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Chrysler Transverse Torsion Bar Car Suspensions, 1976-1989

Introduction: Traditional Chrysler Torsion Bar Suspensions

Chrysler's original torsion-bar suspension, dubbed Torsion-Aire, was the first of its kind to be sold in low-and-medium priced cars - Plymouths and Dodges in this case - starting in 1957. As created by engineer Bob Batchelor, the system used upper and lower ball joints with Oriflow shock absorbers; strategically placed rubber bushings cut down on noise, vibration, and maintenance needs.

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The front end of the torsion bar connected to the wheel's lower control arm; the rear was anchored. When the front wheel rose, the torsion bar was twisted, with the steel's resistance holding the wheel on the road. The anti-sway bar, meanwhile, resisted lean in turns.

Angled upper control arms resisted brake dive; later suspensions added a front upper control arm pivot higher than its rear pivot, so that weight would shift forward when the brakes were applied.

Transverse mounted torsion bar suspensions

© 2010 Curtis Redgap

Chrysler turned to transverse mounted torsion bars for the 1976 Dodge Aspen and Plymouth Volare. One of the major differences is that the whole front suspension was hung on a K-frame member that was isolated from the body by four massive rubber mounts, preventing any metal to metal contact, and thus stopping vibration from reaching the interior of the cars.

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The F-body Volare, Aspen, and LeBaron were joined in 1980 by the M-bodied Dodge Diplomat and the Chrysler LeBaron, all using this system. The J-bodied second generation Chrysler Cordoba and the "new" Dodge Mirada all had the transverse torsion bars.

The isolated transverse mounted torsion bar system was another Chrysler Corporation exclusive. It was quickly accepted; Motor Trend gushed about the "neat, compact set-up that retains the adjustability of the longitudinal bars. The transverse system is aided by a sturdy anti roll bar that allows compliance and controls body roll without compromising the big car like ride." Motor Trend went on to name the F-Body twins as their Car of The Year.

Lanny Knutson wrote about the transverse torsion bar system:

Chrysler's traditional longitudinal torsion bars would have occupied space needed for exhaust emissions control systems. Not wanting to abandon Chrysler's trademark torsion bars for coil springs, engineers devised a transverse torsion bar system incorporating L-shaped bars. The shorter arm of the L acted as a lever to the lower suspension arm. No strut bars were necessary; the torsion bar located the longer arm longitudinally.

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Each bar, made in multiple diameters to equalize stresses, was adjustable. All components were mounted in a self-contained bolt-on unit that would find its way into street rods in years to follow.

Motor Trend enthused: "...the [Plymouth Volare] wagon is no race car, but thanks to the new transverse torsion bar front suspension, it almost handles like one....The Volare stuck to the road like the painted centerline and with no rear end hop or tendency to plow."
The torsion bars were mounted ahead of the front wheels. To keep level during braking, Chrysler raised the front pivot of the upper control arm higher than the rear, to lift the front of the car as the weight shifted forward."

Problems in police use

In 1980, with the introduction of the Chrysler LeBaron and Dodge Diplomat as fleet units, the Los Angeles County Sheriff, which held sway over California fleet testing, along with most western departments, declared that the "torsion bars, designed in a transverse configuration are not acceptable."

There were two main problems with the transverse system. They are completely different, requiring two different methods to correct, and are often confused as being of "the same relationship."

Sagging fronts

First, the transverse mounted torsion bars allowed the front to sag - in fleet use, sometimes within days of being adjusted! This would cause an extreme "toe out" condition along with a negative camber on the tire, which would quickly wear the inside of the tire tread. Further, it would result in severe brake pull, side to side, as well as whip quick changes in steering as one side of the suspension tried to take over from the other side as being in control.

Our fleet records showed that the sagging occurred in direct proportion to the use (or abuse) of the unit. Those used in urban settings, jumping medians, smacking curbs, and running over potholes, sagged quickly. Units posted to the country tended to stay aligned for several oil changes.

I mention oil changes because that is eventually what Chrysler fleet recommended that managers do, is check the ride height at each oil change, or 3,500 miles. That was a simple thing to do. A socket wrench and a 12 inch ruler were all that was required, and it took about 2 minutes per side to adjust. The distance from the head of the K-frame bolt to the ground should be 12 inches. If not, then a couple turns of the socket set the ride height. That was all that was needed.

Impossible alignments

It took three points to mount the bars, and they were outside the protection of the boxed frame structure. The California Highway Patrol, one of the largest users of the "M" bodies, wrote a bulletin that careful assignment of the suspension alignment is critical even after the most minor of collisions.

