Fabricating the adapter plate

I do not get to work on my project as much as I would like and yet I do try to do a bit when I can snag a few minutes so the next blurb is over the space of a couple evenings.

1st evening....

Well as we all know when modifying or upgrading there are lots of subtle changes to be made. Some give and take along the way. This is the first evaporator of this design I have worked with and knew there would be some firewall changes to accomodiate the setup. The inward protrusion of the firewall at the center inside above the hump will not come into play with this special designed evaporator case making it ideal for this model car. The main area of concern is the angle break below the original ducting input hole. This jutts into the engine compartment and leaves a space of some 1.800 inches on the inside at the lower edge and tapers toward the top then angles back to allow flush fit. This recessed area come into play even further down the road when it come to connecting the heater and coolant lines. The coolant lines are actually long enough to facilitate connection of the freon lines but the water hoses are a tad shorter where they stick out of the evaporator case and the loss of 1.8 inches makes connections borderline at best. The ideal situation I think is to fabricate a metal plate of approximatley 3/32 flat metal to affix the evaporator case onto. This when butted against the 1/4 thick polished aluminum plates I made to block the duct and heater thermostat original holes will provide good solid mounting points and at the same time give me the room I need for the bolt heads when I snug the evaporator case to the sheetmetal plate. This plates also add a finished touch to the firewall. The transisitioning metal will shape to contour with the cowl and transmission tunnel on the inside left and at the bottom will be notched to allow connection of the evaporator drain and keep it out of harms way from foot traffic of passenger on that side of the vehicle. The attention to the angled firewall will be dealt with in what I hope to be a piece of metal with a one inch mounting flanges on both front and rear that will affix to the firewall with bolts and acorn nuts for dress in the engine compartment and regular crews and nuts to the transisitioning plate. Careful cutting of this hole along with a rubber gasket will seal out air, dust and moisture and other unwanted items. Main item of concern here is allowing for ample room to make the plumbing connections without it being to tight an access for you to work. I have mocked this item up in cardboard and have stapled to my fiberboard mock up plate, appears to be a very workable solution. The mounting holes for the evaporator have been marked, drilled and test fitted. The evaporator case is not flat in design and has a high spot in the middle..good even mounting will require there be a rubber spacers used top and bottom to keep the case square to the transisitioning plate. The plate is mounted flush at the top inside and this keeps the panel level to the bottom. As for the switches and cables..all is a go..but I am not near as happy with the rotary thermostat switch and it is more than not going to be replaced with a slide lever type. Else I will defeat the operation of the compressor with an inline push button switch to control the clutch. I will have to make a trip to my local supply house and see what, if any, slide thermostats are available. I have in the interim made a belcrank to atttach to the rotary switch to allow activitation of the thermostat but I do not think it will give me the range of control that I will be satisfactory in all temperture conditions. The mounting of the fan switch went as expected as did the water control valve connection and the defrost control. Use of the defrost along with the selectable clutch control will yield de-humidifier action of the system. A definite plus anywhere you happen to live. The stock control panel will give the car a clean period correct look and function quite well to its new devices.

Connecting the evaporator to the existing Dakota V6/C171 compressor and receiver dryer will be done by removing the crimp ferrules and old hose and replacing with corect size and guage hose. new barbs sweated to the existing Mopar stubs and use of new fittings for the compressor connection. This will be done by the local shop as they have the equipement on hand and have done these for me in the past for reasonable money and quick turnaround. I like the clean neat look of crimped hoses over any worm drive clamp. It is worth the extra effort.

So there you have it...Stage I of the install..the mock up. Next report will be on the fabrication of the pieces in metal and the actual fit of the evaporator and adjustment of control cables. Electrically this unit is self contained plug and play harness that has only has to be grounded to the chassis and supplied with 30 AMP power tap which is alread in place with the donor Dakota harness.

Second evening...

Entered next stage of the install last evening after work. Had little time to dedicate to the job so I spent just a bit over an hour transferring my measurements and holes to the aluminum plate I selected for the transisition plate. I got out the right angle grinder with the cutoff wheel and cut the straight lines and scored the curved sections just a tad heavy for eventual breaking off the metal. Then I used my rotary burr to mill the metal back to my scribed line and followed up by sanding the sharp edges off. I fabricated and smoothed my inside opening in similar fashion and with the use of proper sized hole saw. The different sized mounting holes I centered punched and then took to the drill press. The angled piece that forms the recessed box around the stubs that I had fabricated out of cardboard during the mock up phase had now been meausured and drawn out on transfer paper so to be fashioned in metal a bit later. A nice box brake would be handy right now but seems I will have to be content to use my bench top 24 inch brake and finish with the sheetmetal hand brake. I will be backing this fabricated recess with standard 4" 90 degree reinforcent brackets from the wook working department. Plans are to bolt this recess piece to both surfaces with #10 hardware utilizing polished stainless acorn nuts on the engine side of the firewall.

Third evening...

As my metal stock is at smallest 48 inches across I cut three blanks from a single sheer that measured 4 inches by 16 inches. The pattern I then trasferred to the metal and I cut 6 wedges to facilitate the angles to match the firewall bend and and three snips to define the mounting flange that will mate to the transistioning plate. I made my first bend on the benchtop brake. The smaller angle tabs I used my hand brake and formed these. I used a nice chunk of metal that will allowed me to chuck up in the vice and make my last two bends at 90 degrees. The piece is now formed and I finished by welding the corners and splices. The closing of these gaps will ensure good seal on both surfaces and will mate nicely to the firewall. After welding I now fit the piece to the transistioning plate for final fit and drilling of the mounting holes. The preformed corner braces from the wood working department dictate the positioning of the screws. These screws will also be spot welded to the bracket to maintain their position and ease of mounting later. I mock fitted the plate to the firewall and transcribed the inner opening so to cut the firewall properly and mark the screw holes for that side of the recess adapter. All of these screws are out of sight as the transistion plate with this recessed adapter combined with the further negative angle of the lower firewall in regard to the lower edge of the transisitioning plate leaves me just enough room to insert the carpert padding and allow the carpet itself to over lay the panel and thus hide everthing neatlly. The panel now is set aside till I can do my final prep by sandbasting, priming and eventual painting of the assembly. A stop by the hardware store for some peel and stick dense foam insualtion tape will make my final installation complete. Simple disconnecting of the few screws and upper four mounting stud nuts will make the entire assembly easy to remove for any future maintenance. By designing the assembly to firewall mount by studs makes hanging in place easy and allows me to be able to work from the engine compartment solo.