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.
