While building my newest BW, I accidently discovered a quite useful glitch. People have probably already used this glitch, but I had never heard of it so here it goes:
First off, attach a motor. Then, attack a very light extender of some sort which other compoents can attach to like so:

Then, wire your motor to a button or switch and make sure it has adequate battery power.
Now, spin you motor up to full speed. Then switch to another tab so the motor stops (while still retaining its speed). Then, attach a 60 kg sledgehammer like so:

Now, quickly spin the motor again and quickly switch tabs. The axle should have left its socket and be floating outside the motor like so:

Now, you can remove the sledgehammer and extender, and attach components to the motor without the chassis colision mesh to screw you up. An example of this would be a backlash disk, which do not like intersecting the chassis:

Then, you simply spin the motor again and the axle will return to its normal position.
For DSL, which the realistic rule applies, I find this glitch works best with componets that won't attach when they intersect the chassis, which is usually possible to do IRL.
Well... hope you found this useful.