I am really surprised this didn't kick up

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Thats good info thanks for sharing that!! He convinced me! One step I can skip now. I had planned on doing the frame connections
 
Of all the Uncle Tony videos, this one is the only one that I disagree with.
I seriously doubt that any engineer would purposely design their cars to flex. These cars were built to last a few years and be replaced. The tires of the day were narrow and slippery compared to what is available today so the chassis did not flex much then anyway.
I'd bet that very few people ever thought these cars would be collected and restored 50-60 years later. They were people movers, not investments.
Even fewer would have ever imagined that tire science would improve so much.
I have heard his theory shared before and I can see his point, I just don't agree with it.
Chrysler built these cars to meet the standards of the day and to compete against GM and Ford. ALL companies have the capability to make a car that is virtually indestructible but the costs to do so would be astronomical. They could have made the chassis as stiff as new cars are today but to what point? The market tolerated what they were sold, not many people demanded better.
In every case that I have seen, subframe connectors increased stiffness and cut down on squeaks and rattles. In my '70 Charger, it took road bumps and imperfections much better than without the connectors. The car soaks up bad roads and feels solid. It may even ride better because the car isn't skipping or rebounding from bad roads.

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The video put me in a dilemma because I have my college- hood 72 dart swinger that I put connectors on. High sentimental valued car. I have never driven it with the connectors but I can say back in college, the car felt like a row boat in the parking lot. Bad low speed body roll, I mean bad, but it was worn out with saggy doors and all. I had hoped the connectors would fix all that ...... but now I'm not sure.
 
Oh boy. Well, I'll start off by saying- it's on the internet, so it must be true right?

So, this concept that the factory engineers knew best. First off, they didn't. The greatest engineering minds weren't working in the auto industry in the '60's. Even if they were, remember that the goal of the automotive industry is not to create the best engineered car. It's to make a profit selling cars while not killing so many people that the lawsuits cut into your bottom line. So, the engineers aren't making all the decisions. In fact, they're frequently overruled. Now that doesn't mean the CEO decides how thick a piece of metal has to be or how many welds to do per inch. But it DOES mean that you can't assume that just because a car rolled off the assembly line a certain way means that way was the BEST way. It could very well mean it was the cheapest way that still squeaked by the safety standards. Ford Pinto fuel tank anyone? Literally over a few cents per unit.

Something the video did mention that is totally true- let's look at the big picture. What did the factory engineers have in mind when these cars were designed?
  • Bias ply tires: I can't overstate how big a deal this is. Just adding radial tires significantly increases traction compared to bias ply's, especially during cornering. That means significantly increasing the suspension and chassis loads above and beyond what the factory engineers were designing for
  • Horsepower: We all run the stock amount of horsepower and torque right? Oh, no, right. First thing we all do is double the amount of horsepower you could get from the factory. Well, needless to say that has a big effect on chassis loads.
  • Lifespan: These cars were designed to be on the road for less than 10 years and probably not more than 100k miles. Lots of decisions were based on just buying a new car when the old one wore out.
  • Factory race cars: These cars were significantly modified from the factory. They may not have gotten frame connectors, but they got a lot more than just torque boxes. And, they were only expected to last a few seasons, with a dedicated crew of mechanics overseeing them in that time.
And then there's just the history of it. Unibody construction for mass production was still a relatively new concept when these cars were designed. They didn't get it all right. If you look at a modern car this is painfully obvious. Sure, unibody construction is still the primary way to build mass produced cars, but I think we all know that a new HellCat has a chassis that's orders of magnitude stiffer than our A-bodies.

Can you make a chassis too rigid? Yes. And when you do, you get cracking from fatigue at high stress locations. That's true. But you can also get cracking from having too much flex. If the chassis twists beyond the capability of the metal it's made out of it also cracks. That's the kind of stuff that happened on some of those factory race cars, and what some high horsepower cars experience too.

The factory didn't design these cars to last 50 years. They didn't design them to use radial tires. They didn't design them to last very long with 400+ hp. They never designed them for modern tires, or increased wheel rates, or sway bars double the diameter of the factory stuff.

So if you add better tires, what happens? More chassis flex. More than was ever intended. Same for adding horsepower. So what do you do? Well, you stiffen the chassis so you don't tear metal at all the joints, work harden the spot welds and break stuff. You reduce the flex back down to more tolerable levels. Will that cause higher stresses at some of those new joints? Yup. It's a balance, like all engineering is.

For me, the bottom line is you can't start making changes and then say the factory knew best. They didn't know radials were going to be used when they designed these cars, so the moment you slap a set of radials on your car more of the factory engineering goes out the window than most people realize. You want to roll around with 9" drums, /6 bars and bias ply's and Tony has a point. Start changing any of that stuff, and it's not relevant anymore.

