From the December 1987 problem of Automobile and Driver.

Few technical improvements have captured the creativeness of the automobile trade as shortly as four-wheel steering. Though the idea of steering the wheels at each ends of a car is nothing new, its growth for manufacturing vehicles gained no actual momentum till 1983, when Mazda unveiled its MX-02 present automobile. Since then, such dream machines because the Corvette Indy, the Pontiac Pursuit, and the Peugeot Proxima—certainly, most present vehicles which have been greater than mere styling workout routines—have additionally employed four-wheel steering.

What’s extra, as compared with such different trendy developments as turbo­charging, four-wheel drive, and anti-lock brakes, four-wheel steering has superior just about in a single day from show-car curiosity to mass-production actuality. Honda received the race to market final summer season when it launched the 1988 Prelude Si, on which 4ws is non-compulsory. Mazda adopted go well with virtually instantly with non-compulsory 4ws for the brand new 626 Turbo. Extra all-wheel-steer fashions are on the best way from Nissan and Mitsubishi, and several other different producers, in the US and Europe in addition to in Japan, are engaged on their very own 4ws programs.

The producers’ rush to 4ws is shocking in view of the truth that, till the Prelude was launched, their prospects had demonstrated little curiosity within the prospect of steering all 4 wheels. And why ought to they’ve? In contrast to turbocharging, 4WD, and ABS, the advantages of that are simple to grasp, four-wheel steering will not be clearly a technological breakthrough. Point out 4ws to most individuals and you will get clean stares, if not laughter, adopted by sarcastic questions on whether or not it would make their vehicles go down the street sideways.

The truth is, because the producers know effectively, four-wheel steering has a number of vital potential advantages. Each 4ws system that we have seen up to now turns a automobile’s entrance and rear wheels in reverse instructions beneath some circumstances and in the identical course at different instances. Reverse-direction steering makes a automobile flip extra sharply, enhancing its low-speed maneuverability and tightening its turning circle. Similar­-direction steering, in principle, improves dealing with at increased speeds. To grasp why, contemplate that the entrance tires of a conventionally steered automobile develop cornering forces instantly when they’re steered, however the rears develop cornering forces solely when the physique of the automobile has begun to show. On a 4ws automobile in distinction, all 4 tires develop their cornering forces on the identical time. The result’s extra responsive dealing with in transient maneuvers, resembling getting into and exiting corners. Moreover, because the rear tires of a 4ws automobile don’t rely solely on the automobile’s drift angle to provide their cornering forces, the automobile’s tail would not swing out as far in corners or wag as a lot in fast lane adjustments. These benefits are significantly pronounced on slippery surfaces, say the advocates of 4ws.

Dick KelleyAutomobile and Driver

Each Honda and Mazda declare these advantages for his or her 4ws programs, although they’ve provide you with distinctly completely different technique of including rear steering to their vehicles. The Honda system, the easier of the 2, is completely mechanical. A shaft from the entrance rack-and-pinion linkage drives a rear steering gearbox, which steers the rear wheels in the identical course because the fronts when the steering wheel is turned lower than 246 levels from straight forward, and in the other way past that time. Since turning the steering wheel greater than 246 levels from middle is probably going solely at very low speeds, the countersteer mode usually comes into play solely in parking-lot maneuvers. In neither mode do the rear wheels steer very a lot. Their most same-direction steering angle is 1.5 levels, and their most counter-steering angle is 5.3 levels.

The Mazda system operates alongside related ideas however is rather more advanced in design, using mechanical, hydraulic, and digital components to provide an elaborate tailoring of entrance and rear steering angles. With the assistance of pace sensors and a management unit, the system adjusts its operation to not steering-wheel angle however to automobile pace. At speeds under 22 mph, the rear wheels steer reverse to the fronts, as much as a most angle of 5 levels. Above 22 mph, they steer in the identical course because the entrance wheels. The relative steering angles and the transition from countersteering to same-direction steering are regulated by the system’s management unit. The ensuing steering traits are just like the Honda system’s, with one main exception: whereas the Prelude’s steering wheel should be wound significantly earlier than countersteering begins, the 626 countersteers at low speeds at any time when its steering wheel is moved from middle, irrespective of how small the angle. Mazda’s system thus guarantees superior low-speed maneuverability.

