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. 

Motor Mount 2.5

There has been considerable activity on multiple EV fronts, and it is time to start bringing the blog up to date.  The motor mount has presented an interesting challenge.  It was decided to work on a generic motor mount that could allow either a Warp 9 or a Warp 11 to be drop-in exchanged as wanted.  The designed generic motor mount might be referred to as a "clam shell" design.  It is intended to grip the motor firmly and provide mounting faces at the top (to possibly mount a future Soliton 1) and at both sides to provide mounting surfaces that are perpendicular to the base of the car.  The gap between the faces of the vertical mounting surfaces and the studs of the OEM rubber engine mounts will be fabricated as a BMW specific mounting adapter.  Although a great deal of treasure and time was expended on this fabrication, it is hoped to be able to produce for others the final designs as foundry cast aluminum pieces at an economical price point.

The BMW 325i does not allow for much space between the bottom of the Warp 11 and the car frame, thus it was decided to use a 3/8 in x 1.5 inch fabricated steel strap (Picture DSC0041).  The support strap was painted and a 0.125 inch high temperature silicone gasket was bonded to the inner surface.

         Picture DSC 00041 showing the fabricated lower support strap for the Warp 11 motor.

Although the bottom support strap was incorporated into each design, three different upper motor mount designs were fabricated as wooden prototypes. This blog entry will focus on one design that was fabricated from an aluminum billet.

Picture DSC00015 demonstrating a trial fit of one of several wooden prototypes.  Making the top surface parallel to the base of the car provides a possible mounting surface.  The side mounting surfaces, perpendicular to the base of the car, provide points of attachment for a short adapter to connect directly to the OEM engine mounting studs that are bolted to the frame of the car:

 A slab of 1.75 inch x 15 inch x 18 inch Aluminum 7075 aircraft alloy was purchased on EBay ($180) and it was machined in the shop using a rotary table mounted on a Bridgeport vertical mill. 

 

Picture DSC00263 showing brother George carving the initial grooves in the plate using a rotary table mounted on the Bridgeport.

 

 

 

Picture DSC00304 showing the preliminary cuts that are nearly thru the aluminum billet.  A 0.25 inch plywood sheet was then inserted under the piece prior to the last penetrating cuts.

 

 

DSC00314 showing the final machined piece just prior to sectioning into two identical motor mounting adapters.

 

 

DSC00322 showing the top aluminum motor mounting adapter bolted to the bottom fabricated steel support strap.   This was the first time using a Bridgeport mill and only 16 hours was required for the fabrication process!!

 

 

Picture DSC00324 of the installed upper and lower motor mounts.  Note that the wooden prototype shown at the bottom of the picture is for reference only.  The top of the picture partially shows a prototype accessories plate that includes at the top left, the OEM BMW alternator, and at the top right, the OEM air conditioner compressor.   

 

 

Picture DSC00325 with the further band saw shortened BMW OEM passenger side engine mounting bracket in place.  Two mounting plates will next be fabricated.  One plate will be bolted to the aluminum side surface, and the second plate will be welded to the BMW mounting bracket (at the right).  

 

 

Picture DSC00327 of the driver side motor mount.  The black duct at the bottom of the picture is the back end of the OEM BMW alternator that has been mounted on a prototype accessories plate.

 

Although the mounting holes will be predrilled in the plates that are bolted to the sides of the aluminum billet, the correct location for the mounting holes in the modified and welded OEM mounting adapter will be determined only after trial fitting of the two plates together in the car.

 

Motor Mount 2.0

An alternate design being considered would incorporate "BMW style" motor mounts that would be bolted directly to the sides of a "clam shell" that encircles the body of the Warp 11.  This design would use the same foundry casting for the left and right side motor mounts.  The top and bottom castings of the "clam shell" , also identical, would provide an 11.45 inch opening when bolted together.  A differently sized  "clam shell" casting with a 9.25 inch nominal opening would allow for the substitution of a Warp 9 onto the same motor mounts. 

Mounting flanges at the equator of the Warp 11 "clam shell" would mate to integral flanges on the face of each "BMW style" mounting bracket.  To demonstrate the design, the previously sectioned BMW left side mounts were further sectioned (picture DSC05438) to allow room for the two mounting plates.  The sectioned BMW mounts are neither symmetrical or in good alignment when mounted, but they allow for a good visualization of a possible design. 

Picture DSC05438:  View of the final BMW left side motor mount (top casting in picture) after the final sectioning with a hand held band saw.  The additional removal of metal provides space for a flange to be welded to the side of the "clam shell" as well as a second flange to be welded to the mounting bracket.

