Chevrolet Monza

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Chevrolet

Chevrolet Monza

 1974 - 1980
Country:
USA
Engine:
L4 / V6 / V8
Capacity:
2.3 to 5.7 liter
Power:
300 - 360 bhp
Transmission:
3/4/5 man. 3 spd. AT
Top Speed:
n/a
Number Built:
n/a
Collectability:
2 star
Chevrolet originally tried to obtain the Chaparral name from Jim Hall for their new subcompact – but when they were unsuccessful they turned to an old name that, to our mind, was much better anyway. The Monza 2 + 2 was born of thinking similar to that which inspired Ford's Mustang II. Chevrolet discovered, as Ford had, that the American car buyer was now interested in a small, sporty package with luxury features.

Though the Vega was originally conceived as a domestic alternative to the inexpensive small imports, Chevrolet soon found that Vega buyers were more interested in accessories than austerity, adding an average of US$300 worth of extras to their cars. In particular the GT option, initially slated for 8-9 percent of Vega production, quickly jumped to a 30-percent fitment rate as customer demand for the quicker, better-handling and more luxuriously trimmed version soared.

With the demand for a compact luxury GT thus firmly established, Chevrolet planners decided to create a separate model for the market and laid down some design objectives and ground rules. First, there would be only one model: a 2-door, hatchback, 2 + 2 coupe. Why only one model when Ford's Mustang offered two, a notchback as well as a fastback? Hatchback models accounted for 60 percent of Vega sales, a far higher proportion than for Pinto's Runabout; this plus the runaway success of Datsun's 240Z convinced Chevrolet that Americans were most interested in a sporty package with the functional utility of a hatchback design.

One of the primary goals was to design the Monza to take advantage of a new engine – and we are not talking about the 262-cu-in. (4.3-liter) "small-block" V8. In fact the V8 was only added to the Monza program after problems with the GM Wankel rotary pushed it behind schedule, and eventually into oblivion. But evidence of the rotary's influence could be seen in two areas. A bulge in the center of the hood was needed for clearance above the taller standard 4-cylinder and optional V8 engines, and the central tunnel was unusually tall because the rotary's eccentric shaft was higher than the crankshaft of either piston engine.

The high tunnel remained because GM were serious about fitting the rotary engine – but in the end the decision was reluctantly made to stick with the V8, primarily because of the poor fuel consumption of the rotary, and problems making it meet the stringent emissions controls. A major objective of the Monza program was to provide a distinctive GT coupe with maximum use of Vega mechanical components, so the Monza was Vega-based and bore about the same relationship to the Vega as the Mustang II did to Pinto. It shared such things as wheelbase, track, steering, brakes and front suspension, but Monza engineers were given freedom to improve the car where necessary. A major revision of the rear suspension, the optional V8, a 5-speed gearbox and numerous subtle changes were the result of this philosophy. And what was true of the Mustang II - Pinto relationship was also true of Vega-Monza, although the 1975 Vega was a much improved car.

The intriguing similarity between Mustang II and Monza development went further. Ford's Ghia design studio provided ideas for the Mustang II shape. Another Italian coachbuilder, Pininfarina, had a hand in the Monza design as it did in the Corvette mid-engine show car. Pininfarina built the first running prototype from a chassis and a plaster model of the basic design provided by Chevrolet in 1971. According to Chevrolet, several European designs influenced the Monza shape. Ferrari's 365 GTC4 apparently exerted the strongest effect; this was apparently no surprise as Chuck Jordan, then Executive Chevrolet Designer, who was a Ferrari aficionado and owned a Daytona coupe. There were ties with the 2 and 4-rotor Corvette show cars too - the sloping hood with four rectangular headlights and the flaring around the lower portions of the wheel-well openings all showed strong Corvette influence.

