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.

torsion-aire suspension

The front end of the torsion bar connected to the front wheel’s lower control arm; the rear end of the torsion bar was anchored in the sub frame so the bar could not turn. When the front wheel rose over a bump, the lower control arm pivoted around the points where the torsion bar was mounted, twisting the bar. The chrome steel in the bar resisted the twist, holding the wheel on the road. The anti-sway bar, meanwhile, resisted lean in turns, and could be tuned by the factory through varying thickness and suspension tuning. Diagonally mounted steel struts reinforced and positioned the front-wheel lower control arms.

body roll

The angled upper control arms resisted brake dive; and 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, helping to keep the car level. Mopar tuners could easily raise or lower the front end of the car by adjusting the torsion bars; with coil springs, the springs must be replaced. Likewise, if the car sagged with age, the torsion bar on that end could be replaced while a spring would be shimmed or replaced.

Transverse mounted torsion bar suspensions

Chrysler switched to the transverse mounted torsion bar system in 1976, moving away from the longitudinal parallel bars first put on all Chrysler Corporation cars in 1957. In general, the motoring public, the regular car buyers, never jumped up and down about it, since it was considered just another use of the proven torsion bar system. 

One of the major differences of the system 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.

The Volare, Aspen, and LeBaron were not the only cars to use this suspension. In 1980, Chrysler introduced the new M-bodied cars: the Dodge Diplomat and the Chrysler LeBaron. Plymouth got another kick in the teeth, just as it had in 1979, when the R-bodied cars (basically, re-engineered B-bodies) came in. Chrysler also introduced the J-bodied cars, which were also disguised F-bodies: the second generation Chrysler Cordoba and the “new” Dodge Mirada. F, J, and M cars all had the transverse torsion bars.

The isolated transverse mounted torsion bar system was another Chrysler Corporation exclusive. First introduced on the 1976 F-Bodied Dodge Aspen and Plymouth Volare, it was quickly accepted by engineers, auto enthusiasts, and car magazine writers all over the country.  Motor Trend gushed about it, calling it a “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, one of their more memorable choices.

The praise turned quickly sour, and 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.” Thus ended any thought of being a Los Angeles fleet car….. well, almost.

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. Torsion bars did that naturally, over time, usually after years of service. However, in the case of the transverse bars, in fleet use, sometimes the front would sag couple of days after 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.

Ride height is absolutely critical to a Mopar’s ability to handle high speeds, as well as the equally important ability to stop in a straight line. Our fleet records indicated 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, where there were wide open roads, few curbs, and no medians, 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 the ride height was ok, then the alignment was ok. If not, then a couple turns of the socket set the ride height. That was all that was needed.

Impossible alignments

The transverse bars were a part of the suspension geometry, and were mounted differently from the original ones; it took three points to mount the bars. They were outside the protection of the boxed frame structure, as well. 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 vehicle collisions. In one instance, a vehicle rolled back into the front of one of the CHP cars. A relatively minor, but regularly occurring incident. (Nervous drivers do nervous things.) It was thought, at first, that it was only sheet metal damage, however, the mount of one of the bars had been affected, and the handling of that unit was “squirrely” until it was diagnosised. It was also shunned by working Troopers who did not want to try to drive it, quickly turning into a “garage queen.”

The longitudinal bars on the R bodies and earlier cars had beefy anchor points well inside the bodies, and ran straight and true to the A frames on the suspension. The transverse bars were actually serving as the suspension and the locator for the A frame itself, and wrapped around the front end, with three different points for dislocation.  

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 became part of the issue with those vehicles. I had contracted for tires, so it didn't make any real relative 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 getting the new “M” bodies to hold alignments. We too, began to notice a big difference in our ability to perform and hold the regular alignment and ride height adjustment. The problem was frustrating because the issues were easily cured in the past by a simple ride height adjustment, and 4 minutes of time. Now, that was not working at all! Chrysler fleet sent out a confidential bulletin stating that it was “investigating” the issue.

The primary symptom was having no positive camber adjustment available. Even repeated ride height adjustments were not helping. Immediately, the transverse bars were pointed to as the culprits. The good folks at Philadelphia Police Department, loyal MoPar users early on and until the end, said, “not so fast.”

