Making a pick up out of a standard car

what extra braising do i need to do to make it road leagl

In what state? Does the car have a frame?

What model and model year Fiat are you planning to use for this experiment?

What is the factory-rated load capacity of this Fiat sedan?

Are there heavy-duty springs and shocks readily available for this car?

How about availability of compatible wheels that are large enough to accomodate larger tires with a higher load rating?

Are the wheel wells large enough to accomodate larger tires?

Why not just buy a used pickup truck?

A Fiat is barely rigid enough to be a car. If you cut off body panels to turn it into a pickup, the unibody will fold in on itself. Can’t be done.

Tester

Braising? For steel? I don’t think so.
What model and year of Fiat are you working with? What are your skills?

Put simply, making a pickup out of any unibody car will require skills that if you had them you wouldn’t have had to post here. Once you start chopping out large areas of a unibody, the structural integrity disappears. You’d need to have the skills necessary to recreate that structural integrity. To make a pickup out of a unibody car means constructing a subframe…and a ton of creative susspension work. Lots of engineering needs to go with the metalworking.

And steel doesn’t get brazed. Steel gets welded. Bead welded, spot welded, tack welded, whatever, it gets welded. Brazing does not alloy the mated metals and does not have the strength to withstand high stress loads. Brazing is used for metals that do not weld well, like brass and bronze.

Sorry to be a doubting Thomas. Perhaps is the body design allows you could remove the trunk lid, build a box insert, and install that.

“A Fiat is barely rigid enough to be a car”

And, that is when it was new!
Factor in the loss of rigidity over the years as a result of rust, and this is a project doomed to failure at the first big pothole.

I think OP meant ‘bracing’.

For his sake I hope so…

You’re right, that seems more logical. I guess I was flummoxed by the unusual nature of the question.

…even so, after adding the weight of the bracing necessary to reinforce the chassis, the amount of cargo that could be carried would be really small, based on the probable engine size, the springs and shocks, and other factors previously mentioned.

Why are you polishing a turd? This is a worthwhile project if done on a car, not a Fiat. (: