1978 Crown Bus Conversion

[Rawlings]

Hi everyone, we have started our early phase of planning everything out on our Crown bus. I want some ideas or guidance on the floor. Right now it has no seats and on the floor is the original rubber/vynyl flooring it seems to be glued down to the marine grade plywood underneath, I looked all under the bus and there seems to be no rust as it was in desert environment all of its life. The wood seems to be in good shape under the bus, I know most people take the rubber off of bus to look at he shape of metal flooring underneath, but with this being a Crown Bus and having wood underneath, I have heard its a pain in the ass to remove vynyl flooring without damaging the wood that is stuck to it. The bus is mostly Aluminum so I don't think theres much rust issue, my father who will be helping me with conversion (many years experience as a carpenter in both residential and commercial) as advised me to just insulate over the vynyl flooring and then adding the flooring we want over that. Are there any drawback to this do I risk having missed out any damage under the vynyl flooring of the bus that I may not see from underneath? The bus seems in good shape all around, we brought it over to Missouri and have no leaks from the ceiling and only minor rust in areas outside the bus that are not aluminum.

[o1marc]

Most buses have a plywood subfloor under the vinyl mat. Through the life of the bus water leaks in the windows and down the walls and settles on the floor under the wood. That's why it's important, if you plan an expensive build, to start with a solid foundation that doesn't create issues later requiring a complete tear out to fix. I don't know if you have an aluminum floor in yours or not, but corrosion effects aluminum also. You can cut corners, but this far into the gutting do the last step and move forward.

[Rawlings]

Originally Posted by o1marc

Most buses have a plywood subfloor under the vinyl mat. Through the life of the bus water leaks in the windows and down the walls and settles on the floor under the wood. That's why it's important, if you plan an expensive build, to start with a solid foundation that doesn't create issues later requiring a complete tear out to fix. I don't know if you have an aluminum floor in yours or not, but corrosion effects aluminum also. You can cut corners, but this far into the gutting do the last step and move forward.

Thanks Mark, what I'm afraid of is hurting the wood, there's no metal/aluminium flooring under the wood it's just the beams across the floor holding the wood from what I can see, cause I can see the wood outside under the bus. I will try to get some pictures out by tomorrow. If I take the vinyl out I might ruin the plywood and have to replace the plywood wouldn't I?

[o1marc]

Experts will correct me if I'm wrong, but you're saying you have an, exposed to the outside, wood subfloor? Usually there is a metal skin on top the frame and then ply laid on top of that. I would think weather would eat up an exposed wood floor in no time.

[bus-bro]

Those old Crowns have 1" marine plywood attached to the steel framing members. I wouldn't want to pull and replace the plywood unless I really had to. It would be nice though to have a look under the vinyl. I think Crown windows are a lot less prone to leaking water onto the floor. The windows retract between the body skin, so I would assume they leak there and then routed outside by drainage holes.

[Rawlings]

Originally Posted by bus-bro

Those old Crowns have 1" marine plywood attached to the steel framing members. I wouldn't want to pull and replace the plywood unless I really had to. It would be nice though to have a look under the vinyl. I think Crown windows are a lot less prone to leaking water onto the floor. The windows retract between the body skin, so I would assume they leak there and then routed outside by drainage holes.

Thanks for the feedback I will remove parts of vynyl to see some parts and your right about the windows it rained a hell of a lot this last week and I went within hours of storm to check it out and there was no water anywhere inside the bus except the windshield area as the rubber housing is older and I noticed some water getting through ontop of the dashboard. I need to take it somewhere to change those out or maybe use some caulking.

The side windows out the outside had some drainage holes be I was concerned about water.going in there only to find out they go through there and out the bus directly below to the ground. Great engineering I believe.

So am I correct to assume it's fine to add insulating foam pads on top of vinyl as long as I don't see much damage under the bus or in some areas I remove vynil flooring such as closer to the windows? This was a California bus it doesn't rain a lot there although I guess over 40 years would mean kids spilling water, soda, whatever else.

