Technical How many 1956 and older mopars are using original front suspension. Pros and cons

Trying to figure if I need to change anything up front.

 

I haven’t seen one at a get together in years. Too bad as I like 55-6 PlymouthS and Dodges.

 

Rebuilt they should be fine. HRP

 

My Plymouth is a 39 but what I have found is Chrysler used this front design up until they went with torsion bars.

 

Specifically which Mopar are you building?

I had a friend who put 100,000 miles on a '55 DeSoto and considered it a good handling car.

jack vines

 

Jack I have a 1939 Plymouth Coupe

 

I own a '56 New Yorker with the original front suspension under it, and it works OK. Of course it only has 52,000 miles on it, so it's still in pretty good condition. Rides like a fluffy pillow, steers almost too easily, tires wear evenly. I wouldn't want to push it too hard on the twisties though. It's definitely not a "sport" suspension.

 

I have a 1953 Plymouth, but haven't driven it yet.. I am going to use the original suspension and steering but changing to a V8...

 

Not sure what years those suspension systems would have been used; and if Chrysler used them across all separate models.
But, take a close look at the threaded connections for wear. These act as the pivots for the upper and lower control arms. Use a pinch bar to move the control arms in/out to check.
Although it allows fairly easy alignment adjustments according to the book, it strikes me as odd that Chrysler did not use ball joints for the front suspension system. The technology was surely known back then as evidenced by the tie-rod ends.
If the joints have been lubed on a regular basis, they may be OK.
If you can get the alignment to meet specs, it's probably good to use.
On the '40 Chrysler Royal in the avatar, these threaded connections were dry as a bone and beyond repair.
This is the Right side. The upper control arm outboard connection has been adjusted to what looks like to me, anyway, beyond safe. The Left side was in worse shape.



It would have required all new components for a rebuild, so I didn't go that direction.
There have been a few posts and discussions about these threaded connections and people looking for a "tap"
I don't think it's anything standard; only what Chrysler came up with in making the assembly.
Reference the external threads of the short piece at the lower right with a hex and grease zerk.

 

I had a 39 Plymouth business coupe with an original chassis. The original suspension works great with a few minor modifications, provided the frame and suspension are all present and in good condition.
A disc brake conversion and a modern rear axle are great head starts. The original front brakes are a pain to adjust and keep adjusted. Unless you have currently usable front brakes, it will cost more to rebuild them then it will to convert them to disc brakes. Removing the rear drums is enough of an issue to warrant replacing the rear axle alone, but then add the 3:7s rear gear is another good reason.
I would recommend moving the upper front shock mount from the upper control arm to a bracket welded to the frame. There are "kits" to do this as well. Originally, the front shocks were mounted between the upper and the lower control arms, this is what gives these cars that "float on air" ride, nice and soft, but not very pleasant in an emergency. Moving the upper shock mount gives these cars a more modern feel when driving.
A front sway bar from an 80s Jeep also improves the handling, but that would be an option rather then something really needed.
You can lower the car in the front by moving the plate that supports the coil spring from the top of the lower control am to the bottom of the lower control arm, its a matter of cutting 4 rivets on each control arm, moving and flipping the plate, and replacing the rivets with 4 grade 8 bolts. It lowers the front end about an inch to an inch and a half. Changing the existing coil springs with a set of coil springs from a Ford Areostar also gains a bit more lowering. The suspension rebuild kits are available at many auto parts stores, or at www.robertsmotorparts.com and others.

Some people have issues with installing a modern Mopar V8 in this chassis. If you off set the motor and trans about an inch and a half to two inches towards the passenger side of the car, you gain a lot of exhaust clearance on that driver side. I've never had to install any special left side exhaust manifold. I have also never had a clearance issue with the X in the trans crossmember caused by offsetting the motor & trans, there is ample clearance in the ujoints to accommodate the motor & trans shift. You may have to use a hammer to gain clearance on the right side rear valve cover, it usually almost clears, and a slight bumping in of the firewall gives you the clearance you may need. You may also want to cut the factory relief in the front crossmember for the engine pulley another 2" farther forward (and box it back in), that will give a bit of extra clearance for when it comes time to change the fan belts (or you can raise the motor enough to give you belt removal clearance).
For the record, that original flathead 6 with its original 3 speed are heavy! A modern small block V8 & auto trans is lighter then the flathead 6 and its trans.

I've build several 39-48 Plymouth & Dodge cars over the years, in about an configuration you can imagine. Gene

 

My -41 De Soto original suspension.Fluffy pillow ride!

 

Thank you all for your input on this I have a disc brake conversion for this spindle and thought that this would work great with the shock modified upper mount.

 

Gene I was told to use grade 8 bolts to lower the spring pad and you said grade 4. Could you explain why the 4 would be better than a 8 ?

