C Body front subframe swap to 50s Mopar chassis

[trakrodstr]

Today I joined this C Body Forum to get at a specific question. Has anyone reading this post ever heard of swapping the C body front subframe to a 1950s Mopar? In this case to a 1956 New Yorker chassis. The nominal track width for the 1956 chassis is about two inches narrower than a C body front track width.

Yes I know there are hundreds of aftermarket IFS kits that range from inexpensive (Mustang II) to big bucks systems (eg, Roadster Shop, 3D computer scanned system at $25K).

I am frustrated by the lack of modern steering options/upgrades for the 50s Mopar kingpin system. I’ve tried both the vintage manual steering box and the sloppy coaxial “full time” power steering box on my car; the latter being a poor system from the start (sorry this PS system was not Mother Mopar’s finest idea).

Essentially, I want to keep the chassis in the Mopar family with a torsion bar suspension; but with access to upgraded steering gearbox options and ball joints instead of kingpins.

I realize this is a weird swap idea, but I just don’t want a modern A-arm coil over front suspension, I”m not even particularly interested in disk brakes, just a torsion bar/ball joint front suspension with improved steering capabilities.

The 1956 New Yorker frame is massive, and more narrow than a C body front subframe. So I understand major surgery will be required.

When I called some of the nationally well-regarded Mopar restoration/fabrications shops about this idea — I get no useful response. None of the shops were interested. They just want to install an expensive generic “hot rod” independent front suspension kit. Interestingly several of the shop managers emphasized that, whatever I did, I should NOT consider using a front suspension based on the Mustang II “tubular” A-arm system.

Any thoughts or information about the feasibility of this idea?

 

[Davea Lux]

As the saying goes, with enough time and money, a torsion bar conversion could probably be done, but you would need to build a custom frame from scratch. The stub on a C-Body is designed to work with a unibody. The '56 Mopars had a full frame and lack the rigidity to mount the stub from a later Mopar. You would need to chop the existing frame forward of where the stub is going to mount and build the stub mounting points from scratch. You would also need to add the cross rails to the body floor pan to stiffen it up for purposes of attaching the stub to the floor pan and cowl. You will also probably need to design a custom mounting system for the steering column to get the angles right. If you are planning to use the '56 running gear, the mount points for the engine and transmission are going to be a lot different as well. Will also need to fabricate a custom core support and fender mounting system that is compatible with the front clip on the '56. All of this is possible, but it will be a time consuming and expensive ordeal and it will take a high quality custom frame shop to pull it off.

Dave

 

[CBODY67]

The Mustang II deal became the darling of the street rod people years ago. But it's not intended for a heavy vehicle (which most street rods really aren't).

It's been very common to use the Gen I or Gen II Camaro front subframe to go under a whole bunch of '50s GM 1/2 ton pickup trucks, for a good while. With all of the benefits you desire.

Rather than a C-body front section, I saw an article on a '61 or '62 Ford F-100, which seemed to have the same general frame width as the Aspen/Volare cars' front subframe. Which upgraded that old I-beam/leaf spring front suspension to modern disc brakes, power steering, and "bent-bar" torsion bars with a front sway bar in one single "swoop". The article detailed how it was all done, with good pictures. I'd never thought about using that subframe, but it would certainly be better than using an AMC Pacer front suspension. But the main draw of the bent-bar subframe was that the rails were so close to the frame width of the F-100.

About three or so years ago, there was a yellow '56 Dodge Sierra wagon that went through Mecum. It had a Dakota front end under it. Only problem with it was that the track, with the Cragar S/S wheels, put the tire sidewalls just inside of the fender lips. At the auction, it had air bags on the front. When they were deflated, the wheels had to be aimed straight ahead, period. Everything just cleared. A new-style theft deterrent? The new owner wanted the air bags removed, so a pair of Dakota lower control arms and new springs from NAPA fixed it right up. But the tire/fender interface would still be an issue when turning and hitting a bump, I suspect. It had a 440 in it, too.

But that was a coil spring front end. It looked like they just welded the Dak crossmember (and suspension) to the existing '56 Dodge frame rails. Or what we could see that was buried under massive amounts of spray-on undercoat.

What about if you go back to about 1963-'64 C-bodies rather than the '65 and up cars? How do the rail widths and front track widths compare to what you've got? Or some of the B-body cars, even some of the middle-'70s cars? What about steering gear placemment and related steering column angularity?

