I have a Vaterra Ascender, and every time I run it, I see the chassis lean to one side. Why is this happening, and can I fix it?
Because the transmission has more gear reduction than the axles, twisting occurs when the driveshafts try to spin the axles. The twisting motion of the shafts wants to turn the gearbox around, and since it’s attached to the chassis, you get a lean when power is applied. You can’t eliminate the twist, but there are two ways to reduce it. You can mount up an axle with a gear ratio lower than 1.85:1 and increase the size of the pinion gear to raise the gear ratio in the transmission. Or you can install a second threaded collar on your shocks to limit the travel of the top spring and apply pressure sooner to the stiffer lower spring. You can make this modification by getting your hands on a second preload collar and removing the knurled section from it enough so that it will fit inside the springs. Install the modified collar so that it’s about half an inch lower than the top preload collar. Then the bottom collar will stop the travel of the softer top spring when the plastic upper and lower spring coupler hits it. Do this on all four shocks, and make sure they all have the same setting.
Installing the modified preload collar will stop the spring coupler sooner, which then uses the stiffer lower spring sooner and helps reduce torque twist. 27
The Ascender has a transmission with a lower gear ratio than the axles, so this causes chassis twist when power is applied and the driveshafts try to turn the gears in the axle.