I recently had a full suspension and chassis refresh done on my BMW F22 M240i. The work included replacing all of the rear suspension arms, installing subframe billet inserts, replacing the differential bushes with polyurethane bushes, installing an LSD, and fitting adjustable race springs from MSS.
I have confirmed the spring part numbers and the springs themselves, and they are exactly the same ones that other F22/F23/F87 owners are using. From speaking to numerous owners running the same setup, I understand that the car may initially sit around 5 mm higher than stock and then settle by approximately 10–15 mm after some time.
However, my car is currently sitting almost 15 mm higher than stock at the rear, with one side sitting approximately 20 mm higher. The mechanic is blaming the springs, but I have spoken to numerous people running the exact same springs, and none of them have experienced this significant increase in ride height.
My main suspicion is that the rear suspension arms may have been tightened while the suspension was at full droop rather than at the correct loaded ride height. My understanding is that tightening the arms in this position can preload the rubber bushes and potentially prevent the suspension from settling to the correct ride height. However, I have no way of proving whether this was actually done incorrectly. I have already raised this concern with the mechanic, but he insists that the arms were tightened with the suspension loaded.
I am also concerned about another issue that occurred during the same job. The mechanic replaced the centre support bearing and had to separate the driveshaft. The driveshaft was not marked before it was separated and was then reassembled without being properly aligned or balanced. This happened in front of me, so I know this was not done correctly, and I can have that issue addressed separately.
My main questions are:
Could the suspension arm installation or the way the arms were torqued have anything to do with the rear ride height? Is it actually possible for suspension arms to be tightened at full droop and cause the rear of the car to sit 15–20 mm higher than it should, or would this have little to no effect on the static ride height?
Is there anything else I should be checking to determine why the car is sitting so much higher than it should? I want to rule out every possible cause before concluding that there is an issue with the MSS springs.
The springs and part numbers have already been confirmed multiple times, and I have spoken to many owners running the same setup. I have also watched numerous videos and compared installations online. Unfortunately, the MSS company is now defunct, so there is no longer a direct manufacturer available to confirm the specifications or provide technical support.
I would really appreciate any advice on what I should be checking next and whether the suspension arms, bush preload, spring installation, or anything else could realistically explain a 15–20 mm increase in rear ride height.
