I hope I don't jinx myself but I think I figured out the problem I was having with the sabertooth!
First I have to say, I can't believe the dimension engineering help desk never asked or suggested this... All I got from them was some nonsense about regen and battery capacity, they even suggested that I try a 2000mah battery
Ya, where am I gonna put that sucker in is tiny dozer?
Anyway, maybe this will help folks with similar trouble.
I was about to see if a slot car motor would replace the motor on the back end of my gear drive units when I realized the carrera digital motors always use capacitors across the motor leads to suppress noise. So I shortened the motor leads as much as I could, added a cap to the pos and neg poles and grounded them to the can. I also wrapped the signal wires from the blabber tooth to the RX with foil.
Here is a link to one site that I referenced to help with the solution.
https://www.pololu.com/docs/0J15/9
If you guys are thinking, "I always add capacitors to my brushed motors" you won't hurt my feelings if you say so. I just never even thought about it, but it makes sense now! I used to race associated 1/10 scale pan cars on a paved oval and we NEVER installed the caps on the motors back then and that was with old Futaba fm radios and old novak speed controllers.
I have run two battery packs with not a hint of trouble.
I bet on a bigger conversion where stuff is not literally right on top of each other, the problem might not happen.
When the blade servo had the jitters before, I always thought, that seems like radio interference?
Thanks for putting up with my rant...
Jim