[nitrostarter]

Welcome to the forum! But, Information overload...

Lets get some background information first:

What vehicle are we talking about here? 13lbs, 17lb rtr, Thats pretty heavy.

What motor/batteries/gearing are you running? MMM combo?


As far as pushing a 17lb vehicle, I'm thinking you may want to stick to a single setup and just use a bigger motor, something like a Neu 1527 or 2215, on 8-10s. A high voltage setup like I just mentioned will move a vehicle of your's weight with much less effort than say a MMM combo.
I'm not trying to steer you away from dual whatever setup you have, but a single is more often than not easier and less complicated.
More than likely, you're straining the setup way too much with 4lbs of rotating mass and 17lbs of total weight. Thats why you're frying MMM's left and right.

Let us know the motor, gearing, battery, truck setup used before, and we'll advise you in a better direct.