I can understand the reaction you got from some of the custom shops. Expecially with the advent of the newer full-frame universal set-ups that have appeared over the past few years. Coil-overs everywhere! YUK!

I really appreciate your desire to keep everything "in the family"! I wish you luck in that venture!

CBODY67

 

[trakrodstr]

As the saying goes, with enough time and money, a torsion bar conversion could probably be done, but you would need to build a custom frame from scratch. The stub on a C-Body is designed to work with a unibody. The '56 Mopars had a full frame and lack the rigidity to mount the stub from a later Mopar. You would need to chop the existing frame forward of where the stub is going to mount and build the stub mounting points from scratch. You would also need to add the cross rails to the body floor pan to stiffen it up for purposes of attaching the stub to the floor pan and cowl. You will also probably need to design a custom mounting system for the steering column to get the angles right. If you are planning to use the '56 running gear, the mount points for the engine and transmission are going to be a lot different as well. Will also need to fabricate a custom core support and fender mounting system that is compatible with the front clip on the '56. All of this is possible, but it will be a time consuming and expensive ordeal and it will take a high quality custom frame shop to pull it off.

Dave

 

[trakrodstr]

Thanks for your thoughts Dave, you are correct this project would not be for the fainthearted. The reason I got to thinking about the C body stub frame is due to its integrated OEM structure, which if it could be grafted to an early perimeter frame would have OEM geometry fixed in place.

The frame rails of the NY chassis are about 5x5 inches near the plane of the firewall, pretty stout. I guess the idea would be extra massive "frame connecters" to mate with the early chassis....

I also of course thought of the 57 family of chassis which have ball joints and torsion bars, but not much improvement in the steering dept. So even if the 57 front clip worked out, the marginal steering would not warrant the effort.

By the way, another problem is that the track width of the C body stub frame is 3 inches wider than the 56 New Yorker chassis; this might be finessed with wheel back spacing.

Thanks again
Charlie

 

[trakrodstr]

The Mustang II deal became the darling of the street rod people years ago. But it's not intended for a heavy vehicle (which most street rods really aren't).

It's been very common to use the Gen I or Gen II Camaro front subframe to go under a whole bunch of '50s GM 1/2 ton pickup trucks, for a good while. With all of the benefits you desire.

Rather than a C-body front section, I saw an article on a '61 or '62 Ford F-100, which seemed to have the same general frame width as the Aspen/Volare cars' front subframe. Which upgraded that old I-beam/leaf spring front suspension to modern disc brakes, power steering, and "bent-bar" torsion bars with a front sway bar in one single "swoop". The article detailed how it was all done, with good pictures. I'd never thought about using that subframe, but it would certainly be better than using an AMC Pacer front suspension. But the main draw of the bent-bar subframe was that the rails were so close to the frame width of the F-100.

About three or so years ago, there was a yellow '56 Dodge Sierra wagon that went through Mecum. It had a Dakota front end under it. Only problem with it was that the track, with the Cragar S/S wheels, put the tire sidewalls just inside of the fender lips. At the auction, it had air bags on the front. When they were deflated, the wheels had to be aimed straight ahead, period. Everything just cleared. A new-style theft deterrent? The new owner wanted the air bags removed, so a pair of Dakota lower control arms and new springs from NAPA fixed it right up. But the tire/fender interface would still be an issue when turning and hitting a bump, I suspect. It had a 440 in it, too.

But that was a coil spring front end. It looked like they just welded the Dak crossmember (and suspension) to the existing '56 Dodge frame rails. Or what we could see that was buried under massive amounts of spray-on undercoat.

What about if you go back to about 1963-'64 C-bodies rather than the '65 and up cars? How do the rail widths and front track widths compare to what you've got? Or some of the B-body cars, even some of the middle-'70s cars? What about steering gear placemment and related steering column angularity?

I can understand the reaction you got from some of the custom shops. Expecially with the advent of the newer full-frame universal set-ups that have appeared over the past few years. Coil-overs everywhere! YUK!

I really appreciate your desire to keep everything "in the family"! I wish you luck in that venture!

CBODY67

 

[CBODY67]

In looking in the specs at www.jholst.net, the '55 Chrysler sedan (non-wagon) front track is 60.2", with the wagon being 61". The rear track on the sedans is 59._" and the wagons being 61". Wagons having pretty much the same track, f/r, as the Imperials, that year. Might those changes be due to a wider wheel, or something similar?