The rear-end treatment was all 1974 Camaro, itself a handsome design. There was a significant increase in glass area compared to the Vega and the beltline was unusually low. At the cars release, it was reported that, according to one GM designer, this dropping lower window line was "an attempt to recreate the open-air feeling of a car like the Jaguar XK-140." Rectangular headlights were more than a styling gimmick: they allowed a slightly lower hood profile for improved forward vision and aerodynamics. The thick, louvered B pillars, straight from the GTC4, were also functional, serving as exit ducts for the flow-through ventilation system and providing integral roof strength. Chuck Jordan said at the time that the Monza was the first example of GM's plans to "clean up" the exterior of its cars while placing emphasis on interior room. There were some at GM, Jordan among them, that thought a car with the external dimensions of the Monza –Vega, but with nearly as much room as the Camaro inside, could almost serve as a smaller Camaro. This statement said something not only about the compact design of the Monza but also about the relevance of the Camaro, aside from its handsome styling.

The V8 Monza weighed 450 lb less than the Camaro but appreciably more than either its Vega Hatchback counterpart or its import competition , but it wasn't as heavy as the Mustang V8. The rear seats were narrower than the Vega's because of tunnel intrusion, and deeply contoured for increased headroom. Here the Monza did suffer in comparison to the Camaro, but at least Chevrolet made no pretense of calling the Monza anything but a 2 + 2. Tall drivers would have appreciated the Monza's additional 1 in. of front legroom compared to the Vega, resulting from a lengthened seat track. With the new rear suspension a pocket in the floor pan was eliminated, which allowed the rear seats to be relocated rearward 1 in. also, so there was no reduction in rear legroom with the front seats fully rearward.

Structure & Body



Although the Monza had all-new sheet metal, the unit body was designed to be compatible with the then current Vega Hatchback as far as fabrication techniques and assembly-plant facilities were concerned. From the firewall forward the structures were common. The center and rear floor sections were similar but the Monza had the wider, higher tunnel for the (never to be used) rotary, increased kickup for axle clearance, a two-piece rear pan with two longitudinal bars to support the bumper energy-absorption units, and provision for rear suspension modifications during the life of the model. Front and rear bumpers were attractive as well as regulation-conforming: the impact bars were of weight-saving aluminum and end caps were body-colored plastic similar to those of the 1974 Corvette. Overall height of the Monza 2 + 2 and the Vega Hatchback was the same but the Monza's windshield was raked at a more acute angle, accentuating the low and sweeping look of the car.

Chevrolet engineers worked diligently on reducing noise and vibration in the Vega, which was very rackety in its original form. For the Monza's luxury "image" an even better acoustical package, with added deadener and sound insulation material, was developed. The Monza was a heavier car than the Vega, so its performance with the standard 4-cylinder engine was bound to suffer by comparison: weight difference between comparable 1975 4-cylinder Vega (the 1975 Vega was about 50 lb heavier than the 1974 version) and Monza models was around 150 lb. Increases in glass area, the acoustic package and the revised rear axle and suspension accounted for much of the increase. The V8 Monza is heavier still; the total car-weight increase (engine plus required accessories) for the V8 vs the 4-cylinder installation was about 250 lb.

Engines & Transmissions at Launch



The base engine was Vega's optional 2.3-liter overhead-cam 4-cylinder with 2-barrel carburetor. In general there were no changes in this engine except for the slight retuning for better fuel economy and drivability the catalytic converter allowed. The small block V8 was essentially a de-stroked and de-bored 350, the 262 V8 weighed only about 14 lb less and retained the traditional oversquare bore-to-stroke relationship, having only a slightly smaller bore and longer stroke than the original 1955 265 V8. Cylinder-bore diameter was 3.67 in. and crankshaft stroke was 3.10 in. for an actual displacement of 262.5 cu in. or 4302cc, making it the then smallest of any Chev V8. The main difference between the old 265 and the 262 was bearing size: by retaining the larger bearing diameters of the 350 V8 the 262 could be built on the same case-machining and assembly line as the 350. Outside dimensions of the 262 block were the same as those of the 350, but many ancillary components had to be shrunk: for instance, the exhaust manifolds were of a more compact design and the intake manifold had small runners like those of the 307-cu-in. V8.

