In addition to what seaball said, I will add that in a belt driven car the linear speed of the belt also has an influence. Hence when X-Ray designed their low ratio pulleys, they did increase the number of teeth on the primary pulley and decrease it on the diff pulley.
By this they reduced the linear speed of the belt (compared to the whells turning the same speed with the "normal" pulleys) which is also good for acceleration but not that much for top end (as the speed of the belt increases the centrifugal force stretches it a bit and it frees the drive).
Originally posted by Neil Rabara That's a really good question Kenneth. Since the cars are geared the same for a particular motor, but have different internal drive ratios, in theory they should be the same. But since they are two completely different cars, one belted the other shaft, you will feel and notice a difference in performance. As far as the internal drive ratio specifically has a performance advantage or disadvantage, keep in mind the tire/wheel rotation compared to the motor's rotation. If the SD car has a IDR of 2.353, that means that the wheels are turning 2.353 rotations for every one rotation at the motor.
I`ve been told by many drag racers that the larger the ring gear the better the car spools up. They say that the car will climb the ring gear easier.
HOBBYWING NORTH AMERICA /FALCON SEKIDO/ TEKNO RC TEAM/VBC Racing America/VP-PRO RACING TIRES/2010 R.O.A.R. VTA National Champion Driving a T2R PRO/NANO-TECH Batteries Paul Rush
Slotmachine is correct about the drag car wanting to climb a taller spur gear...he is also correct in his choice of avatars, but that is another story.
This discussion also seems very similar with the comparison of gear ratios with 64 and 48 pitch and with that I can tell you that a 4.0 to 1 with 48 pitch maybe the same with a 4 to 1 on 64 pitch, but the performance is much different...Just something to think about.