Torque boxes: Worth it?

[Madman Stephan]

Hi, has anyone installed these and noticed any difference in handling? They usually come in a set of four and are really supposed to reduce body roll. I've already added a front and rear swaybar, so would this make much of a difference?

Auto Rust Technicians talk a lot about these on their website.

Thanks!

[dusterbd]

well, they supposedly increase chassis rigidity by triangulating and reinforcing the corners of our subframes on the unibody structures. this makes sense to me, as he factory did it on convertables to help with the rigidity due to no roof structure. my opinion is, that after 30+ years, ungodly miles, and the abuse that most owners gave these cars, strengthening anything may not be a bad idea. it may only bring it back up to a factory level of rigidity, but thats better than before.
mike

[Clair]

I've got them on my Valiant (2-door post car), and although I'm sure they help, I can't say that I noticed a difference. I installed the ART subframe connectors first, and they made a HUGE difference. I used to think my little post car was pretty rigid, but apparently it wasn't. I used the 2x2 SFC's, since I can't penetrate the floor boards due to the rules of the autocross class I race in. However, since torque boxes were OE on verts and hemi/6-pk cars, they're legal for me. Every little bit helps... Also, FWIW, on my A-body, even the 2x2 SFC's are supposed to penetrate the floor boards, but I rearranged things a bit (and dimpled the floor) to make it work without.

If you don't already have SFC's, you can do a neat experiment and let us all know how well the torque boxes work before doing the SFC's. IMHO, the best bang for the buck is the SFC's, though.

Clair

[dusterbd]

agreed. sfc's first, torque boxes second, tube frame third

[Madman Stephan]

Yes, I already have sfc's and front and rear sway-bars, but I figured as long as my underbody isn't completely finished, I still have time to add some torque boxes....

[dwc43]

The tq bones wont make much of a diff, but the sub frame connectors or a roll cage will work wonders.

[eckertt@epri.co]

I know nothing about sub frame connectors (SFCs.) But this is what I am guessing they are; please correct me as needed....

I think that our Mopars are unibody cars; they don't have a full frame. Rather they have a sub frame in the front third of the car for the front suspension and they have a subframe in the rear third of the car for the rear suspension. These two subframes are only connected to each other through the sheet metal of the unibody car. (Right so far??)

So SFCs must be some heavy wall channel steel that connects the front subframe to the rear subframe. Again I am guessing that there must be two channels, one for left side and one for right side. I assume these must be welded in? or are they a bolt in thing?

What is an approx cost for SFCs? and what is a good vendor for such? Experience about installing them? Do they interfeer with any other component such as exhaust pipes, e-brake cable, or other?

Thanks for the education I hope.

Tim Eckert
Concord NC
72 Cuda
360/904

[ehostler]

You can buy bolt in sub-frame connectors; however, the holes will oval out over time. Custom fabrication is the way to go.

http://www.bigblockdart.com/connectors/connectors.shtml

[dusterbd]

i did these subframe connectors on my duster. they ARE NOT as easy as this site claims. i had to dimple my floorboards for clearance. they really tigtened the car, though. good investment. just make sure that you have all your supplies before you start, like grinder wheels, sawzall blades, and welding gas...
mike

[Fast_Eddie]

Nice site, very valuable information and install how-too.

Looks to me though, that the way the author installed those SFC's that no dimpling of the floorboards was necessary.

[George G. Leverette]

Mopar Performance sell a prefabricated subframe connector for A-B-E body cars for a about $100 with discount. I have them on three crs and they make a significant difference. Although they are advertised as bolt-ins, I bolt them into position and them have them welded in place. Every thing needed is included in the kit they wrap round the rear sub frame extension.

[cutting torch]

I use 3" square tubing, .090 wall, and pass it through the floor. The front floorpan area barely needs to be cut, but the sfc will be about an inch above the bottom of the rear floorpan, front to back. I weld the floor to the sfc, then cut 1' thick hard styrofoam to fill in the floorpan around it, then cover it all with the carpet. No one knows the difference!

torch

[Fast_Eddie]

Good article in this months Mopar Muscle Magazine on the subject of installing torque boxes.