Intake valves (the valves had hydraulic lifters) were smaller than the 350: 1.72 in., vs 1.94 for the 2-bbl 350 and 2.02 for the Z28. The 1.50-in. exhaust valves were the same size as those of the 2-bbl 350; 1.60-in. valves were used in the Z28. Combustion chamber shape was still a modified wedge design and provided an 8.5:1 compression ratio with flat-head pistons. Connecting rods were shared with the 350 V8. The camshaft had reduced overlap for low-speed tractability but would interchange with any 350 cam, including the high-performance Z28 part. The hotter camshaft bolted right in, but because of increased valve lift some head work was necessary to prevent the valve springs from going solid. As one Chevrolet engineer stated at the time, "The 262 V8 was designed mainly to be smoother and quieter than the 4-cylinder, not a barnburner," its output in stock form wasn't overly impressive - only about 110 bhp at 3600-4000 rpm compared to 85 bhp for the 2-bbl 4-cylinder. Chevrolet did not publish precise performance figures (at least from what we have been able to find out) but they did say an early development car equipped with V8, automatic transmission and a 2.56:1 final-drive ratio accelerated from 0 to 60 mph in about 12 seconds. The engine can be wound to around 5500 rpm, but this was so far past the power peak it was pointless. Breathing ability was restricted by the "emission" camshaft and the 2-bbl carburetor with its minute 13/32-in. Venturis. Chevrolet engineers were quick to note, however, that a 2-bbl carburetor with larger 1%-in. Venturis and the same throttle bores had been used on previous GM engines and would allow up to a 60-percent increase in airflow.

Then as now, low emissions were obviously an important consideration in any new engine and the 262 incorporated control systems similar to the 2-bbl 350. Along with the usual exhaust, crankcase and evaporative emission-control devices, the 262 used a catalytic converter to reduce hydrocarbon and carbon-monoxide emissions downstream of the engine, allowing more spark advance for improved fuel economy and drivability, but exhaust-gas recirculation was necessary as the converter had no effect on oxides of nitrogen emissions. Keeping the engine in tune for long periods of time was another way to reduce emissions. Consequently, GM's integrated ignition system consisted of breakerless distributor, coil and transistorized power module in one compact unit as standard. Output of this system was 35 KV (1 KV= 1000 volts) vs 25 KV for a conventional system. To obtain the necessary capacity, sparkplug gaps were widened and the wire diameter of the silicon sparkplug leads was increased. Using unleaded fuel plus this high-energy ignition system resulted in a considerable increase in miles between required maintenance: sparkplug changes and idle adjustment were needed only every 22,500 miles (up from 6000 and 15,000 miles respectively); oil and filter changes went from 6000 to 7500 miles.

At launch, the standard transmission for the Monza was the 4-speed manual which was optional on the Vega. Because of the increase in tunnel height the gear lever was positioned a bit forward of the Vega location, making the throws slightly shorter. The 4-speed gearbox had sufficient capacity for the greater torque of the V8 and bolted on unchanged. An automatic transmission (three speeds with torque converter) was optional with both engines. With the V8 an 11.75-in. torque converter was used; a 10-in. converter with higher stall speeds was used with the 4-cylinder. To improve fuel economy in city traffic, light-throttle 2-3 upshifts were moved downward 3-4 mph. In addition to the extensive engine-development program to reduce fuel consumption, axle ratios were selected to increase fuel economy. With the 4-cylinder engine 3.42 and 2.93 final drives (the latter for owners who drove mostly on highways) were offered. An unusually low 2.56 ratio was standard with the V8, but the 2.93 was required with air conditioning and recommended for mountain driving.

Suspension, Steering & Brakes



With few exceptions the front suspension was carried over from Vega, although to support the added weight of the V8 the control arms were of heavier-gauge steel and incorporated larger ball-joints with wear indicators. Shock-absorber attachment points were reinforced for the same reason and spring and shock rates were computer-selected according to weight and options. Suspension geometry was unchanged from the Vega's, but according to Chevrolet the Monza was a softer car in terms of ride harshness and impact. The chassis was tuned for radial tires with the use of pads at the top of the coil springs front and this resulted in better noise control. Front and rear anti-roll bars were the same diameter as the ones used on the Vega GT, and because the standard suspension was essentially what Detroit called a "handling package," there were no suspension options. The rear suspension was extensively redesigned and went some way to eliminating most criticism of the Vega's 4-link trailing-arm design.

