Old fat man's Crown conversion

[ddwbeagles]

Really more of an self introduction than much of build post yet but I am in the process of converting a 1977 Crown into a (prefer the name Tiny Home) over Skoolie since the end intent is to live in it.

Bus had the fairly standard Detroit Diesel 6N71 match to a 10 speed Road master.

Confession: I suck at quick and smooth double cutching down shifts.
Anyway, here is a pic of current progress. About 70% done with removal of interior wall/ceiling panels.

[rossvtaylor]

Welcome! There are several of us here, on Skoolie.net, who have Crowns. And I happen to think the 6-71 is one of the best engines ever built. I'll definitely be following along and...if you ever need help with that great bus...just shout out here. And if you really get stuck, just type... "Crown, Crown, Crown" like a modern-day Dorothy... and you'll summon the Crown master.

[ddwbeagles]

Lol. Instant laugh. I'm get my Ruby slippers ready too.

[rossvtaylor]

It'll be a journey worthy of ruby slippers. There are several of us here who own more than one Crown. They can be addictive. Back East, especially, I'll bet you'll get lots of attention and questions in that Crown.

We're off I-40, near Flagstaff AZ. If you're passing by someday, please stop and show her off.

[Rwnielsen]

Nice looking bus. You have the Holy Grail of drive trains. I put in offers on 2 crowns and was largely ignored. Congratulations

[flattracker]

Nice to see another Crown. I am working on my second Crown Conversion. Did your Crown have the ceiling panels attached with the infamous "Crown screws" or were they rivited? Either way it is a lot of work to remove those panels.
Have you already designed your layout?

[musigenesis]

Originally Posted by ddwbeagles

I am in the process of converting a 1977 Crown into a (prefer the name Tiny Home) over Skoolie since the end intent is to live in it.

I also intend to live in my bus rather than traveling and I sort of prefer "self-propelled tiny house", but "skoolie" is less of a mouthful.

[rossvtaylor]

Like you and MG, our conversion of our '74 "humpback" Crown will also become our mobile tiny home...and we'll live in it, both here on our property and mobily (that should be a word). It's not going to be a vacation RV.

[Tejon7]

Originally Posted by ddwbeagles

Confession: I suck at quick and smooth double cutching down shifts.

Glad I'm not the only one!

Those ceiling panels are a real chore. Good work! In my bus, the rear curved ceiling panels had ~100 1/2" rivets that were not connected to the bus frame, so do not need to be removed. I wasted a bunch of time on those before I realized that I needed to focus on the 3/16" rivets. Looks like they changed a few things between '77 and '90, so this may not apply in your case.

Looking forward to seeing your progress!

PS I prefer "bus conversion", but it seems like that is generally used for coach buses? Anything is better than skoolie IMO, but I think we may be stuck with it.

[rossvtaylor]

If you do find that you have Gulmite screws in your bus, you'll also find that it's tough to source drivers for those. I do have one Gulmite socket, which works on the approx 3/8 inch head. For the others...like all the tiny 1/4 heads in our Atomic Crown...I have had really good luck with two different "screw removal" pliers. These both have serrated recesses in the end of the jaws, so they work well on the Gulmites. On my pair of Engineer pliers, I ground the outside of the jaws to allow access into some tighter places. Here are photos I snagged from the web, so you know what I'm recommending.

[ddwbeagles]

Flatracker - The ceiling panels were riveted as were the sides below the window line. However the trim immediately below the windows had a few hundred of the infamous Gulmite screws. Good time for sure. : )

As far as the design. That's tough to answer as I would say, "which version". I have several on Sketchup but to be honest, I need to get final measurements once the floor is out so I know exactly where to put the bathroom, shower, grey/black and water tanks. I don't want to start the framing only to realize later that I have obstructions beneath the floor that complicate the build.

[flattracker]

I found during the first conversion that I did that the unique construction of a Crown made for some challenges in the layout. I am sure that you already know about the need to not cover over the mid floor hatch cover. Part of my design criteria was to minimize any difficulties in performing maintenance on the bus once the conversion was done. I designed my floor plan to maximize any unoccupied areas under the Crown. In my thread "The conversion of my 86 Crown Supercoach" I started out listing a set of requirements for the conversion. My approach is not the only way for sure. See the thread by Tejon7, who is also converting a Crown. My second Crown is a 40 footer but the layout underneath is the same as yours, except for a second differential. The "old Crown" has a Detroit engine like yours, but with the Alison Automatic Trans.


I am not sure why you would remove the ceiling panels in your Crown though. Both of my Crowns came with insulation in the ceiling. Depending on options ordered the roof vents may be a major cause of heat loss in cold weather. The old Crown came with four vents and each has a rotatable louver to close them off while the new Crown has six that don't have the louvers.

[rossvtaylor]

Originally Posted by flattracker

I am not sure why you would remove the ceiling panels in your Crown though. Both of my Crowns came with insulation in the ceiling.

