Originally Posted by Silverexpress

Sorry for all the probing questions, but Im trying to calculate your rollout ratio. The rollout ratio is the ratio between your motor rpm and your rear tires rpm. It should be 1:1....one turn of the motor should equal 1 turn of the tire. Anyhow since I dont know your motor, I'll just assume it's roughly at 2500 kv which is common for a 17.5T motor. Knowing that TLR kept the same diff as version 1.0, this gives us a diff ratio of 2.43 (see your manual).

Finally, let's just add to the assumption that your tires are 3.35" in dia, and with a 70/32 gear combination this gives us a rollout ratio of 1.98. At 8.3v your 22 will hit 38 mph. Unfortunately, you want a rollout ratio of 1.0, so the bottom line is your overgeared for that motor. Ideally a 17.5T motor will be very happy with a 76/18 combination and this roughly provides a rollout ratio of 1.02 at a top speed of 20 mph. Now this can be stretched with either a taller pinion, and or timing via the endbell or the esc but doing so you will need a temp gun. Because once you start to deviate from 1.02 you'll start raising the temp of the motor/esc/ batteries. A temperature of 180 degrees F seems to be the accepted upper limit. Beyond this temperature you start to cook the glue that holds the magnets inside your motor.


Bottom line, you will have to upgrade your motor to give you that top speed of 38 mph. It's surprising that the manual gives a 70/35 combination since that's a rollout ratio of 2.16!!!! With a top speed of 43 mph!!! It's got to be a typo. For that type of performance your looking at a motor with 8.5T or a 9.5T geared down for torque to keep things nice and cool. The version 1.0 manual calls out a 76/30 combination, and that gives a rollout ratio of 1.7 at a speed of 34 mph. That's more believable, but I'd still take a temp gun to it just to be sure. It is really strange to see 70/35 for the v2.0 since they added so much weight to it also.

Do a google search for "rc rollout calculator"....

Have you taken the temp of your motor after a 6-7 minute run through a course? If so what did you get?