IIRC, the tread widths on the '65-'68 Chryslers were similar, but the '63 Chryslers might be similar? Have to look to see.

CBODY67

 

[trakrodstr]

Thanks CBODY67

Yes I did consider the Aspen/Volare front subframe. In my opinion, this too was not one of Ma Mopars finest ideas (for lots of reasons) and decided that this was a no-go for me.

Very interesting you mentioned pickups. A few weeks ago I ran across and article stating that some Ford Ranger pickups had torsion bars, with rack and pinion steering! I did not find any good FSM drawings on the web, but it might be worth a bit of searching as the track width of the Ranger is (if I remember correctly) 60", while the New Yorker chassis is 59.1"....very close. I certainly wouldn't mind rack and pinion steering. I am a big Mopar fan but also partial to many FoMoCo products, so I might be able to swallow my Mopar pride a bit. No GM though.

I fine it curious why no one sells an aftermarket torsion bar based kit. The low center of gravity, the significant reduction in unsprung weight and the ability to position the T-bars at the rotational axis of the lower "A-arm" pivot are real world advantages.

As you suggest, I have considered the early Mopar unit body front suspensions, some of which come very close to the 59" track width. I guess it's possible to do, but the complex geometry would have to be spot on. That's why I considered the C stub frame as it comes as a fixed OEM designed package.

Regarding keepin' the faith — when I designed my 50s era track-nosed roadster it included a four-corner torsion bar suspension, 36 Dodge "artillery" wheels, 56 Dodge brakes, 30s Dodge gauge faces and a 57 Dodge 325 Hemi. Yeah.

Regards,
Charlie

 

[Big_John]

Now you are probably going to ask me why I'm doing this, but one of the best places to get the dimensions for the K frames as a starting point is in the factory service manual. You can download some here: MyMopar - Mopar Forums & Information - Service Manuals

You might be able to do some measuring based on the numbers there

A little more info here: 1969 - 1971 C body Stub Frame (subframe)

Although that's really not related to much of what you are doing, it still may help.

Now you might be able to do some measuring based on the numbers there.

The C body stub frame might really work for this. Everything is located with correct geometry.

 

[trakrodstr]

Now you are probably going to ask me why I'm doing this, but one of the best places to get the dimensions for the K frames as a starting point is in the factory service manual. You can download some here: MyMopar - Mopar Forums & Information - Service Manuals

You might be able to do some measuring based on the numbers there

A little more info here: 1969 - 1971 C body Stub Frame (subframe)

Although that's really not related to much of what you are doing, it still may help.

Now you might be able to do some measuring based on the numbers there.

The C body stub frame might really work for this. Everything is located with correct geometry.

 

[trakrodstr]

OK Big John I'll check out the links you sent, thanks.

I agree that the stub frame is a well engineered and an integrated "device".

Meantime, "Don't let the bastards grind you down."

Charlie

 

[traintech55]

I like "C Body 67's" idea of using the "K" frame from any "F, M, J" body car with the "J" torsion bars. If the mounting points fit your frame width this would be perfect. You get the new style engine mounts, And the police versions had the heavy duty Torsion bars and sway bar. Plus disc brakes. Hope this works out for you.

 

[Wonderwagon]

Out of Ma Mopars family, but how about a Crown Vic front end swap?

 

[Big_John]

A friend had a '34 Plymouth with a Volare front end under it.

It worked, but it always just looked "clumsy", for lack of a better word. The work was done well, just didn't seem to fit the car.

But, yeah, the Crown Vic... Of course, I think if I were to look at doing a Crown Vic swap, I'd get a tape measure out for the entire frame.

 

[CBODY67]

Apparently, the lower-control-arm pivot/attachment point for front torsion bars design is a patented Chrysler item. Reason? When GM used torsion bars on their '62-'63 light and medium-duty trucks, AND later (90s) light-duty 4wd Suburbans/Tahoes/pickups, they mounted the front of the torsion bar to the lower control arm (same hex-shaped end) a few inches outboard of the lca pivot point. Which makes the front of the bar move in an arc, rather than just rotate.

There were also some Durango 4wds with front torsion bars, too. When I discovered that (on a rental unit!), I smiled and thought that it might be worth the fuel economy hit to have a torsion bar/leaf spring suspension on a modern vehicle (with 4wd).