I agree, if there's insulation in there it's quite usable. Both our '74 and our '80 have decent fiberglass insulation in there...and we have the build sheet for the 1980, which shows that the buyer ordered that option. Heck, if you are buying a top-of-the-line bus why wouldn't you order the insulation option? But I just saw another Crown with no insulation in that space. Cheap bastards...

OP, if you pull out a light fixture you should see if you've got it or not.

Our 1937 Crown doesn't have insulation...but that might have been before it was invented.

[Crown_Guy]

Originally Posted by rossvtaylor

Welcome! There are several of us here, on Skoolie.net, who have Crowns. And I happen to think the 6-71 is one of the best engines ever built. I'll definitely be following along and...if you ever need help with that great bus...just shout out here. And if you really get stuck, just type... "Crown, Crown, Crown" like a modern-day Dorothy... and you'll summon the Crown master.

Yep. Pretty much all that's needed is to put "Crown" in the thread title.

Couple questions of interest to me. Is the 10spd Road Ranger Transmission an overdrive?? Relax, It's easy to determine based on where the 4th and 5th gear positions are located. If the 4th and 5th are located in a normal 4th up and 5th down location then it's definitely NOT an overdrive and the 10th gear is a 1:1 direct gear.

The overdrive setup will have the 4th down and to the right and the 5th will be straight up and to the right. Swapping positions essentially. Then the 10th gear is an overdrive of about .87:1 which gives you about 10mph of added road speed at the engine governed speed, which should be set to about 2350rpm for the very best performance and driver flexibility.

Assuming it has the usual rear end ratio put on all the school bus fleets, it will be the 4:10 rear end, which will yield about 63mph in a direct 1:1 top gear at about 2300rpm. The OD will add that approx 10-12mph to that giving a nice comfortable road speed of close to 70mph without pushing the engine over red line.

Being a 1977 year it may or may not have a turbo installed, in which case the Naturally Aspirated typical school district rating would have been about 210 hp and quite fine at low altitudes and on flat land. Gaining altitude will show a progressive loss of power and an increase of Black smoke due to running too rich and lack of oxygen. Can't be helped and all part of the charm.

There is no way to over emphasis just how much performance enhancement the 10spd will offer as you gain altitude and need to shift going up hills. The normally installed 5sp was a complete pain in the ass when going into the hills due to the inability to shift on hills, even as the engine was able to still pull the grades.

The 10spd solved that. It won't add more power, or torque, to the engine and you will end up going up grades at about 30mph, which was oh so typical, but it will give you an edge and slow the rapid descent to that hill climbing speed. It allows for you to keep the engine in it's very narrow sweet spot of producing usable power between 1900 and 2300 rpm. The higher the better and always keep the rpms up close the governor when climbing hills. Always.

When it drops to about 1800 or so, downshift to the next lower gear and it will drop in around 2300. Keep doing that until it stabilizes and doesn't drop any more, that's the gear to climb that hill with. Try to do it at about 2200 or so just below the governor cutoff.

Watch your water temp gauge and NEVER let it get above 215 degrees without immediately downshifting to increase the engine speed and circulate and cool more water through the engine.

Also don't let it pull hard at full throttle at anything around 1600rpm for very long, even if the engine continues to pull without dropping rpms. That's BAD and will eventually get it HOT and that's what's defined as LUGGING the engine. Downshift to the next lowest gear where you can keep the rpms at or around 2000 to 2200 for a long hill pull.

You must drive all Detroit 2-strokes like you're mad at them and that means keeping the Rpms up high and your foot mashed to the floorboard when up-shifting and accelerating normally. They need and thrive on this style of driving. Don't baby it thinking it will appreciate being asked not to work so hard. Work them HARD and they will reward you with 100's of thousands of miles of trouble (mostly) free service.

I'm real curious where that Crown came from. It's obviously a Kalifornia Crown and appears to have been operated by a Charter company because of the flip-down light covers on the red lights, and the removable panels over the School Bus lettering. No school district would do that. But Charter companies would since they did non-school Charter trips and ran faster than 55mph then. That would explain the 10spd too. You may have gotten lucky and they put in an overdrive so they could go 70mph which was perfectly legal for Charter buses, and still is today.

Let me know any other details and pics you can show of the Crown. Feel free to PM me and I'll give you my email and we can do this more directly.

[Ronnie]

Stephens City is only about an hour from me. I do not have a Crown (yet). But do have Detroit diesels, and have worked on them for many years.

[LargeMargeInBaja]

Originally Posted by ddwbeagles

...design...I have several on Sketchup...I need to get final measurements...so I know...where to put the bathroom, shower...tanks. I don't want to start the framing only to realize...I have obstructions beneath the floor...

