Subframe connectors for a driver/cruiser, necessary to weld to floor?

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Like said before , buy 2 x 3 x .125 mild steel tube.
I have had BB B body 4 speed cars that were twisted and could have used a good set of connectors.
 
Hey
Bodyperson said:
I have not been involved with the "weld to floor" designed connectors. What I gather from the internet is that the weld to floor connectors are cut from channel and get seam welded to the floor. This is a less than desirable design. If the channels had flanges and could be plug welded to the floor with tight tolerance, I would be more inclined to consider that design as equal to or even superior to the square or rectangular tubing. I can see the existing "weld to floor" design tearing out or separating as Brooks James has witnessed. Just an old, burned out Body Man's opinion.
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Yeah I don't think the open channel, weld-to-floor style connectors are as good as they could be. It would be better if they actually mimicked the original frame rail design. Again, I won't go as far as to say one type of connector is better than the other because there just isn't any real data, and it's a complicated system. But I do know that installing that type of connector is 10x more work, and there are more than a few drawbacks to that design. Both have their pros and cons, no doubt.

MRGTX said:
There’s an echo in here. :D

Based on the historical application of these two measures, I think there is a strong case for the OP to use this option. His car sounds like it has been upgraded to at least the level of cars that would have come with this equipment and while it’s not being raced, it’s not being driven like a fragile Model T nor is it being put-putted around to car shows like a *gasp* priceless Hemicuda either.

I guess the problem is that it’s very hard to have real data on how much these things help and therefore very hard to compare one chassis flex countermeasure over another. Nobody is sacrificing their own car to chassis rigidity testing and even if they did, these are all half-century old, used and often abused platforms making control data nigh impossible to come by.

Anecdotally, torque boxes seem to have made a huge difference in preventing chassis twisting/long term damage when big power and slicks were added to the formula…so even without data, I’m pretty confident that they do something helpful.
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I mean, the torque boxes on my car are pretty visible in the pictures I posted:p

But yeah I don't think anyone is going to do the actual chassis analysis needed to prove this out. The factory installed torque boxes for a reason, and from a chassis construction standpoint by connecting the frame rails and the rockers they're basically gusseting the corners of the box, so it makes a lot of sense that even being a small addition they would make a significant difference. And again, the factory didn't do anything it didn't think was necessary because that definitely cost money.

The subframe connectors I think we can all agree from an anecdotal standpoint do something. Door gaps stay true even with the car on jacks, less body rattles and creaks while driving, the whole car feeling more planted and accurate through corners, etc. I install both on everything I'm driving.

The other thing is these cars are all 50 years old. So, even if you made the argument they didn't need them from the factory, there's a good argument that after 50 years of wear, tear, metal fatigue and rust that pretty much everything out there now would see an improvement from their addition.
 
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As for torque boxes, high power manual transmission cars can certainly benefit. Any of them can, really, but Chrysler must have thought the same as big power cars with manual transmissions got torque boxes a good bit. Just look at the "whole kit" US CarTool offers for our cars. That should give you a good idea of what all you can add to strengthen these old girls up.
 
I haven’t done final body and paint yet, no idea when/if I ever will lol, but based on the advice in this thread I will definitely install subframe connectors before final body and paint. Who wants to risk cracks and broken glass?

Right now that sort of thing wouldn’t be as big of a deal.
 
Well it seams to be my words on this topic that draw the red x I will try again.
The original post says he's just smoking tires and not racing.... and I high lited that.
People here put there own **** in every post, you've got to do it my way because I am right, I know my **** I'm better than you.
The truth is you don't need frame connectors for doing burnouts.
I have a ten second Volare that I didn't put frame connectors in until I needed a cage, at that time it was 12.0 in the quarter. The car hooked hard enough to pull both front tires 12"+ running 12.10s. Sure it was better after I added the weight of the cage and subframe connectors, but did I need them. The car slowed down until I added power.
How many frame connectors do you need to make a Hellcat run tens? None
I do agree with putting them in a convertable, watching the dash shake isn't cool.
Now my little 289 Fairlane will get frame connectors but no cage, it will be capable of low 11.0s I will just run 11.50s.
 
