Rear end overhang height?

[rwd4evr]

I have a 1988 s1853 40ft bus. I'm building it to haul a car in the back. It's been a few years long project waiting to be started, been back and forth on how to do it best, on the back on a flat bed. A rollback type deal or a ramp truck. I think I've decided I want to keep it enclosed as originally planned but getting a car 43" up is not really a feasible setup. I'm thinking I'll have the ramp level off over the rear wheel tubs and angle downward to the rear where it will be hinged at the bottom. I'll cut a pie section from the frame up to the top rail, behind the spring perches, remove all the rivets holding the floor box/c channel sides to the body and bend the entire frame and floor down. it will be reaatached to the sides at the proper height required to keep the structure solid. I'll trim the frame ends to be level with the ground at the desired height and plate and box the entire rear section. Slice the rear body cap off and frame up inside to be the folding door/most of the loading ramp.


I can't find my dimensions at the moment but I believe my back bumper is 30" off the ground. There is a 4" exhaust pipe that's never touched ground below it, so like 25" I think off the top of my head. I'm trying to figure out how low I can reasonably safely go back there without causing myself issues. It's not going to be off road adventuring. Just thinking about the occasional weird parking lot hilly entrance and dragging the tail. It will be super beefy but i will need to be sure I don't ever tweak anything that could cause door opening issues. Looking at an angle from above the rear wheel wells rearward an ideal ramp height at the rear of where the cap ends would be about 22-24“ and the floor is 3“ thick plus a few inches for the frame cap with the massive pivot pins for the door.

So essentially I'm trying to get some feedback on how low anyone has had the rear of thier buss without a big scraper problem, maybe how high your hitch is without issue on a fullsize bus?

If I could get away with 18" it would be awesome for my needed ramp length.

 

[rossvtaylor]

There are some other factors I didn't see mentioned...like, how long is the overhang past the rear axle? The longer that distance, the more likely you are to experience some dragging in those situations. I've owned lots of school buses and lots of other buses...transit and coach styles...and every school bus has a lot more clearance than the transit and coach buses. Some of those don't even have the 18" you're hoping for, and they work fine in most places if you're aware of the limitations.

 

[Booyah45828]

My back steps are 12" or so off the ground, the genset in the middle of the bus is about 10" off the ground. Neither has scraped, and I'm not sure if either has been close to it.

I'm asked all the time how neither scrape, and I think most buses have gobs plenty of ground clearance to begin with. Being built that way, anything below the 2 foot body line causes people to get nervous and question.

There's plenty of threads on here about ground clearance. Search around and see what you find. But with a bus that's predominantly on pavement, I've got no worries about it. Maybe if you were in the mountains then it might be a concern.

 

[fo4imtippin]

You might look at converting the rear to air ride. You can find rear clips from heavy trucks at junkyards. You can dump the air for loading and get about 4 inches lower, but not have to sacrifice as much clearance as loaded.

 

[s2mikon]

Before you do a lot of mods and make it un insurable as a motorhome you better check with the insurance people first. I would also check with the state to make sure it would still be a motorhome after the mods. Otherwise you may find yourself in commercial vehicle territory with all of that BS.

 

[rwd4evr]

There are some other factors I didn't see mentioned...like, how long is the overhang past the rear axle? The longer that distance, the more likely you are to experience some dragging in those situations. I've owned lots of school buses and lots of other buses...transit and coach styles...and every school bus has a lot more clearance than the transit and coach buses. Some of those don't even have the 18" you're hoping for, and they work fine in most places if you're aware of the limitations.

I don't have that measurement at the moment but if you've had a full length school bus I can't imagine make and builder would change that overhang more than a foot or two which would only change the drag height a small amount. But yes I get that whole dynamic. It is pretty long which is the whole reason I have concerns.

I was actually just thinking about air ride. What if I just pulled a bunch of leaves out and added air bags to get it to ride height with whatever load? Rather than having to modify everything and I would guess make a pan hard bar mount. That junkyard air does intrigue me though.

I hadn't thought about the insurability issue. I probably should get that handled and get the title all set in my name as an RV before chopping stuff.

 

[rwd4evr]

The overhang is 12ft ft from wheel center to the back edge of the bumper. 29" high at the bumper and 25" under the exhaust tip that hasn't scraped ever. Getting the low point to 20" would make my plan a whole lot easier.

 

[jenandjon]

Just get some ramps and drive it up there. I my other group people drive smart cars up on the back of a semi truck.

 

[rwd4evr]

Do you have any idea how heavy or expensive 18' ramps would be? I know a guy that did it out of aluminum and they're still heavy and they cost him $2500 in material. My bus was 1400$. A smart car is not a car. They have almost no overhang. I'm talking about a race/drift car. It's low. At the same angle as my dolly or trailer ramps id need 18' to clear the nose and not drag the belly over the top onto flat. Thanks for the great and well thought out idea though.

