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Removing z4 roof.
Here are some nice instructions with pictures.
E86 z4 coupe roof lining removal.
I know how to remove the covers on the a and b pillars.
At around 18 minutes when screwing in the hydraulic line bolts back into the motor tighten these two bolts up to manufacturers spec.
Pull this ring pull out by about 1 4 and turn it through 90 degrees and this will lock the hydraulic bypass valve in the open position this will then let you lower the roof by hand.
A replacement motor was a cool 350 plus a new housing and hydraulic repair kit bringing the total to 450.
Momo1 officially a forum statistic.
Replacing the motor involves removing the entire roof assembly which is a fiddly and laborious job and is an expensive option if you are going to get this done at an indy garage.