Project SR E30: Part 2 – Making Custom Motor Mounts

In the last episode, we managed to make an SR20DET fit inside an E30. Now it’s time to actually make it stay there. In this installment, we will be fabricating custom motor and trans mounts.

The first step, is to forget about the cherry picker. We need to be able to manipulate the engine in every axis. To do this, we will “tripod” the engine. What I mean by that, is we use 3 Harbor Freight jacks, placing one under the transmission, and two on each side of the oil pan (with 2×4’s to prevent damage). By doing this, we can yaw, tilt and roll the engine while also moving it left, right, forward, backwards, up, down by either raising/lowering the jacks, or simply rolling them around.

We start by finding the center of the engine bay. We simply measure the frame-rail to frame-rail distance, and divide it by two. As you can probably guess, it helps tremendously to have a straight car.
We use the crank pulley as the center reference on the engine. We then simply push the engine around on the jacks to get it perfectly centered.
Now we set the roll of the engine. We use an angle finder and a level across the core support to zero the angle to the chassis. Again, it really helps to have a straight car when doing this.
We use the bottom of the oil pan to get the engine’s angle. Since SR20’s are slanted engines, everything above the oil pan is tilted and can’t be used for a reference. Now we can simply raise the left or right oil pan jacks to get the engine perfectly level.

Next we will set the tilt and yaw of the engine. This is step is very important, and should not be overlooked. The goal is to get the output of the transmission and input of the differential to be exactly parallel. Since driveshafts do not utilize constant velocity joints, they will cause the output speed to oscillate if the U-joint operating angles are not equal, causing driveline vibration. Watch this video for an excellent demonstration.

Leave a Reply

Your email address will not be published.

*
*