Allow me to “frame” the question

As I’ve noted ad nauseam, I’m not the sharpest tool in the shed when it comes to all things mechanical.

So here’s my question re trucks:

If trucks are built on a solid steel frame, unlike a car’s unibody structure, and especially the Raptor with its strengthened frame, then why is there body flex and shake/shimmy over bumps?

I‘m not complaining, mind you, as I think my Raptor is a perfect long haul cruiser. I just don’t understand why, more so in the Gen2 with leafs, it would feel like the cab and the bed were two different pieces.

After all, isn’t the bed itself basically a lightweight shell sitting on top of the same frame?

Is my question off base and it’s really more suspension related that makes trucks in general feel that way?

I await my education And ty in advance. Kinda like when you get up in the morning and for sh*ts and giggles apologize to your wife for the rest of the day should you f up. Lol.

why does your weiner jiggle when you shoot a rifle? surely its not touching the rifle

fab=-fba science stuff

eh.... formula not quite accurate since the different objects are different weights, but to sum it up is close enough. also have to figure in different formulas in regards to kinetic energy transfer, your body weight, material flex, etc. newton....you never had to study newton?

Newton? Is that a menthol cigarette?

A general answer is a unibody is globally stiffer than a body on frame. Traditionally unibody’s are globally strong and locally “weak”. Example would be the K member on say a mustang.

Another example would be the stock driveshaft is aluminum, fairly large diameter, and relatively thin walled.

In the trucks example, it is body on frame, the body is mounted on rubber mounts so it is going to bounce around quite a bit.

The truck bed is a bad shape to take torsion. You could think of it like a channel with the flanges facing upwards. Torsion is what you would see the vibration from, think right front and left rear hit a bump at the same time and it tries to twist the frame and body.

Same reason a commercial aircraft's wings flap (flex) in flight. I used to build parts of them. It is designed in because believe it or not a structure that has some flex can out last a structure that is rigid. It flexes instead of catastrophically breaking. A failure do to a bent frame is much more desirable than one that snaps in half!

MDJAK said:

Newton? Is that a menthol cigarette?

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i dont smoke menthols. i smoke real cigarettes.

read up on newtons laws of motion. although you being from new york might have a better understanding by riding in differen taxicabs in the potholed streets of new york instead.

MDJAK said:

Newton? Is that a menthol cigarette?

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Stop it.
I almost lost my breath at work. LOL

The Car Stereo Company said:

i dont smoke menthols. i smoke real cigarettes.

read up on newtons laws of motion. although you being from new york might have a better understanding by riding in differen taxicabs in the potholed streets of new york instead.

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Ha. My dad was a medallion cabbie in NYC, drove a Plymouth, then a Checker, from 1957 to 1980. Bought his medallion for 15k. Sold for about 175k. Then they went over a million, enter Uber, Lyft, and market sank.

This is a perfe

Zeusmotorworks said:

Same reason a commercial aircraft's wings flap (flex) in flight. I used to build parts of them. It is designed in because believe it or not a structure that has some flex can out last a structure that is rigid. It flexes instead of catastrophically breaking. A failure do to a bent frame is much more desirable than one that snaps in half!

Click to expand...

This is a perfect example. Very nice.