[Iceni John]

All Crowns have floors made from two pieces of 3/4" marine ply (the good stuff) with a layer of bitumen-like insulation between them, and some additional undercoating on the underside to protect against any damp coming up from below. In other words, you have 1.5" of the most durable floor that you'll find in any bus, period. It should never need to be replaced. The Armstrong 1/8" rubber floor on the top is perfectly good as an additional layer of moisture-proofing and insulation, and then you can lay your finish floor straight on top of it. You'll probably however want to remove the curved coving on the floor's edges against the walls - it's held down with small nails into the floor and small self-tapping screws in to the wall, and it's a PITA to remove! Once it's gone, you'll have several inches below the seat rail on the wall that can be used as a chase for wiring/plumbing/etc. Just try to cut the rubber flooring so it can be reused back to the wall.

And the reason you didn't get so much as a single drop of water coming in from the side windows is simple, and one of the reasons that Crowns are better than any other buses! Any rain water on the outsides of the windows will just pass down behind the steel corrugated section of bodyside below the windows and harmlessly sluice out at the bottom. It's called the Crown Dry Wall design, and it absolutely prevents any water from seaping in past leaking outside windows seals, for the simple reason there are no outside window seals! It's the most intelligent design I've ever seen to keep water out, and only Crown ever used it.

As you progress with your conversion please take the time to think about what you see while you take things apart. Crown's engineers were some of the finest bus builders in the country, along with GM's, so it's usually best to not second-guess why they did something a certain way and just trust that it was, and probably still is, the best way of doing something. For example, between every piece of aluminum outside body panel and every steel rib is a layer of insulating mastic to prevent galvanic corrosion, so don't forget to do the same if you're working on the body. You have the finest school bus ever made.

John

[Rawlings]

Originally Posted by Iceni John

All Crowns have floors made from two pieces of 3/4" marine ply (the good stuff) with a layer of bitumen-like insulation between them, and some additional undercoating on the underside to protect against any damp coming up from below. In other words, you have 1.5" of the most durable floor that you'll find in any bus, period. It should never need to be replaced. The Armstrong 1/8" rubber floor on the top is perfectly good as an additional layer of moisture-proofing and insulation, and then you can lay your finish floor straight on top of it. You'll probably however want to remove the curved coving on the floor's edges against the walls - it's held down with small nails into the floor and small self-tapping screws in to the wall, and it's a PITA to remove! Once it's gone, you'll have several inches below the seat rail on the wall that can be used as a chase for wiring/plumbing/etc. Just try to cut the rubber flooring so it can be reused back to the wall.

And the reason you didn't get so much as a single drop of water coming in from the side windows is simple, and one of the reasons that Crowns are better than any other buses! Any rain water on the outsides of the windows will just pass down behind the steel corrugated section of bodyside below the windows and harmlessly sluice out at the bottom. It's called the Crown Dry Wall design, and it absolutely prevents any water from seaping in past leaking outside windows seals, for the simple reason there are no outside window seals! It's the most intelligent design I've ever seen to keep water out, and only Crown ever used it.

As you progress with your conversion please take the time to think about what you see while you take things apart. Crown's engineers were some of the finest bus builders in the country, along with GM's, so it's usually best to not second-guess why they did something a certain way and just trust that it was, and probably still is, the best way of doing something. For example, between every piece of aluminum outside body panel and every steel rib is a layer of insulating mastic to prevent galvanic corrosion, so don't forget to do the same if you're working on the body. You have the finest school bus ever made.

