Quote:
Originally Posted by graysquirrel
I was almost in a similar situation. The shifter on my Z4 started becoming a little loose. Dealer offered to glue it on for me. I ended up getting a replacement knob, and when I went to take off the original, the plastic retaining ring all just about disintegrated. The original knob matches the tan leather interior perfectly. If I wanted to reattach it, what would be the best way to go about it without ending up with a glued-on knob?  |
I know I'm a bit late with this response, but I thought I can help.
So all BMW manual transmission shift knobs snap onto the gearshift shaft. There is a slot milled into the top of the shaft that fits an internal block molded into the top of the interior of the shift knob cylinder. The fit between the slot in the shaft and the block in the knob cylinder is known as an interference fit, where the block slightly deforms as it is snapped into the slot.
Over time and use, the plastic degrades and eventually the knob becomes loose and can pop off the shaft when shifting from 1st to 2nd, or 3rd to 4th. It is a classic issue with BMW manual transmissions, because the plastic block eventually starts to break away from the top of inside of the knob's cylinder. The only non-damaging repair is to replace the shift knob with a new OE BMW shift knob. Non-professional repairs, which the subject of this thread is about, some dumbass uses an adhesive to affix the old broken knob to the shift lever shaft. This type of repair ruins the original intended design of the knob fitment. Again, the only correct repair is to replace the knob with new original equipment BMW knob.
There are aftermarket knobs that solve the problem. I use a Momo shift knob to replace the BMW OE knob, even on new a BMW, because the knob breaks and slips off eventually. Momo uses three small pointed set screws to affix the knob to the shaft. Other brands use other mechanical methods as well.