July 06 2008

Body surgery - floor modification for the motor to fit.

There was a little problem surfaced when trying to fit the motor under body where the gas tank was. The distance between lowest point of the floor and the underbody level was about 200mm while the motor is 245 x 245 mm square in the crossection. This means even if it's against the floor, it still sticks below the underbody level by 45mm. Not good. I hoped for this not to be the case, but was ready to face it. Well, I have to raise the floor by 45mm + some margin for insulation and vibration dampening material thickness. So the section if the floor panel right behind the front seats will have to be cut out and raised floor fabricated from a steel sheet welded in its place to restore rigidity and accommodating the motor dimensions. Quite straight forward task. I removed rear seat cushions, protected interior with cloth from flying sparks from sanding ands welding and invited good friend of mine to do the job. Here is what we did:

The holes defining the corners of the rectangular to be cut out were drilled through.
 Using battery operated electric reciprocating hand saw it took less than a minute to open the hatch.
This section of the floor is gone.
Close up - trimming the hole to actual dimensions needed.
There were two thick spot welded plates reinforcing the floor in strategic places. I didn't want to cut into those; instead we made edges vertical by expanding the hole and bending the metal. It is impossible to just hammer the floor here, we used bottle jack to slowly reshape the metal and were able to watch deformation and stop exactly when desired outcome was achieved.
Once this was done, it's a good idea to try to fit actual motor, not the cardboard mock up - the motor has flanges, cable glands mounted on the terminal block, mounting eyelets etc. that were not replicated on the mock up but can actually interfere.
View from the right side. It is clearly seen that because the floor is at the angle following rear seat cushion contour, the rear side is the lowest and so interfering the most. Front end of the hole (e.g. rear of the motor) could clear the underbody but barely. IT makes sense to just make a floor after entire motor shape. The terminal block will face sideways.
Trial fit view from the rear differential side. I will not offset the motor o one side (because of the diff pinion shaft offset). Rather, the half shafts will be fabricated with different lengths to accommodate actual position of the diff depending on its width. I still haven't decided on the diff type (and I will not use Ford 9" one for sure), so the half-shafts will remain open question for now.

The new floor was stamped out of steel sheet metal about 1.5mm thick and shaped to close the hole leaving 7-8 mm gap around the motor. It was trimmed to fit as tight as possible for good welding. The floor edges were sanded and the sound deadening compound was removed from the top around the hole to avoid melting and creating a mess (not to mention catching fire. For that mater a garden hose was close enough to spray water if needed). After trimming and bending the hole edges, closing the gaps, the floor patch was tack welded in and get ready for actual weld with continuous seam. This will happen a week from now. So for now the progress was up to the tack welds as shown below:

Sanding the metal. It is symbolic that all the power tools to work on this EV were battery operated (including this sander)!
This is done and surfaces are prepared for TIG welding.
The steel floor patch cut and bent to fit.
Trimming the corners and final preparation of the patch.
Trial fit.
Closing the gap between the patch and floor edges bent 90º upward.
Finally tack welding the patch. The weights were placed on top of it to prevent movement.
Closer photo of TIG welding process.
Here is want the weld points look like. The gaps around will now be minimized and final welding will take place.
Finishing the floor from inside.