just wondering...

[BrianG]

Simple way to lock it is to use JBWeld inside the diffs. Very thick oil (200k-500k) can almost lock it, but still slips.

Not really like a slipper clutch, although the effect is similar. With a CD, it starts to wheelie and when the front gets lighter, power gets routed to the front tires. This reduces the power to the rear tires and the front doesn't go any higher. If you are really giving it a lot of power, this results in worn front tires, not to mention a lot of front tire ballooning. All this keeps more of the tires on the ground and offers better control on a track. Wheelies are impressive, but does get a little old when you aren't trying to do so.

On a track (bashing) I rely on the surface to provide slip.

[jhautz]

Another less permanent way to lock the center diff is to open it up, drain the oil and pack some silly putty in there. If you ever want to go back to a normal diff you just remove the silly putty and put the silicon oil back in it.

JB Weld is permanent.

[Marvin]

On my first brushless conversion (a Losi 8ight), it'd wheelie with only 7k weight diff oil in there. The smile on my face was huge. Until I realised that I had to turn it down as I'm a racer...