I fitted the gear knob I bought from cotball today - I was expecting a pretty straight forward job, how wrong I was!
Step 1 was to remove the old gear knob - I tried twisting it, but I got bored so decideded to cut it off instead. To do this, I cut a line from front to back all away around the knob, then used a screw driver to separatete the inner plastici bit. It then lifted off nice and easily. step 1 - done!
Step 2 was to modify the gear knob inside collar as the center hole was a bit to small. I drilled it out with a 12.5mm drill and it fitted perfectly step 2 done nice and easy!
Step 3 was to secure the collar to the shaft, then screw the knob onto collar - this is where it all went wrong (not cotballs fault, the guy in Germany that made them obviously didn't check them properly)! The thread on the collar and inside the knob did not match, and after about 2 turns, it got stuck (and no I did not cross thread it). I tried to undo it, but it was properly stuck. Luckily I didn't screw the inside collar onto the shaft very tight, so I was able to twist it off the shaft with the collar still inside. This meant I had to get the collar out, so I drilled 2 holes in the base of it, then made a tool much like the one that comes with an angle grinder as a key. The collar was so stuck inside that I had to put rubber around the ball and clamp it in a vice before I could get it to unscrew (took ages)! So then I had to tap the inner thread to match the collar helix, but I didn't didnt have a tap big enough! So I slowly used the collar along with some grease as a tap. After about an hour, I managed to get the threads matching
So back to the car, this time all went smoothly! And the results were worth it imo