BMW 428i 2014-2016 Suspension Bolt Torque Specifications

Using the correct torque specification ensures the fasteners are tight enough to prevent loosening under stress but not so tight that they damage the threads or the component. Over-tightening can lead to bolt stretching, thread stripping, and component failure, while under-tightening can result in the bolt loosening during operation, potentially causing a catastrophic failure of the suspension. Imagine hitting a pothole and the suspension components come loose due to under-torqued bolts; that could lead to loss of control.

Yes, it is generally recommended to use new bolts, especially for critical suspension components. Many of these bolts are 'torque-to-yield,' meaning they stretch when torqued to their specified value and should not be reused. Reusing them can result in incorrect clamping force and possible failure. For instance, reusing a stretched strut bolt could fail under heavy braking.

You should use a calibrated torque wrench that covers the range of torque values specified for your vehicle. It is best practice to use a click-type or a digital torque wrench for accuracy. A beam type wrench should be checked for calibration. Using an accurate torque wrench is important; a low quality wrench can misread the value leading to under or over torquing bolts.

Generally, bolts for suspension bushings, such as those in control arms or sway bars, should be tightened with the suspension at ride height. This ensures the bushings are not twisted and preloaded when at rest. For most strut and shock mounts it is fine to tighten at full droop, though refer to manufacturer recommendations for each bolt. If you torque these bolts in the air, when the vehicle is back on the ground the bushings can be in a bind and wear prematurely.

It is a good practice to check the torque of suspension bolts after any suspension work or if you suspect they might be loose, and at intervals such as every 12,000 miles or once a year for general maintenance. If you drive hard or on rough roads regularly, you might want to check them more often. A loose bolt on a tie rod, for example, could lead to erratic steering and is very dangerous.