RX4
 





If the press had been enthusiastic about earlier Mazdas, it hit a rotary redline on the RX-4. Car and Driver went "Mazda has mated its new fifth generation rotary engine to a flesh hardtop coupe. The end result is a Japanese 2-door edition of the Jaguar XJ--impeccably mannered where comfort is involved and fleet of foot to set tile pace in rapid transit. The Mazda RX-4 is going to be one formidable contender in the $4,000 division." Road & Track called it "nimble and responsive" and a "quieter, more refined car in almost every way than either RX-3 or RX-2."


The RX-4 was offered in 1974 in sedan, wagon, and as shown, coupe versions Mazda; Automobile Quaderly Photo and Research Library


The RX-4's tail was busy with lights, reflectors, and trim. The medallion on the C-pillar was an interior exhaust vent Road & Track

The new 1974 RX-4 was longer and wider if not lower--than its showroom siblings, and more powerful too. The RX-4 marked the US debut of the 13B rotary, and it was in fact the first time the engine had been used anywhere in the world. With power being sapped from the 12A by emissions controls, the 13B was a logical reaction by Mazda engineers to get more power from the rotary: Widen the bore another 10mm, this time to 80mm, for a single chamber displacement of 654cc. (Although the 13B was intended for US consumption initially, consideration for use in the Japanese market was obvious from the outset, Applying the 1.5 factor--used to compare rotary to piston-engine displacement to the 13B's nominal 1308cc dis placement kept the engine just within the 2L tax bracket in Japan, above which road taxes skyrocketed.)

The 13B was substantially similar to the 12A, and over the years, to one were paralleled in the other. The 13B came with cast-iron rotor tip seals from the beginning, for example, though Toyo Kogyo cryptically told the press only that the material was "metal." Seals also had a new two, piece design, with a wedge end piece that provided better end sealing than the earlier design that relied on careful fitting for gas sealing (and even with the best fit let gasses by) Side seals went from two to one, the combustion recess was reshaped and deeper, cooling capacity was increased and a five bladed fan installed for better air conditioner performance, and coolant passages in the engine were enlarged. The 13B had a single distributor, though with separate points and ignition coils for leading and trailing spark plugs.


78 RX4 Coupe




A semi automatic choke appeared with the 13B as well. This device had a dashboard knob that had to be pulled out manually to engage it. After the engine warmed, the choke would disengage, retracting the knob back into the dash. Another real-world device was the "sub-zero fluid" injector: If the rotary engine failed to start immediately at below-zero-Fahrenheit temperatures, water vapor from gasoline that had burned could freeze in the cold zones of the rotor and housing. To prevent this, a small pump squirted a 90 % antifreeze & 10 % water mixture into the carburetor from a separate under hood container.

The engine was rated at 110bhp SAE net and was the quickest Mazda to be in the US, cracking tile 10sec 0-60mph mark for tile first time. A torquier mid-range also helped around town drivability, whether with four speed manual or optional three-speed JATCO automatic. Tbe RX-4 chassis, despite its larger, more luxurious mien, reverted from the RX-3'S multi-link coil sprung rear axle to a seemingly primitive semi-eliptic leal spring arrangement. Nevertheless, the RX-4 was praised for an improved ride on roads both smooth and rough; Road & Track cited the rear gas shocks as a likely contributor. Torque control rods were optional and intended to eliminate spring windup, though both Read & Track and Car and Driver discovered axle tramp upon acceleration. The latter blamed it on excessive squat, which did bad things to the U-joint angle where the differential and drive shaft met. Wheel hop under braking, however, was not a problem, and both magazines praised the disc/drum setup, though again the suspension allowed too much nosedive.

Bigger radials: BR70-13 helped in braking performance and handling as well. Road & Track found body roll "well controlled," while Car and Driver criticized a prevailing understeer that limited ultimate cornering power.

The interior featured a cockpit-styled dash with separate gauges for each instrument, which included a 130mph speedo, 8000rpm tach, a trip odometer, coolant temp gauge, ammeter, and clock. The shifter was mounted in a center console and had a neat soft boot. Seats were either standard slippery vinyl or optional crushed velour (Can disco be far away?). The RX-4's longer wheelbase allowed adquate headroom for adults even in the back seat of the coupe, which was Mazda's first "pillarless" coupe. A loophole in the new US bumper law permitted bumpers on the 1974 RX-4 coupe to be different from those on the RX-4 sedan and wagon, which had full width barrier bashers that protruded from under the grille in a manner as ungainly as any of those designed under the early bumper laws.

How it was supposed to be: The Japanese market RX-4, designated Luce, lacks massive overriders of the US market coupe, Mazda; Automobile Quarterly Photo and Research Library


The front end of the RX-4 sedan resembled that of the coupe, but had full-width "federal" bummper beggining 1974. The trim patrol didn't neglect the rear of the RX-4 sedan. 
Note the odd charcter lines and embllemishment of the C-pillar and the add-on rear reflector and back-up lams below the main taillamps. Mazda Curtacy Road & Track

The short-wheelbase pillarless coupe exemption, however, allowed massive over-riders to be added to the flush-style bumper, with which the car was undoubtedly originally designed. From 1975 on, coupes had the full width crash bumpers.