John

John thank you so much for your input. I really appreciate it. I do plan to remove the corners that connect to the wall since they are curved and would make it easier to add the cabinets etc. Would I have to remove the wall shiny paneling to remove this part of floor vinyl? I read there's something holding it together by self tapping screws on the wall. I'll take some pictures and add them hopefully by the end of weekend. I plan on keeping most of the vynyl and adding additional layer of insulation on top of that and then flooring of our choice. There's not a hole lot of room down below for water tanks I plan on putting the grey water tank below for gravity reasons and I might have to put the fresh water tank inside which is fine if I use an electric pump to get water out to the shower and sinks.

[Iceni John]

Do NOT remove the dimpled aluminum inner wall paneling unless you want to entirely reconstruct the inner side of the Crown Dry Wall design! Remember, what's inner wall at one point becomes outer wall elsewhere.

I've used 3/8" plywood for my inside walls, with 1/8" Celtek board covering it and all the interior divider walls; the plywood is screwed to the outside edge of the chair rail and to the top of the wall just under the protrusion below the windows (flush to the outer face of that protrusion), with polyiso insulation behind it to augment the fiberglass already inside the lower walls. This makes it almost perfectly 90 degrees to the floor, assuming the coving is removed. At the protrusion under the windows the walls begin to slope in by the windows, then the structural rectangular box section longitudinally above the windows (that the body ribs and roof ribs are welded to) is again perpendicular to the floor. It sounds more complicated than it is! If you make your inner walls this way, you've wasted the least possible space, and from floor to windows the walls will be almost straight up to help mount cabinets and appliances inside.

Plumbing will be a challenge with any mid-engine bus. Some folk have used small holding tanks under the shower and sink, from where the gray water is pumped to the main gray tank elsewhere. You'll need to spend some time under the bus carefully measuring every bit of available space for tanks/batteries/etc, but for cold-weather use it's not a bad idea to have the fresh water tank inside, maybe under the bed. The gray and poo tanks can have waterbed heaters under them to prevent them freezing, but all the piping and valves will also need heat tape if it's that cold. I've hung my four tanks, 400 gallons in total, under the floor, but I intend to never be anywhere so cold that I need to worry about freezing! Just don't block any under-floor access to the engine or transmission, and don't cover over the floor hatch above the engine.

Jerry Campbell and Brown Crown have both made beautiful conversions from mid-engine Crowns like yours, so with enough imagination and determination it's definitely possible. It's just not as easy as with a FE or RE bus, but the best things in life are never easy.

John

[Rawlings]

Originally Posted by Iceni John

Do NOT remove the dimpled aluminum inner wall paneling unless you want to entirely reconstruct the inner side of the Crown Dry Wall design! Remember, what's inner wall at one point becomes outer wall elsewhere.

I've used 3/8" plywood for my inside walls, with 1/8" Celtek board covering it and all the interior divider walls; the plywood is screwed to the outside edge of the chair rail and to the top of the wall just under the protrusion below the windows (flush to the outer face of that protrusion), with polyiso insulation behind it to augment the fiberglass already inside the lower walls. This makes it almost perfectly 90 degrees to the floor, assuming the coving is removed. At the protrusion under the windows the walls begin to slope in by the windows, then the structural rectangular box section longitudinally above the windows (that the body ribs and roof ribs are welded to) is again perpendicular to the floor. It sounds more complicated than it is! If you make your inner walls this way, you've wasted the least possible space, and from floor to windows the walls will be almost straight up to help mount cabinets and appliances inside.

Plumbing will be a challenge with any mid-engine bus. Some folk have used small holding tanks under the shower and sink, from where the gray water is pumped to the main gray tank elsewhere. You'll need to spend some time under the bus carefully measuring every bit of available space for tanks/batteries/etc, but for cold-weather use it's not a bad idea to have the fresh water tank inside, maybe under the bed. The gray and poo tanks can have waterbed heaters under them to prevent them freezing, but all the piping and valves will also need heat tape if it's that cold. I've hung my four tanks, 400 gallons in total, under the floor, but I intend to never be anywhere so cold that I need to worry about freezing! Just don't block any under-floor access to the engine or transmission, and don't cover over the floor hatch above the engine.