THE TRUTH IS... hotrod swinger wants to put subframe connectors in his "73 Swinger. (SARCASM)Damned people putting THEIR own **** into THEIR posts. How dare they share and discuss their experiences with A-body cars on an A-body discussion forum. (SARCASM OVER)
The truth is, you don't NEED much of anything to do a burn out. hotrod swinger would LIKE to put in subframe connectors and asked if he should weld them to the floor. He did not ask if he NEEDS subframe connectors. People here (namely Oldiron440) who try to put **** in peoples mouths and then compare their non related **** to the original post SEEM think their **** is better than other peoples ****.

I apologize if for some reason I have taken this too literal. It could be that I missed something and that Oldiron440 is being sarcastic and having a little fun. I hope so because otherwise his postings seem rude and not typical of the responses usually generated on this type of discussion.
 
Oldiron440 said:
Well it seams to be my words on this topic that draw the red x I will try again.
The original post says he's just smoking tires and not racing.... and I high lited that.
People here put there own **** in every post, you've got to do it my way because I am right, I know my **** I'm better than you.
The truth is you don't need frame connectors for doing burnouts.
I have a ten second Volare that I didn't put frame connectors in until I needed a cage, at that time it was 12.0 in the quarter. The car hooked hard enough to pull both front tires 12"+ running 12.10s. Sure it was better after I added the weight of the cage and subframe connectors, but did I need them. The car slowed down until I added power.
How many frame connectors do you need to make a Hellcat run tens? None
I do agree with putting them in a convertable, watching the dash shake isn't cool.
Now my little 289 Fairlane will get frame connectors but no cage, it will be capable of low 11.0s I will just run 11.50s.
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A Hellcat?! Besides fitting into the general definition of being a unibody, what exactly do you think a Hellcat chassis and an A-body chassis have in common?

I mean, seriously. Do you actually think that's a legitimate comparison? Because from a technical standpoint you might as well be comparing a Cessna 172 to an F-35. Yeah they're both airplanes, but I wouldn't say the Cessna doesn't need a propeller just because the F-35 doesn't need one. Good grief man.
 
72bluNblu said:
A Hellcat?! Besides fitting into the general definition of being a unibody, what exactly do you think a Hellcat chassis and an A-body chassis have in common?

I mean, seriously. Do you actually think that's a legitimate comparison? Because from a technical standpoint you might as well be comparing a Cessna 172 to an F-35. Yeah they're both airplanes, but I wouldn't say the Cessna doesn't need a propeller just because the F-35 doesn't need one. Good grief man.
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Pretty sure a Hellcat would laugh at subframe connectors
 
If you have the means to do it then go for it. I think everyone (including myself) pretty much agrees you don't need them but they will still make a difference. Home-made steel box tubing worked for me (not welded to floor) and made a noticeable improvement in how solid the car felt. Not just in handling but going over bumps and opening and closing the doors, the whole car just feels tighter and more sturdy. It won't have an effect on how good your burnouts are lol but you'll appreciate the feel of the chassis being stiffer.

Thinking out loud about torque boxes, for one they're much smaller and cheaper to make and install compared to subframe connectors. IIRC they were also already designed for convertibles before the Street Hemi came out so 2 reasons there for the factory to do it. I imagine it helps beef up the area around the front spring perch which is seeing all of the forces from the drivetrain trying to push and twist the car, but when things get more serious the unibody between the front and rear subframes can still start to buckle and twist which torque boxes don't really help. Or maybe they do because they were originally designed for convertibles... idk lol. I do know my MP Chassis manual mentions subframe connectors and that pretty much any unibody Mopar will benefit from them.
 
Oldiron440 said:
Well it seams to be my words on this topic that draw the red x I will try again.
The original post says he's just smoking tires and not racing.... and I high lited that.
People here put there own **** in every post, you've got to do it my way because I am right, I know my **** I'm better than you.
The truth is you don't need frame connectors for doing burnouts.
I have a ten second Volare that I didn't put frame connectors in until I needed a cage, at that time it was 12.0 in the quarter. The car hooked hard enough to pull both front tires 12"+ running 12.10s. Sure it was better after I added the weight of the cage and subframe connectors, but did I need them. The car slowed down until I added power.
How many frame connectors do you need to make a Hellcat run tens? None
I do agree with putting them in a convertable, watching the dash shake isn't cool.
Now my little 289 Fairlane will get frame connectors but no cage, it will be capable of low 11.0s I will just run 11.50s.
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Hellcats flex more than an A body does . They have frame connector kits for them.
 
