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Project SR E30: Part 2 - Making Custom Motor Mounts

by Nikita Rushmanov

 

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 2x4’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.

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Comments
Crousti
Croustilink
Monday, December 18, 2017 2:13 AM
Question about motor mounts deforming. You are accounting only for the weight of the SR, but when that thing comes on boost, it creates a lot of torque which transfers in the mounts, with a "leverage" going from the motor mount to the crankshaft. This would compress the mount on one side and extend it on the other side far more than 2mm, am i right ?
JR
JRlink
Monday, December 18, 2017 6:27 AM
What are you cleaning the motor with to get it to look new?

Are you just sandblasting and cleaning it all down and then spray painting it silver?
stylngle2003
stylngle2003link
Monday, December 18, 2017 8:29 AM
hey guys, any one else having issues getting to part 1 of the series?
Nikita Rushmanov
Nikita Rushmanovlink
Monday, December 18, 2017 11:47 AM
@Crousti that's why we gave them 6mm to move about. That motor mount will never compress that far.
Nikko
Nikkolink
Tuesday, December 19, 2017 9:17 AM
i hope they are plating the top of the DOM tubing used for the transmission mount spacers.
Caithness
Caithnesslink
Thursday, December 21, 2017 12:11 PM
I cannot access part 1 of the series- the link redirects to the home page.
Sootfoot
Sootfootlink
Thursday, December 21, 2017 7:08 PM
@Caithness - try it again
Rockwood
Rockwoodlink
Friday, January 05, 2018 9:33 AM
I'd add a fish plate to that subframe just to make sure it doesn't crack along that perfectly straight line of HAZ you put in it. :)
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