In fact, the design ideas of the 2 programs inform us little about how they work on the street. The one unquestionable advantage of 4ws is improved parking ­lot maneuverability. The Prelude’s system reduces its turning circle from 34.8 to 31.4 ft; the corresponding figures for the 626 are 38.0 and 36.1 ft.

To look at the results of 4ws on higher-speed maneuvers, we ordered two-wheel-steer and four-wheel-steer examples of each the Honda Prelude Si and the Mazda 626 Turbo and mapped out a collection of dealing with exams. Along with observe testing within the managed confines of Chrysler’s proving grounds in Chelsea, Michigan, we might drive the 4 vehicles on the street and be aware any subjective dealing with variations. Our function was not a direct comparability of the sporty Prelude and the four-door 626. Slightly, we might search to find the results of four-wheel steering by pitting Honda versus Honda and Mazda versus Mazda. Within the course of, the relative deserves of the 2 makers’ approaches to 4ws would additionally turn out to be obvious.

It was vital for our testing that the 2ws and 4ws variations of every mannequin be as related as attainable. The one distinction between the 2 Preludes we ordered was that one had the 4ws bundle, which incorporates alloy wheels, energy door locks, and bronze-tinted glass. Each vehicles had been outfitted with the identical springs, shocks, anti-roll bars, and tires, although Honda specifies 28 psi of tire stress throughout for the 4ws Prelude and two kilos much less for the rear tires of the 2ws mannequin.

Sadly for our functions, Mazda would not supply 2ws and 4ws 626s which are as equal as the 2 Preludes we ordered. Mazda’s 4ws choice is offered solely on the turbocharged, automatic-transmission, four-door 626. The identical fundamental automobile is offered with 2ws, however all 2ws 626 Turbos are outfitted with Mazda’s Auto Adjusting Suspension. The AAS system employs three-position shocks, and not one of the damping settings corresponds to the fastened calibration used on the 4ws automobile. Furthermore, the springs and anti-roll bars that include AAS are softer than the {hardware} fitted to the 4ws automobile. To compensate for these softer parts as a lot as we might, we set the AAS system of our 2ws Mazda in its Sport Auto setting, which yields considerably stiffer damping than the 4ws automobile’s shocks. At the very least the wheels and tires of the 2 vehicles we ordered had been an identical.

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Our testing targeting dealing with in transient maneuvers, since 4ws should not have any impact on straight-line driving or steady-state cornering. Probably the most helpful transient-handling exams are the slalom and the double lane change. The slalom take a look at requires driving a serpentine path as shortly as attainable by means of a line of evenly spaced cones. Different issues being equal, vehicles with a good grip on the street and constant steering response carry out finest on this take a look at. Our double-lane-change take a look at requires switching quickly from one twelve­foot-wide lane to a different, then again once more, at factors marked by cones. Good efficiency on this take a look at requires controllability and fast and correct steering response throughout the two sharp cuts. For each exams, we various the scale of the programs to review the results of 4ws on completely different pace ranges. And, as a result of 4ws is claimed to be particularly useful on slippery surfaces, we performed most of our exams each on dry pavement and within the moist.

Dry Efficiency

Dick KelleyAutomobile and Driver

Though 4ws theoretically has no impact on steady-state dealing with, we started our testing on Chrysler’s 300-foot skidpad to see how the vehicles would examine in roadholding. The Hondas had been shut, with the 4ws automobile having the sting, 0.78 to 0.77 g. The Mazdas had been unfold a bit additional, with the 4ws automobile at 0.76 g and the 2ws mannequin at 0.74 g. Given the 4ws Mazda’s extra favorable weight distribution (contributed by the rear-steering {hardware}) and its typically firmer suspension, its skidpad benefit was not shocking.

