Correct. Your stock spur is 87t. The stock pinion is 20t. If you're looking for less acceleration (higher top speed, less torque to stop wheelies) you're going to want to gear up (higher tooth pinion, lesser tooth spur).
Generally, your pinion will add more gradual changes as you experiment with different options. It's more of a fine tuning approach. Your changes with a lesser tooth spur will provide more dramatic results to your performance.
It might be a good idea to invest in a decent set of both pinions and spurs and see what you're liking the best both combination and performance-wise. Just remember to keep a close eye on your temps during running. Get yourself an infrared (laser) thermometer to monitor. You'll save yourself a lot of frustration and heartache with a $20 temp reader, you don't want to go frying your perfectly good components!
Anyway, back to gearing. Yeah, I have several spurs and pinions to play with, my pinions are 19, 20, 22, 24, 26, 28, and 30. Two tooth changes at a time are usually best for changing pinions.
As for my spurs, I have a collection of 72, 75, 81, and my stock 87 that came with my ECX Boost. Unfortunately ECX only provides the 87t spurs, if you want to change it, you will have to get the Associated spurs for the T4 and B4 vehicles.
For some reason I am getting away with a 75/30 combo with my 15t Dynamite motor. This has changed my drive ratio from 11.3ish (stock) to 6.5 (current) that's a pretty big slam in gearing. I don't know why, but it's working in my car and the temps are nice and cool all around. I DON'T recommend you doing this, but it's working for me, and my car flies on that brushed motor.. About 36-38 mph.
Just start with your pinion.. Go up 2 teeth - check your temps on your ESC and motor. If nice and cool (under 160 Fahrenheit) gear up two more teeth until you are either getting the speed you want OR getting close to thermal limitations.. If you're up to a 30t pinion and still have room to play around with, change your spur to a lower tooth and start over with your pinion to be safe (Go down a few teeth and work your way up as you experiment). Keep in mind the less teeth on the spur, the smaller diameter it will have and you will be limiting your pinion options because lesser tooth pinions are usually smaller diameter and it may leave you too big of a gap to meet the two gears to mesh them. I had to go thru this the hard way..
Have fun, and watch those temps!
(Last edited by JroX : 2.04.12 at 7:29 pm)
60% of the time, it works every time.