1960-1962 Chevrolet - GMC question

[James B.]

There has bee a puzzle looming at our house about the history behind GM’s decision to use a different convertible car like frame on the 1960-1962 Chevy and GMC light duty trucks along with torsion bar suspension? Then they dropped it all for a more conventional setup in 1963. Some say the X was needed for the torsion bar system but it was anchored to a separate cross brace running between the side rails. Some say that Chrysler sued GM over patent infringement over the torsion bars but I have found no evidence of that in newspapers or legal journals of the time.

This may be one of those urban legend things or someone believing the outcome to drop torsion bars for coil springs was simply plausible stating Chrysler had a hand in it. Truth is, torsion suspension has been around since 1921 in the US and Europe and GM used it on the first generation front wheel drive Cadillac Eldorado and Oldsmobile Toronado. In fact, I don't even find a patent for Chrysler's design used starting with 1956 production of 1957 model year cars.

There was a lawsuit by Czechoslovakian Tatra cars against Ferdinand Porsche and VW for using their torsion bar design and VW lost in 1961 having to pay 3-million DM. The time frame fits but the manufacturers don't.

Any ideas... suggestions as to why GM dropped the working torsion bar suspension for coil springs in 1963? Even if they removed the X brace (and why did they use it for only 3 years) they could have still used the bars like they continued with the rear suspension without the center X brace.

Jim<!-- google_ad_section_end -->

[NTX5467]

A key item . . . at the time (as I understand it), torsion bars cost more than coil springs. I saw that in an article which stated that some in Chrysler wanted to get away from torsion bars due to the additional cost over coil springs. Luckily, the value of torsion bars over coil springs was seen and Chrysler did not make that (at the time) fatal mistake as it would have probably hurt Chrysler by taking away one of their "unique" features which many purchased their cars to get.

At the time, too, there was a certain "feel" to Chrysler's ride dynamics which coil spring suspensions (of the time) did not duplicate. NOT road noise or similar, but ride "feel". Plus, it was all tied into the particular suspension geometry of Chrysler products which gave the outer wheel in the turn negative camber and the inner wheel positive camber. As the vehicle leaned in the curve, the wheels would remain more upright and better-braced the sidewalls of the tires to better take the cornering forces. GM and Ford had camber patterns which kept the wheels more perpendicular to the chassis, not the road surface.

As for "patent infringement"? Just look at how the GM Light-Duty and Medium-Duty suspension is configured. The KEY difference between the GM and Chrysler systems is that the Chrysler's torsion bars (which came out first in 1957) attach to the lower control arms AT the inner pivot point. The GM system, including current light-duty 4-wheel drive models, have the torsion bars slide into the lower control arms about 3" outboard of the lower control arm pivot. This also means that rather than just the normal twisting action, the GM bars also have a slight arc they move through, too. IF GM has licensed the Chrysler design, you can imagine the hoots and hollers that would have resulted, including those INSIDE of GM!

Several years ago, there was a very good article on the Chrysler Torsion Bar Suspension in the Walter P. Chrysler Club monthly magazine. Such a suspension design tends to spread out the suspension's forces in the chassis platform, rather than concentrating them in one small area of the chassis. For example, the rear bar mounting was said to be in a part of the platform where there were NO stresses in the structure. On the front subframe, there are about 4 bolts, spaced (probably about 24-30" apart, front to back) which hold the front K-frame to the subframe. With the torsion bar's rear mounts a ways back of those bolts, you can see how any forces through the suspension were disbursed into the structure rather nicely.

On the GM "front crossmember", all of the suspension forces (along with braking and steering) are concentrated into a space of about 18" between the two bolts on each side of the frame rails. Certainly, the frame rails are C-section items, there can still be some rotational forces working upon those frame rails, front to back, much less the possible flex from one wheel encountering a deep pothole as the other one does not.

But for a company as large as GM, the main issue would be the cost of the springs per vehicle . . . which could add up rather quickly with the hundreds of thousands of light truck platform vehicles they might build every year.

In the 4 wheel drive world (and earlier front wheel drive, circa 1965), it's easier to have a torsion bar front suspension as there is no real issue with drive axle shafts having to clear coil springs and shock absorbers inside of said springs -- a packaging situation. On the later models, they went to a coil-over style spring/shock assembly, which also requires a much taller front suspension dimension to accomodate it. Just like the McPherson Struts on the front of front wheel drive vehicles have been a major vehicular design influencer since we first got front wheel drive vehicles . . . determining the shape and height of the vehicle's fenders and hood lines.

