International 3800 adventure bus build

HazeltheMooseWagon

Active member


*Off-highway large family overland build*

I’ve been reading this forum for a few years now and a few months ago I decided to purchase an 11 window International 3800 school bus to convert into an adventure rig. I hate calling it an RV, motor home or camper. Is that weird of me? The reason I decided to use a bus for a starting point for the build is my disdain for the disposable manner in which most RVs and motor homes are built.

We are a family of nine and enjoy camping and exploring the National Parks. I like primitive tent camping, but my wife and young kids enjoy bathrooms and showers and such. A rugged vehicle capable of supporting our family with a kitchen, sleeping areas, and a functional bathroom while off-grid was the goal. I started a build thread over on skoolie.net, however, I feel that our intentions for the bus are more in line with those of this community as opposed to the tiny-home group.

The bus is a 1996 model with a P-pumped DT466 and an Allison AT-545 transmission. It has 200K miles, air brakes, and tires with about 25% life left in them. I purchased the bus for $2500 a couple hundred miles away from home and drove it the 4hrs back through the Ozark mountains of Arkansas.

Adjustments.jpg

The seats and flooring were already removed when I got it. I removed the interior wall and ceiling skins for installing better insulation. Also removed all glass except the windshields and raised the roof 12”. I took it to the scales and it weighed 14,700 lbs, equally balanced, when fully stripped. It now sits at 11’ high overall. I will clean, tint, and reseal all but 4 of the windows and reinstall them after I paint the bus olive green.

Adjustments.jpg

I have this winter to finish all of the exterior sheetmetal and body work, skylights, roof deck mounting points, etc. before painting it next summer. My plan is to rebuild the rusty stairwell with 4” additional ground clearance and provisions for insulating every surface on them. I will likely be removing the excess side-skirt material and doing a reverse dovetail behind the rear axle to help with the departure angle.

I would like anyone who is willing, to critique the build to point out the rig’s weaknesses for overland travel and perhaps point out ways to solve each problem. I have decent fabrication skills and do not shy away from major modifications or thinking outside the box. This build will take years to complete and will be a one-of-a-kind when I’m done with it. It will probably only loosely resemble a school bus when finished.

More to come...


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Last edited:

shortbus4x4

Expedition Leader
Skoolies.net, lots of info there. You have a good engine, transmission is going to be your weak point if you do much mountain driving. You can do it just be aware of the transmission and it's weak points. Skoolies.net has info on mountain driving with your transmission.
 

HazeltheMooseWagon

Active member
I have located a couple of 13 speed Eaton RoadRangers in the $2500 range. I will likely be performing that swap before venturing too far away from home. The 545 doesn’t lock up in any of the gears. It still managed 10 mpg on the trip home with my foot flat on the floor. I want a heavy truck manual for strength, good PTO gearing options, and the ability to roll start in case an EMP takes out the starting system somehow ;) The flywheel housing has a SAE2 pattern and most RoadRangers have a SAE2 clutch housing option.


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heimbig

OnTheRoadAtLast
This isn't an overland vehicle and can't be converted into one - it's way too long. I have 200 inch wheelbase which caused occasional problems during my two and a half years of travel. You're way over 200". I suggest you make it as functional as possible for the paved road where you'll be 98% of you're driving miles in North America. And then make sure you provide protection for areas under the vehicle for rocks or otherwise being hit by the Earth - which is going to happen and looks like you're addressing at least some of those issues. I think it's a great choice for a family of nine!
 
D

Deleted member 9101

Guest
I definitely wouldn't worry about the departure angle or anything related to going off road. Its a bus, a large heavy pavement pounding bus... The sooner you accept that the better your build will be.

As for the transmission, I'd go for a straight 9 or 10 (which ever is cheaper). You don't weigh enough to make a 13 speed worth the cost or complexity.
 

HazeltheMooseWagon

Active member
Thanks heimbig, the bus is 33’8” (404”) long bumper to bumper right now. I am considering axletech 4000 steer axles front and rear in the future. In your opinion, how beneficial would 4-wheel steering be in a vehicle like this for the purpose of accessing a few more areas? I’m not looking to take narrow mountain jeep-type trails with insane switchbacks. I’m really wondering if 4-wheel steering could make a vehicle function as if it had half as much wheelbase?


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ITTOG

Well-known member
Four wheel steering can help in your basic campgrounds at times so definitely a benefit. But, is the cost and complexity worth it. I would use it for a couple years and see how many times you feel you would have benefitted from four wheel steering. This will also tell you if the bigger issue is steering, ground clearance, or approach/departure angles.
 

shortbus4x4

Expedition Leader
If you're swapping to a manual then you'll be fine. I work for an International dealer that also sells lots of school buses so a large percentage of my jobs are for school districts. If you do the axletech swap I would keep the rear axle a non steer. Put a diff in that has a diff lock and you'll be surprised at how many places your bus will go. Most Forest Service and BLM roads were built for resource extraction or exploration and that calls for semi trucks so your bus will have no problem on them. Use your bus as a base camp that can tow a Suburban for town runs and exploring the tighter trails. I actually own a 1972 International 1700 4x4 short bus that is ex Air Force, it's geared to be very slow.
 

HazeltheMooseWagon

Active member
I appreciate your feedback ITTOG. My suspension and axle modifications will come after the bus has been used as a base camp for a couple years. I am pretty good at documenting and studying the ins and outs of what works and what doesn’t. My biggest priority right now is getting the bus to a point that we can enjoy it. The reasons behind any of our rigs should be the experiences we have in them. I am a firm believer that any vehicle that works for your family and does what you ask it to do reliably is a success. I also see my rig as a work of art and a showcase for innovation. Not to say that I am an engineer or professional fabricator, but I do the best I can and am not afraid to try things.


