Another Camper Subframe Thread

[Di0n]

I’ve recently bought a 1994 Toyota Toyoace 1.5T truck. It’s got the 2.8 3L diesel from the Hilux/Hiace with a R151 (actually a R452) gearbox. I have bought a transfercase and 80 series diffs for it to convert it to 4x4 but it has already become apparent that I am going to have issues with chassis flex/twist when offroad. I am planning to build a fibreglass pop up camper for it that will bolt to a subframe so I’ve been reading a lot of threads about subframe design (3 Point, 4 Point, Rigid, Floating etc).
Currently I’m leaning towards building a subframe that rests on top of the chassis rails and uses long bolts with springs that allows the subframe to move independently of the chassis. I think the 3 and 4 point designs are too heavy and complicated for a truck of this size but I’m also interested to hear what others think.

 

[LocalmotionSC]

I'm curious if you found a solution. I may be buying a similar truck (1.5 ton 1990 Toyota Hiace truck) and am beginning to research how to mount a flatbed or box to the chassis. Have you determined how you will do so, or are you still researching?

 

[pairospam]

Hello, Di0n:

First of all, great to know about crazy projects like this. I really love them.

Maybe you are afraid of weight and complications about the three-four-point pivoting systems because they almost always refer to big trucks, over 6 tonnes, and big living boxes. Don't be.

Just seeing the picture of the chassis I imagined the subchassis of any living box with both front two pivoting points bolted to the frame rails and the rear, third, longitudinal pivoting point, solidly bolted to the reinforced cross member. You don't even need to drill as you have all the holes you need on the frame already.

I think it is just a matter of maths, proper size, and good sense. It is short, so you don't need a fourth point. If you build light, not big reinforcements either, but some you will need, of course.

Moreover, if you do the homework correctly, you don't have to oversize the subchassis to stand the forces resulting from stressing the top box against the springs and the frame rails, as you would need if you go for other designs.

Probably, in my humble and poor opinion, anything else will make your fiberglass top box crack and go to pieces sooner or later.

The best of lucks with your project!

Pairoa