I've logged almost 20k miles since I did the frame connectors on my Duster. I run a 300 lb/in wheel rate, 3x what the factory ran. I use 275/35/18's, run 400+ hp, have 13" disks. And frame connectors, and torque boxes, and significantly more chassis stiffening than that too. I've popped exactly zero spot welds. No cracks.
 
2nd mod I made to my Daily driver, 1 owner raced and bad roads no negative affects in 16 years of driving. My $.02
 
I get what he is saying however the factory's deal of putting in torque boxes to prevent frame twist was the cheap and quick way on the assembly line for stiffening a vert, 4 speed or hemi car using an existing chassis. Too much twisting and moving will eventually result in cracking sheetmetal and popping spot welds. Remember that just like anything else, when brand new these cars were only intended to last maybe 15 years, not 50 !! The torque boxes were what the engineers needed to design to stiffen em up and what the bean counters were happy with because it was cheap. Had it been cheaper to subframe connect all the performance models on the assembly line, they would have done so.

My 67 has subframe connectors and homemade front and rear torque boxes, my sons 69 will have them too. You also have to realize that when these cars were designed they had bias ply or poly glass tires typically F78-14 tires on 14x5.5, wide pizza cutter rims and tootsie roll diameter sway bars soft rubber bushings, smaller diameter torsion bars etc

they didnt have todays performance suspension parts available for them like polyurethane bushings, huge sway bars, huge torsion bars, and certainly not today's shocks or tires. You put all that stuff on, without seriously stiffening up the frame and have a car that twists like a wet noodle with all this stuff installed and that high zoot suspension system will never work to it's full potential because it will force the chassis to flex, not the other way around with the chassis forcing the suspension to work.

For stock restoration stuff, sure do as the factory intended. If you plan on putting more power, and some serious make it handle parts in there, then you would be wise to sub frame connector it, and torque box it. Less chassis flex with a high performance suspension system is best.

Just my .02
Matt
 
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Wow I got a disagree X for saying "thanks for sharing" :rolleyes:
That's a new one for me! :realcrazy:
 
This guy is only partly right- he needs to go to engineering school. I have been involved with motocross since the '60's. Those who really want to understand chassis stresses and flex and their effect on suspension and handling need to get educated. Beware this guys advise.
 
The reason why this topic has not come up yet ... lots of people watch and respect
Uncle Tony and his good common sense low buck old school videos. Not to show
disrespect to the man thats why. I have liked and mostly agreed with his videos,
goes to show not everyone is right all the time.
 
72bluNblu said:
Oh boy. Well, I'll start off by saying- it's on the internet, so it must be true right?

So, this concept that the factory engineers knew best. First off, they didn't. The greatest engineering minds weren't working in the auto industry in the '60's. Even if they were, remember that the goal of the automotive industry is not to create the best engineered car. It's to make a profit selling cars while not killing so many people that the lawsuits cut into your bottom line. So, the engineers aren't making all the decisions. In fact, they're frequently overruled. Now that doesn't mean the CEO decides how thick a piece of metal has to be or how many welds to do per inch. But it DOES mean that you can't assume that just because a car rolled off the assembly line a certain way means that way was the BEST way. It could very well mean it was the cheapest way that still squeaked by the safety standards. Ford Pinto fuel tank anyone? Literally over a few cents per unit.

Something the video did mention that is totally true- let's look at the big picture. What did the factory engineers have in mind when these cars were designed?
  • Bias ply tires: I can't overstate how big a deal this is. Just adding radial tires significantly increases traction compared to bias ply's, especially during cornering. That means significantly increasing the suspension and chassis loads above and beyond what the factory engineers were designing for
  • Horsepower: We all run the stock amount of horsepower and torque right? Oh, no, right. First thing we all do is double the amount of horsepower you could get from the factory. Well, needless to say that has a big effect on chassis loads.
  • Lifespan: These cars were designed to be on the road for less than 10 years and probably not more than 100k miles. Lots of decisions were based on just buying a new car when the old one wore out.
  • Factory race cars: These cars were significantly modified from the factory. They may not have gotten frame connectors, but they got a lot more than just torque boxes. And, they were only expected to last a few seasons, with a dedicated crew of mechanics overseeing them in that time.
And then there's just the history of it. Unibody construction for mass production was still a relatively new concept when these cars were designed. They didn't get it all right. If you look at a modern car this is painfully obvious. Sure, unibody construction is still the primary way to build mass produced cars, but I think we all know that a new HellCat has a chassis that's orders of magnitude stiffer than our A-bodies.

