RCCrawler Forums

Gimbal · 07-19-2011, 09:04 PM

Twin Force
Dewalt 14.4v motor on 14.8v 4C lipo
Fast Gearing

I have a choice: right side or left side pumpkin.
Counter Clockwise drive shaft rotation.

The motor, battery, trans, and chassis will all be traditional sprung setup.

In theory it makes more sense to go with right side pumpkin. The source of the twist (drive shaft) is farther away from the pivot point (left tire)...therefore in theory taking more force to lift the right tire.

On the other hand if pumpkin on left then there is more physical weight to lift on the right... Plus the weight of the right tire and rim is farther away from the source of the twist (drive shaft)...

The second question, should the sprung weight of the motor, battery, and the chassis be balanced, or off-center? I am assuming balanced...

sweli · 10-25-2011, 05:41 PM

Anyone have any input on this?
Wraith came out with offset axles, but mainly for higher center passthrough height.

Taking into account, the moment arm length, I would think the lower pic would be better at a forward climb to reduce torque twist.
But would be worse if you were backing up under a torque.

Moment arms, torque, weight, spring rate, shock fluid weight, link geometry, squat, antisquat.........................

sweli · 10-30-2011, 08:42 AM

I know there are lots of theories on torque twist. I have searched and read a lot of them.

If torque twist is due to the chassis reacting in an opposite direction of the drive shaft turning, then would it be better to move the pumpkin towards the wheel that lifts on the front axle, or away from the wheel that lifts?
I am thinking towards it!?!?

Anyone have some thoughts?

EeePee · 10-30-2011, 09:05 AM

How about the moment arm formula?

07-19-2011, 09:04 PM	#1
Gimbal Rock Crawler Join Date: Mar 2004 Location: Where it's wet Posts: 833	Torque Twist Engineering Twin Force Dewalt 14.4v motor on 14.8v 4C lipo Fast Gearing I have a choice: right side or left side pumpkin. Counter Clockwise drive shaft rotation. The motor, battery, trans, and chassis will all be traditional sprung setup. In theory it makes more sense to go with right side pumpkin. The source of the twist (drive shaft) is farther away from the pivot point (left tire)...therefore in theory taking more force to lift the right tire. On the other hand if pumpkin on left then there is more physical weight to lift on the right... Plus the weight of the right tire and rim is farther away from the source of the twist (drive shaft)... The second question, should the sprung weight of the motor, battery, and the chassis be balanced, or off-center? I am assuming balanced...

10-25-2011, 05:41 PM	#2
sweli RCC Addict Join Date: Jan 2008 Location: Lake Michigan Posts: 1,898	Anyone have any input on this? Wraith came out with offset axles, but mainly for higher center passthrough height. Taking into account, the moment arm length, I would think the lower pic would be better at a forward climb to reduce torque twist. But would be worse if you were backing up under a torque. Moment arms, torque, weight, spring rate, shock fluid weight, link geometry, squat, antisquat.........................

10-30-2011, 08:42 AM	#3
sweli RCC Addict Join Date: Jan 2008 Location: Lake Michigan Posts: 1,898	I know there are lots of theories on torque twist. I have searched and read a lot of them. If torque twist is due to the chassis reacting in an opposite direction of the drive shaft turning, then would it be better to move the pumpkin towards the wheel that lifts on the front axle, or away from the wheel that lifts? I am thinking towards it!?!? Anyone have some thoughts?

10-30-2011, 09:05 AM	#4
EeePee MODERATOR™ Join Date: Jul 2004 Location: Ohio Posts: 18,928	How about the moment arm formula?

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