XRAY - Model racing cars

Hi everyone,

I need help on Gear ratio for the X12 with Reedy Sonic2 17.5T.
I am using the Hobbywing 1S ESC with 30 deg Timing boost.
Rear tire around 45.5mm dim.

I tried 80/43, 80/40, 80/37 spur/Pin combo, still I have poor acceleration and less speed on the straight compare to others 1/12 in a medium size indoor Capt track. I asked one of the 1/12 driver, and he said he is using 85mm rollout.

Should I go back to the stock 96T Spur ?

Thanks,
Aki

hello

With 80 spur, you need pinion about 45 (45 gives around 79mm roll out )

So 45 is good starting point, also set your speedo as this guy's one
Watch temp. of motor and speedo every 2 mins in first run
(Max temp for motor [it depends] are around 80*C)

PS
Roll out is how far car go when motor does one turn

(wheel dimension in mm) * 3,14 (pi) / (Gear ratio>spur/pinion) = rollout in mm

For you > 45,5 * 3,14 / 1,77 (80/45) = 80,7 mm roll out

Have Fun !

We run around a 85 roll out at our track as well (owned by XRAY's Drew Ellis )

With fresh cut tires (44mm), I run a 74 spur / 46 pinion = 85.92 roll out with 13.5 motor.

With 17.5 it appears that everyone runs 96-102 (depends on the motor).

Hope this helps some