Can you make a chassis too rigid? Yes. And when you do, you get cracking from fatigue at high stress locations. That's true. But you can also get cracking from having too much flex. If the chassis twists beyond the capability of the metal it's made out of it also cracks. That's the kind of stuff that happened on some of those factory race cars, and what some high horsepower cars experience too.

The factory didn't design these cars to last 50 years. They didn't design them to use radial tires. They didn't design them to last very long with 400+ hp. They never designed them for modern tires, or increased wheel rates, or sway bars double the diameter of the factory stuff.

So if you add better tires, what happens? More chassis flex. More than was ever intended. Same for adding horsepower. So what do you do? Well, you stiffen the chassis so you don't tear metal at all the joints, work harden the spot welds and break stuff. You reduce the flex back down to more tolerable levels. Will that cause higher stresses at some of those new joints? Yup. It's a balance, like all engineering is.

For me, the bottom line is you can't start making changes and then say the factory knew best. They didn't know radials were going to be used when they designed these cars, so the moment you slap a set of radials on your car more of the factory engineering goes out the window than most people realize. You want to roll around with 9" drums, /6 bars and bias ply's and Tony has a point. Start changing any of that stuff, and it's not relevant anymore.

I've logged almost 20k miles since I did the frame connectors on my Duster. I run a 300 lb/in wheel rate, 3x what the factory ran. I use 275/35/18's, run 400+ hp, have 13" disks. And frame connectors, and torque boxes, and significantly more chassis stiffening than that too. I've popped exactly zero spot welds. No cracks.
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Agree w/ ttat, they weren`t computer designed either, makes a big diff. in the chassis !
 
66jim said:
The reason why this topic has not come up yet ... lots of people watch and respect
Uncle Tony and his good common sense low buck old school videos. Not to show
disrespect to the man thats why. I have liked and mostly agreed with his videos,
goes to show not everyone is right all the time.
Click to expand...
I'm not saying he is right or wrong I simply do not have enough knowledge to debate either way but I feel he has enough experience with classic cars to make an impression on my opinion.
 
Rainy Day Auto said:
The video put me in a dilemma because I have my college- hood 72 dart swinger that I put connectors on. High sentimental valued car. I have never driven it with the connectors but I can say back in college, the car felt like a row boat in the parking lot. Bad low speed body roll, I mean bad, but it was worn out with saggy doors and all. I had hoped the connectors would fix all that ...... but now I'm not sure.
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I couldn`t hear him, my speakers and p.c. are messing up.
From reading these posts , I totally disagree w/ him tho .
Ever twist a B body so hard , the door bounces back at u when u slam it !?!
 
Lots of debatable info.Flex was definately a part of engineering our vehicles.They used to say a Model A would flex through any rough road of the day and that is why their frames weren't boxed.
Think of a long piece of steel and apply weight to the centre...it will form a smooth gradual bend.Now reinforce the centre 50% and apply the weight again and you will probably break the ends off.
I don't think it will matter for the majority of us one way or the other.
 
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I think his point that it’s not necessary for frame connectors unless you have a car just for competition is valid.
 
I have always wondered why those that add frame connectors don't stiffen the front section.The connectors are usually applied but nothing is reinforced from the crossmember forward which contains a tremendous amount of weight with the front of the vehicle and all the engine ,suspension, tires etc...maybe 40% of the whole vehicle?
 
Rainy Day Auto said:
The video put me in a dilemma because I have my college- hood 72 dart swinger that I put connectors on. High sentimental valued car. I have never driven it with the connectors but I can say back in college, the car felt like a row boat in the parking lot. Bad low speed body roll, I mean bad, but it was worn out with saggy doors and all. I had hoped the connectors would fix all that ...... but now I'm not sure.
Click to expand...
The connectors will help alot along with boxing in the torque boxes to stiffen up the chassis. But will work even better once you upgrade your springs, shocks, use polyurethane bushings, bigger sway bars and wider better tires. By themselves you will notice a difference but not as much as if you took care of the rest.
 
I think Chrysler should have tied the frame rails together on every unibody car they made. Period. All you have to do is look at the difference on the drag strip of one tied together VS not tied. The one tied together comes off the line much straighter and truer and if the rest of the car is right, when the front tires come back down, you're still straight. Yeah I know "but that's a race car......." Just about everything that makes a race car safer and easier to drive transfers over to the street. I've seen a LOT of Mopars tied together and owned some too. I HAVE YET to see any of them break spot welds. ANYWHERE. Also, where he compares a framed car and says they have bushings to take up flex......people have been using both poly and aluminum body bushings in full frame cars for decades with no ill effects.

