Thread: Knee action Indipendent suspension

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I always read about late 30's cars having knee action front suspension, particuralrly GM cars, what is it exactly? I asked my teacher and he didn't know. I searched and found that knee action is a common name for dubonnet indipendent suspension. thanks in advance

The Dubonnet suspension is still used in a lot of farm equipment today. The axle is mounted rigidly to the frame. A support arm pivots on the kingpins to provide steering. The wheel strut is attached to the support arm with a spring or torsion bar to provide flex. This setup provides true vertical motion to the front wheel.

thank you. I will print the picture and show it to my teacher, he was interested to find out what it was also.

Find out what you can about a late 30's ('37 will do) Chevtolet "Master DeLuxe", Matt. They came with the duBonnet knee action front end.

Jim

Henry, could you explain the theory on knee-action shocks? I know what they are, but never did figure out how they work.

I have knee action on a 36 pontiac, in theory you have less weight moving up and down so you get a better ride. According to my older brother the shocks didn't last very long on rough country roads and had to be rebuilt at about every 1o k mikes and it was expensive the suspension is similar to early VW Bug, Bug has 2 arms back to the spindle while GM Knee had one arm

i had a old timer say they filled them with stp? he may have been pulling on some thing? but they went bad alot .i have been told

The way a knee action shock worked----the shock was a cylindrical housing, with a vane that moved around the inside on a central shaft similar to a vacuum windshield wiper. There was a fixed divider wall in the cylindrical housing that ran from the center of the housing out to the side opposite of the vane. There was a small hole in the divider, and the cylindrical housing was filled with oil. As the vane rotated about the shaft, it forced the oil thru the small hole to the other side of the "divider". The resistance of the shock was established by what viscosity the oil was. The shaft was mounted to the cars frame, and had a lever on it. The lever was connected by a "link" to the cars front or rear axle. As the cars axle moved up and down on the springs, the lever rotated the shaft, which moved the vane, which moved the oil thru the orifice. Different weights of oil gave different ammounts of "firmness" to the shocks.---- There was also a type of knee action shock absorber that had a piston which moved back and forth in a cast iron cylinder to displace the oil thru an "orifice" the piston was moved back and forth by means of a rack and pinion, where the pinion shaft connected to a lever wheich was connected by a link to the cars axle. (that type of shock also mounted to the cars frame). I had a knee action 34 Chev car. The axle was mounted solid to the frame. Instead of a rotary housing and vane, there was a linkage which moved a large piston back and forth in a cylinder which was full of oil, and the piston moved the oil back and forth thru an orifice-----same kind of deal, only with it there was a honking big spring in the cylinder, on one side of the piston, which actually was the spring for the front wheel on that side. Apparently this type of suspension was very smooth, but after about 2 or 3 years time the seals would go and the oil would escape. The spring would still work allright, but with no oil being moved to control the rebound, it was just like driving a car with no shocks at all.----The reason that these shocks "worked better in theory" was that they were attached to the frame, thus giving less "unsprung weight" to the cars axle. The less "unsprung" weight an axle has, the less inertia it has to overcome in order to move, thus making it more "responsive" to changes in the road surface.

Thank you Brian for the explanation. I had those on the front of my '36 and never really understood how they worked. I suspect that by the time I acquired the car the oil had leaked out which would explain why the car bounced so much on rough roads.

if that picture had the names of the parts, mixed with Brian's explanation.. I may be able to 'see' it better