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HazeltheMooseWagon

Active member
Good to hear from you shortbus4x4. It sounds like you have already experienced some of the bus love that I have recently found. I don’t want to venture more than a couple hundred miles from home with the current automatic trans. I will wait till after the manual swap before taking it out West to the Rockies and such.

The standard air locking diff and air-disc brakes are my biggest draws to the AxleTech 4000. It seems like it is built very stout and is cheap enough for my needs. If I use a steer axle in the rear, it will need to have some type of spring actuated lock-out device to keep it centered until needed. Im thinking of an pneumatic cylinder to override the spring lock-out device and allow it to steer. I may even figure out a way to release air from that cylinder when moving above 10 mph or so to make sure it can’t steer when moving at highway speeds. That’s just my thoughts for now, like I said, that will come after the bus has been used for a while.


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shortbus4x4

Expedition Leader
You should be able to switch your rear diff out to one that has a selectable diff lock if it doesn't have one already, they aren't hard to do. I would probably wait until your trans swap was done though in case you want to change gearing. Some of my more rural bus routes with smart bus mechanics actually spec their buses new with a diff lock. A diff lock with traction tires is amazing, it makes the bus into have 4 wheels driving.😉 Have a set of tire chains and some mats and you will be amazed at where your bus will go. I did a reman Weller third member and I think it was only $500 extra to add the diff lock, of course we spent some more on getting the controls and lines for it. The driver loved having it as it made his job way easier.
 

ITTOG

Well-known member
I’ve been reading this forum for a few years now and a few months ago I decided to purchase an 11 window International 3800 school bus to convert into an adventure rig. I hate calling it an RV, motor home or camper. Is that weird of me? The reason I decided to use a bus for a starting point for the build is my disdain for the disposable manner in which most RVs and motor homes are built.

We are a family of nine and enjoy camping and exploring the National Parks. I like primitive tent camping, but my wife and young kids enjoy bathrooms and showers and such. A rugged vehicle capable of supporting our family with a kitchen, sleeping areas, and a functional bathroom while off-grid was the goal. I started a build thread over on skoolie.net, however, I feel that our intentions for the bus are more in line with those of this community as opposed to the tiny-home group.

The bus is a 1996 model with a P-pumped DT466 and an Allison AT-545 transmission. It has 200K miles, air brakes, and tires with about 25% life left in them. I purchased the bus for $2500 a couple hundred miles away from home and drove it the 4hrs back through the Ozark mountains of Arkansas.

View attachment 616138

The seats and flooring were already removed when I got it. I removed the interior wall and ceiling skins for installing better insulation. Also removed all glass except the windshields and raised the roof 12”. I took it to the scales and it weighed 14,700 lbs, equally balanced, when fully stripped. It now sits at 11’ high overall. I will clean, tint, and reseal all but 4 of the windows and reinstall them after I paint the bus olive green.

View attachment 616148

I have this winter to finish all of the exterior sheetmetal and body work, skylights, roof deck mounting points, etc. before painting it next summer. My plan is to rebuild the rusty stairwell with 4” additional ground clearance and provisions for insulating every surface on them. I will likely be removing the excess side-skirt material and doing a reverse dovetail behind the rear axle to help with the departure angle.

I would like anyone who is willing, to critique the build to point out the rig’s weaknesses for overland travel and perhaps point out ways to solve each problem. I have decent fabrication skills and do not shy away from major modifications or thinking outside the box. This build will take years to complete and will be a one-of-a-kind when I’m done with it. It will probably only loosely resemble a school bus when finished.

More to come...


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I forgot to mention I like the change on the top you made. Looks good.

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By the way:
A little research shows that the Roadranger 13 speed is apparently available only with a #1 clutch housing. It has a~16.5:1 gearing spread. OTOH the 11 speed 9ALL has a 35:1 gear spread. It works with either a #1 or 2 clutch housing.
My personal experience is that S-L-O-W is better with large bulky heavy vehicles with fragile precious cargo like camper contents, pets, children....
1st gear with a 9ALL is ~26:1. 11th is 0.73.
 

HazeltheMooseWagon

Active member
By the way:
A little research shows that the Roadranger 13 speed is apparently available only with a #1 clutch housing. It has a~16.5:1 gearing spread. OTOH the 11 speed 9ALL has a 35:1 gear spread. It works with either a #1 or 2 clutch housing.
My personal experience is that S-L-O-W is better with large bulky heavy vehicles with fragile precious cargo like camper contents, pets, children....
1st gear with a 9ALL is ~26:1. 11th is 0.73.
I have considered the 8 or 9ALL for the super low low side gears but I would really like to be able to split the upper gears without having to move the shifter. My thought was I would eventually add a transfer case with a low range. I love really low gears but I’m not sure how low You can go before it becomes impractical. The jury is still out between the 9ALL and 13 speed. You can definitely get a SAR2 clutch housing for the 13- speed though. Part number is A3722. The highest gear ratios are the same on the two of them but the 13 speed has a .73 and .86 overdrive gears. Except the RTOO which has a .62 overdrive. Hey assume you know about this page: https://www.eaton.com/EN/rr/ProductsServices/ProductsbyCategory/Transmissions/PCT_486870
 
I have never actually seen that particular page - I saved it.
The VMS auto shifting version of the 9ALL I’d like to drive.
The auto shifting 8 speed on my Unimog works well.
I might be guilty of exaggeration but I think you can never have gears that are too low. Maybe my 55.7:1 crawler gears....
 
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