Our first transient take a look at was a really gradual slalom, fashioned by eleven cones spaced solely 25 ft aside. Our intention was to power the vehicles’ speeds low sufficient to convey out the results of countersteering within the 4ws fashions. With speeds within the 12-to-13-mph vary, we definitely succeeded; nevertheless, we needed to wind the steering wheels so vigorously that not one of the 4 vehicles’ power-steering programs might sustain. Because of this, this slalom turned out to be little greater than a take a look at of our upper-body energy. The minor pace distinction between the 2 Hondas (see chart) signifies nothing greater than the relative skills of their power-steering pumps.


Honda Prelude Si, 2WS/4WS

Roadholding, 300-ft-dia skidpad: 0.77/0.78 g

25-ft cone spacing: 12.5/12.0 mph

50-ft cone spacing: 31.5/31.5 mph

100-ft cone spacing: 62.0/62.0 mph

Lane change, low pace: 30.5/34.0 mph

Lane change, excessive pace: 57.5/61.0 mph


After we elevated the cone spacing to 50 ft to review the results of same-direction 4ws, the power-steering issues disappeared and our testing started to point the dealing with skills of the vehicles. The 2 Hondas turned in the identical pace, 31.5 mph. Each turned sharply and exhibited good management, although the 4ws automobile required a bit extra steering effort.

The 2 Mazdas had been a lot much less alike. The 2ws automobile turned in properly and saved its tail effectively managed, whereas negotiating the course at 32.0 mph. The 4ws automobile required a bit much less steering movement than its mate, but it surely suffered from a slight two-step impact in its steering response when switching from one course to a different. Its pace by means of the cones was solely 30.0 mph.

Dick KelleyAutomobile and Driver

With the cones spaced 100 ft aside, the 2 Hondas now not felt related. The 4ws Prelude turned in fantastically and appeared to have great grip at each ends of the automobile. The 2ws mannequin exhibited a lot higher tail swinging and required significantly extra steering correction. The 2 backside strains, nevertheless, had been an identical: each Preludes negotiated the course at 62.0 mph.

The 2 Mazdas reversed their positions within the 100-foot slalom. Though the 4ws automobile nonetheless had a twitch in its steering, it ran the course at 58.0 mph, 1 mph quicker than the 2ws automobile. The front-steerer felt higher on the wheel, however its softer suspension restricted its pace.

Summing up our dry-slalom outcomes, the 4ws Honda was extra controllable than its 2ws counterpart, however no quicker. The 2 Mazdas had been additionally roughly equal in pace, the 2ws automobile’s extra linear steering compensating for its softer suspension.


Mazda 626 Turbo, 2WS/4WS

Roadholding, 300-ft-dia skidpad: 0.74/0.76 g

25-ft cone spacing: 13.0/13.0 mph

50-ft cone spacing: 32.0/30.0 mph

100-ft cone spacing: 57.0/58.0 mph

Lane change, low pace: 32.5/32.5 mph

Lane change, excessive pace: 61.5/61.5 mph


Within the double-lane-change take a look at, we once more began on the low finish of the pace spectrum. Our first course consisted of a 25-foot phase for the primary lane change, adopted by a 50-foot straight run, after which one other 25-foot slot for the return to the unique lane.

Dick KelleyAutomobile and Driver

The 4ws Prelude was considerably faster by means of this course than the 2ws mannequin, beating it 34.0 to 30.5 mph. The 2 didn’t really feel very completely different on the restrict, nevertheless. The 4ws automobile required extra steering effort and felt considerably extra secure, however each Preludes displayed constant understeer and saved their tails beneath tight management.

In distinction, the 2 Mazdas turned in the identical pace, 32.5 mph, however they felt markedly completely different from one another. The 2ws automobile understeered steadily and was simple to drive. The 4ws automobile additionally understeered, however its steering was a lot much less clean. Its power-steering pump once more couldn’t sustain with the sudden steering motions required by the course, inflicting a significant spike within the steering effort required throughout the lane adjustments.