I'll put it this way. Even if I leave the stone stock 170 in my 64 Valiant, it's getting US Car Tool frame connectors. They are something that should have been there to begin with. You want to know why Chrysler didn't tie the frame rails together? Simple. They saved the company millions of dollars by not doing so. Chrysler was a cheapass company that saved a penny anywhere they could. If you don't think they knew it would have added strength, you gotta nuther thing comin. Build the car so it'll bend when it already has a suspension.......yeah that's genius engineering. NOT. I love Tony all to pieces but I cannot agree with him here.
 
Yep, back then 50 years ago this stuff was slapped together for the lowest dollar they could get away with. There was no competition from the Japanese (yet). They had to meet the corporate 5/50 warranty. Typically once this stuff hit 5 years and close to 50k on the odometer they were traded in on a new car, hit the used car lot and were used up at 10 years and 100k. They used current tire technology that was available to them.

These cars when built rode just fine for 98% of the people who bought them. They were new cars then. Most people bought them for the same reason you would buy a toaster or a refrigerator. It was an appliance. It was bought to be used to get to work, during the week, and go see Aunt Bessie 50 miles away on the weekends. People put bumper hitches on em and towed trailers with em. Heck my pops had a 1973 Dodge Polara sedan with a bumper hitch on it. Used to pull a starcraft pop up camper and car had a bike rack on the back to go with it.

Heck the reason the pentastar is only on the passenger side is the bean counters and marketing arguing over the cost to put them on every car. Marketing wanted it on both sides, bean counters didnt want it on there at all. In the end they both conceded. The star would be passenger side only since its curb side, only half the costs.

So I guess along w subframe connectors, Uncle Tony would be horrified at my home made lower radiator support made with 2x3 boxed steel like my connectors. As well as my fully welded K frame with strengthening gussets, and skid plate. I intend to do these same mods to my sons 69 notchback as well. Not H or M code cars so who cares. I like stuff that handles. Notch out on my lower support is fully boxed and is for the radiator lower tank. This way it tucks up nice and tight

Had a T Top Daytona Shelby in the late 80s. You could hear this car creak and pop like a bowl of ******* rice krispies when pulling into a driveway. It didnt help matters that the T Top daytonas were done after they left the St Louis assembly plant by an aftermarket company. This meant the roof got surgically sawsalled off behind the windshield, and forward of the rear hatch all the way across, and a T bar frame panel was installed to stiffen it back up with big assed steel pop rivets. I jacked it leveled it square, removed the seats, and carpet, then proceeded to tie in the front and rear subframe with 2"x2" 1/8" thick boxed steel. Had to slot the floor pan to fit them, added extra carpet padding in spots, reinstalled everything. What a difference it made, even over a Daytona Shelby hardtop. This was a more modern car, had heavier spring rates 225-50 VR15 tires on 15x6.5" rims, used a 1&1/4" front sway bar and a 7/8" rear sway bar. I forced the suspension to do its job. Car felt more solid, was more precise. So heres a case of a more modern vehicle benefitting from the same modification. I have another Daytona shelby z t top car. If I ever get to it, I will be welding in the T bar panel to the body structure and welding in subframe connectors, as well as seam welding the K frame, and bracing the strut towers to one another and the cowl with a triangulated brace.

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plumkrazee70 said:
Hmm... I get what he is saying. I already have my frame connectors in, tho. I wonder if anyone who daily's their car has experienced any real world negative effects.

@72bluNblu or @TrailBeast ??
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One of the best things I have done to my car, and especially when the oversized torsion bars, poly bushings and stiffer shocks went in.



ir3333 said:
I have always wondered why those that add frame connectors don't stiffen the front section.The connectors are usually applied but nothing is reinforced from the crossmember forward which contains a tremendous amount of weight with the front of the vehicle and all the engine ,suspension, tires etc...maybe 40% of the whole vehicle?
Click to expand...

That is exactly why some add the front supports from the firewall across the top of the shock towers and down to the frame rails.
I have seriously considered adding these to my daily driver because of all the uneven surfaces and dips in the roads I drive.
If you add frame connectors, stiffer bars and shocks where is all that torque going now? (through the inner fenders, fenders and firewall)

When I made my connectors I added a 1/4 plate to the front bottom end that ties into the rear section of the front frame rail where the torsion bars cross member meets it.
It's not much I'm sure, but at least some of the load is transferred directly to the front section instead of counting on the cross member to transfer it all.
 
i don't think frame connectors were left off to save money.If the engineers felt they were a benefit a simple change in the die could have added 2 more folds in the floor.I'm betting the stock stamping matched the strength of the unibody ahead and behind it.
As for twist, adding torque boxes would provide a gusset type re-inforcement and there is nothing so strong as a triangle, but adding frame connectors seems to be adding 2 more 2x4's to a stud wall which it seems wouldn't help much.
...i just tryin' to look at things logically.
 
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