Enjoy!
CBODY67

 

[bigmoparjeff]

The Volare front end is the simplest swap because the entire suspension system is contained in one unit. The criticism of this suspension mainly comes from one person, Rick Ehrenberg, and I think he's just being too much of a stickler engineer on the subject. He doesn't like it because the bars don't travel in the same arc as the control arms. It's not ideal on paper, but works just fine in the real world. This front end survived tons of abuse in police cars, and was also used on the most expensive car you could buy in 1981, the new Imperial. The biggest test: it survived my grandfather's driving for 43K miles of hitting just about every pothole in the city of Philadelphia with just one bad upper ball joint.

Another suspension to consider is the isolated 1973-up B body system, which continued on to the Cordoba and R bodies. All your geometry for the upper and lower arms is set on this one as they are all mounted to the K frame. Unlike the Volare front end, the rear torsion bar mount is separate, so there would be some careful measuring and fab work to do to keep it all in the right place. The B body track width will likely be closer to your original too.

I wouldn't consider the Crown Vic swap. The track width is a real problem on those because they use the oddball front wheel drive style rims.

Jeff

 

[trakrodstr]

I like "C Body 67's" idea of using the "K" frame from any "F, M, J" body car with the "J" torsion bars. If the mounting points fit your frame width this would be perfect. You get the new style engine mounts, And the police versions had the heavy duty Torsion bars and sway bar. Plus disc brakes. Hope this works out for you.

traintech55,

Many thanks, I'm grateful for your time and knowledge and the other enthusiasts who have offered advide. I seems this is a active info packed forum.
Charlie

 

[trakrodstr]

I like "C Body 67's" idea of using the "K" frame from any "F, M, J" body car with the "J" torsion bars. If the mounting points fit your frame width this would be perfect. You get the new style engine mounts, And the police versions had the heavy duty Torsion bars and sway bar. Plus disc brakes. Hope this works out for you.

Apparently, the lower-control-arm pivot/attachment point for front torsion bars design is a patented Chrysler item. Reason? When GM used torsion bars on their '62-'63 light and medium-duty trucks, AND later (90s) light-duty 4wd Suburbans/Tahoes/pickups, they mounted the front of the torsion bar to the lower control arm (same hex-shaped end) a few inches outboard of the lca pivot point. Which makes the front of the bar move in an arc, rather than just rotate.

There were also some Durango 4wds with front torsion bars, too. When I discovered that (on a rental unit!), I smiled and thought that it might be worth the fuel economy hit to have a torsion bar/leaf spring suspension on a modern vehicle (with 4wd).

Enjoy!
CBODY67

CBODY67
Very interesting insight, I'm learnin' . Thanks

 

[trakrodstr]

The Volare front end is the simplest swap because the entire suspension system is contained in one unit. The criticism of this suspension manly come from one person, Rick Ehrenberg, and I think he's just being too much of a stickler engineer on the subject. He doesn't like it because the bars don't travel in the same arc as the control arms. It's not ideal on paper, but works just fine in the real world. This front end survived tons of abuse in police cars, and was also used on the most expensive car you could buy in 1981, the new Imperial. The biggest test: it survived my grandfather's driving for 43K miles of hitting just about every pothole in the city of Philadelphia with just one bad upper ball joint.

Another suspension to consider is the isolated 1973-up B body system, which continued on to the Cordoba and R bodies. All your geometry for the upper and lower arms is set on this one as they are all mounted to the K frame. Unlike the Volare front end, the rear torsion bar mount is separate, so there would be some careful measuring and fab work to do to keep it all in the right place. The B body track width will likely be closer to your original too.

I wouldn't consider the Crown Vic swap. The track width is a real problem on those because they use the oddball front wheel drive style rims.

Jeff

Jeff,

Great info regarding the 1973-up B body system, food for thought. i should probably plan a major junk yard search mission.

Many thanks
Charlie

 

[CBODY67]

By observation, the earlier Crown Vics, which used wheel bearings, had normal type rwd-offset wheels. The later ones, apparently went to front bearing hubs (as all fwd cars are) and that's when the fwd-style "flat" wheels came into use. Bodies looked pretty much the same, but the wheels were different. That change is when their "wire mag" alloy wheels went away.

Enjoy!
CBODY67