The Conversion of my 86 Crown Supercoach

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I do not still have the template that I used in the previous conversion, so I needed to produce another. I concluded that the tools with the thin metal fingers held in a row and made to capture the profile of moldings and such would work, but found that the ones I could find locally were made to capture just six inches of profile. My solution was to attach two of them to a piece of steel strap so I could capture almost 12 inches in length. In the second and third pictures I show the details of the tool.

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I captured the profile I needed, ultimately needing to move the tool lower to get the lowest parts of the profile. Each capture was traced into foam/cardboard poster board.


Afterwards I cut the resulting template out, and after making minor adjustments, trimming the template I produced the template shown in the last picture.
I will transfer this template to a sheet of aluminum to produce a durable one.

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My next post documents the production and installation of two air conditioner plenums on the roof of the Crown.

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This post documents the production and installation of air conditioner plenums through the roof of the Crown bus. The Crown bus has a very strong roof, supported by high strength steel ribs. The ceiling has an inside layer of aluminum about 60 thousands thick, riveted on one inch centers to steel ribs that cover side to side as well as additional ribs that go front to back. On top is another 60 thousands thick layer of aluminum riveted to the ribs on one inch centers.


A 250 lb person will not dent the roof.


The problem with the Crown's roof is that it is curved more than the usual motor home or other RV. I have not looked close at any other brands of skoolie to see what level of curvature they are so I cannot say about them.


But, given the curvature of the Crown's roof and the fact that RV air conditioners are flat on the bottom, this creates a need to address this.


I was left with almost a 4' x 6' piece of aluminum sheet 100 thousands thick. This provided the raw materials for the plenums.


Since the air conditioners were designed for the 14" x 14" openings the plenums needed to provide that.
Using the low cost Harbor Freight hand grinders with cutting wheels was a good way to cut out the top part of the plenums. With practice one can cut reasonably straight lines in aluminum, using multiple passes. Inside corners can be finished using a hack saw blade. Being unsure how tall the plenum actually needed to be we cut them taller than we expected them to be. Removing metal is much easier than adding metal.
The outside dimension of the plenums was made larger than needed also.
The first picture shows a plenum after taping the pieces together for mockup.

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Being the plenums are made of aluminum they were welded using the TIG process. I need some practice using TIG so I brought the job to my son Perry, as he has a TIG welder and has done it more than I have.


He started out the welding by tack welding the pieces together. By welding only small beads to start out, it minimizes distortions due to expansion from the heat of welding.


He welded both plenums with beads a couple inches at a time. Distortion was kept to a minimum.


In the next picture, the short tack welds are visible on the outside of the sides of the plenum, while the full length beads are visible on the inside.



In the second picture both plenums are shown.

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Installation of the plenums required cutting square holes through the roof of the Crown.
Once again, I produced a template, this time out of cardboard, with a 14" x 14" opening cut in it. Using a tape measure, we found the centerline of the bus (which has a line of rivets down it) and using the template drew the square on the roof using a sharpie. This process was repeated for the front opening location on the bus.


The first picture shows one of the openings.

The second picture shows the template and the marked location for the opening.

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Because we had cut the openings in the Crown's roof a little undersize, the openings had to be fitted to the plenums. More work with the low priced hand grinder accomplished this and the plenums now fit through the openings well. The two openings, while the same size, where placed differently in relation to the supporting rib in the roof. The rear one had a rib going accross the middle of the opening, while the front one we placed between two ribs. We ended up removing a small amount of each rib in the front one and removed a portion of the one rib passing through the rear one.


To the rib passing through the rear one we added brackets to attach the plenum to, to secure the plenum to the bus. A large amount of silicone caulk was added to the underside of the plenum in the rear and then the plenum installed into the opening. A tool box full of tools was placed on top for weight. The next day the air conditioner was placed on the plenum and bolted down.
The securing of the plenum get finished tomorrow.

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Another picture of one of the plenums set into the opening in the Crown's roof. In this image it is easy to see the curvature of the roof compared to the flat plenum.

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An update on the conversion of my 1986 Crown:
air conditioners are now mounted to the roof of the bus. I have some pictures of the results.

The pictures show the mounted and covered units on the bus.

