[Ho Lee Kow]

Hello. How can I make a motor slower? It is fast andI need to slow it down some way. Is it for a resistor in the motor wires or what can I do? thank you.

[Grah1]

A resistor  will  get  warm  ,a  chain of  diodes   will  reduce  the  voltage  to  the  motor  by .6 volt  per  diode  I  have  a  diode  chain  on a  rotary  switch     wired  into  my  controller   so  I  can step  down the  voltage  until  the  car  becomes  driveable  ,However   this  has  to  be  adjusted along with  the   power  control  to  the  transistor   in order  to ensure  the  car  has  sufficient  power   to  start   on the  lower voltage . If  you  are  using  a  resistor  type  controller   the   resistance  of    the  controller  will  need  to  be  reduced  as  the  voltage  drops .
Personaly    I  would  source  a  slower  motor   there's  plenty  about .

[dvd3500]

You could change the gearing
or reduce the voltage
On Scaelxtric ARC you can make the change in the APP: https://www.scalextric.com/uk-en/shop/se...l-arc.html

[autoavia]

As you reduce the voltage to a motor you will also reduce the torque which the motor produces so it will be much less progressive. You will eventually find a point where the voltage is too low to allow the motor to turn at all.

One solution is a adjustable controller like a Slotit or Truspeed but this is quite expensive. As Grah1 has already said another much less expensive option is a lower revving motor.

It might help if you posted more details about the car that is causing problems and what track, power supply and controller you are using and explain exactly why you need to slow the car down..