Right. Since I had such a hard time trying to find an aftermarket gearshift for my Brera, I decided i had to do a small project and document it for others that may be contemplating the same thing.
I don't like the feel of the original Brera knob, I wasn't overly impressed with the Giulietta's - I just wanted to swap my manual Brera's gear shift knob for a classic weighted metal ball (It all started back with my second car - a Black X1/9 Lido edition... but i digress) anyway, there are limited options if you stick with the STUPID (IMHO) set up of the 157/Brera with the OEM bolt-on design.
It was hard to find a generic metal ball for a reasonable price... but as luck would have it, I stumbled on Hill Engineering's aftermarket Ferrari shifters. General consensus says these are far superior to the OEM Ferrari part as the OEM one has a clear coat that scratches/cracks off apparently. PLus you can get it in polished chrome or anodised (matches the Brera interior)... AND there's an option for the 6 speed shift pattern engraved. GO YOU GOOD THING!
Problem is, the Brera has an unthreaded smooth shaft... and the Ferrari's are all M10 x 1.25 pitch thread.
Measured the Brera - it has a 10mm shaft. BINGO.
So here's my how to thread the shaft using a M10 x 1.25 die nut, and install a Hill Engineering anodised shift knob with the 6 speed pattern, just like you'd get in a V12 Ferrari 575 (well... "almost").
Buy this Hill Engineering Shift Knob (Or another one of your choice :-)
You'll Need a M10 x 1.25 thread pitch Die Nut to Cut the a thread on the shaft.
You'll need some tools. The shift ball i bought uses a locking nut underneat - it requires a 17mm spanner to tighten it (gently).
Remove the original Brera knob by taking off the top cap
Use a 10mm socket (ratchet) to remove.
Start threading the shaft by holding the die flat (90 degrees to the shaft). I recommend getting a friend to hold the gear shift steady while you do it.
My father in law's a mechanic so i borrowed his die set and got him to help. His opinion was that the Brera's shaft is hardened because it took a little while to bite and when it did, it was a little tricky to make sure it was threading true.
If you haven't threaded a shaft before (like me), i recommend watching a couple of you tube videos first.
The hardest part was getting it to bite in at first. Once it took, it was a piece of cake.