Noob with Mi5 questions
 

Just picked up a used Mi5, this is my first ever RC race car and looking through the set ups online is interesting but I still have a few questions as a noob.

My car came with 74T and 85T 48dp Spur gears, what pinions should I get just to practice with on tarmac?
Why do some setups change pitch 48/64?
There seems to be a lot of slop in the spool, about 30 degrees worth, normal?

i used to have an mi5, think the spool had plastic inserts in the drive cup which may well be worn, as spools are quite hard on them.

pinion will depend greatly on motor and where you are running the car, i ran 28 tooth pinion on a 13.5 but we run at a slippery indoor venue.
74 tooth spur will be needed for larger pinions and the 85 for smaller as there isnt much movement on the motor mount.
the reason some people use the finer 64dp gears is it gives more choice of gear ratio's, downside is it gets damaged much easier, just stick to 48dp unless you are just running on carpet