GM used the torsion bar front suspensions on ALL of their light duty (up to C30) and medium duty (the C40-C60) models for the two model years. The first time I rode in a '61 Chevy C10 pickup, I knew it rode more like our '66 Chrysler than it did our '69 Chevy C10 pickup. When I carefully asked what was different about it, the owner (our service station mechanic at the time) laughed and mentioned the "Chrysler-like" front suspension. I did some research in the brochures I'd collected and GM touted their torsion bar front suspension as a "more efficient" design (paraphrasing). Not unlike they touted their "Switch-Pitch" THM400 torque converters (when they had that feature), but called the "non-switch-pitch" models the next year as having "better durability" with less heat buildup -- just depends on what they're trying to promote.

Remember, with respect to the GM use of torsion bar front suspensions, it's NOT the use of torsion bars as such, it's the DESIGN of the suspension that is "patented" or "copyrighted", as such, by both Chrysler and GM. Hence, the different places on the GM lower control arms (at least on the truck chassis vehicles I know about, but also very possibly on the fwd Eldos and Toros) where the front of the torsion bar engages the lower control arm itself. Other than that one item, the rest of the suspensions are architectured similarly (although there could be some differences in the length of the adjusting arm and such, too).

Enjoy!

NTX5467

[john2dameron]

When did Chrysler stop using torsion bar suspension? I had a '68 Chrysler 300 I bought new and tire wear was awful. It seems I must have had the frontend lined up 3 or 4 times a year and high dollar tires never seemed to last over 6,000 miles on the front end. I'd take it to get the front end aligned and the first thing they did was take a yard stick and measure from the front fender opening to the road. Usually it would measure around 24-1/2 to 25 inches and they'd go under the car with a large wrench and adjust the torsion bars. They told me the fender to road measurement was supposed to be 26 inches (or maybe 26-1/2, I don't remember) and they would not touch the alignment until they leveled the front end back up. I never did understand what would cause it to sag. I also had owned a '60 Chevrolet 1/2-ton pickup which was the first ones Chevy used torsion bars on and I don't recall ever having a problem with it but I did not keep it very long. My brother wanted it and we traded trucks the same year I bought it.

[James B.]

I think 1972 was the last year Chrysler used torsion bar suspension.

[Dave@Moon]

Chrysler cars began using tortion bars in 1957. They used a longitudinally mounted system that continued in some models until 1981. The 1976 Aspen/Volare introduced a transverse mounted tortion bar system that ran through the last rear wheel drive cars in 1989. Dodge (now Ram) trucks continued to use the system for some time afterward, and may still.

Citroen intorduced the system in 1935 or 36 with the introducton of the Traction-Avant line. Tatra also used the system in the 1930s. I don't believe anyone has a patent on the system, and in fact the E-Body GM cars of 1966 and up (Toronado, Eldorado) used tortion bars, as did 4WD Chevy S-10 pickups and Astro vans.

[Dave@Moon]

. Dodge (now Ram) trucks continued to use the system for some time afterward, and may still.

Thanks to Google I now know they stopped using tortion bars with the 2009 models.

[James B.]

Thanks Willis, that was a great well thought out response.

Jim

[NTX5467]

James2, I'm not sure WHY you had those problems as tire wear on our '66 Newport, my '70 Monaco, my parents '72 Newport Royal, and my '67 Newport was NEVER an issue--period. Other friends and associates with C-body Chrysler products of that time had similar experiences as mine, with all due respect. The front ends stayed at "level" height (as in "rocker panel level" and tires, even bias ply ones, would last 40K+ miles (I did keep the cold inflation pressure at 30/28 f/r as that ensured a full tire footprint on the front tires and also matched with the recommended psi for 70mph driving--the factory inflation pressure bias is just opposite of what I did, though). Handling was great and responsive and the ride with HD shocks is "just right". The real measurement to take was not the fender line (as that could vary with various build tolerances in the body's sheet metal adjustments), but on front suspension components. Many did use the fender wheel openning measurements as a general guide, though, but I never saw Chrysler's factory service manuals have specs for anything other than measuring the front suspension component dimensions. In any case, though, the rocker panel "line" should be dead level. If you want to do the adjustment with simulated driver and front seat passenger loads, that's fine, but probably not reallly necessary, by observation.

