Anyways, if you use a mechanical brake, you'll have to use a biiiiiiiiiiiiiiiiiiiiiiiiggg pinion to avoid the motor can to hit the brake pads.
For me, it's not a good idea to use the mechanical brake with this kind of mount.
The best way to use mechanical brake is to use the RCM revo motor mount on truggy or buggy setup. Work very well for me!!