For our higher-speed lane change, we doubled the lengths of all three segments of the course, growing the size of every crossover part to 50 ft and that of the straight stretch to 100 ft. The 4ws Honda maintained its strong benefit on this take a look at with a 61.0-mph docking, in contrast with 57.5 mph for the 2ws model. Not solely was the 4ws Honda quicker, but it surely negotiated the course with a lot much less fish-tailing as effectively. The 2ws automobile’s wagging tail was not significantly tough to manage, but it surely did make us work more durable on the steering wheel.

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Dick KelleyAutomobile and Driver

The 2 Mazdas once more turned in the identical pace, this time 61.5 mph. Nevertheless, as was the case with the Hondas, the 4ws mannequin was the better automobile to drive. It fish­tailed lower than the 2ws 626 and was typically extra benign, regardless of a little bit of power-­steering lag.

Our lane-change outcomes converse higher for 4ws than our slalom findings, at the least within the case of the Honda system. The 4ws Prelude was each quicker and extra controllable than the 2ws mannequin. Certainly, the pace distinction was so massive that driving the 4ws Prelude by means of the double lane change on the 2ws automobile’s limits was just about easy. In distinction, the Mazda 4ws system was a combined blessing. Though the 4ws 626 felt higher than the 2ws automobile within the high-speed switches, its lagging power-­steering system made it more durable to steer. Extra vital, 4ws didn’t enhance the Mazda’s pace by means of the programs.

Moist Efficiency

Dick KelleyAutomobile and Driver

We thought it doubtless that the claimed stability benefit of 4ws could be extra obvious in our moist testing, since any such benefit needs to be exaggerated on slippery pavement. Chrysler’s low-friction Jennite floor, totally wetted by a sprinkler system, was excellent for our functions, and we repeated most of our dry exams on it. We did not repeat the 25-foot slalom, as a result of that train had examined the vehicles’ power-steering programs greater than their dealing with. And since Chrysler’s Jennite floor is not massive sufficient for a 300-foot skidpad, we ran our wet-road­holding take a look at on the circle we usually use, with the assistance of a tough rain.

Our wet-skidpad outcomes had been shocking. 4-wheel steering ought to make no distinction on the skidpad, since solely steady-state cornering is concerned, however each 4ws vehicles in truth misplaced floor to their 2ws siblings in shifting from the dry to the moist take a look at. The 4ws Honda went from a 0.01-g benefit within the dry to a 0.03-g drawback within the moist. The 4ws Mazda misplaced its 0.02-g benefit, tying the 2ws mannequin. We’ve got no rationalization for this shift, but it surely instantly known as into query the supposed slippery-surface advantages of 4ws.


Honda Prelude Si, 2WS/4WS

Roadholding, 300-ft-dia skidpad: 0.76/0.73 g

50-ft cone spacing: 24.0/24.0 mph

100-ft cone spacing: 44.5/44.5 mph

Lane change, low pace: 28.0/27.0 mph

Lane change, excessive pace: 49.5/47.5 mph


After we moved to the 50-foot-interval slalom course on the moist Jennite, we once more discovered no benefit for 4ws. The 2 Hondas felt just about alike by means of the course and turned in precisely the identical pace, 24.0 mph. The 2ws Mazda was really faster than the 4ws mannequin, 24.5 to 23.0 mph. And though each Mazdas understeered, the 4ws 626 understeered extra. We additionally felt its tail wiggling a bit by means of the course, although with none discernible impact on its dealing with.

Dick KelleyAutomobile and Driver

Growing the cone spacing to 100 ft introduced out higher variations between the vehicles. The 4ws Honda felt safer than its sibling, retaining its tail effectively in line with out displaying extreme understeer. The 2ws automobile was additionally admirably secure, however its tail was extra prone to step out because the automobile’s traction restrict was reached. Regardless of its benefits, nevertheless, the 4ws Prelude couldn’t enhance on the 2ws automobile’s 44.5-mph pace.