Picture DSC05452:  Top view of the prototype installed on the top surface of the Warp 11.  Note the asymmetry at the mounting brackets.  The angle of the picture does not demonstrate the fact that both pairs of flanges are parallel to each other and equidistant to sides of the Warp 11 motor.

 

Picture DSC05451:  Anterior view of the top half of the four piece design.  Wood wedges were inserted to correct for a slight misalignment.  The wedges will be glued in place, and new dimensions confirmed on the workbench after the assembled framework is removed from the car.

Picture DSC05454:  Close up view of the left side mounting flanges.  The top and bottom halves of the "clam shell" will be joined together with a pair of vertical threaded rods or bolts (not shown).  A rubber trim element will be glued to the inner contact surfaces of the "clam shell" to provide for a snug fit and to reduce any vibration noise.  

Fabrication:

The design was initially drawn on 3/16 inch plywood and cut out with a table top band saw.  The outline of the design was then traced onto prototyping foam (McMaster Carr, part 3152T41).  The foam pattern was cut out and the two plywood pieces then glued to opposite sides of the foam spacer.  Two sets of temporary nuts and bolts were added to provide strength while the glue was setting and the sides sanded.  Four 4" by 4" plywood "flanges" were cut out with two of them being hot glued to the sectioned BMW mounting brackets.  During the trial fitting it was found that the alignment of the flanges on the "clam shell" was not correct, and wooden shims were required to correct the alignment.  The wooden flange on the "clam shell"(including the shims) were then glued in place so that upon removal from the car, the final dimensions would be maintained and measured on the workbench.

In the final design, both pairs of flanges would be parallel to each other and perpendicular to the horizontal plane of the car.  The foam core adjacent to the motor body was recessed to allow for clearance of the red painted bolt heads (two of which are visible in picture DSC05454).  These bolt heads are part of the Warp 11 motor.  The top surface of the "clam shell" is flat, parallel to the floor, and wide enough to assist in the mounting of a controller.  The merit of this design is that only two different castings are required for the project.  The top and bottom of the clam shell are the same casting, and both the left side and the right side mounting supports are the same casting.  A differently sized "clam shell" casting would allow for the use of other Warp style motors without changing the mounting brackets.

Motor Mount 1.2

The initial design, based upon the measurements described in the previous blog entry (dated 2/14/2013, Part 1), was constructed using 3/16 inch plywood, 1" thick wood blocks, and nuts, washers, and bolts.  The final finished product would be fabricated using plate steel and a good welder. 

The concept is to have a metal arch that rests directly on both BMW motor mounts.  By using three nuts, four washers, and a fully threaded bolt, it was possible to rigidly hold the two wooden arches parallel to each other during trial assembly and fitting.  The final design would include a metal band bent with a radius of about 5.725 inches (11.45 inches is the outer diameter of the Warp 11).  The base of each arch would be welded to the curved band.   Strategically drilled bolt holes in the curved base band would allow for the insertion of bolts directly into the motor housing.  These bolts would help prevent torque induced rotation within the motor mount while under full load.

Picture DSC05424:  View of the assembled wooden model of a mounting harness for the Warp 11.   The blocks of wood at 3:00 and 9:00 have not yet been trimmed to match the contour of the lower arch.

Picture DSC05423:   Anterior view showing the top half of the wooden prototype positioned for a trial fitting.

Picture DSC05420:  Top view of the top half of the wooden prototype.

This design requires that the arches be cut from steel plate, a curved base plate formed, and final welding all three pieces together.  The final height required to provide adequate strength of the arch (and the depth of the arch below the motor) has not yet been determined.  If the top of the arch were made flat, then the surface could be used as a mounting point for other components.  This design is simpler, but less universal, when compared to attempting to incorporate a modified BMW style left side motor mount as was previously described.   

Motor Mount Adapter 1.0

 

Taking measurements within the motor compartment presents quite a challenge.  It is difficult to measure between the studs and the sides of the motor, the vertical aspect, etc.  The following method was decided upon, with full understanding that although the measurements will not be exact, that they should be sufficiently close to achieve the required result.

Part 1:
 

Sooooo, having said that, the Warp 11 was initially positioned as close to center (between the two motor mount stud bolts) as could be measured.   The focus was more upon having an identical distance from the center of each stud to the side of the motor, than having the exact measurement itself.  Both dimensions were adjusted until they were eventually different by less than 1 mm.  The base of the motor was previously shimmed with wooden wedges to elevate it off the frame and position it vertically.  The actual vertical height above the frame (and relative to the engine mounts) will be reported later once there is greater confidence  in the measurement.

