1934 Chevy front suspension: what the...?

[Matt Harwood]

It isn't often that I see something I've never seen before. Sometimes I see an unusual car, but it's rare for technology to surprise me, especially on a mainstream vehicle like a Chevy. But when Roman, my mechanic, called me back to the shop to look at this neat little 1934 Chevy coupe that they were photographing on the lift, I spotted it right away. First I thought, wow, look at those giant shock absorbers, and figured they were some kind of aftermarket add-on. Then I looked at little closer and saw that there is no front axle, no springs. That cross-member is being used in place of an axle and is rigidly bolted to the frame. These giant things are a spring/shock combination and it appears that the front wheels hang on them like the trailing arm suspension on a trailer.

 

Is this stock? It has to be, right? It's much too complex to be some kind of aftermarket setup. It pre-dates the knee-action setup by a year or two, but the other 1934 Chevys we've had didn't have anything like this.

 

So I guess I'm wondering: is this a factory front suspension? I'm doing some internet research right now, but I figured there would be someone here who would spot it right away and know exactly whether it's stock or aftermarket. Is it simply a Standard vs. Master series difference in 1934? Very cool, but very weird!

 

Check it out (click the photos to enlarge):

 

Here's the car, a fairly nice 1934 Chevrolet Master 5-window coupe:

 

The "axle" is obviously rigidly bolted to the frame like a cross-member:

 

 

It has these giant things hanging off each end of that "axle:"

     

 

The "axle" does not extend to the wheel hubs, which appear to be suspended by the arms of that giant shock/spring unit. The steering seems to turn the whole assembly on some kind of kingpin bolted to the end of that "axle."

 

 

Here's a different 1934 Chevrolet coupe with a standard leaf spring/axle setup on the front:

 

I'll do some homework, but does anyone recognize this who can offer more details? Interesting technology and fascinating that someone would come up with this before they figured out the standard A-arm arrangement. Like disc brakes, I guess something seems easy and intuitive only after you've seen it. Coming up with it in the first place is always the trick.

[1939_Buick]

Like this??

• https://en.wikipedia.org/wiki/Dubonnet_suspension
• https://wikivisually.com/wiki/Dubonnet_suspension
• https://www.google.com/search?sa=X&biw=1366&bih=607&source=univ&tbm=isch&q=dubonnet+suspension&client=firefox-b-d&ved=2ahUKEwiyxsC8r57tAhVvyzgGHd-LD9oQjJkEegQIAhAB
• https://www.jalopyjournal.com/forum/threads/1934-chevy-knee-action-droping-need-advise.1139048/
• https://forums.aaca.org/topic/229650-newbie-with-a-1938-chevrolet-survivor/

 

and

https://www.applehydraulicsonline.com/products/dubonnet-knee-action-shock-absorbers-yours-rebuilt-master-deluxe-1934-38

Edited November 25, 2020 by 1939_Buick (see edit history)

[Matt Harwood]

2 minutes ago, 1939_Buick said:

Like this??

https://en.wikipedia.org/wiki/Dubonnet_suspension

https://wikivisually.com/wiki/Dubonnet_suspension

https://www.google.com/search?sa=X&biw=1366&bih=607&source=univ&tbm=isch&q=dubonnet+suspension&client=firefox-b-d&ved=2ahUKEwiyxsC8r57tAhVvyzgGHd-LD9oQjJkEegQIAhAB

 

Cool! I've heard of the Dubonnet suspension but I guess I've never seen it in person. Looks like Chevrolet did use it for a while until knee-action took over. Thanks for giving it a name!

[JV Puleo]

Yes, it's the way they came. I've worked on two '34 Chevys (one of which I briefly owned) at various times in the past. I don't think it was used on the pickup trucks. There was a segment on The Old Motor about that suspension system some months back.

Edited November 25, 2020 by JV Puleo (see edit history)

[Bloo]

Yes. it's a Chevrolet Master thing. Not sure about 1934, but by 1936 it was possible to order a Master without Dubonnet, however very few people did. Pontiac also used the Dubonnet suspension, but like Chevrolet, they left it off of their cheapest model.

 

They drove better than straight axles, but their downfall was leaks. With the 1930s seal technology it was tough to keep them full of oil, and when they were low there was no shock absorber action.

 

 

Edited November 25, 2020 by Bloo (see edit history)

[Rusty_OToole]

That was the original Knee Action independent front suspension,which debuted in 1934 and was built under license from the French Dubonnet patent holder. It was used on Chevrolet, Pontiac, and Buick but only for a few years, and not on all models. Last used on a Chevrolet in 1938.

 

It turned out to be a disaster, the joints soon wore and the front wheels turned knock kneed. Most were scrapped because they cost too much to repair. GM soon dropped the Dubonnet system and copied Chrysler's setup, which also debuted in 1934 but they kept the Knee Action name for some time, and never stopped claiming they were the first with IFS.

 

Incidentally, the Dubonnet who invented it was a big sports car racer of the time and heir to the Dubonnet aperitif family.

Edited November 25, 2020 by Rusty_OToole (see edit history)

[PFitz]

A friend's 33 Pontiac convertible coupe has them.

 

If I remember, he had them rebuilt by Apple Hydraulics on Long Island, NY.

 

Paul

[dictator27]

Vauxhall continued to use a modified version for several years after WW2.

One odd characteristic was that under hard braking the front of the car would go up not down.

[Rusty_OToole]

The Dubonnet system was used by a few European cars including Simca  BMW and Alfa Romeo as well as Vauxhall. Apparently they worked well as long as they were maintained meticulously, meaning they had to be greased frequently and the oil in the shocks topped up.

[PeteL]

There were actually two quite different independent front suspension systems introduced by GM in 1934 although GM referred to both of these systems as “Knee Action”. In his letter to shareholders in the 1933 General Motors Annual Report, GM President Alfred Sloan had this to say about the 1934 models:
“The development of “knee action” wheels took the engineering form of two quite different interpretations which justifies the Corporations policy with respect to engineering in general. The Corporations motor car products are developed in a large part independently by entirely self-contained engineering staffs, a component part of each car manufacturing division, on which the engineering responsibility rests.”.
The “different interpretations” that Sloan referenced were the two different “Knee Action” designs that GM adopted for its 1934 models. Lower-priced GM cars, Chevrolet Master and Pontiac, used a Delco-manufactured independent suspension system that was designed by André Dubonnet. GM’s premium-priced models adopted a “Wishbone” type of front suspension, also referred to as a short-and-long arm design, that was developed by General Motors chassis engineers under the leadership of Maurice Olley. (The value-priced Chevrolet Standard series retained a beam axle suspension for 1934).
The Dubonnet system was named after its originator, French racing driver and Dubonnet aperitif wine heir, André Dubonnet. According to an article on Mac’s Motor City Garage, the “-- Delco-manufactured Dubonnet-type unit, employing two concentric coil springs and a double-acting hydraulic shock absorber, with the top cylinder managing bump motion and the bottom cylinder handling the rebound.” 
The Dubonnet system proved to be trouble prone and in 1937 Pontiac changed from the Dubonnet system to the conventional “Wishbone” type short-and-long arm design of front suspension, and Chevrolet followed in 1939.
 

[pont35cpe]

My `35 Chev Master has the Dubonnet sus. with manual brakes, my `35 Pontiac has the Dubonnets with juice brakes.