What kind of motor need in PMD reduction 4:1 ?

[mavrick0]

Most people that run the GRU just run the stock motor. If it's only making noise in 1st and 2nd then I'd say it's in the tranny. Make sure your servo is shifting the tranny properly and not over or under shifting and making the gears jump. Also another thing I've seen a lot is the pinion on the motor isn't sitting right and the little set screw actually rubs on the spur gear and causes some noise as well.