Tuesday, July 31, 2012

Motor Shaft Hub Adapter - Key Way Style 1


Below is a pdf of a CAD drawing that shows the design of a key way style motor hub adapter that we recently received.  At the top center is a brass bushing inserted into the steel adapter that functions as a pilot bearing for the end of the transmission shaft.  We would have preferred a ball bearing, but brass was chosen by the machinist instead.

9/21/2012
Correction:  John Emde at Pioneer Conversions indicated that the pilot bearing is made of a Bronze alloy that is designed for this type of application.

The darker vertical rectangle on the left side is the key that is shown inserted between the adapter and the motor shaft.  The two light areas on the left side of the adapter and adjacent to the key, are set screw insertion points.

The two vertical light sections at the top left and the top right aspect of the adapter represent insertion ponts for two of the eight bolts that mount the flywheel to the adapter face.

The motor shaft is at the bottom of the drawing.  Note that the motor factory provided for a pilot bearing by predrilling the motor shaft.  This detail will not be used in our design and for strength we would prefer the shaft to be solid right to the tip of the motor shaft.



 
 

Saturday, July 28, 2012

Adapters have ARRIVED !!

The men at Pioneer Conversions in Lemont Illinois, have provided a thing of beauty.  This week we received the mounting plate, spacer, and the Warp 11 shaft hub adapter.  Take a look !!

I have confirmed that the adapter fits perfectly on both the 1992 BMW 325i E36 from the original build car, as well as on the 2002 BMW 325i E46 backup transmission that was purchased from a wrecked vehicle.

                                     

Picture 4802:  Shows the three pieces of the adapter plate upon arrival.  Note that there is a positioning ring that fits into opposing steps on the face of the Aluminum pieces.  When assembled, the two larger pieces are flush together.  The two dowel pins are hidden on the other side of the right hand plate.

Picture 4789: Showing end view of the 2002 BMW 325i transmission.


Picture 4788: Shows the adapter plate positioned on the face of the 2002 transmission.  There are two 14.5 mm dowel pins on the opposite side and there is no wiggle whatsoever in the assembly.


Picture 4790:  Showing the center ring in place in the machined slot.


Picture 4791:  Showing the spacer that is positioned on top of the centering ring.



Picture 4795: Showing oblique view of adapter plate and spacer on transmission face.

Picture 4803: Warp 11 shaft hub adapter.


Picture 4811:  Oblique view of the hub shaft adapter positioned on the Warp 11 shaft.

The next phase will be to assemble all these components (starting with the Warp 11 motor, then the hub adapter, spacer, transmission face adapter, racing clutch assembly, and fiiiiinaaallllly attachment to the transmission.  This single assembly will then be lowered with my garage overhead chain hoist into what we will now call the "motor compartment" of the car.  After the drive shaft is reinstalled between the differential and the transmission flanges, the rear transmission mounts will be bolted into place and we will adjust the transmission and drive shaft for the proper vertical and horizontal alignment.  When in final position, we will make measurements and begin the fabrication of the anterior Warp 11 motor mounts.

On a parallel path, David is now working with both the foundry and his machinist to make the prototype of his Aluminum casting concept.

Friday, July 20, 2012

2002 BMW 325i E46 Transmission


The fabricator that is working on the key way adapter (Plan A) has had the original 1992 BMW 325i transmission in his shop for the last 5 weeks.  It is also not known when he will be finished with his manufacture.  Sooooo, another BMW owner’s car crash and bad luck resulted in a super deal on a 2002 BMW 325i E46 transmission becoming available.  The available online information indicates that this transmission should be identical to the one being used in the 1992 build.  We will now be able to confirm the interchangeability of the adapters being made on both years transmissions.



Picture 4767 showing the Getrag 2002 BMW 325i E46 transmission upon arrival.



Picture 4768 showing internal view.  Note the dowel pin outboard to the starter bolts (at 1:00) in the picture.  In the original 1992 transmission, this opening was vacant, and it was assumed to be a bolt hole.


                           

Picture 4771 showing distal view including shift mechanism and the substituted  shift knob (NOT the original BMW part).  That must be why the price was so good.   

Thursday, July 19, 2012

Final Dimensions


The adapter casting still requires exact measurements for each of the holes required for both mounting and alignment.  Not having access to automated measuring equipment, the plan is to take measurements using a Fowler 24” span caliper. (All-Spec Industries, Inc. part number 541000241).


Picture 4754 showing the 24” span Fowler caliper next to a 6” Mitutoyo electronic caliper.

The Fowler instrument has a resolution of 0.0005 inch,  but we understand that its accuracy is to  within 3/1000 of an inch, so a calibration may be necessary.  A series of measurements will be taken between all of the mounting locations, the dowel pins, and the flywheel flange face.  Finally, the average values will be calculated.  Some math, with the help of some PC software, will then be used to calculate the final dimensions required by the machine shop.  The dowel pins must be correctly located relative to the spline shaft to minimize both wear and vibration during operation.

 

Sunday, July 15, 2012

Aluminum Adapter Casting Process


It is clear to me that one of the reasons that EV conversions are not more popular is the difficulty of getting the adapter plate and hub adapter. 

