.  Be careful not to drop a beam torque wrench as it may bend the indicator arm.  A clicker torque wrench is more precise when properly calibrated.  It uses a preloading clutch mechanism to release (causing a clicking noise) when you’ve reached a predetermined force.  Don’t use clicker torque wrenches to loosen tight nuts/bolts as it can affect calibration and leave it set at about 20% of its full scale when not in use to keep it calibrated.

sarah forst torque wrench

There are a few other handy tips to keep you applying the correct torque.  Don’t jerk on a torque wrench- tighten the bolts with a steady motion.  Look straight down at a beam type torque wrench as you may get an inaccurate reading when viewing the scale from an angle.  Only use general torque specs when you can’t get manufacturer specs.  Generally bolts should be torqued down in a crisscross pattern but I can’t state this enough- use an FSM to get proper torque specs and order!

But there are some general guidelines regarding maximum torque specs, depending on the grade and size of the nut/bolt:

bolt torque graph
These guidelines are for dry/clean threads! (CLICK IMAGE FOR LARGER VERSION)

Once again, these are general guidelines only!  For some nuts/bolts such as heat shields and other components that just need to be tight but not exact, these guidelines will work fine.  But anything that involves your engine, brakes, many suspension pieces, and your lug nuts, you should ALWAYS consult the FSM for the proper torque specs!  Keep excess torque to the engine!

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