Your info is still a bit vague..
Are you still using the RC4WD trans? If so, what's the reduction of it? Or are you connecting a gearhead motor direct to your 1st axle? What's the ratio of your axles? What's the diameter of your tires?
Using my knowledge of the wdc 740 as an example..
motor 5000rpm
trans in 2nd gear, 11:1 reduction
axles reduction 15:1
tire diameter 122mm
5000/11/15= approx 30 rpm @the wheel center
I was looking thru your photos of your ADT project, you've got a serious problem with your hinge joint & how/where your universal joint is connected. A sharp turn left is going to put that universal joint beyond it's capable angle of operation & wear out quickly or even lock it up all together.
I would suggest you remake your hinge point so your universal joint is directly below center of your hinge pins and your driveshaft going forward to the front prop shaft is fixed to the front body half. It would also improve longevity of that shaft's fixed centering point if it were bearing'd on two points of contact.
Does that make sense?
Pic of 740 hinge
