Following the posts of user
Shipkiller in the thread "
Z4M left front lower control arm", I remembered that I have in the garage a used (but still re-useable) Z4M front control arm. Unfortunately, the control arm bushing (CAB) is installed and I didn't want to ruin it by removing the CAB from the control arm finger (pintal).
The control arm finger has a hexagonal shape, with two particularities:
- rounded corners;
- one extended diagonal (marked with blue color in the picture).
Therefore, as the above picture shows, I could only measure the distance "a" using a caliper. Note that a caliper it's not so precise as a micrometer, the position was not optimal, and the temperature was around 0 deg. C.
Consequently this measurement should be only considered as "indicative", until a precise one will be taken.
From a= 21mm one can calculate the theoretical circle that the hexagon inscribes in: radius= 12.125mm, diameter= 24.25mm. Note that these values are calculated starting from an imprecise measurement.
Unfortunately, I had no way to take reasonable measurements of the extended diagonal ("b" in the picture above).
As
Shipkiller suggested, since there are no aftermarket CABs for Z4M, a possible solution may be to use offset CABs for E36 M3. But those have a round hole, instead of a hex one.
If the Z4M control arm finger is large enough, then maybe it can be machined down to fit the E36 round hole CABs. Of, if the finger is too smal, then maybe a sleeve can be inserted over the Z4M control arm finger.