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Today I took the Crown out for a drive. I needed to see how everything done so far would work going down the road. I left the storage yard at Bly, headed for Lakeview, about 42 miles from Bly, in the next county. I mounted the GPS on the windshield so that I would have a good read on my actual speed. The route I used is on Oregon hwy 140. This stretch of highway is a two lane back road with moderate curves and some hills to climb. The highest elevation is about 5100 feet. Bly is about 4300 ft elevation.
With the cold weather we are having the bus does not like to start cold as the Cummins Big Cam engine does not have glow plugs. I had a new engine block heater installed on the replacement Cummins engine. I started out by plugging the block heater into the temporary electrical box, starting up the generator (which has glow plugs) and running it for awhile. While waiting for engine block warmup, I filled the one low tire on the bus. Once the block was warmed, the bus started fine. This is my first time out with the new engine and taller gearing with a gps so that I really knew my speed. The first thing I discovered was how easy 70 mph was to reach. Considering the elevation, and the fact the Big Cam engine in the bus is strictly mechanical, I was a little surprised. When the speed was about 50 mph, the bus was a little doggy, with an estimated rpm about 1500 (haven't replaced the tach yet), but when going at least 60, additional speed was easier. I had to keep an eye on the speed because several times the bus got to 70 mph and I don't want attention from the State troopers. (yes they were there) The trip was uneventful. There were no squeaks from the air conditioner mounts. Some parts of this stretch of highway are real bumpy, with some vehicles worse than others and the Crown did not like the bumpy parts. I'm now thinking that maybe front shocks would be in order. Other than the bouncy ride I was very satisfied with the performance. I think open highway and freeway performance will be more than adequate. I decided that next on the list is installation of the new tachometer. By the way, ISSPRO still has tachometers in stock for Crowns. My Crown has the pulse generator driven by the fuel pump via cable, and they also still stock the pulse generator used with that setup. I will post the results of the tach installation next.

[JamesKS]

The crown is coming along great! I think you are doing the right thing by driving it and figuring out the issues before its all built out. Obviously you are fairly committed to this bus with the new engine, but it would be terrible to build it and realize it just wont work for traveling. Thanks for the updates.

[Alsbus]

I love all this Crown Talk! I'm a little jealous of your power upgrades but you just get used to going up hills slow. Well, sought of!

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My old Crown is the same as yours on hills. It is possibly the main reason I bought the new Crown. The theme song for the old bus was "Slow Ride". I remember climbing the Grapevine at 25 mph, and the grade coming North out of Dunsmuir at 18 mph. I will say the old crown did get 10 mpg though.

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The other day, searching ebay and looking at solar panels I found some that are rated for twice the power but not much larger, so I bought a couple. Attached are some pictures of the top of the bus with tone of the new panels laying on it and a comparison of one of the 100 watt panels overlaying one of the 200 watt panels. Using a slightly larger panel with twice the power is appealing. With the two air conditioners mounted, there is less real estate for solar panels.
I will be removing the school but flashing lights, with interest in the old style look for the bus. I don't yet know how large an opening I will find beneath the large flashing lights. Has anyone else removed them and seen the opening size. Since that portion of the Crown's roof is steel, I plan on mig welding covers in place. I am thinking about what to do the the fold out stop sign at the rear of the bus. It will not remain in it present location though.

[Tejon7]

Originally Posted by flattracker

I will be removing the school but flashing lights, with interest in the old style look for the bus. I don't yet know how large an opening I will find beneath the large flashing lights. Has anyone else removed them and seen the opening size.

Are you referring to the upper front and rear red flashers? The 'eyebrows' as I call them? If so, mine had an opening about the size of a quarter for the wiring to pass through.

Thanks for the updates!

[Crown_Guy]

Originally Posted by Tejon7

Are you referring to the upper front and rear red flashers? The 'eyebrows' as I call them? If so, mine had an opening about the size of a quarter for the wiring to pass through.

Thanks for the updates!

Yep. There's only a small hole for the wiring, plus the 3-4 screw holes used to mount the housing which will be there as well.

[flattracker]

Originally Posted by Crown_Guy

Yep. There's only a small hole for the wiring, plus the 3-4 screw holes used to mount the housing which will be there as well.

Thanks Tejon7 and Crown guy for the info about the "eyebrow lights". The ones on the new Crown aren't two bad to look at but the ones on the old Crown are really large and ugly with two light on each light assembly. A quarter sized hole will not be difficult to deal with. I look forward to an afternoon without rain to deal with them.

