Belly pan

Belly pan All the items listed in the title of this page are not really necessary for an average EV conversion. Well, I dare to think that my conversion is better than average and I wanted to get maximum out of it. So he it came - belly pan and wheel covers (which supposedly reducing air drag) and electric door locks.

I am saying "supposedly" reducing air drag because I did not make formal measurements with and without pan and covers, in non-windy weather both directions and record Wh consumed. I will probably never take the pan off just for doing these experiments - too much work and little practical benefit. To me it is intuitively obvious that the smoother underbody - the less C_d, and the fact that I can't attach a hard number to my thinking does not discourage me from doing it. Plastic is cheap (I use two 122x244 cm (4'x8') polyethylene sheets about 2 mm thick, similar material to what a gallon bottles for milk are made out of, just thicker) and easy to cut to required shape. Pick the material which is easy to bend and cut but not very flexible so it does not vibrate at high speeds.

All I needed is to cut out some material where suspension parts stick out and screw the sheets by the edges to the underbody with metal self threading screws and large fender washers. The rear sheet goes first and the front one - second so the pocket between them is facing rear of the car. Another side benefit - your under hood compartment is always clean and free of the water and road dirt spread around by spinning tires.

The process is somewhat labor intensive but straight forward. Preparation is a key - you'll need a scissors capable of cutting plastic, drill and sheet metal screws with large fender washers. Raising the car is almost mandatory. A grease pit comes very handy; realizing benefits of having it I decided to make it which by itself tuned into another big project...

So, first you make a templates for the pan shape. Take a large enough piece of clear wrapping plastic film and temporary stick it to underbody with a pieces of modeling clay. Ideally, it's 3 person's job, two stretch the film from the front and the back of the car, and the third one glues it to under body. When done, take a fat permanent marker and outline the cut outs for suspension members, driving shafts, anything which moves and would interfere with the pan if covered. Mark approximate places for screws bolting pan to the body. Don't forget to wrap the plastic to the wheel wells.

When that done, cut the real plastic based on the pattern you outlined leave the front part of the front piece and rear part of the rear piece uncut yet - you'll do it to fit after pan will be installed. Also don't drill any holes at this point yet - if you do, they will be in wrong place. In my case I had two pieces and since the front one will cover the the rear one overlapping about 10 cm, the rear piece gets installed first. Even if you find one solid piece of plastic I wouldn't recommend to make the pan as one piece - it is awkward to handle and unless the car is up side down, will be hard to line up and put in place.

Pan The front section of the pan pre-cut (on the wet garage floor) and prepared for installation.
Pan The rear section of the pan.
Pan The bottom is prepared. Plumbing for water cooled charger and the tube to the vac pump.
Pan Rear section going in the pit to be installed first.
Pan The lower arm of the rear suspension.
Pan The middle section of rear sheet is attached to the battery box with plastic tie-wraps
Pan Working the way toward middle of the car. Insides tied first, edges - last.
Pan Large fender washers hold the plastic in place.

Belly pan The holes into the body for the screws should be drilled through the plastic as it pressed against the metal - this way both holes (in the pan and in the body) will match. Do one hole at the time because when a screw is tightened, it tends to pull and slightly shift whole piece and other holes will not match.   Usually underbody is stamped not flat and have a profile designed for rigidity, so the bumps, pits and flat parts of the metal all arranged to maximize body strength. Try to pick sticking out areas for screws - this ensures that the plastic will stay flat and reduces risk of poking the carpet through from underneath.

Pan The front edge is not bolted in - it simply goes under lip made on the bottom edge of the front bumper.
Pan The front section tied half way, view from the rear side.
Pan Ends are wrapped and bolted to the side in the wheel well. A cut out for stabilizing bar is visible.
Pan View on the front wheel well from the top.
Pan All done, view from the front toward rear.
Pan View of the front suspension.
Pan Closer straight up view of the front suspension (passenger side).

Wheel covers and door locks

The wheel covers probably do not reduce C-d measurably and mainly there for aesthetic reasons. Also they serve as lug nuts protectors making it more difficult for casual "passer by" to take the wheel off. They are made of 2.54 mm (0.1 inch) thick aluminum. Now the car really has distinctive look earning reputation of being head turner, neck twister and eye brow lifter...

The idea behind electric door locks was to be able to open the doors remotely. It is not the same as remote unlock in modern cars where push of a button on a tiny remote unlocks the door but you still have to lift the handle from outside to actually swing it open. My doors will be gas spring loaded and can be unlocked AND opened at the push of a button on the remote. Unfortunately I don't have the images for the lock units (when I made them for DC car I did not own a digital camera nor a scanner). Basically, made from scratch and incorporated into the doors, they consist of a small automotive 12V electric motor (similar to used for wipers movement) coupled with a lead screw. A "nut" moving along the screw as the motor shaft rotates is linked to the same pull cord the lock handle used to be linked to. A couple relays and micro-switches do the rotation direction change providing back and  forth nut movement. So now the doors can ONLY operate electrically. Therefore I don't even have stock locks and handles outside the doors. Later on a small RF or IR transmitter will activate relay which energizes the motor in the look and opens it. For now a reed switch behind glass window is sufficient.

Wheel cover Look ma, no handles!
Wheel cover The wheel cover.