Motor Mount 3.0

The fabrication of the flanges for connection of the shortened OEM driver side engine mounts to the top half of the aluminum clam shell began with cutting four 3.75” x 4.0” x 0.5” plates.  Two of them were then drilled to each accept four 5/16”-18 bolts.

 

Picture DSC00345 showing the four holes and the first countersink drilled into the flange.  The flange is 0.50" thick and the countersink is 0.25" to permit recess of the bolt heads.

 

 

Picture DSC00348 showing one of two completed flanges.  The flange (left) was then carefully positioned on  the clam shell (right) and a center punch used to locate the future position of threaded holes in the clam shell.  Note that the left flange was rotated 90 degrees before the picture was taken and when attached to the clam shell it is identical in height (3.75") to the clam shell on the right.

 

Picture DSC00349 shows the awkward setup that was required to use the Bridgeport to drill holes in the ends of the clam shell.  The mill table was in full down position and there was still barely sufficient clearance to drill the pilot holes in the clam shell.

To prepare the clam shell for 5/16" hex head bolts, the clam shell was first drilled 1" deep with a 17/64”bit.  It was then threaded with a tapered 5/16"-18 tap and finally the threads extended to nearly the bottom using a 5/16"-18 plug tap . 

 

 

Picture DSC00356 showing the flange bolted to the clam shell motor mount.  The gap from the face of the BMW OEM piece and the face of the flange is slightly grater than 0.5”.

Picture DSC00361 showing the placement of the second 0.50" flange (center with red X on edge) that will be welded to the remnant of the OEM engine mount (bottom center).
 

 

Picture DSC00363 showing the outboard flange hot glued to the BMW OEM engine mount support.


 

Picture DSC00365 showing a view of the passenger side hot glued pieces as viewed from the front of the car. By hot gluing the two pieces together it was possible to fix the precise orientation top to bottom, front to back, and left to right.

Picture DSC00366 showing the outboard view of the hot glued pieces.  The square flange is connected to the shortened BMW OEM engine mount (foreground).

It is preferred that the BMW OEM engine mounting bracket face be fully welded to the flange on all four sides.  To allow for greater welding surface, a different and larger outboard flange will next be fabricated.  The larger outboard flange and the BMW OEM engine mount will then be welded together at a fabrication shop. It is anticipated that the welder will first tack weld the pieces, then remove the residual hot glue, and finally weld the complete outer circumference of the modified BMW OEM part.