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A small update on my conversion:
I decided to use different solar panels in the array. I will be installing five 200 watt panels instead of 10 100 watt panels. I ordered the fifth one today of eBay. I will be gluing a layer of the aluminized insulation between the panels and the bus roof. I will initially install the frontmost panel without insulation and will be measuring temperatures of that panel and comparing the temperatures of the other four panel. I want to determine if the heat from the bus roof makes the panel hot or does the panel increase the temperature of the roof. Later I will re-install the front panel with insulation to make all panels consistent.



If anyone else has already performed this exercise with/without insulation please let me know.



I also wanted to post a tip about dealing with corrosion, an enemy of all old skoolies. Years ago when doing my first annual on my plane I was introduced to ACF-50 anti corrosion treatment. When applied to the inside of the engine cowling (made of aluminum) I watched it actually lift the corrosion of the aluminum. You leave it on and it provides continued protection. You can sray it on electrical parts and connections according to the can. It is made in Canada by Lear Chemical Research. You cannot paint over it. For that one would need to clean the surface with solvent first to remove the ACF-50. I was told it also works on steel. It is expensive, as a 13 ounce spray can costs $25. I am sure it is safe to use as it is used on airplanes.
(The FAA can be very difficult if they don't like something) I am going to be using it one the front roof of the Crown this spring in hopes of rust removal. At that time I plan to remove the school bus lighting at the top front and rear.

[Crown_Guy]

Originally Posted by flattracker

Thanks Tejon7 and Crown guy for the info about the "eyebrow lights". The ones on the new Crown aren't two bad to look at but the ones on the old Crown are really large and ugly with two light on each light assembly. A quarter sized hole will not be difficult to deal with. I look forward to an afternoon without rain to deal with them.

I meant to reply to this earlier, so sorry for the delay. The normal historic Crown Red Light Crossing lights and housings here in Kalifornia were always just the single, (each side) red lenses (glass)sealed beam 7" PAR#xx. Common as grass and still very available today. Washinton and Oregon States had different laws and required the dual lights per housing in each of the front and rear corners. That's always been a dead giveaway, along with the extra crash belts half way up the sides of the bus on each side below the windows. These features always made them out as Washington or Oregon Crowns.

The physical casting that mounts and screws into/onto the front and rear panels for the red crossing lights assemblies are probably the same. The difference being in the actual single or dual lamp assembly that then mounts to that casting. I may be wrong on this since I don't see the dual lights here much at all, but in either case and no matter what you have on there now, it should be no problem to find and install the single lamp casting and assembly if you wanted to keep some lights up there.

I personally don't mind having the single lamp assemblies in place and plan on replacing the Red lamps with clear high intensity driving lights up front and general illumination white floods in the rear. The wiring is easily changed to allow for each lamp to be powered as you see fit with switches since they all come down to the breaker/distribution panel where the 4-way red light crossing flasher is mounted. This is located under the front heater grill and at floor level by the front steps. Most all wiring comes here with circuit breakers to protect individual functions and the two flasher modules are in here too.

Of course if you like the clean look with no light housings at all then they come right off with only a few little holes to patch. But if you want to convert to the single lamps per each location that's real easy to do and they are findable in scrap yards and from others who are taking them off.

[Tejon7]

The clean, rounded look without the flashers is nice. Then again, those CA-style single bulb "eyebrows" are uniquely cool. I'm going half and half - kept the front flashers, but removed the rear ones. My back ones were leaking like crazy and when I took them off to inspect, I found that I liked the smooth look so much that they never went back on.

Anyway, I now have a set of the single-bulb style flasher housings in my garage if you want them. These were from the rear, but if the cast aluminum pieces were universal then it sounds like the black bits in the picture below might bolt straight onto what you already have.


Side note - the bulbs for my CA-style flashers are PAR46. I replaced the front red bulbs with clear halogens for ~$35 from NAPA. Once we've driven out into the deep dark desert a few times, we'll reassess how useful those upper lights are and decide if it's worth the extra $$$ for LEDs.

*EDIT* I just went back and looked at some of your pics of the "new" Crown. Now I see that you already have the the same flasher style as me. Whoops, sorry for the confusion! Now I understand... your "Old" crown is the one with the larger, weirder lights like this pic (stolen from the internet):