brushless upgrade

[gtv1]

Hi folks, sorry if this is a noob question.
I have a B4 which I am now looking to upgrade to brushless. I used to race for about 15yrs but got out just when brushless was coming out, so I have very little knowledge of brushless setup.
Now I think I am going for a hobbywing esc and 13.5T motor, but my question is what size pinon should I run? is there a final ratio I should be looking for and what do people recommend?
Many thanks for any help you can give.

[juicedcoupe]

This should get you close. It's from the B5 manual but both have the same gear ratio transmission.

[gtv1]

This should get you close. It's from the B5 manual but both have the same gear ratio transmission.

Screenshot_20240317_160835_Drive.jpg

Thank you for that. helped alot

[1911Colt]

I see you have your answer, but for others just starting with brushless: the motor manual will have a target FDR for your vehicle type (2WD, 4WD, Short course, etc).

Spur gear teeth divided by pinion teeth times transmission ratio gets you your final drive.

For example, my motor manual called for 8:1 for a 2WD buggy. The Top Cat Pro transmission has 2.066 internal ratio. 89 tooth spur / 23 tooth pinion x 2.066 transmission ratio gives FDR of 7.99.

Then just check motor temp after a good run. Excessive heat will shorten the motor life.

[gtv1]

Cheers for that, I have checked and it should be ok, but wil keep an eye on the temps