Hi all I was wondering if its worth time and effort to strengthen the stock torque boxes on my 69 barracuda? The car will have a 350hp 360 3.55 gears and a 3000 rpm converter. I will also be running drag radials, adjustable pinion snubber and 150 shot. The car will be mostly street driven but will see some track time. Looking for any cheap mods to help reliability and improve traction.
Thanks

If you have a sawzall and a welder, you can fab up a set of subframe connectors that will provive far more stiffness. I used 3x3 box tubing, .120 wall. I used cardboard to make templates of the floorpan, then traced the pattern along the 3x3 so that the connectors sat flush against the floor. I sprayed rubberized undercoating on the underbody, and the job actually looks like Ma Mopar did it! The car I have is a 74 Duster.

I thought about torque boxes, but I raced my car for 9 years with only sub frame connectors and no issues. I now have it on the street and it rides great. The car ran 11.10 consistantly so I don't think torque boxes are needed. If you have a trans brake and lots of HP, it may be a good idea. The mods besides frame connectos that made the car more consistant and solid is mono leaf springs and CalTracs. You can get mono leafs with different ride heights so you can set the car a litle lower or higher as desired.

Thanks guys, that car is getting subframe connectors. I dont think this car will run anywhere near the 11s, I also dont think the car will ever have a trans brake either so probably not worth touching the torque boxes then.
thanks again

If you really want to help the car weld some plate steel on either side of the bulkhead the leaf spring bracket studs pass through, this will help stabilize the forward leaf spring hanger and prevent the torsional loading from ripping the studs loose. Hemi cars had them from the factory for this reason (along with torque boxes). These are the B-body style but can be made to work for A-body cars as well.

Here are some rear leaf spring stabilizer plates installed on a B-body

Here's what the front bulkhead plates look like installed

other side, same torque box

IMHO, the torque boxes are a step (or two) below subframe connectors. In the '60's, the unit body construction was an engineering advance by Chrysler, and if they then added subframe connectors, it would be admitting a design weakness. In lieu of doing this, they came up with the torque boxes as a compromise(again my opinion).

But modern chassis' are very stiff to help handling, and I think for the most part they are a factory combination of unit body and subframe connector construction.

Frame connectors do allot for connecting the front and rear of the unit body and lowering the amount of chassis twist. However, frame connectors do NOTHING to reinforce the leaf spring mounting locations or the cowl to front subframe rigidity which is what torque boxes (and the plates inside them) were designed to do.

Not wanting to put words in your mouth, but are you then saying that modern chassis' use torque boxes? Then again they may not be as necessary anymore since torsion bars and live rear axles are long gone...

I am not talking about anythong modern? Where did you come up with that?

My comments pertain ONLY to any unit body construction Mopar from the early 60's up to the early 70's.

After further inspection, I am going to do some reinforcement to the torque boxarea, and will for sure do some reinforcement to the rear spring hanger area, since I found some rust and cracks in the passanger spring hanger. its getting boxed in, the torque box are is going to get plated and reinforced.