preload questions

[deanomyte]

I'm about to finish up my rear suspension overhaul, and everything is going back together! My question is, do I need to torque everything once the wheels are on the ground? I am worried about preload. My plan was to snug everything up & then get the wheels on the ground, then torque all the bolts. What do you all think?

[=BA=]

yes that is the official procedure also stated by BMW. Put weight on and then torque everything :) This is like you say to prevent preload in bushings etc.

[deanomyte]

thanks for the confirmation! I thought I was right, but needed to make sure!

[YAOGinanM3]

yes that is the official procedure also stated by BMW. Put weight on and then torque everything :) This is like you say to prevent preload in bushings etc.


This only applies to both (4) inner control arm bushings and if the chassis is a '95 M3 the lower outer bushing if it has not been upgraded with a balljoint. The RTABs are aligned using the casting marks (check the BMW factory shop manual) to set them level and torque to spec. no control arm ball joints need to be torqued with the car on the ground. All four subframe bushings are torqued with the suspension hanging, the three diff bushings should have been torqued in the subframe before you installed the subframe in the chassis.

There is an easier way to achieve the same thing. Put the car up on stands, set the RTABs to the right position within their cassettes and torque to factory specs. Then you install the RTAB cassettes back in the chassis wells, remove the lower damper bolts to allow pulling out the rear springs and support each side with a jack, support the axle to static ride height (measure from the top of the wheel arches to the axle centerline) and torque all bushings and ball joints. Then you simply drop both sides reinstall the springs, lower damper bolts and then drop the car and torque the lower damper bolts to spec. It's a lot easier this way than trying to crawl under the car with a torque wrench with the car on the ground.

HTH!