A July 1974 Road & Track compact station wagon comparison test matched the RX-4 "Rotary Wagon" (as badging on the car's liftgate identified it) against wagons from American Motors, Peugeot, Toyota, Volvo, and Volkswagen. The test found that the Mazda was "not only one of the least expensive cars but its performance put every other wagon except the V-8 Sportabout to shame." But also noted were "considerable bucking on de celeration at low speeds, backfires (reduced in number and intensity from the RX 2 and RX-3, however) and, something new to Mazdas, reluctance to start and some stumbilng when cold. The RX-4's response, smoothness, and power out-weighed these disadvantages, however, and the magazine named the RX-4 as best of the wagons for "all-around fun," with "excellent performance...good ride and handling, a comfortable and well planned interior, adequate cargo space and reasonable price." Fuel mileage was--no surprise -- "mediocre"

Alas, another comparison test by Road & Track this one of sports sedans in the March 1977 issue, found the RX-4 sedan firmly in last place. The editots faulted just about everything on the car As for exterior design, they wrote, "Toyo Kogyo's ginger bread, letter, badge and stripe departments are still working overtime and the car is massively overdecorated," and for the interior, "velour up holstery looks like the late American boudoir or classic Las Vegas" and "It takes the Japanese to devise a center armrest that's part of a console and interferes with shifting and reaching the handbrake.

Don't they realize you're supposed to be able to drive the car?" Road & Track even found fault with the engine: "No longer as smooth, powerful or exhilarating as it once was" and "If you back off the throttle and get on it again, the engine reacts as if someone stuffed a potato up the tailpipe. For 4-5 seconds it accelerates much less briskly, then suddenly it starts accelerating again at its original rate. This behavior is probably tied to emission controls."Road & Track concluded, "Perhaps while we haven't been looking, Mazda has been quietly turning the car into a family sedan."

Such indeed was the cause, along with the need for better fuel economy, the relative lack of which had been cited in every Mazda road test. Mazda addressed the problem with smaller, more restricrive ports beginning with the 1976 model year. Even with the First Great OPEC Oil Crisis in full swing when the RX-4 was introduced, Car and Driver served passing notice to the fuel economy question by stating that the RX-4 would sidestep the whole issue by being a luxury sedan, with an emphasis on the luxury Rival Road & Track was more concerned, yet noted that the RX-4 offered "an attractive alternative to large, heavy domestic cars with big V-8 engines, in a relatively compact car that's not nearly so thirsty"

The "big" 13B rotary engine looks lost in the roomy RX-4 engine compartment Road & Track

A bland, American-style grille was for the 1976- 78 RX 4 sedan and station wagon Mazda; Automobile Ouarterly Photo and Research Library

Both magazines underestimated the public's reaction. Mazda sales plummeted, and Toyo Kogyo reacted by modifying the rotary engine and increasing emphasis on piston-engine cars such as the 808 and Mizer, GLC, and 626. The RX-4, along with the like motored RX-5 Cosmo and the 12A-powered RX-3, were withdrawn from the American market at the end of the 1978 model year. The 13B would take a sabbatical from the US as well though it would still be used in the larger Japan-market cars--until the 1984 introduction of the RX-7 GSL-SE But that's another story.

What to Look For 
The RX-4 is rapidly becoming a difficult find. It wasn't sold in the numbers that the RX-3 was and it wasn't popular for racing. The coupe, especially the first year with its smaller bumpers, is the best looking model, though the Rotary Wagon has a funky appeal. The front end of the 1976-78 sedans and wagons abandoned the recessed grille originally installed on the model in favor of bland, Americanesque front end styling, hardly befitting the revolutionary rotary engine behind it. Preferences depend upon personal choice, but the styling of the first RX-4 series is certainly more distinctive.

Another reason to stay away from 1976 and later cars are changes to the 13B engine that made it more fuel efficient and less polluting. Almost every road test showed declining speeds and increasing times. Ports were smaller beginning in 1976, so these cars in particular will be slower and have less of the high-rpm snap that make the rotaries so much fun.

From a practical standpoint, collectors will find most to be a problem in the salt belt. Look for it in all the usual places: rocker panels, door bottom edges, rear fender lips, etc. Small parts are hard to find, and you may have to improvise or custom make interior parts and upholstery as they may not be available in salvage yards. Bumpers and such can be found but not always easily.

Mechanically the cars are restorable, even if some waiting may be required for parts, Service parts for the 13B can be found, or for the later model engines substituted. The manual tram mission is stout, and though synchros can give trouble, they can be replaced. Rear ends and parts are available too. Again, the best advice is to buy the best RX-4 you can find and all the parts cars your spouse and neighbors will tolerate.