E53 Front and rear suspension torque specs

[andrewwynn]

Advised torque for M10.9 class bolts (what most suspension gear is made from)


M14: 202 N·m
M12: 123 N·m

(That's for medium not course pitch).

The variance for the torque is not difficult to calculate you don't need a extra special tool if you can get a wrench on it or a socket with breaker bar you can use a few options.

1. Use a breaker bar and a spring scale (think weigh a fish) for some old school foot-pounds.

2. Use a 1/2" wrench with a low profile socket adapter to adapt to the size needed. You do a little math to figure out the ratio of torque read to actual torque. (you can also use this method to read CCW torque on a CW only torque wrench

2.1 to figure out the ratio you measure the length of your torque wrench (to the handle pivot) to the length of handle pivot to the center off the extension. Example: if tq wrench effective length is 15" and your 1/2" wrench is 5" long the ratio is 20:15 or 4:3. You will torque to 4/3 of the set value: set to 3/4 of what you need or 75 to get 100. If you can put the adapter at a 90° angle off the torque wrench you can set to what you need.

3. Practice. Tighten a large bolt to the torque you need eg lug bolt that is similar torque. Do that 5-10x and get used to how much effort/pain that is in your finger tips. You will be able to repeat with muscle memory pretty close.

Those 59 etc numbers are for use with the special tool that ratios the torque wrench.

You can safely tighten 10.9 bolts to the advised torque listed above. BMW sets slightly lower for a safety margin (or possibly using slightly weaker steel).

M9.8 steel:

M14: 155 N·m
M12: 97 N·m