hi, i was ive noticed when i run 3s on my hyper tt the esc gets hot so i hear that if you lower the pinion and higher the spur gear"s teeth then the motor and escwill cool down, is this true and how many teeth will i have to go up or down

cheers!

its kind of a experiment there is no real hard number.
you could try dropping the pinion 2-4 teeth and see how that effects it

will it still fit with the spur gear well though?

and do i need to then increase the spur gear's teeth?

Are you running the stock electronics? I don't believe the stock brushed motor is going to like 3S. But if you insist, what is the temp of the ESC and the motor? Gearing will be determined by what both are doing.

You really need to usea temp gun and let the temps tell you how to gear your car with the following general limits:

Battery < 120°
ESC < 140°
Motor < 160°

hot battery = replace with higher C rated pack
hot motor + cool ESC = under geared
hot ESC + cool motor = over geared
hot everything = WAY over geared

Start with your stock gearing and then go from there... also keep in mind that driving surface conditions, tires, worn bearings etc all effect your temps... always check your temps just like a 1:1 car has a temp gauge to tell you the overall health of your system.

Remember, a temp gun is the single most important tool to own in this hobby.

you will need to adjust the mesh of the motor it should slide over to mesh if you go down teeth on the pinion (unless its already at the nax but I doubt it)

im using the castle creations combo, and my motor gets too like 140-160 , my esc gets to 190 but i dont let it get any hotter thatn that so i stop the car and the battery is fine so wat do i do. ive brought a 11 t pinion, the stock was 13 so . will that fit with the spur?
thanks

As long as both spur and pinion are of the same PITCH (tooth size), any pinion will "work" on any spur.  Whether that gives you the best gear ratio or not then depends on the size of your wheel-tire combo, the motor you're running, and the terrain you're running on.  Usual recommendation is to start with stock gearing, then go up or down a couple teeth on the pinion.  Changing pinions means you'll need to reset the mesh of the pinion to the spur by loosening the motor mount screws and moving the motor so the pinion is closer or farther from the spur.  Setting mesh too loose can result in stripped spur teeth. Too tight, and the motor bearing will be stressed.