My 1974 E-300 has been modified a bit, the deck out back is now 5 X 9 ft. Imagine putting a 14 ft. long car on this. From the back doors to the rear axle is 4 ft. The car is probably front end weight biased, but the rear axle will hit the car right about under the firewall of the car.
Is it crazy/dangerous to have 10 feet of car cantilevered out that far? I saw a Mini on a motorhome and it looked bad, but was assured the Mini weighs less than the shower, tanks etc.
Whatta ya think?
What kind of car (i.e. how heavy?) I would guess that as long as you get the engine over the axle you would be okay.
How hard would it be to extend the frame? You have some welding skills, access to frame rails or rectangular tubing, and can probably fab up a two piece drive shaft. I think that would be a better idea, certainly more stable.
Or you could add a second axle behind the driving one. Sort of a trailer that's there always.
In reply to nocones:
I like this idea - old gutted rear end, small trailer tires and wheels, air bags to raise and lower, regulator to control pressure..... possibilities are endless.
Like a tag axle on a dump truck...
put it on sideways!
Depends on how much the car weighs and where it's center of gravity is located. FWD 60+% on front. Opposite for a rear engine.
'Crazy' probably has little to do with it. You're just asking for the DOT to climb up your axx and your van's axx every time you hit the road......
The piggy back is front engine rear wheel drive.
nocones wrote: Or you could add a second axle behind the driving one. Sort of a trailer that's there always.
Wouldn't that make it turn like a freight train? You'd need to find a turnpike to make a 180 turn.
Could you just move the factory axle back as far as possible?
A couple ideas:
I think that much dead weight sticking out back there, that high up, is going to dramatically unload the front end of your truck. Scarily unload it. I think 4 out of 5 doctors recommend against trying this.
Cut the frame box and add 36" to the truck's wheelbase. Much much happier doctors.
Duke wrote: I think that much dead weight sticking out back there, that high up, is going to dramatically unload the front end of your truck. Scarily unload it. I think 4 out of 5 doctors recommend against trying this.
4 out of 5 GRMers who want to see an old cut up van carrying a small car doing wheelies recommend it. Besides it just might be your way in to win one of those darwin awards.
You could simplify the problem down to a very basic moment arm. You'd probably get fairly close for a static calculation (I'd be sure to include a fairly significant factor of safety). Now once you add in the torque of the rear wheels, that's going to change things a bit, but as long as you're not drag racing, it shouldn't have a massive effect (especially considering the aforementioned factor of safety).
What I'm curious about, is you say the bed is 9' long, but you've got a 14' car. To me, that seems like you're cutting it awful close for the wheelbase of the car to be contained on the bed, especially when you take into account the car's front overhang. Are you going to build a wooden platform back there or something to contain the entire wheelbase?
Personally, I think as long as your piggy-back car is lightweight, it will probably be alright. The way it looks to me right now, the bulk of the weight will be centered right over the rear axle. Which seems to me no more dangerous than carrying a heavy load in the bed of a pick-up that's centered over the rear axle. If you can get the basic F/R weights of the truck and car (along with the wheelbases, and where the front wheel of the car will sit), I can do the static calculation for you. That will, at the very least, give you a quasi-informed idea of the weight distributions, and how much is riding on the rear axle (and thus the tendency for it to wheelie/have light steering). If you can lengthen the wheelbase of the truck, that of course, would be the preferred route.
Please note: Everything in the above post is wild speculation. It's all at your own risk, but I'll help with the calculations if you'd like. I am in no way informed, coherent or qualified to make any judgments of "safety".
914Driver wrote: Is it crazy/dangerous to have 10 feet of car cantilevered out that far?
My gut says yes.
Hmmmm.... Thanks for the imput.
Anyone need a one ton van with a patio? 302, 3 spd on the column, new alternator, water pump and another set of wheels & tires. The ones on the van are split rims, no one will work on them.
Swap for a trailer?
Dan
Paint a green 88 on it and sell it as a NASCAR collectible
914Driver wrote: Hmmmm.... Thanks for the imput. Anyone need a one ton van with a patio?
dan, you need to quit being such a Bob Costas. stretch the wheelbase of the van chassis about 3 feet and call it a day. looks like it shouldn't be too hard to stretch the chassis via box tubing. if you only relocate the rear axle and springs, make sure the chassis is strong enough back there to handle the forces, as the chassis was not originally designed to have the suspension forces reacted through it back there.
but yeah, as-is, you're asking for trouble. imagine hitting a bump while driving up an incline: instant spark show from the back, accompanied by complete lack of directional control. Hello, Darwin?
302 - three on the tree? Maybe I expect too much, imagine lugging this thing through the hills of Pennsylvania. 
AngryCorvair wrote: instant spark show from the back, accompanied by complete lack of directional control. Hello, Darwin?
So... huge wheelie bars with flint on them would keep the awesome spark show but force the front wheels back down...
914Driver wrote: 302 - three on the tree? Maybe I expect too much, imagine lugging this thing through the hills of Pennsylvania.
sounds like the wheelbase isn't the problem, then. do you really think extending the chassis three feet and the deck by whatever amount is required to package your towed vehicle is going to add so much weight as compared to the other friggin' vehicle on the back that the extension is the deal-breaker?
sell it to supercoupe. it would be perfect for his fiat 500 challenger.
I think everyone in this thread is being a nilly . I guess I don't see how a small and very lightweight racecar would be that much different than having a full loaded bed in a pickup? Especially if you could get the car close enough to have the center of mass over the rear axle? Would you run that truck with 1700lbs of cement on the patio? The lightest part of the car (the trunk area) would be the part cantilevered way out there. I think you should just load it up and see what happens, if you can pick up the front of the truck by hand, don't run it :-)
Make a ramp truck out of it.
You could open the back doors of the van and put the nose of the car part way inside.
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