In reality, the ONLY reason for the adjustments to not hold would be the "nut" the adjustment bolt screwed into to set the suspension's ride height. Or the threads on the bolt itself were flaky and the bolts needed replacement. To me, the ONLY time the "fender to road" measurement would be completely accurate was when the vehicle was on a front end alignment "rack", which is supposed to be completely level . . . front to back and side to side. Otherwise, there might be enough imperceptible angle in the floor/road surface between the tire's contact patch outer edge and where the plumb line from the edge of the fender might fall to influence the accuracy of such a measurement. PLUS, that measurement probably changed a little from year to year, with different body contours and styles . . . why the rocker panel "level" is a better way to eyeball things . . . without a measuring stick. Look at the factory brochures, side views, and you'll see that the rocker panel "line" intersects the wheel cover centers at the same general place, front to back, year to year.

One OTHER issue on Chrysler torsion bar front suspensions, but one which did not really surface until they had much more than about 2 years of age on them, is the lower control arm pivot insulator, which is rubber. With time and age, the rubber will age and start to crack, which can let the front of the car settle a little and still have the correct front suspension component measurements. It's a "normal replacement" item after the car gets to be about 15 years old or so, but also one that might not indicate the need for replacement unless alignment angles suggest it needs to be replaced.

When the front suspension is at "spec height" and the front end alignment is set "to specs", if the front end height drops, it puts the front wheels in a negative camber position, not drastically so, but it does do that. If it's too high, positive camber results. Toe-in might change a little, too, but not much. I don't see that caster would reallly change, though. As the old Mopar Performance Race Manual states, regarding setting front end alignment for drag racing activities, if the front end ride height is within about + or - one inch from specs, things should be close enough to work. They advocated setting drag race vehicles' front end alignment with the front end jacked up (probably under the front crossmember) 1", then set everything to spec, with the toe-in toward the "0" setting within the stated specs. This ensured that the front wheels would "run true" and have the least rolling resistance for better elapsed times in the drag race.

When Chrysler went to front wheel drive, those cars had McPherson Strut front suspensions. As stated, the "bent bar" Aspen/Volare (original use) platform was the last to use torsion bars in the CARS. 4wd SUVs still used torsion bars, though. Think Dodge Durango and similar, which also still had rear leaf springs until the last body change.

With all due respect, James2, I can't understand why your car had those continuing issues -- period. Nor can I understand the very excessive tire wear if everything was "set to specs". For the car, any car, to wear tires THAT soon and quickly, it would have had to be a terribly-handling vehicle, all things considered. It would have skated on the wet roadways, much less icy ones! Caster and camber will not necessarily "eat" tires, but toe-in will. Even if the front end was 2" lower than specs, the caster and camber would not have changed enough to cause severe wear issues, but toe-in might have . . . still with "loose handling" resulting, plus possibly decreased fuel economy.

I also know that many front end alignment mechanics did not like the "eccentric washer/bolt" type of alignment adjustments. They claimed that it "could change", whereas the GM-style shim adjustments "didn't change". But again, if the bolts are torqued securely, they won't change. I did run across a guy that put GM front control arms on his '76 Charger (with what I call the "slip 'n slide" alignment system) as he was prone to "drive in ditches" sometimes . . . he didn't have the presence of mind to "mark" the upper control arm adjustment bar so he could put it back were it used to be each time, it seems, so he wanted it set up to "bend something that would need to be replaced", instead.

One day, in my '70 Monaco, I had to swerve onto a center median to avoid hitting another car which pulled out in front of me on the highway (55mph). There were no control issues, but I wanted to get the suspension alignment checked for good measure. Driving over that curb at 40mph, onto the median dirt, and then back into the left turn lane a little ways later, might have changed things no more than about 1/8 degree, but it was virtually unchanged after that one incident. The local dealer, where we got most of our Chrysler service work done, did the alignment . . . using equipment which would look plain "antique" by modern electronic standards, but it worked and worked well.

First, they'd bounce the car, as suggested by Chrysler. Then, the front wheel covers were removed. Then the grease cap. If needed, the front wheel bearings were adjusted. Then the Weaver "level" was attached to the front spindle and the front wheels were lowered onto the turntables. The level was calibrated, if needed. The front wheels were turned 20 degrees to the right, the level "zeroed", then turned to the left until 20 degrees past "center" was reached. This difference gave the caster reading. With the wheels back at "center", the camber reading was noted. Then, the car was rolled backward "by hand" and the toe gauge was placed on the floor. The car was pushed, by hand forward over the toe gauge, which gave the toe-in reading. If the car had the Chrysler chrome Magnum 500-style road wheels, the spare had to be installed on the front wheel being checked as it was not possible to attach anything directly to the front hub . . . one reason that dealer did not generally order cars with those wheels.