Philadelphia PD said that it was NOT the torsion bars this time out. It was a weak and bending K frame! Imagine the eruption of incredulity that went countrywide. 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 from the beginning. The wrong tensile steel was used, and it was not sufficient in thickness. Over time, repeated 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 which helped 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. That is, until the 1985 and 1986 models came along. In those years, widespread cracking was noted. When trying to determine the base reasons for this, the issues get cloudy.

Chrysler fleet blamed the Mexican production facility using inferior steel. The dies used to stamp out the frames were “old and worn” and out of proper specification. This would tend to explain the flexing of the shock towers which were causing the problems. However, weak steel and poor stamping just does not get by when you examine the total issue: poor quality from the start. 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. And a fleet arm that seemed not to give a damn!

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. And that would be the greatest user of the MoPar, the California Highway Patrol. They always spoke softly, but they held the greatest stick!

Now, Dodge stuttered, fluttered, twisted, and mumbled a lot, but the CHP kept their arms crossed, and kept their demands the same. Over 2.5 years, Dodge finally came up with a definitive solution — but it was carefully confined to only the California Highway Patrol! Which made it appear as though the CHP was the only source of the problem. California, though, felt that Dodge should be held responsible, and made to pay for the fix. The CHP won.

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. California would have it no other way. 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. Installation paid for by Chrysler Corporation. 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.) That probably amounted to 15% of the CHP’s total units.

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; but by then, most of the major police agencies had stopped buying the MoPar units. The CHP stopped with the 1988 model Diplomat. Los Angeles PD had not used a MoPar since 1981, and the LA County Sheriff, against their own advice, last bought Gran Furys in 1982. The Michigan State Police left MoPar in 1981, when the Chevrolet Malibu bested the Plymouth Gran Fury in bid price only, but came back in 1982, sticking with Mopar through 1986. The Chevrolet Caprice bested MoPar in 1987, and earned top honors for the next 10 straight years! By the end of 1989, there were no more M bodies, and Chrysler was effectively out of the fleet business.

Other transverse torsion bar notes

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.

Each bar, made in multiple diameters to equalize stresses, was adjustable as Chrysler's torsion bars had been since 1957. 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. We found ourselves batting around curves and turns that would have normal wagons cornering on the door handles...The Volare stuck to the road like the painted centerline and with no rear end hop or tendency to plow. Most pleasant. The steering is pleasantly quick, and the wagon was able to dart in and out of holes in traffic like a car half its size.”

In 1978, Chrysler gushed over the LeBaron’s suspension, shared with Volare, Aspen, and Diplomat: “Isolated transverse torsion-bar front springs, mounted ahead of the front wheels and iso-clamp multi-leaf rear springs-all rubber-isolated from the car structure. The transverse front torsion bars and multi-leaf rear springs contribute to ride stability, smoothness and handling responsiveness; the rubber isolation quiets the ride and increases the degree of smoothness. Mounting the transverse torsion bars to the isolated front structural crossmember is particularly effective in isolating noise and ride roughness from the car body.

“Torsion bars can be adjusted easily to keep the front end of the car at the proper height, regardless of the car's age or its mileage. Turning an adjusting bolt raises or lowers the front of the car.

“To keep level during braking, Chrysler engineers raised the front pivot of the upper control arm higher than the rear. This design causes the control arm to impart a lifting force to the front of the car as the weight shifts forward during braking. The lifting force resists brake dive to help keep the car nearly level when the brakes are applied.”

After rear wheel drive: resurrection of torsion bars

Bob Sheaves added: “Chrysler developed longitudinal torsion bars into a high science, but the transverse bars of the M-body (when used in police service) had an annoying tendency to allow the front suspension to lose alignment whenever a curb was hit. The same engineer (Bob Batchelor) responsible for the M-body design corrected the problems on the [Eagle] Premier, in that the bars were "folded" together into a single, more compact design that was more rigid in bending and smoother riding, due to lower rate and greater travel.”

The Eagle Premier had the usual-for-1980s-front-wheel-drive-cars MacPherson strut front suspension, but instead of a solid beam rear axle in back, used an independent torsion bar rear suspension.

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