 

[DeMac]

Do you have any idea how heavy or expensive 18' ramps would be? I know a guy that did it out of aluminum and they're still heavy and they cost him $2500 in material. My bus was 1400$. A smart car is not a car. They have almost no overhang. I'm talking about a race/drift car. It's low. At the same angle as my dolly or trailer ramps id need 18' to clear the nose and not drag the belly over the top onto flat. Thanks for the great and well thought out idea though.

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www.skoolie.net/demac-albums

 

[Albatross]

The overhang is 12ft ft from wheel center to the back edge of the bumper. 29" high at the bumper and 25" under the exhaust tip that hasn't scraped ever. Getting the low point to 20" would make my plan a whole lot easier.

Then I would figure out a way to put air-bags on the back of the bus for suspension, and add a compressor and tank somewhere that you could 'slam it' down to make loading easier. And the air-bags would probably make the ride a lot nicer, too.

 

[Booyah45828]

Then I would figure out a way to put air-bags on the back of the bus for suspension, and add a compressor and tank somewhere that you could 'slam it' down to make loading easier. And the air-bags would probably make the ride a lot nicer, too.

It will also make a steady platform while loading, as a deflated suspension will have very little give. Movement while loading can make things hairy.

 

[fo4imtippin]

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www.skoolie.net/demac-albums

That Brumos museum is about 5 minutes from my house. I really want to go see that stacker bus, but its $25 per person admission and i'm cheap about that stuff.
https://www.thebrumoscollection.com/

 

[rwd4evr]

It will also make a steady platform while loading, as a deflated suspension will have very little give. Movement while loading can make things hairy.

I do like the air idea, I will have onboard air for the “shop". Only issue is cost and maybe durability. I would need to buy all the air stuff plus the air compatible rear suspension and axle. Maybe if I can retain my suspension by removing a bunch of leaves and adding air bags but I don't think I'd get the same effective lowering. I have considered mounting some air bags on top of the front axle to lift it up a bunch for load and unload. Maybe I can find a cheap rear cut with air and a highway gear that would save me the trouble of regearing my axle. I have Dayton hubs/wheels and hydraulic brakes though so that's less likely.

 

[Metalriff]

Did you continue with this project?

 

[J-C-C]

I am on a very similar path as the OP with a Thomas 40' Bus. I plan to leave hauled car hanging out the back approx 3'. Car will ride inclined on internal ramps. It will be winched into position. Rear altered bus height will be lowered to approx 34" by as Op mentioned pie slicing the rear frame rails rearward of the rear suspension. I would like to go air ride, which would allow use of a suspension dump valve to lower another 4"? , and I like the improvement of ride with an air suspension. That conversion would be after I get Bus hauler tested and on the road. My ramps will be 16' carbon fiber for min weight, stored under car. Car weight is approx 3400lbs. I have the option of leaving a flatbed car trailer connected as a mid platform and then ramp off of that. I 'm relocating the OEM rear bus door to driver side of rear bus compartment for easy in place car access. The new wide rear door enclosure will be a full size top hinged composite hollow aero tail.

 

[cadillackid]

I am on a very similar path as the OP with a Thomas 40' Bus. I plan to leave hauled car hanging out the back approx 3'. Car will ride inclined on internal ramps. It will be winched into position. Rear altered bus height will be lowered to approx 34" by as Op mentioned pie slicing the rear frame rails rearward of the rear suspension. I would like to go air ride, which would allow use of a suspension dump valve to lower another 4"? , and I like the improvement of ride with an air suspension. That conversion would be after I get Bus hauler tested and on the road. My ramps will be 16' carbon fiber for min weight, stored under car. Car weight is approx 3400lbs. I have the option of leaving a flatbed car trailer connected as a mid platform and then ramp off of that. I 'm relocating the OEM rear bus door to driver side of rear bus compartment for easy in place car access. The new wide rear door enclosure will be a full size top hinged composite hollow aero tail.

if it overhangs i think you just have to flag it and obvipusly have rear lights fully visbile for all vehicles coming up on it.. ..


my biggest thing would still be all that weight behind the rear axle if the car is overhanging that much from a normal 40 footer that im familiar with would be mostly behind the axle..

 

[J-C-C]

I don't believe I have ever seen a aero rear tail flagged, being they are mostly fiberglass the aero tail itself weighs hardly anything. My cars typically weigh 3200lbs, 55%+ is on the front acle of the car, and that works out to be a foot in front of the bus's rear axle, so ultimate rear weight overhang will be less than 15 100lb kids in a typical school bus, so I am not overly concerned in that regard.
Light visibility is a given, where they need to be located is questionable. In Florida anything transported beyond 4' of rearmost part of vehicle must be flagged and also lit at night. My tail will be under 4' regardless.

Thanks.

 

[cadillackid]

you could use a portable light bar like the tow trucks use.. there are versions which are wired and wireless.. wired obviously you dont have to worry about comms or a dead battery as its vehicle powered..



make a mount for it to fit on your ramps when you arent hauling a car.. and maybe some extension it could sit in or a hitch mount on the car being hauled to carry it when hauling a car.. just a thought..



you would also keep permanent lights say on the back of your bus just in case the state said "must also have permanent installed lights".. as im sure some do.. covers both bases.. visible when hauling and also permanent lights..