Had it just been the use or relative abuse offered up by police and taxi fleets, the transverse mounted bars problem may never have come to the attention of the public. The "F" and "M" bodies were quickly adjusted by fleet owners, and in some cases, the managers just put up with the exaggerated tire wear, rotating tires. I had contracted for tires, so it didn't make any real difference whether I used 10 or 1,000, it was roll away price, paid yearly. To my credit, I did not ignore the alignment problems.

Things began to change in early 1983. All around the country, regular alignment shops began reporting problems. We too, began to notice a big difference, frustrating because the issues were easily cured in the past by a simple ride height adjustment. The primary symptom was having no positive camber adjustment available. Even repeated ride height adjustments were not helping.

The good folks at Philadelphia Police Department, loyal MoPar users early on and until the end, said it was not the torsion bars this time out. It was a weak and bending K frame! The single most counted upon part of the car, and Chrysler was building that to crummy standards!

Fortunately, it did appear that the problem was more or less isolated to fleet cars, and not ones from general use by the public. In regular everyday service, the transverse suspension was apparently fine. No recalls were ever done, and no accidents involving any horrendous injury or death were ever noted due to suspension issues. Most importantly, no lawsuits were initiated.

The K frame member was not built properly. The wrong tensile steel was used, and it was not sufficient in thickness. Over time, abuse was causing the K frame to bend, which pulled the front shock absorber towers inwards. Then there was no way to be able to adjust the camber enough.

The K frame held the support brackets that extended upwards to the shock absorber towers along with the upper A frame suspension control arms, and the tops of the shock towers. When the K frame bent, the towers would go inward, causing the suspension camber to go negative or "dip in at the top." The inside of the tires would then wear and scrub off quickly. You could not find any means to make enough adjustment to cure the negative condition using the regular fixes as we had. That meant of course that the handling got squirrely, the brakes would pull side to side, whichever side felt like it was in control first, and tire mileage was just plain nonexistent.

Chrysler finally issued a technical bulletin, #P-4482, which recommended shimming the support bracket to move it out. Another method, issued from a taxi garage, was to offset the upper control arm pivot bars. The third method was to simply bend the towers back in place. Which made me wonder how many times you could do that without cracking or breaking the metal of the frame.

Cracking of the K frame did occur, all by itself! This happened somewhat infrequently on the 1983 and 1984 "M" body vehicles, but, was not a widespread issue - until the 1985 and 1986 models came along.
In those years, widespread cracking was noted.

Chrysler blamed the Mexican plant for using inferior steel. The dies used to stamp out the frames were "old and worn." The wrong steel, the wrong tensile strength, the wrong reinforcement, and material too sensitive to strength variation, built wrong from the start, especially in the "M" bodied cars.

What covered most of the problems with the cars is the fact that most police agencies only keep their units for one year. By the 1985 model year, 99.9% of the '82, '83, '84 models were gone, and moved either to junk, or sold to civilians who did not abuse the cars to the point of causing alignment issues with them. By 1986, 99% of the '85 models were off the fleet rolls. Thus the problems tended to get swept away in model changeover.

However, there was one agency that did not intend to roll over for Dodge or Chrysler Corporation, and dug in its heels, demanding a permanent fix - the California Highway Patrol. They always spoke softly, but they held the greatest stick! Over 2.5 years, Dodge finally came up with a definitive solution - but it was confined to only the California Highway Patrol!

There were two fixes available for the CHP. The first involved the earlier service bulletin, #P-4482, which was expanded. It included shimming the towers with over-strength steel shims, along with assorted hardware, and installation of new steel A frame pivot arms, anchors, with assorted bolts, nuts, washers, and hardware, all designed to be overstrength for the job. This did cure a huge majority of the CHP cruisers, permanently.

There was one other cure, not to be mentioned except to those agencies which carried on the loudest. That solution: replace the K-frame! Free. A totally new K-frame made of the correct steel, the right tensile strength, reinforced correctly, and stamped to closest of tolerances. The California Highway Patrol claimed that about 500 new K-frames were installed on its Dodge fleet, up through the 1987 models. (Chrysler also put the new K-frames on its unsold 1987 models that were in the fleet bank storage lots. "M" bodied production had moved with the 1987 purchase of American Motors to Kenosha, Wisconsin.)

For 1988, Chrysler had modified the K-frame to the CHP standard, and all new "M" bodies, fleet or civilian were built with it, thus ending the K-frame bending saga. No more issues with suspensions occurred in the 1988-89 model years.

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