 

The way the measurements were determined was as follows.  A 30”x24”x 0.125” cardboard sheet was first measured to mark the mid line, allowance was made for a minimum space of 1" at the top of the cardboard (for a future cross brace).  The outline of the 11.45" outer diameter of the Warp 11 motor was centered, outlined, and cut out.  The drawing was then cut in half, so that the bottom edge of the cardboard would essentially be at the height of contour (ie., the "equator" of the Warp).  The final dimension of the top cardboard piece (which only has half of the Warp outline) was 10.625" tall x 24" wide.  This allowed the cardboard template to drop snugly onto the top of the Warp 11 motor.  The centers of two smaller square pieces of cardboard were then marked so that they could be aligned very closely with the centers of the M10 studs that protruded from the rubber engine mounts.  The edges of the cardboard squares were exactly flush with the metal landing areas of the engine mounts.  When all three pieces of cardboard were stable and in direct contact, 1.875" wide Scotch tape was carefully applied to bind all of the pieces together.

 

 Picture DSC05406 showing the cardboard template positioned on the Warp 11 and the cardboard "feet" resting on the motor mounts. All three pieces were then taped carefully together.

 

 

The entire cardboard jig was then pulled directly out of the motor compartment and laid on a fresh 20" x 30" cardboard sheet.  The relationship of the bottom edges of the small cardboard were then transferred to the new cardboard and a full scale drawing made to show the final relationships of the Warp 11 and the mounting pads.

 

 

Picture DSC05404 showing the cardboard "template" positioned on a fresh cardboard for transfer of the critical dimensions.

 

This process did not require that the car be level, nor did it matter if the 12"x24" cardboard piece was level to either the floor or to the plane of the car.  As it turned out, after drawing a horizontal line that connected the midpoint of the base of each mounting stud, and extending the lines that represented the landing area of  the mounting pads, the extended landing area lines joined at almost exactly the mid line, and at 150 degrees relative to each other !!  Thus, the motor mounts are each -15 degrees relative to horizontal !!!

 

Measured Approximate Dimensions of 1992 BMW 325i motor mounts:
 

Distance from center to center of studs (of engine mounts): 23.8125 inches

Angle of landing pads of engine mount relative to the horizontal plane: -15 degrees.

(Both motor mounts angle downward toward the mid line of the car.)

Height of the M10 studs embedded in the hard rubber mounts: 1.0625 inches

Approximate diameter of the metal landing area that is cast into the rubber engine mount: 1.75 inches.

Part 2:
 

It appeared that the BMW driver side motor mount (it arches over the steering column) might provide some useful dimensional information.  Two new units were purchased directly from Patrick BMW (in stock and $38 each) and then with a band saw, a series of sections were removed and the resdiual mounting piece then bolted to the motor mounting studs to better visualize the spatial orientation.

 

Picture DSC05348 showing bottom (left) and top (right) views of the BMW driver side motor mounts.

Picture DSC05349 showing the leading side view (left) and trailing rear view (right) of the BMW driver side motor mounts.

Picture DSC05386 showing the sectioned views of the BMW driver side motor mount during trial fittings.

Picture DSC05393 showing the final sectioned BMW driver side (left) motor mount bolted to the driver side mounting.  The steering column is to the upper left.

Picture DSC05388 showing the second sectioned BMW driver side motor mount bolted to the passenger side (right) motor mount.

Picture DSC05398 showing the top view of both motor mounts bolted to place on the engine mounts.  Note the lack of symmetry.  The actual distance between the mounting brackets and the sides of the Warp 11 are essentially the same.  The apparent difference is due to the camera angle.

The next task will be to weld mounting plates to the face of each sectioned motor mount.  Finally, a clam-shell design circumferential clamp will be made that can be bolted to both the motor and to the welded plates on the sectioned engine mounts.  Generation 2 motor mounts will be made from scratch as symmetrical castings with mounting points pre-drilled and ready for attachment to a clam shell designed circumferential clamp.

1992 BMW 325i Crankcase Position/RPM sensor 2.0

The intention is to install the BMW harmonic damper, recovered from the M50 engine, onto the Warp 11 shaft.  The CPS (crankcase position sensor) will then be mounted in close proximity to the teeth of the damper.  During shaft rotation, the iron teeth of the damper will cause a change in the magnetic field within the Aluminum clad sensor and the wire coil within the CPS will generate an AC output signal.  With luck, the generated signal will directly drive the rpm gauge in the existing instrument cluster.  The additional benefit of this idea, is the availability of the integral pulley wheel that can be used to power accessories as needed. 