Jerry Campbell and Brown Crown have both made beautiful conversions from mid-engine Crowns like yours, so with enough imagination and determination it's definitely possible. It's just not as easy as with a FE or RE bus, but the best things in life are never easy.

John

Awesome thank you again for the feedback I am learning so much, so don't remove the dimpled aluminum wall paneling, I wanted to leave some exposed as ours is in very good shape. Some parts will be covered but I wanted to leave some exposed as its so nice. So the curved area on the floor that meets with the wall is hollow? If I remove the Vinyl part of the flooring that meets the wall, you are saying its basically hollow cause under there its actually 90 degree from wall to floor? Why would they make it curved like that with the vinyl and leave space behind that area?

[MarkyDee]

Originally Posted by Iceni John

You'll probably however want to remove the curved coving on the floor's edges against the walls - it's held down with small nails into the floor and small self-tapping screws in to the wall, and it's a PITA to remove! Once it's gone, you'll have several inches below the seat rail on the wall that can be used as a chase for wiring/plumbing/etc. Just try to cut the rubber flooring so it can be reused back to the wall.

I think I have something similar in my coach bus. Can you give some instructions on how to remove the coving, please?

[EastCoastCB]

Originally Posted by o1marc

Experts will correct me if I'm wrong, but you're saying you have an, exposed to the outside, wood subfloor? Usually there is a metal skin on top the frame and then ply laid on top of that. I would think weather would eat up an exposed wood floor in no time.

Yep. No metal floor on a Crown. Just wood.

Its real marine grade so it lasts a long time.

[Rawlings]

Originally Posted by EastCoastCB

Yep. No metal floor on a Crown. Just wood.

Its real marine grade so it lasts a long time.

Should I go under the bus and try to repaint that wood? Its now in Missouri where it rains and snows, sort of worried with rain and dirty road getting the wood all wet underneath the bus?

[o1marc]

Originally Posted by Rawlings

Should I go under the bus and try to repaint that wood? Its now in Missouri where it rains and snows, sort of worried with rain and dirty road getting the wood all wet underneath the bus?

Marine plywood is sealed so not effected by water. You wouldn't be able to get every inch of the floor coated from underneath.

[Rawlings]

Okay, so we want to enjoy the bus this summer while we start doing some of the build, we obviously need to be able to cool the bus and I am planning on getting Deep Cycle batteries and also be able to run off of shore power in some of the state parks we will visit.

I understand roof mounted AC units are probably the most used or best bet but we are not ready to add this until later, in the meantime we would like to add one of those portable ac units such as this one

https://www.wayfair.com/home-improve...-dlla1087.html

It states 8,000 btu for cooling space up to 300 sqft. When I went online and did a btu to watts conversion it gives me 2300 watts. However on the link above on their description it says 850 watts. Not sure which is correct, We can connect to shorepower but I would also like to hook it up to 4 or 6 deep cycle batteries on an inverter and or a generator. Could anyone point me in the direction of how many batteries, how big an inverter, I would need? We only need to power that AC and maybe 1 32 inch LED TV and charge our phones for right now.

(Yes I plan on growing and purchasing additional batteries or bigger inverter as we get build going but we also want to start enjoying the bus this summer before it gets cold and will be parked in the fall which is when we will get even more busy doing a full blown electrical system / solar, generator etc)

[o1marc]

My heat pump went down on the house so I bought a unit like that to cool the den. It works well but it produces massive amounts of condensation. Make sure you have it drained properly.

Here's the specs on mine.

[Rawlings]

Originally Posted by o1marc

My heat pump went down on the house so I bought a unit like that to cool the den. It works well but it produces massive amounts of condensation. Make sure you have it drained properly.

Here's the specs on mine.

At 3600 watts per hour I'm guessing 4-6 batteries wouldn't last very long? Wonder what the starting wattage needs to be? That way I can tell if my generator will do it or if I need a bigger generator.

