When frame connectors are not enough?

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Longgone

Longgone

John/68 Barracuda & Dart
Joined
Jul 12, 2005
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What can you do to strengthen the frame of your car if you`ve already installed frame rail connectors? Even with the frame rail connectors I`m experiencing cracking at the rocker panels just below the door corner and again at the base of the A-pillar. If possible I don`t want to install a roll bar and I`d like to do the most non-invasive thing possible. Are there any other remedies?

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What kind of frame connectors do you have; welded-in or bolted in? If bolted in, they aren't doing any good and my be doing some harm. What size frame connectors are ty? Do they run through the floors at all? What are you doing to get these cracks in the body anyway? Pulling wheelies? Might have to remove the old connectors and get 2x3 rectangular tubing and make your own. Is the car rusted badly underneath?
 
Valiant63 said:
What kind of frame connectors do you have; welded-in or bolted in? If bolted in, they aren't doing any good and my be doing some harm. What size frame connectors are ty? Do they run through the floors at all? What are you doing to get these cracks in the body anyway? Pulling wheelies? Might have to remove the old connectors and get 2x3 rectangular tubing and make your own. Is the car rusted badly underneath?
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The frame connectors are approximately 2 x 3 bolt in connectors that have been welded in. They do not touch the floor. A big 500 c.i. engine and 5 spd.manual trans is causing the cracks. The car is sound with only minimal surface rust.

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Yikes! That thing must be putting out some power if the frame isn't rusted full of holes!

A 4 point bar would probably be the easiest thing to do, but it'll pretty much cost you the back seat (even the ones that go around the back seat don't really allow for safe passenger transport in the back). But if you're hauling groceries and not passengers some of the 4 points are easy enough to deal with.

You can get creative though. I've heard of guys running 1 1/2" tubing down the insides of the rocker panels to tie the subframe outriggers together, that will stiffen torsionally better than the frame connectors. And might be your ticket since you're flexing at the rocker panels.

You could also go for some "through the floor" frame connectors, they're a little larger and don't step down to avoid going through the floor boards, the larger cross section will resist torsional load better. They also get welded to the floor boards, adding stiffness not only by being larger but by reinforcing the floor. The other ones would have to come out for that though.

Take a look at some of the XV products as well. At the moment they only make the lower radiator support for A-bodies, but their engine compartment and inner fender braces (for E and B bodies) would help stiffen things up at the A pillar if you did something similar for the A-body. I understand they're working on more stuff too, might be worth calling them and seeing if they're planning a release of any more chassis products for the A's. Otherwise you could do some custom ones yourself.

That's about all I've got, unless you start welding 3/16" steel plates in for floorboards. :-D
 
sydcuda said:
What about torque boxes?
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:eek:ops:

Forgot about those! Yes, torque boxes will help. I'm not sure that in this case they'd be enough by themselves though. They do help stiffen the floor and rockers a little, although I'm not sure if sheet metal is going to solve this extreme of a problem. A set of 1 1/2" tubes down the rockers in conjunction with torque boxes though might help quite a bit, as that will stiffen the corners and tie things together better.
 
Longgone said:
The frame connectors are approximately 2 x 3 bolt in connectors that have been welded in. They do not touch the floor. A big 500 c.i. engine and 5 spd.manual trans is causing the cracks. The car is sound with only minimal surface rust.
Click to expand...

With that engine and setup your probably going to have to buy
extra bodies to strenghen then break:toothy10:
 
72bluNblu said:
Yikes! That thing must be putting out some power if the frame isn't rusted full of holes!

A 4 point bar would probably be the easiest thing to do, but it'll pretty much cost you the back seat (even the ones that go around the back seat don't really allow for safe passenger transport in the back). But if you're hauling groceries and not passengers some of the 4 points are easy enough to deal with.

You can get creative though. I've heard of guys running 1 1/2" tubing down the insides of the rocker panels to tie the subframe outriggers together, that will stiffen torsionally better than the frame connectors. And might be your ticket since you're flexing at the rocker panels.

You could also go for some "through the floor" frame connectors, they're a little larger and don't step down to avoid going through the floor boards, the larger cross section will resist torsional load better. They also get welded to the floor boards, adding stiffness not only by being larger but by reinforcing the floor. The other ones would have to come out for that though.

Take a look at some of the XV products as well. At the moment they only make the lower radiator support for A-bodies, but their engine compartment and inner fender braces (for E and B bodies) would help stiffen things up at the A pillar if you did something similar for the A-body. I understand they're working on more stuff too, might be worth calling them and seeing if they're planning a release of any more chassis products for the A's. Otherwise you could do some custom ones yourself.

That's about all I've got, unless you start welding 3/16" steel plates in for floorboards. :-D
Click to expand...

