He he he that's the thing with the bonzer... It likes to kill motors... I remember one guy, had great success using a 600 size brushed motor... It was the only thing I've ever heard of that increases speed and torque... Well apart from brushless... But then again there has been so many people converting them to brushless just to find out the KV is to high and cogs.
For crawling, brushed motors on a higher voltage is the best... Other than that sensored brushless is ok to...
I really don't recommend using a sensorless combo like I did.
Because sensorless motors have a minimum running speed... Anything below that and they do nothing.... They don't even try.. So u can't smoothly bring up the throttle from a stand still and u can get that really low low speed u can from brushed motors. On the controller it feels like there is a dead spot just ne'er the centre...
by the looks not manny people have used the rc4wd GRU, but from what I can understand it will get the gearing closer to what it should of been. I think u could nearly run any motor..and u shouldn't have motor problem again lol
best bet would be to try.... Do u have anything els u could borrow a motor from just for testing? That way u could get the GRU then test before ordering a motor?
1900kv x 7.4v = 14,060rpm / 4 = 3515 pinion rpm
and we know this from before, so there is no point working it out because we know it will be slower
5,500rpmx47.37mm=260,535mm/min 15.6km/h 9.7mph
by the sounds u want the pinion spinning at 8,000rpm... So u would need something that's pulls 32,000rpm
32,00rpm / 7.4v = 4,324kv
this would do it....but its sensorless
or there is somethink like this.... But its overkill