 

^^ 4) grade 8 bolts (4, as in quantity)

 

I see that I read that wrong thanks.

 

Scrap metal I live just north of Huber and I like the 53. My mother had a 54 Plymouth convertible up until 1965 I loved that car.

 

Cool pic ^^ paul!!!!

 

The previously mentioned modifications; relocated shock mounts, bigger sway bar and disc brakes makes them drive quite well. I did a ‘46 and a ‘51 and was happy with the result. There are may conversations on this site about them. The only drawback to the early front end is the frequent lube of every 1000 miles.

 

The suspension on these cars was ahead of other auto companies. I have a 55 and a 56 Dodge. the only change I would make is putting on disc brakes. If you want to lower it, you can either go with Fat Mans lowered uprights or like someone else suggested with the lower control arm. I have disc. brakes on my 55 and in process of putting disc brakes on the 56. The change in the shock mount is for earlier MoPars like the 46-48 models. Not sure when the mount was changed to the way my 55 is.

 

Old '39-ish cars will ride like one with stock suspension. Granted better shocks and radial tires will smooth it out a lot. Any '49-'53 Mopar I have driven was nice even with manual steering.

 

Stan Back, chassis swaps are not HAMB friendly. Posts like yours could get this thread closed.
I've had both original suspension with the mentioned upgrades and I've also done frame swaps on this era Mopar cars, I can tell you for sure, if the original frame is good, and the suspension is in good shape, a frame swap has very little gain over the original stuff with the few upgrades. Most of the cost for the upgrades is equal to the cost of original brake replacement and isn't much different then the cost of replacing the brakes on your frame swap with a lot less work. Gene

 

Thanks Gene from what I have found the 39 suspension was the beginning of what Chrysler used up to 1956. As I said earlier my mother had a 54 Plymouth and I had a 47 Dodge when I was 16 so I have been planning to keep it I just wanted to know if anyone had a problem with this suspension. I know about the shock mount being moved and the disc brake up grade. My car has a sway bar but I would like to know about the up grade to the Jeep sway bar. I have a 392 HEMI to put in this with a 5 speed from a Dakota.

 

I have had my Oz 1940 Dodge since 1971 with a 318 Poly & Torqueflite since 1973.....the front suspension setup is as follows.........original 1940 lower A Arm, Moog 1941-56 style cast steel X style Upper A Arm, (stronger version of the stamped steel mopar part), original 1940 Spindle, 1941-56 style Stub Axle, shortened and reforged steering arms, narrowed by 9" Austin 1800 Rack & Pinion, relocated upper shock mounts, original shaped but custom made 1" thick Sway Bar with 5/8 Heim Joints on an adjustable link..........its handles fine........front brakes are Oz P76 PBR 11" vented discs & Calipers, rear are the stock 1989-94 Oz Ford Falcon solid discs on the Oz 1989-94 Borg Warner rear axle, PBR P76 master Cylinder & Booster...........as far as swapping front end bits..........1939 Upper A Arm inner pin/bush uses only 2 mounting bolts to the chassis however from 1940 thru to 1956 the upper inner pin/bush uses 4 bolts and the upper arm is the same from 1941-56........the lower A Arms as far as I know will swap from 1939 thru to 1956 but the later years have the sway bar mounts attached.........dunno if this helps...............Andy Douglas

 

My brother built a 34 Plymouth coupe with a Chevy 427 back in the 70's . The car drove pretty good considering the weight of that iron headed big block . He upgraded the brakes with mid 50's brakes off a dodge police car he found in a salvage yard.
In the 90's he swapped in a 69 Nova clip . It moved the small block he had swapped in down and back for better weight transfer when he decided to drag race the car.

 

Pros you do not have to engineer anything con ball joints made things simpler and lighter. Early replacement parts are hard to find.

 

"Stan Back, chassis swaps are not HAMB friendly. Posts like yours could get this thread closed."

Well, take another look at my Plymouth. Outside of the wheels, what offends you? Things you can't see? Disc brakes? 3-Speed automatics? Easy to find chassis parts? Twelve volts? Where's the cut-off? Power steering? Power brakes? Tubeless tires? Adapting parts you can't see to an "era" car? This one's nosed, decked, chanelled and has an engine swap. Is it the frame configuration that offends you? Or is it the fact that we did it on a budget and all the chassis parts are readily available at rock-bottom prices – or even didn't need to be updated or replaced?

I just saw the AMBR cars here. I also didn't see all "era" there.

 

There is nothing about your car that offends me. My 48 Plymouth has a modern chassis under it as well.
But the reality is, lately there have been a lot of threads locked down because of modern chassis swaps. Chassis swaps are not HAMB friendly these days. Its not about me, but about the web site. Gene