[Tigerman67]

Originally Posted by Rawlings

Okay, so we want to enjoy the bus this summer while we start doing some of the build, we obviously need to be able to cool the bus and I am planning on getting Deep Cycle batteries and also be able to run off of shore power in some of the state parks we will visit.

I understand roof mounted AC units are probably the most used or best bet but we are not ready to add this until later, in the meantime we would like to add one of those portable ac units such as this one

https://www.wayfair.com/home-improve...-dlla1087.html

It states 8,000 btu for cooling space up to 300 sqft. When I went online and did a btu to watts conversion it gives me 2300 watts. However on the link above on their description it says 850 watts. Not sure which is correct, We can connect to shorepower but I would also like to hook it up to 4 or 6 deep cycle batteries on an inverter and or a generator. Could anyone point me in the direction of how many batteries, how big an inverter, I would need? We only need to power that AC and maybe 1 32 inch LED TV and charge our phones for right now.

(Yes I plan on growing and purchasing additional batteries or bigger inverter as we get build going but we also want to start enjoying the bus this summer before it gets cold and will be parked in the fall which is when we will get even more busy doing a full blown electrical system / solar, generator etc)

The portables tend to leak and radiate heat out of the exhaust hose and back into the area you are trying to cool. You can insulate the hose and prevent some of that. The one hose models also use your already cooled inside air to cool the condenser and exhaust it outside, so the two hose models that use uncooled outside air to cool the condenser and then exhaust that tend to be more efficient.



But if its enough cooling to do the job its not a huge deal that one model is more/less efficient than another, you are just running it a bit longer and using a bit more power on the less efficient ones.



I saw something that the govt recently changed how some of the portable AC's are rated, so if you are looking at new vs used, or what size was effective for someone else a few years ago. You could see some apples to oranges comparisons. Here is a mention of it I found with a quick google search. https://www.sylvane.com/blog/introdu...tu-guidelines/

[Rawlings]

Originally Posted by Tigerman67

The portables tend to leak and radiate heat out of the exhaust hose and back into the area you are trying to cool. You can insulate the hose and prevent some of that. The one hose models also use your already cooled inside air to cool the condenser and exhaust it outside, so the two hose models that use uncooled outside air to cool the condenser and then exhaust that tend to be more efficient.



But if its enough cooling to do the job its not a huge deal that one model is more/less efficient than another, you are just running it a bit longer and using a bit more power on the less efficient ones.



I saw something that the govt recently changed how some of the portable AC's are rated, so if you are looking at new vs used, or what size was effective for someone else a few years ago. You could see some apples to oranges comparisons. Here is a mention of it I found with a quick google search. https://www.sylvane.com/blog/introdu...tu-guidelines/

Thank you so much for your feedback, I actually was reading a lot about these units and I read they aren't as efficient as window units, I'm now thinking of adding a window unit sort of how this couple did it on YouTube, since they didn't want to have the unit hanging out of the bus for safety reasons or violations, they created a box for it to sit "inside the bus" but it is separate from the rest of the bus so that it keeps heat exhaust out.

That video is below
https://youtu.be/cB1Ur8QaIaI

Picture of it below. However it might be too much work if we are thinking of eventually doing roof mounted ac

[o1marc]

Originally Posted by Rawlings

Thank you so much for your feedback, I actually was reading a lot about these units and I read they aren't as efficient as window units, I'm now thinking of adding a window unit sort of how this couple did it on YouTube, since they didn't want to have the unit hanging out of the bus for safety reasons or violations, they created a box for it to sit "inside the bus" but it is separate from the rest of the bus so that it keeps heat exhaust out.

That video is below
https://youtu.be/cB1Ur8QaIaI

Picture of it below. However it might be too much work if we are thinking of eventually doing roof mounted ac

Video link is not active.