[skydome]

The idea of the torque box is it allows the rocker to be utilized as a SFC. While it is not 100% as effective as the SFC's we install ourselves. It was a good trade off for production. If the factory decided that they were needed, that should tell you something.
I only speak for A bodies, but I know all 4SPD cars had them and all Abody Police/Taxi also had them.

[Fast_Eddie]

IMO, if you want to do "everything" you can to aleviate body twist, short of instaling a roll bar, then do both, torque boxes AND sfc's.

[Dick]

OK guys, help me out here. I am in learning mode. Please describe a torque box and an SFC. My last exposure to chassis mods was Traction Masters. Do they even make them anymore? Thanks!

[Fast_Eddie]

Originally Posted by Dick

OK guys, help me out here. I am in learning mode. Please describe a torque box and an SFC. My last exposure to chassis mods was Traction Masters. Do they even make them anymore? Thanks!

Dick,

SFC = sub-frame connector. Basically, this ties the rear sub-frame to the front sub-frame via bolt-in or welded in steel. This helps in "beaming" and "compression" strength, but does very little in terms of torsional strength.

TQB = torque boxes. They add torsional rigidity to a body by tying the front and rear subframes to the rocker panel, effectively using the rocker panel as a corner gusset.

For a really good explanation on torque boxes and how to install them, check out the latest Mopar Muscle Magazine (Jan 2005 - Boxing Match) or check out this link:

Chassis stiffening for dummies

Some additional reading:

Frame Connectors

Torque Boxes - Why their good for your Mopar

Photos:

Rear with both TQ boxes and sub-frame connectors installed:


Front with both:


Those two links are from the autorust website. Be sure to check out the gallery photos from both those articles.


Build a 2" x 4" "box" frame out of wood. Grabbing 2 sides, you can twist and change the "squared" shape very easily.

Now add to the inside, 2 more beams of wood inside the box (like adding sfc's). Again, its still pretty easy to twist it and change the "squared" shape. BUT, anything you place on top of the frame is pretty strong with the new "beams".

Now, take and add corner gussets to all four corners, they don't even have to be very big.

Now, it's almost impossible to twist or chage the squareness of your frame.

Get it?

I know it's simple, but it should give you the basic idea.

[Dick]

Thanks, Eddie. Great pics. I now have a better understanding. Am I correct in thinking that these mods are only used in a uni-body car?

[Fast_Eddie]

Originally Posted by Dick

Thanks, Eddie. Great pics. I now have a better understanding. Am I correct in thinking that these mods are only used in a uni-body car?

Pretty much the case Dick.

Although, even in full-frame cars you can add a shit load of rigidity by "boxing" the frame rails themselves, and/or adding corner gussets.

Here's another photo:

[70Barracuda]

ALL 4 speed cars have these stock?

[dwc43]

No, they do not. Only Hemi cars and convertables had them. They still don't add enough strength to justify the work. Sub Frame connectors are ten times better, and next step is a full cage.

[skydome]

They weren't just in hemi cars. I have had several Darts with Torque boxes. I should have cut a set out, but I didn't.
HP stick cars had them, Automatics didn't. Taxi and Police had them regardless of trans choice.

[Fast_Eddie]

Originally Posted by dwc43

No, they do not. Only Hemi cars and convertables had them. They still don't add enough strength to justify the work. Sub Frame connectors are ten times better, and next step is a full cage.

They were NOT just on Hemi and convertible cars. They were also on all cop cars, taxi cars, and most 4-speed performance models (both small and big block).

dw3,

Perform the simple test I suggested with a wood frame before you determine whether they are worth the work or not. Corner gusseting DOES add strength, and this is basically what torque boxes do.

SFC's do little to nothing at all in terms of increasing torsional strength in a unibody car.

And installing torque boxes is about as difficult as installing SFC's.

If you don't believe me dw3, I could show you some pictures of a '72 Demon 340 4-speed car that came from the factory with torque boxes.