In distinction, the 2ws Mazda was once more dearly superior to the 4ws model, by 42.5 to 40.5 mph. It additionally felt a lot better. The tail of the 4ws automobile was very free and threatening, and we discovered it tough to clean off extra pace with out getting sideways. The 2ws 626 did not really feel comfy with its tail out, both, but it surely was a lot much less prone to undertake that angle.


Mazda 626, 2WS/4WS

Roadholding, 300-ft-dia skidpad: 0.77/0.77 g

50-ft cone spacing: 24.5/23.0 mph

100-ft cone spacing: 42.5/40.5 mph

Lane change, low pace: 27.0/25.5 mph

Lane change, excessive pace: 46.0/46.0 mph


The 4ws vehicles did not enhance their standing on the moist lane-change programs. The 2 Hondas felt very a lot alike on the low-speed course, exhibiting regular understeer. However the 2ws mannequin ran 28.0 mph, 1.0 mph quicker than its 4ws sibling.

Equally, the 2ws Mazda beat the 4ws automobile, 27.0 to 25.5 mph. The 2ws automobile negotiated the course with barely much less understeer, although the 4ws 626 felt equally secure in different respects.

Within the high-speed moist lane change, the 2 Hondas felt roughly equal, although the 2ws automobile was a bit of extra susceptible to swinging its tail out. Once more, nevertheless, it was additionally quicker than the 4ws Prelude, operating the course at 49.5 mph, versus 47.5.

Dick KelleyAutomobile and Driver

The 4ws Mazda improved its place on this take a look at, however solely sufficient to tie its 2ws sibling, at 46.0 mph. And the 2ws 626 felt a lot better, exhibiting solely average tail-happiness. The 4ws automobile wagged its tail continuously, irrespective of how fastidiously it was pushed.

Regardless of the theoretical benefits of 4ws on slippery pavement, each 4ws vehicles on this take a look at had been slower than their 2ws counterparts in three of the 5 moist trials and no quicker within the others. And though the 2 Hondas had been about equal in controllability, the 4ws Mazda was clearly much less secure than its sibling in many of the exams.

Conclusion

Dick KelleyAutomobile and Driver

After we conceived this take a look at, we anticipated that any dealing with advantages of 4ws could be most obvious within the moist. As an alternative, we discovered simply the alternative. The 4ws Prelude carried out higher within the dry and worse within the moist than the 2ws Prelude—not a worthwhile trade-off. And though our comparability of the 2 Mazdas is considerably tainted by their completely different suspension calibrations, the 4ws 626 was no higher in any respect than the 2ws automobile within the dry and was decidedly inferior within the moist. We will solely conclude that, as at the moment developed, neither Honda’s nor Mazda’s system represents a lot of an advance in steering expertise.

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These new steering programs do not come free, both. Honda’s 4ws bundle provides 28 kilos to the Prelude’s curb weight and $1300 to its worth. Mazda’s 4ws system provides virtually 100 kilos to the 626 and, adjusting for the suspension variations of the 2 vehicles examined, prices about $1385. Each programs do enhance low-speed maneuverability, which is effective, however we doubt that many patrons would spend a lot cash simply to make parking simpler.

Does this imply that 4ws will not be, in spite of everything, a big advance in automotive engineering? The one affordable reply is that it is too early to say. Do not forget that the Honda and Mazda programs are the primary manufacturing functions of what’s, in impact, a brand-new expertise. And simply as Honda’s and Mazda’s approaches are vastly completely different, different producers are sure to develop their very own distinctive approaches. Of the 2 programs launched to this point, the Honda design is the extra profitable. It prices and weighs much less, is far much less advanced, and does ship a number of clear advantages. However each it and the Mazda system require additional refinement if they’re to appreciate their potential. We stay hopeful that, ultimately, 4ws will dwell as much as its promise. Honda and Mazda deserve credit score as pioneers, however, for now at the least, 4ws is not any nice leap ahead.


