Originally Posted by
Justin33
Just getting into 1/12th again gonna be running a bmi db12r and looking for some gearing advice i'm running a murfdogg 17.5 with a lrp sxx stock spec v2 esc running max boost and timing not sure about tire diameter but it'll be the crc tires straight out of the box. Any help on spur and pinion size would be great thanks alot.
Originally Posted by
AdrianM
Run a roll out of 100mm in 17.5. That's a 56 pinion with a 76 spur with 43mm tires. Temp you motor after 2 min and gear up or down to stay lower than ~155 deg F. If you are at 100mm roll out and the motor is cool bump up the timing 5 deg at a time until you are around ~150deg.
Check your lap times as gearing up or increasing timing with no lap time improvement means you are over geared or over timed. You may never get to 150 deg if the room is cold.
If you are running on carpet cut your tires to 41.5mm F/43mm rear or your car will be traction rolling/lifting/diffing out.
NOOOOO, Do NOT go to 100mm of rollout in BOOSTED 17.5, the car will be a dog or burn up. If you have the murfdog 17.5, which I think is the same as a Reedy 17.5, and the LRP Stock Spec V2 ESC at full song on boost, gear about 70mm of rollout with neutral timing on the endbell, whatever comes as stock and reads zero. Set Torque/Feel at about a 3 or 4, five really only generates more heat, and in order to get more boost into the motor you will have to gear DOWN, not up, to get more boost as the LRP boost is RPM based, more RPM means more boost. I have run nearly this exact combination of ESC settings and spec motor, and it can run hard and pull RPM a long way, but it's not intuitive as saying 'gearing up gives you more heat and top end speed'.