[eckertt@epri.co]

I bought a set of the sub frame connectors (SFCs) from ART (Auto Rust Technicians) for our 72 Cuda. The instructions that I found in the box don't answer my question:

Do I have to cut some of the rear floor pan to install these? I have been under the car for the last 2 hours working the fit-up; and I need the rear of the SFC to go 1/4" higher so it fits better with the rear sub frame. But parts of the rear floor pan get in the way. I placed a hyd jack onto the SFC, expecting that it would 'bend' the rear floor pan a tad and get it out of the way, but it only raised that side of the car! That rear floor pan must be a lot stronger that I was giving credit for.

So, anyways, I am getting ready to make some cuts into the rear floor pan, but wanted a "sanity" check beofre I did. And it is Sunday night and the guys at ART are not at work.

Specifically, these are 'weld-in' SFCs from ART on a 72 Cuda. Anybody else on this forum done this before??

Thanks, Tim

eckertt@epri.co
72 Cuda 360/904

[dwc43]

Originally Posted by Fast_Eddie

They were NOT just on Hemi and convertible cars. They were also on all cop cars, taxi cars, and most 4-speed performance models (both small and big block).

dw3,

Perform the simple test I suggested with a wood frame before you determine whether they are worth the work or not. Corner gusseting DOES add strength, and this is basically what torque boxes do.

SFC's do little to nothing at all in terms of increasing torsional strength in a unibody car.

And installing torque boxes is about as difficult as installing SFC's.

If you don't believe me dw3, I could show you some pictures of a '72 Demon 340 4-speed car that came from the factory with torque boxes.

Well show me the ones that don't exist on my Duster with the 4 spd or the '70 Challenger 4spd car that I sold to Mike a few years ago. Both are low mile original cars without any torque boxes.

[dwc43]

Originally Posted by eckertt@epri.co

I bought a set of the sub frame connectors (SFCs) from ART (Auto Rust Technicians) for our 72 Cuda. The instructions that I found in the box don't answer my question:

Do I have to cut some of the rear floor pan to install these? I have been under the car for the last 2 hours working the fit-up; and I need the rear of the SFC to go 1/4" higher so it fits better with the rear sub frame. But parts of the rear floor pan get in the way. I placed a hyd jack onto the SFC, expecting that it would 'bend' the rear floor pan a tad and get it out of the way, but it only raised that side of the car! That rear floor pan must be a lot stronger that I was giving credit for.

So, anyways, I am getting ready to make some cuts into the rear floor pan, but wanted a "sanity" check beofre I did. And it is Sunday night and the guys at ART are not at work.

Specifically, these are 'weld-in' SFCs from ART on a 72 Cuda. Anybody else on this forum done this before??

Thanks, Tim

eckertt@epri.co
72 Cuda 360/904

Yes, some of the cheaper not so well thought out sub frame connectors require the floor to be cut up. Just notch it enough to clear and reweld the floor to the connector and it will actually be a little bit stronger that way.

[eckertt@epri.co]

Thanks DWC, that is what I was thinking.

Tim

[cutting torch]

I've never seen an aftermarket SFC that i've liked, that's why I make my own. I have always wondered how much difference they can make when the tubing that they use is so small.

torch

[dwc43]

Originally Posted by cutting torch

I've never seen an aftermarket SFC that i've liked, that's why I make my own. I have always wondered how much difference they can make when the tubing that they use is so small.

torch

I agree. If they are not 2x3 then they are not really worth messing with.

[Clair]

I wouldn’t say that the ART SFC’s aren’t well thought out at all. On at least the A-body parts, they account for the emergency brake cable where the MP SFC’s don’t, which is a big deal for a street car. That said, I didn’t install mine just like they suggested, since I can’t have any add-on structural reinforcements that penetrate the floor pans according to the autocross rules I race under. If I wasn’t worried about those rules, I think I would have gone for the 2x3” rather than the 2x2” that I used, and not worried about the bumps in the rear floor pans. I was able to make them work by dimpling the floor pans, and trimming the ends a little differently than they suggested, so it worked out well for me. I’ve got another set waiting for my ‘67 convertible, too. I don’t think there would be much benefit from using material substantially thicker than the steel used for the subframes. ART uses 1/8” thick tube, which is probably twice as thick as the subframes it’s being attached to. Using 3/16” or 1/4“ would just add