The machine shop fabricated a sleeve on the lathe that would serve as a spacer between the existing shaft (7/8” in the older style Warp 11 being used), and the 32 mm ID inner opening of the BMW harmonic damper hub.  The shop also produced a spacer (Picture DSC05315) that is about 0.0605” thick x 1.1330” ID x 1.2577” OD, and it can be used with the newer version Warp 11 motors produced after 7/1/2012.  The thicker sleeve was produced on a lathe and the key way was cut with a mill, while the thinner sleeve was rolled from galvanized steel plate.  I will have some extra adapters made and they will be available to other EVers upon request.

 

 

 

 

Picture IMG6595 of adapter sleeve used to connect the 0.875" shaft of the Warp 11 to the BMW damper hub whose ID was 32 mm.  Final dimensions of the sleeve were: 0.878 ID x 1.258" OD x 1.375 Long.

Picture DSC05315 showing the rolled adapter used to connect a 1.125" diameter Warp 11 shaft to the BMW damper hub whose ID was 32 mm. Final dimensions were about 1.1330 ID x 1.2577 OD x 1.3900 Long. This adapter has some flex during installation. 

  

 

 

 

Picture DSC05306 showing 7/8” drive shaft, machined sleeve (0.878” ID x 1.258” OD x 1.375" Long), and a 3/16” key, fully inserted and engaging both the 32 mm (1.260“) harmonic damper hub key way and the motor shaft key way.  The key way on this sleeve was over sized at 0.250" and future sleeves will have a key way slot of 0.1875" to better match the 0.1875" key.  The installed key dimensions were 0.400” x 0.1875” x 1.2502 and it was cut using a band saw from steel plate that was 3/16” x 1.25” x 6” (McMaster Carr).

 

Picture DSC05309 showing the 58 tooth damper bolted to the damper hub, and secured to the 0.875” Warp 11 commutator end shaft.

Picture DSC05310 showing oblique view of the installed harmonic damper.

 

The CPS will be mounted on an accessories end plate (currently under fabrication) and it will be in close proximity to the 58 teeth of the damper.  An Aluminum set screw shaft collar (picture DSC05317, McMaster Carr part 9946K22) was mounted on the shaft in direct contact with the motor bearing and the damper hub.  This collar fixes the dimension between the motor bearing and the damper hub. 

 

 

Picture DSC05311 showing a close up side view of the installed harmonic damper.  Note that there is sufficient room for a 0.625” (15.875 mm) Aluminum accessories end plate to be mounted on the end cap of the Warp 11.

 

 

 

Picture DSC05317  showing the set screw shaft collar prior to installation between the damper hub and the motor bearing.

Energized test of the drive train !!

(Updated 1/22/2013 to include photos)

The Warp 11 and Getrag transmission were bolted together on the bench and the rear transmission cross member attached to the transmission prior to lowering the assembly into the motor compartment with a chain hoist. The front of the Warp 11 rested on the car frame with the rear of the transmission being supported with a floor jack.

Picture 05218 showing the lowering of the Warp 11/Getrag into the motor compartment.

Using a rolling floor jack, the weight of the transmission was supported and the assembly moved toward the back of the car. Four replacement mounting bolts (obtained from Patrick BMW, $8.00) were used to attach the cross member to the undercarriage of the car. The drive shaft was then installed, first attaching the four bolts at the rear differential joint, followed by attachment of the center support bearing. The bolt heads of the flex joint would not clear the rear transmission cross member, so the rear transmission cross member bolts were removed from one side, and loosened on the other. This provided enough clearance for the flex joint to wiggle into the space and mate to the transmission flange. Luckily, the red paint marks previously painted on the drive shaft, transmission flange, and differential flange, were all intact, so it was possible to realign all the components without difficulty.

Picture 05302 showing the undercarriage view of the installed drive train and drive shaft. The rear transmission cross member was previously sand blasted and repainted prior to attaching it with new mounting bolts.

Picture DSC05213 showing the empty motor compartment with the ICE engine mounting brackets in place.

Picture DSC05297 showing the position of the left hand ICE mounting bracket after the Warp 11 had been secured to the drive shaft and differential. The bracket will provide some dimensional information, but it is not usable in its current form without significant modification and welding.

Picture DSC05303 showing the available space in the motor compartment after the Warp 11 had been secured to the drive shaft and differential.

THE WHEELS TURN !!!!

Video MOV05299 showing the operation of the temporary trunk located on/off switch, the rotation of the rear wheels, and a view of the operating motor in the motor compartment.