James2, unfortunately my experiences and observations on Chrysler Torsion Bar Front Suspensions do not match yours, with all due respect. I regret you had such problems on such a beautiful car . . . and one of my favorite Chrysler styles of that era.

Respectfully,

NTX5467

[john2dameron]

NTX, my Chrysler was a 300 convertible. I ordered it in January of 1968 but didn't get it until about the first of April. Found out when it finally arrived that the trucking company went on strike and the car was locked in a parking lot in Pittsburgh, PA. I ordered the car with the heavy duty suspension, heavy duty brakes, 440 engine and what Chrysler called styled steel wheels. I had the car lined up several times at different places. The place I had long had alignments did at finally gave up on it and recommended the guy at the local Dodge/Chrysler. He had formerly worked at the Ford dealership and had the reputation of being the best alignment guy in town but he couldn't help the Chrysler. I finally started running Michelin radial tires on it and that got the mileage up to about 18-20,000 miles. The car handled great. It would outrun about anything around including a SP patrol car one night. A few months after I got the car, with less than 10,000 miles on the car, I picked up a young guitar genius and took him to a neighbor's house to play some music. The car had an annoying habit of dying when I would go to pull out from a red light or stop sign. That night I pulled past the friend's driveway and started backing in. Just about halfway into the turn the steering became unresponsive and I thought the engine had died. I stepped down on the gas and the car jumped backwards. At about the same time the boy yelled, "this thing is on fire." Smoke was rolling out from under the hood. That car was made with a power steering hose twice as long as it needed to be. It came off the steering unit, ran back under the length of the exhaust manifold, made a U-turn and returned to the PS pump. The hose had cooked and ruptured. I got a new hose and routed it through a bicycle tire and had no more problems with that. When the '69 models came out, the first thing I did was raise the hood on one and look at the PS hose. It was short like mine should have been. The dealer never successfully treated the stalling out problem but a Firestone dealer did. The car was beautiful. It was white with a black interior and an olive green top and was the talk of the neighborhood. One of the most annoying problems I had with the car was the starter solenoid failing to send power to the starter but I finally fixed that also. I got tired of jumping the solenoid with two screwdrivers when it would not fire.

[James B.]

NTX, I ran across this 2011 post which is interesting and possibly you can expand on?

Torsion bars were a patent by the Chrysler Corp. If you remember correctly, a lot of Chrysler, Dodge, Plymouth products used them. Desoto exterminated with them in the mid 50s, and the patent was purchased from this dying company. When GM used them on their pickups, they broke a patent infringement. Gm hoped they would get by by altering the design. It didn't work, and GM had to pay a patent infringement fee. To keep using them they would have to pay Chrysler Corp an annual fee. GM thought it would be better to just drop them. So they went to coils. My father, who is now 78, remembers watching the news about the lawyer battle between the two and how it turning out. He has been an avid GMC pickup truck fan since his first pickup. His latest, and probably his last GMC is an 08 half ton of which he and I do the auction trips. GMC has lost a lot of the luster it had fifty plus years back, when it was the ICON of pickups. Still a good buy though. Nice web site, keep her up

And....

This makes some sense but even if DeSoto had the patent, it would fall under the

Chrysler umbrella. That said, the torsion bar setup was into play by 1956 for

installation of the 1957 production year. Yet, I find no patent for this

timeframe but I do find one filed in 1959 and approved in 1962 for Chrysler and

the inventor is listed as Maurice D. Karlstad, Jr. (# 3027177) and stated it was

an improvement of another design not used (#2972489) also registered by Karlstad

and another person named John E. Collier. But it too was filed well after the

suspension system was being used. GM also had various torsion suspension patents

filed around 1959 as well.

Thing is that I did not find anything in

newspapers about a patent infringement or lawsuit nor in archived law journals I

have electronic access to. Was this a low key deal settled out of court? I need

to look further but came up empty today. Has anyone found anything along those

lines?

And it is known that the X was more stable and showed after it was

removed for the 1963 model year by the way bed slide-in campers aligned up with

the cab. But if it worked so well, why only use it 3 years?