need help properly mesh pinion and spur also suggestions on brushless setup

[bro_die]

I replaced my stock 27T motor and esc to xl5 with titan 550 motor. It was workign fine but after a day the motor jsut got weak and um stippping spur gears left to right. I already went thu 3 gears. At a steep climb or tree stumps and tight climbs thats when it happens there are times when the motor will smoke up. Is this a defective motor or my meshing is not right at all or could it be a wrong pinion and spur gear combo. IM using the stock 14t pinion and stock spur. Please help me out im tired of this thing and want to go brushless but undecided which one to get. I want to be able to have torque and speed at the same time. Im looking towards the velineon BUT i also want to have drag brakes. Im really lost at this point and dont want to spend on the wrong system.