 I have an order in for a machined set of transmission and hub adapters, but after 5 weeks, no news.  And not even any news about the news.

On the bright side, David Fischer has been busy this last week in Boston working on Plan B, and he has prepared the mold template that we will use to have a foundry cast our Aluminum adapter concept.  I will share some thoughts about the process and some  photos.  This process can be done for any transmission.

Disclaimer:  I am not an expert, but I will try and explain what I think that I have learned about each of these processes.

Point:  There is trade off between expensive precision machine shop time and careful EV‘er  fabrication time.  Regardless of which method is used, all have in common the requirement to know the precise orientation of the alignment dowel pins relative to the center of the spline of the transmission.   Additionally, the overall distance between the face of the engine block and the face of the drive shaft flange (“the critical dimension”) must be measured so that the final hub adapter will correctly embrace the spline of the transmission. 
In theory, if time and money were of no concern, one could buy a thick and expensive slab of Aluminum, and after the machine shop CNC is programmed, after many hours, the Aluminum would be carved away to create a three dimensional adapter made from a single piece of Aluminum.  Lastly, the required precision dowel, Warp 11, and mounting holes would all be bored.

In an alternative second way, one can take three separate slabs of Aluminum.  The first slab is cut to the required dimension to allow the entire face of the transmission to be covered.  The second piece would be faced so that the Warp 11 can be bolted to it.  The third piece, essentially a gigantic Aluminum washer, would separate the Warp 11 mounting plate from the transmission mounting plate.  The overall thickness of the three plates must match the dimension required to properly locate the future hub (or key way) shaft adapter relative to the spline of the transmission.  As an aside, one would need to drill and insert roll pins to lock all three pieces together before the machine shop does its magic and bores out all the required mounting, dowel, and the 4 inch center hole for the Warp 11.  This second approach might be expected to be less expensive, since less Aluminum would be sent to scrap, and less CNC machine time would be required.
Both of these methods have in common that each adapter is custom made, one unit at a time, with very significant machine shop billing.  The precision dimensions that were required and measured for the first build, represent the only part of the fabrication that would transfer to a future build.

A third way is to prepare a wooden form that can be used over and over by a foundry to make multiple copies of the same adapter upon demand.  After the crude Aluminum casting is heat treated, it would then be sent to a machine shop, and if properly designed, less overall machine shop effort would be required to refine the rough casting into its final precision form.  We will have several castings made in the first run and we will machine 2+ of them for testing.  After we have installed and fully tested the prototype, we hope to be able to offer these adapters to other EVers. 
If the mold form is properly constructed, the machine shop would take the Aluminum casting and face only the limited area that contacts the transmission face, the landing area of the Warp 11, and the small landing areas of each of the bolt heads that are used to attach the adapter to the transmission.  Finally, the precision bore holes for the dowel pins and the remaining mounting holes would be referenced to the exact center of the 4 inch opening required by the Warp 11.

The mold form that David is making is being fabricated from poplar wood board stock from his local lumber yard.  The piece was not wide enough, so he cut and glued the required pieces to create boards of the required width.


                          
Picture 0774 showing the glue assembly of poplar boards to create sufficient width for the adapter plate construction.

The largest piece of the adapter will be mounted against the face of the transmission.  It must allow for all of the mounting holes and it will have precision bored holes for the dowel pins.  The wooden form must also be larger than the final casting by a calculated amount so as to compensate for dimensional changes as the casting cools back to room temperature.


Picture 5641 showing the forming of the transmission mounting outline.  A digital image was first printed on paper and then glued to the surface as a guide for the cut.



Picture 0778 showing one of two required round spacers prior to being glued together.




Picture 5634 showing the two glued spacers after lathe work that created an inner ledge.  The ledge in the final Aluminum casting will be machined so that the heads of the Warp 11 mounting bolts all rest in the same plane.




                         

Picture 0789 showing the view from aspect of the Warp 11.  Note the glued disks that are positioned for the dowels pins and the mounting bolts.  These small areas will require less machine shop time to face off as compared to facing the entire surface.  The center of the wooden circular area will next be drilled out to about a 3.75” diameter.  The final 4” center Warp 11 hole will be precision formed at the time that the dowel pins are bored  by the machine shop  These are critical dimensions.  The remaining mounting holes are much less critical.


                         


Picture 0792 showing the view from the aspect of the transmission.  The outer (top most)  face, when cast in Aluminum, will bolt against the transmission housing.  This outer top face and the opposite face shown in picture 0789 must both be machined flat and parallel to each other to force the transmission face to be parallel to the Warp 11 motor face. 

After drilling the 3.75” center hole in the wood pattern shown in picture 0792, our next step will be to obtain good dimensions of the relative positions of all of the bolt holes relative to the dowel pins and the center of the spline shaft.  These dimensions will allow the machine shop to complete the fabrication after the casting faces have been prepared.  The thickness of the casting, and therefore the separation distance between the face of the Warp 11 and the transmission, will be finalized when the transmission face is machined flat.  This last machine shop work will allow for any variations in the casting thickness to be corrected.

Stay tuned.