I put them in every car I build bc they do stiffen the car up considerably and do make the car handle better. I cannot say they would make a car launch harder bc I don't have any direct experience with that, but in "theory" I would think they might as they would facilitate a better transfer of power.

Whether to weld or to bolt in I guess comes down to a variety of factors but I always weld them in. To me its kind of like getting a Tattoo, once you have one you might has well get more... in this case it is more bracing and I like my bracing to be permanent to the car.

Ultimately its your car do what you want.
 
I intend to install bolt-in subframe connectors on my 69 Dart but I am unclear where to get them as it seems there are plenty offer for 70 and up years but not so much for 69. Does the 69 have a 108" WB? I was looking at Mopar Performance or Hotchkiss.

Many have commented "You don't need them" regarding these. How is it that we don't apply this axiom to any other changes we chose to make on everything else on the car?
Upgraded brakes, tires, suspension, electronics, cooling, power and other "not needed" stuff we don't seem to have trouble dumping money into.

We "unnecessarily" changed the steering on my son's 65 Nova to an aftermarket power rack and pinion unit and added subframe connectors. That converted a 5-turn LTL poorly handling death trap to a slot car.
 
108" wheelbase is 67-69 barracuda, 70-76 duster, 71-72 demon, 73-76 dart sport.

67-76 dart 2 door and 4 door, 4 door valiant, and plymouth scamp are 111" wheelbase

There may be others, but there are 2 different wheelbases
 
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sorting out the floors on my Barracuda with the screen out, the door off and the floor cut out it's visually quite scary how little metal there is holding the car together.

I would say one main reason for fitting them is to stop or reduce the cabin folding around the occupants in a head on or rear end crash. Although i'm using box as a frame connector i'm also tying the seat mount points to the box as the floors flex quite a lot . (Felt as i knelt on the floor to weld and evidenced by cracks at the seat mount points.)

Probably find Mopar didn't add frame connectors as an upgrade because it could be said the body isn't strong enough in the first place then.
 
moparmat2000 said:
108" wheelbase is 67-69 barracuda, 70-76 duster, 71-72 demon, 73-76 dart sport.

67-76 dart 2 door and 4 door, 4 door valiant, and plymouth scamp are 110" wheelbase

There may be others, but there are 2 different wheelbases
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The 67-76 Darts and 4 doors are 111”, not 110”.
 
There's no guessing on 50+ year old rusted sheet metal. I run street radials on my 4-speed '69 Dart. Engine is a built 418. My 1/4's are flexing. The car has the factory torque boxes and home made subframe connectors, also 4-link coil over rear suspension. I know that it will be a lot of work winter project, but the old torque boxes and sub frame connector are coming out and will be installing the uscartool torque boxes and sub frame connectors.
I really don't want to put a roll cage in.
So all advice here is good, but every car has its own weaknesses.
Good luck with what you do.
 
I have seen them welded to the floor pan and eventually metal fatigue has allowed the metal to rip
 
72bluNblu said:
The 67-76 Darts and 4 doors are 111”, not 110”.
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I’ve been looking closer at sub frame connectors since I’m going to need them. What about the USCT connectors was it you weren’t fond of? I don’t mind fitting them. Was it you don’t like the way they weld to the floor?

I also need to duplicate your slider brackets. That’s a fall project.
 
Rat Bastid said:
I’ve been looking closer at sub frame connectors since I’m going to need them. What about the USCT connectors was it you weren’t fond of? I don’t mind fitting them. Was it you don’t like the way they weld to the floor?

I also need to duplicate your slider brackets. That’s a fall project.
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I have heard that they dont fit well to the ribbing in the floor because every car is a little different, requiring a lot of weld to fill gaps. USCT IS Definitely not a project to be done unless the car upside down on a rotisserie. I did both of mine with 2x3 steel box tube layed on its side, and slotting the rear foot wells.
 
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