Originally Posted by
rendizzle
ah gotcha. Now we’re talking about driver preference and feel. I run on high-bite clay, so take this info for what it’s worth. When I ran the motor ‘back’ with the 72 spur, my car pushed more than I liked on quick chicanes or hard 180s. My driving style, and especially in 17.5, I’m not on the brakes much when the wheels are on the ground, so I ran about 15-18% of drag brake to help load the front and get some steering...when I ran a 72. Since moving to 75t spur, I’m running at most 7% drake brake. The car feels more balance on/off throttle, and I’m able to carry more corner speed. I also feel I can slide the rear easier if I need to tighten up my line with a blip of the throttle. Is this feel ALLLLL from motor position? Probably not. Spring weight, shock oil weight and all that affects that too. Motor position was just an easier path for me.
again there is no right or wrong. By no means married to that setup. I could still make my car work with a 72. The recent layouts at OCRC trend to taller gearing for me. If I kept with the 72, I probably be running a 30 or 31t pinion, which I didn’t feel like buying.
This is something overlooked by many and I regularly switch between pinion/spur combinations to move the motor around. My standard gearing is 25/78 with a HobbyWing 7.5, I can achieve the same ratio with 23/69 , 24/72 , 26/78 and 27/81. Each of those steps is gives 2mm between the centre of the motor shaft and layshaft, obviously this isn't directly 2mm difference in horizontal motor placement as the layshaft is higher than the motor shaft, in reality it is around 1.6mm.
Consider that moving the battery around is a noticeable change (my LCG CENTRO 3200mAh packs are 152g) and the steps with the standard mount are 4mm, 2mm if you rotate the mount every other adjustment .... you did know the lipo mount was offset didn't you?
Now my HobbyWing V10 G3 motor is about 160g so similar to the LiPo, now those 1.6mm steps actually sound like they could be quite useful for weight distribution.
Also ...
In addition to simply moving the weight around the torque reaction between the motor's rotor mass and the axle mass (wheels, shafts, diff) changes proportionally to the distance between those two masses and also between the rotor and the centre of mass of the off the whole car, this is somewhere in the battery tray / electronics area on a B6 based car depending on the installation used.
When you consider that moving the motor around looks like it might be similar or slightly more significant than moving the battery .... well it is, give it a try.