Necessity of prescribed torque tightening


Many auto parts are fixed by bolting, and there are various sizes and shapes of bolts and nuts used.
And most bolting operations have a specified tightening force (=torque). Even parts that require uniform force on the contact surface have a fixed tightening sequence. 


Why is the torque regulated?
The vibration that comes inside when you drive a car is a small vibration that is damped by many parts.
Various parts such as rubbers and springs used in automobiles are absorbing vibration for riding comfort.
In fact, more vibrations and shocks stress auto parts. 


- Continued driving without one of the two bolts securing the rubber mount bracket. Eventually, the bracket was torn - 


If the tightening torque is lower than the specified torque, there is not enough friction between the bolt and the counterpart screw thread.
In other words, the bolts do not have sufficient frictional force due to continuous vibration and shock, so they are gradually released.
Bolt loosening can lead to bigger accidents. 






Conversely, what if it is tightened to a higher torque than the specified torque?
The bolt is slightly elastic. When tightened to the specified torque, the thread of the bolt is slightly stretched, and this elasticity maintains the fastening of the bolt. The specified torque is probably the best tightening of these bolts.
If tightened with a force higher than the specified torque, the bolt will be stretched more severely, and the stretched bolt will be rather dangerous because it will lose the tightening.
If the bolt is not damaged, the counterpart may be damaged. Plastics, such as head covers, can break and damage to aluminum threads, such as cylinder heads, can lead to higher repair costs. 


Make sure to check the prescribed torque or tightening method in the maintenance manual.
Enjoy safer driving! 

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