The bracing down the rocker panel sounds like a plan, I will look into that and check out XV Products. Thanks for the input!

sydcuda said:
What about torque boxes?
Click to expand...

You know I had thought of torque boxes as used on the convertibles. I will look into what`s available there. Perhaps a combination of several things here will get the job done. Thanks!
 
whats that thing pushing , when i get my duster going im scared this is wats gonna happen to me =( my body filler is gonna twist off and hopefully i can still open and close my doors
 
I think the frame connectors would work better if they were welded to the floor. Like the us car tools. Or better yet like the one pictured below. That and a set of torque boxes. Don't know what else you could do besides a cage.

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was going to say torque boxes too.

What rear gear do you have with your 5spd? I'm running a 3.91s and with the 3.27 1st gear it's like having a 4.56 in the rear. This could be part of the problem too. :) A fun problem I mean. I know the tko-600 has a smaller first gear. Maybe a with 3.23s it will still launch nicely but not as violently?

The rocker rail suppports sounds good too. Something for me to keep in mind as well. Of course I'm not runnig a big block beast. :)

Goodluck with it. US Car Tool does have the TQ boxes.

I'd go 6-pt cage if it conitues.
 
These are all great ideas and I`m going to try to see what I can incorporate from all of you. The car is running a 440-6 pack stroked to 500 c.i. with port, polish, and bowl work on MP aluminum heads, ported intake, and KB pistons at 11-1 c.r.. The trans is a TKO 600 with a 3.27 first gear. Rear gear is a 3.91. It will tear up the car if I don`t either drive it with great reserve or do something to stengthen the frame. I like the idea of both adding tubing inside the rockers and somehow combining that with torque boxes. That still may not be enough, and will never be as good as caging it but it`s a start. I spoke to a fellow just this afternoon who is well known in the Hot Rod circle here and he said he would be glad to take a look at it. This car hasn`t been tubbed or modified to the point of no return and I`d like to keep as much of the car that way as possible. I really like having a full interior without tubing crisscrossing throughout.
 
I don't believe you will solve your issue without a cage or serious roll bar, as least one with a pair of door bars. The cage will transfer the energy through the car. You have localized flexing and no reasonable frame connector will hold up to what you are running through the chassis
 
The areas you show cracked are normal cracks for A bodies. Both of these areas were joints that are filled from the factory with some type of filler, not lead.

Since the twist action starts at the front, many don't realize the stiffening process must take place at the cowl forward. Surface plate testing proved it. The frame connectors are fine, but add the rad support an underhood brace and reinforcement from the cowl to the shock tower and you will notice a huge improvement. TOrque boxes couldn't hurt either. I bought a set from Auto Rust that are thicker than the orig.

I had some issues too, like popping the welds off the floor from the rear seat X brace, drivers floor pan breaking welds at the firewall, cracks in the floor and a crack on the firewall in the corner of the bulkhead pass through. Weird stuff happens when the unibody is not rigid enough.
 
My 67 Dart has the same types of stress cracks. I just added the same type of subframe connectors and I'm looking into strengthening the front end as well. I guess cracks like this are to be expected in cars this old. I don't think our cars were ever built to survive as long as they have.
 
This is what I'd do.

US Car Tool makes floor molded subframe connectors. These are stronger than 2x3's you have welded in as they stiffen the unibody's floor.

US Car Tool makes inner fender shock tower braces. These are going to stiffen the front engine cage to the firewall and prevent the stress cracks at the A-pillar.

The core support on the A body cars is weak and allows the motor to twist the engine cage when you push the torque through it. Cutting off the bottom and installing a rad support stiffening kit will greatly help. XV motorsports makes the best looking one.

Torque boxes should round the whole issue. These are tie together the front and rear frames to the outer pinch welds helping to reduce flex.

If all else fails, you'll need a roll bar. Prolly an 8 point.

Riddler
 
Just curious.
Anybody know if and what changes were made
to strenghten the hemi a-bodies frames on
factory cars?
 
Torque boxes will definetly help with being a 4 speed.My 73 Dart Sport 340 4 speed has the torque boxes with the 2x3 frame connectors.I also run comp. engineerings slide-a-link(similar to caltracs)I,m running 452hpand 440ftlbs and have had no issues with twisting so far,after about 40 passes.
 
You know Longarm, looking at the size of those connectors and the fact you welded them in I'm having a hard time believing that you need more strengthening. I realize that you've built a torque monster but hell I wonder if you haven't got another unlying issue like maybe the front subframe welds to the front body are coming loose or worse yet cracks. I know that sub frames aren't the end all be all but the extreme damage to the body doesn't add up for me.

Terry
 
I don`t know how I missed this when it came up a week ago. I`ll try to get a photo up of the rear of the connectors soon.
 
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