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JeepEV: Electric Vehicle Conversion Project
Torque Rod


     The Jeep will now be using an electric motor for propulsion power. One thing that needs consideration with an electric motor is torque. Electric motors by nature produce a lot of low-end torque -- usually more so than a comparable Internal Combustion Engine (I.C.E.). This means that a lot of torque is placed on the drivetrain when accelerating hard, such as from a dead stop. The torque from the motor can and will cause the transmission to want to rotate, something which the transmission must not be allowed to do. It is for this reason that most electric vehicles must have a "torque rod" attached between either the motor , transmission, or transmission bellhousing and the frame of the vehicle to prevent any such unsafe drivetrain movement. Also note that the o-clamp mount which surrounds the motor is not suitable as a torque rod because it is not able to clamp down with the force that would be required. instead, a seperate torque rod must be made.


Torque Rod #1 (No Longer in Service):

     I made the first torque rod to bolt between one of the bolt holes on the end of the motor and the driver's side motor mount. I'll tell you right now that this torque rod FAILED and was replaced with a newer, better torque rod design. Here's how the first one was made anyways, since I'm sure you're itching to know: The base piece for the torque rod was a dog-bone style mount which was left over from one of Austin EVs previous EV projects, and provided a nice big rubber isolator eye for mounting. The first thing I did was cut the dog-bone mount in half with my jigsaw. Next, I drilled two holes through the flat side of the mount, and cut a piece of flat steel. After drilling two corresponding holes in the flat steel, I bolted the two pieces together with two 5/16" grade 8 bolts. About this time you'd wonder why I'm fooling around with bolts when I have a welder. The reason why is that the dog-bone is made out of aluminum which is a metal that dissapates heat quickly, and thus requires a bigger welder than I currently have access to. Hey, Bolts are good too!

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The First Torque rod attempt is made then fastened at the face of the
motor and the driver's side old engine mount.



Too Much Torque, and the Result:

     Well, during the test run phase of the project, on what I believe was the 8th test drive, we had a problem. We were driving the Jeep around the block as usual. As the clutch was being engaged (clutch pedal being brought up), we felt a jerk and the Jeep began to make a popping/clunking sound while barely continuing to move. It crept back to the garage where we investigated what went wrong. Immediately it was evident that the motor (and transmission/ t-case attached to it) had rotated close to 15 degrees in the o-clamp mount towards the passenger side of the vehicle. This was discouraging news. It was obvious the drivetrain was out of alignment due to this, and the cause would have to be determined and fixed.

     The reason the drivetrain rotated itself was excess torque. We discovered that this torque came from the rear drive shaft, which we were aware was slightly binding occasionally at the U-joints. What happened was that the u-joints had apparently bound up slightly. The real question was: why did the torque rod fail to do it's job? A probable reason is that the rod only bolted to the motor in one spot, which prevented direct spinning (left/right) movement in line with the rod, but didn't protect the motor from moving in all dimensions (such as front to back). This really is necessary to protect against since the transmission is mounted on a rubber mount which allows it to move around from side to side and front to back some if not held steady by the motor. Another flaw with the first torque rod was the rubber bushing which didn't provide enough rigidity to keep the bolt from moving around in it.


Torque Rod #2:

     Before attempting to make a new and improved torque rod to replace the first design, the motor clamp was loosened and the drivetrain was realigned in the mounts. However, due to an issue with the clutch pilot bearing (which is detailed here: [comming soon]), we decided to completely remove the motor from the Jeep so that work could be done. Once the motor was reinstalled, the measurements for the new torque rod were taken. The second torque rod design utilizes the two pre-drilled bolt holes on the rear face of the motor for securing to the motor. It then uses the driver's side old engine mount and the passenger side new motor mount to bolt to the vehicle.

Torque Rod Page Photo
The locations indicated by the red arrows are where
the new (second) torque rod is made to attach to.

     After measuring, we cut three sections of square tube steel to form a three sides of a square. Next, one long piece of square tubing was cut to run from the driver's side engine mount to the passenger side motor mount. Lastly, a section of "L" channel was cut in order to complete the connection at the driver's side engine mount. Once cut, all the pieces were welded together to form the new torque rod. Then the holes were drilled through the square tubing to allow two 3/8" bolts to bolt to the corresponding holes in the face of the motor casing.

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The steel is welded together to create
the new torque rod.

     After the torque rod was welded together, it was cleaned with the electric grinder and painted. Lastly, it was installed in the Jeep. The new torque rod is stronger and will keep the drivetrain from rotating due to torque.

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The Torque rod is painted then
installed in the Jeep.


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