What's the job of the torque boxes on unibody.

[Nacho-RT74]

What you read!

[Lennard]

Keeps the body from flexing and sheet metal from buckling and cracking.

[303 Mopar]

Torque boxes (front and back) are good, but IMO subframe connectors are more effective.  Of course all of it would be even better.   

[green69rt]

If I had to make an explanation it would be this....  Modern cars are built with a lot of rigidity built in.  Modern design includes all the little bends and folds in the sheet metal that adds stiffness.  How many times do we read that a new model car is 30% stiffer than last years model?   Our old cars did not benefit from the years of engineering experience that new cars use.   To make up for that lack we add torque boxes, frame connectors and what ever else we can think up.  

[Laowho]

We're adding SFCs but stopping short of the boxes. Was assuming SFCs came first and the boxes were only for more extreme apps, but if we'd notice a difference for a daily driver we'll add them.

[Nacho-RT74]

I'm trying to imagine the forces applied on areas were torque boxes supposed to be, but can't think on anything really important. Unless I'm missing something

[Laowho]

I've read that for strip they'll help keep a straight line but no idea whether it'd be true. If anything, I'd think they help w/ hard cornering.

[Troy]

Well, the primary purpose is to connect the front "stub" (for lack of a better word) to the rocker panels. These cars don't have a solid rail from front to back. It's only front and rear frame sections with skinny cross members linking them to the rocker panels. The torque boxes originally came about for convertibles because a lot of the strength was lost when the roof was removed (ie. it would sag in the middle). Convertibles also had bracing inside the rockers as far as I know. The front torque boxes "box in" the rocker, door support, lower firewall, and torsion bar cross member. This adds strength vertically and horizontally (side to side and diagonally). This is a high stress area due to the steering components and suspension acting against the main body of the car.

Troy

[Scaregrabber]

What Troy said. It's like adding a gusset to a right angle joint of two pieces of channel. It ties things together and helps stop them from tearing apart.

Sheldon

[Mike DC]

Imagine the car body driving around with the doors removed.  It can use stiffening help between the front & rear ends. 

[HPP]

Ditto what Troy said.

Torque boxes were the factory solution to flex. Sub Frame connectors are the aftermarket solution. Both accomplish similar tasks with different methods. IMO, you wouldn't need both, unless your SFCs were an X.

[Nacho-RT74]

ooook, so both are designed to the same ? I meant... of course both are designed top give more strenght, but attacking same forces ?

so, let's say... I know with SFC if I jack up the car with the original jack to replace a tire, the car will be steady as a rock and doors will be able to be oppened easily.

should happen the same with just the torque boxes ?

[Mike DC]

      
The factory took one extra step to stiffen the unibodies on Hemi/4spd cars.  They used torque boxing, not subframe connectors.  Torque boxing definitely does some good.  

By the 1973-up years the factory had made more stiffening efforts standard on all the cars.  Torque box plating, shock-tower-to-firewall bracing, and lower radiator support boxing.  If you want to stiffen the car up these are all the lowest-hanging fruit.  



Subframe connectors can definitely help too.  But IMO a couple of factors have probably magnified their popularity over the years: drag racing, and rusty rocker boxes.  The factory's mods are probably the most helpful on street-only cars without rust issues.

[Laowho]

We're goin SFC b/c I've read the engineers asked for full frame rails but bean counters said no; they look great; they'll stop any/all creaking by tying together all the floor pans, and; better ride.

[Nacho-RT74]

I was thinking on get some stiffened my car... initially was thiking on SFC, but then though on SFC AND Torque boxes.

But if torque boxes make the same job and kinda same efficient ( specially for a street car ) I could preffer to go just with torque boxes... is kinda more "stock" feature

the deal, is make torque boxes are maybe more complicated than the SFC due the shape.

and buy them is out of my pocket, specially if there is not a guarantee about 71/72 pieces fitment on 73/74 ( although IT SHOULD fit the same )

[Nacho-RT74]

old thread about, here:
http://www.dodgecharger.com/forum/index.php/topic,39740.0/all.html

[Mike DC]

 
SC's are good but I think people a prone to overdoing them sometimes.  Some extra metal between the subframes is good but that doesn't mean more is always better.  It only helps to beef-up any certain spot until it stops being the weakest link in the chain.

[HPP]

ooook, so both are designed to the same ? I meant... of course both are designed top give more strenght, but attacking same forces ?

Basically, yes. They resist beam bending forces, or the up/down movement of the mid section of the car that is produced by going over road irregularities or drag strip launches.

Rockers are large, heavy, vertical deflection resistant components. If you tie the subframes into the rocker via torque boxes they increase resistance to bending.

SFC are large cross section bars that resist vertical deflection by  joining the sub frames and floor and together.

[Nacho-RT74]

Ok let's see

Here is a NOS 3rd gen rear torque box.

https://www.ebay.com/itm/361455004321

The shape tells me it welds to the floor board, just right at rocker panel area BUT not to the rocker panel...

But aftermarket pieces are diff

[HPP]

The torque box piece creates the final two sides of the cube that joins the frame rail, spring hanger mount, rocker panel, and floor board. It is not a box in and of itself.

[Nacho-RT74]

yes I got that, just that made me courious the original seems not to be welded to the rocker itself, like the aftermarkets do