4ws on the Street

Dick KelleyAutomobile and Driver

Driving vehicles on a take a look at observe is one of the best ways to outline their absolute efficiency, however driving them in the true world is not any much less vital to an intensive analysis. When one is struggling to keep away from crunching pylons flashing backward alongside each flanks, it is easy to miss subtleties that may be vital in on a regular basis driving. To verify we ignored nothing in our examination of four-wheel steering, most of our employees drove all 4 vehicles on this take a look at on public roads close to our Ann Arbor places of work. Every staffer drove the vehicles again to again, each regular driving and onerous flogging had been inspired, and a few staffers drove in each rain and shine. Our function, as in our observe testing, was to see what variations we might detect between the 4ws and 2ws vehicles.

We went to uncommon lengths to make sure that every take a look at driver might consider the dealing with of the vehicles objectively. First, we taped over the figuring out labels on the 4ws vehicles and the corresponding places on the opposite two. Second, as a result of Honda’s 4ws bundle contains distinctive alloy wheels, we exchanged two wheels and tires from the 4ws Prelude with a set from the 2ws automobile. Lastly, we requested our take a look at drivers to keep away from tight maneuvers at low speeds, as a result of the 4ws vehicles’ tighter turning skills would shortly establish them. Not till the drivers had completed their four-car stints and reported their findings had been they permitted to play carhop in our parking zone.

Many of the testers needed to focus onerous to detect any distinction in any respect between the 2 Hondas. The truth is, one staffer, who mistakenly thought he knew which Prelude had 4ws (the vehicles had been painted completely different colours), accomplished his drives of each Hondas with out realizing his error.

Though some drivers noticed that the 2ws Prelude displayed extra lift-­throttle oversteer than the 4ws automobile, most of us discovered steering effort to be probably the most obvious distinction between the 2. The 2ws Prelude has a delightfully fluid steering really feel, with a really linear buildup of power because the wheel is rotated from middle. The 4ws automobile steers virtually as properly however requires a bit extra effort. It feels stickier, as if it has extra mechanism to maneuver—which, after all, it does. Given the shortage of different variations between the 2 vehicles, our drivers unanimously most well-liked the 2ws Prelude.

Telling the Mazdas aside was a lot simpler. Each staffer noticed that the steering of the 4ws automobile was a lot lighter than the 2ws automobile’s. Within the 4ws 626, the steering wheel strikes off middle with virtually no resistance, and the hassle barely will increase because the wheel is turned additional. In distinction, the 2ws automobile has a constructive on-center notch, and its steering effort builds strongly because it’s become a nook. The distinction in steering effort between the 2 Mazdas is 5 or ten instances as nice as that of the 2 Hondas.

The 2 Mazdas additionally felt very completely different to our testers by means of the seats of their pants. The 4ws automobile adjustments course with a willingness that makes the 2ws automobile appear virtually sluggish; one positively feels one thing particular in the best way it turns right into a nook, all 4 tires directly. Nonetheless, many of the staffers regarded this conduct as twitchiness. Coupled with its mild steering effort, the 4ws Mazda’s eagerness to show made it appear a bit of too nervous in a straight line, particularly at excessive speeds. Nobody discovered the 4ws automobile unstable, but it surely did not observe with the sureness of its 2ws stablemate. Even in corners, the mixture of sunshine steering and sudden turning offered too little street really feel for many of our testers. Admittedly, that impression would in all probability fade with time.

In our parking zone, our testers had nothing however reward for the tighter turning circles of each of the 4ws vehicles. Though the enhancements over the 2ws variations look modest on paper, they contribute to markedly higher maneuverability. In a 4ws automobile, one can whip into parking areas and round tight comers with exceptional ease.

However is that sufficient? Improved low­-speed maneuverability could also be useful on the tightly packed roads of Japan, but it surely’s hardly important in America. Within the absence of different important dealing with enhancements, all of the take a look at drivers felt let down by each Honda’s and Mazda’s 4ws programs.

As one tester put it, “4-wheel steering turns that further pair of wheels much more than it turns my head.” —Csaba Csere

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