.
Instead of a two-dimension image on a flat computer-screen, I am better working in three-dimensions.
.
I fabricate card-board mock-ups of my furniture and cabinets.
This gives an idea of traffic and access... and obstructions.
.
Switching them around, I can also place my window cut-outs for light and ventilation.

[flattracker]

The floor plan in your Crown needs to work around the items under the floor. The left side of your bus has a radiator, air cleaner, batteries, and exhaust. Those all must be taken into consideration in your planning.
The right side of your bus has the steps, and spare tire.
Items that take the full width of the bus are the engine, fuel tank, and trunk.


In my thinking, placement of the spare tire is flexible. In the "old Crown" I moved the spare tire to the trunk. My brother and I have debated whether I should even carry a spare. A tire and wheel from a Crown weighs a couple hundred pounds and takes a lot of torque to remove and replace the bud lug nuts that mount them. He used to be a OTR driver and says call the mobile mechanic if you get a flat. I haven't made the final decision there.


What this is leading to is the space available where the spare tire goes. On both of my Crowns I put the generator in there, with a gas/fuel tank. There is lots of room in there for those things. Along side of the transmission is more space. In both Crowns I put the holding tank there. Above the holding tank I placed a propane tank.



The floor of your Crown should be about an inch and one half thick, in three layers plus the glued rubber flooring on top. The top layer of plywood is reasonably thick, the middle layer is soft pressed sawdust not strong, and the bottom layer more plywood.


You can easily cut through that with a hole saw.


I almost forgot: The large access panel in the floor, don't obstruct that. If I recall correctly there is a number of items on the engine that you would access through that cover (with Detroit motors).


After reading all of this:


From front to back:
Both of my Crowns have a front room for tv sitting eating, etc.
Next is the kitchen, On the "old Crown" the sink and range on the right side, fridge on the left, counter space also. One could stand in one spot and reach everything easily. The new Crown has range/counter on left side, sink/fridge on the right. Same convenience but different. The fresh water tank is under the sink in both Crowns. Water pump to the rear of the tank in the New Crown, to the front in the old Crown. Bathroom is behind the kitchen, with shower on the left side, toilet on the right side. In the New Crown, the toilet and sink are in a "water closet" with enough room for comfort. In both Crowns, the bedroom is in the very back. I made the bed from scratch in each Crown. Both are queen size. Think like an old water bed as far as looks, very strong.


Why did I do things the way I did?


The shower has drain plumbing that goes through the floor inboard of the batteries. There is room for plumbing there. There is room for Propane plumbing in the same area. In each Crown the kitchen needs aisle space in the middle. over the engine is a good place for that. The engine compartment has enough open space on the right side for drain plumbing. The space along side the transmission is open enough for a holding tank and Propane tank. Vertical space is sufficient so that the holding tank can be placed high enough so that it doesn't protrude below the body of the bus. I also added an additional access hatch on both Crowns, on the right side for access to the underfloor stuff.


Tejon7 has laid out his bus differently than I did. There is not only one way to do this.
The new Crown with tandem axles has more room in the back than the old Crown.


From lessons learned: Don't put any water pipes under the floor, don't use copper plumbing.
Put good tires on your bus, no split rims (yes Crowns used split rims).
My thread is "The conversion of my 86 Crown Supercoach" if you want to see how I did things.

[rossvtaylor]

I agree with Flattracker about leaving the engine access panel in the floor, but would add a slight modification. The existing access panel cover is pretty wide and it's possible to make that more narrow, while still having access to the important bits...like the starter and the blower intake and the fuel pump. Those are more on the driver's side, in a mid-engine 6-71 setup, so you could cut the engine access panel to create a narrower hatch. I think it's safe to split it 2/3 on the driver's side, which you can hinge, and leave the 1/3 on the passenger side permanently in place. If you're young and flexible, you could even split it in half and still get access to what you need. This gives you a bit more flexibility with your design - not a ton, but more than leaving that entire huge hatch accessible.

While not directly applicable, I did upload a video about changing a starter in a mid-engine Crown and (especially near the end) there are some parts showing the engine bay.

https://youtu.be/iFVPtWcLcGM

[flattracker]

I forgot on important point to mention about Crowns:
On the floor you will find metal plates, two in the front and one in the back. Those two in the front provide access to connections for coolant hoses. I believe that is the only way to reach the hose connections. Do not make those plates inaccessible. You could find yourself broke down and needing to replace a hose that connects under those plates. The one in the rear I believe provides access to the top of the fuel tank for access to fuel sender units, etc.
If you do have a coolant hose failure,any NAPA store will have replacement hoses as Crown only used straight hose and where bends needed to occur they used brass tubing (if I recall correctly).

[Tejon7]

Of those front two small access panels that flattracker mentioned, the rearward one also allows for greasing the fan. At least on my bus, there's a grease fitting down there that is inaccessible from anywhere else. It's still hard to access, even through the hatch. I can't get my hand down to it and my ~16" grease gun nozzle won't quite reach either.