This new torque-arm suspension consisted of a live axle located by lower control arms that controlled fore-and-aft driving and braking forces, a Panhard rod for controlling lateral movement and a long torque arm running from the axle housing forward to the transmission case to control axle wind-up forces. This arrangement left the coil springs and shock absorbers free to perform the single function of ride cushioning. Because of the extremely long length of the torque arm, its attachment bushings could be very soft; Chevrolet cited improvements in ride, reduced power hop and better isolation from road noise and harshness for this system compared to the Vega's. The front-disc, rear-drum braking system carried over from Vega. Vacuum assist was an option (Vega got this for the first time in 1975) and was standard as part of the V8 option package. With the 4-cylinder engine the non-assisted recirculating-ball steering or variable-ratio power steering of the Vega was offered. The Monza ran on 6-in.-wide steel rims (same as for the Vega GT) with molded plastic wheel covers. Forged aluminum wheels, also 6 in. wide, were optional. The standard tire with either wheel was GM's BR78-13 "corporate" radial. At launch no other tire was available with the V8 but a then current Vega option, a bias-belted A70-13, could be ordered in place of radials with the 4-cylinder engine.

On the Inside



Because the Monza was designed as a well equipped car the option list was shorter than usual for a U.S. offering. There was only one basic interior trim, for instance: the only choice the buyer had was whether they wanted vinyl or cloth. The surprisingly complete instrumentation was essentially the Vega GT option and included large round tachometer and speedometer surrounded by four smaller gauges. The padded, small-diameter GT steering wheel was standard, and as on the Vega it still partially blocked the two upper gauges. Pleated map pockets and armrests with integral door pulls and lock buttons were features of the door trim panels. Dash-level ventilation ducts were positioned the same as in Vega but airflow was improved. Air flow to the rear of the car ran through vents inside the interior trim panels and exited through the B-pillar louvers.

Although reclining seatbacks were neither standard nor optional, the 2-position Vega seat that allows 4 degrees of rake adjustment for the driver was an option. For a car with a 2 + 2 designation the Monza had a bit more rear-seat room than usual. Seating configuration iwas a definite compromise (occupants had to assume a knees-into-chin position) but children could be taken with reasonable comfort for short trips. When the rear seat was empty the seatback could be folded flat to extend the fully carpeted cargo area accessible through the wide-opening rear hatch. The Monza 2 + 2 was viewed by Chevrolet as strong competition for not only the Mustang II but the sporty imports such as the Capri, Celica and even the Datsun 260Z. Although in some respects it was a poor-mans Camaro, Chevrolet believed it would take sales away not from the Camaro, but from Ford’s larger Mustang II.

Model Updates



The 1976 140-cubic inch four-cylinder engine, as used in the Vega got some refinements. Named "Dura-built 140", it features quieter hydraulic lifters eliminating valve adjustments. The basic four developed 70 horsepower, but two-barrel carburetion upped the rating to 84. 1976 saw the introduction of Chevrolet's new 5.0 liter (305 cid) V8 engine with a 2-barrel carburetor generating 140 horsepower (100 kW) at 3800 rpm, but only for California and high-altitude Monza customers, and replaced the 350 CID (5.7 liter) V8. The 262 V8 was again, the optional engine in the 49 states. A mid-year option for the 1976 model year was a sport front end available for the Towne Coupe, which features the 2+2's urethane front end and quad headlamps. The Monza Spyder option package was first introduced in 1976. It features a 2-barrel carburetor version of the 4-cylinder engine as standard, a floor console, F41 suspension with larger front and rear stabilizer bars, and special shock absorbers. This equipment had been standard on the original 1975 2+2 (excluding the mid-year 'S' model).

The 1977 Monza was highlighted by the addition of a two new Spyder option packages, a $274 performance package, the other a $199 appearance add-on package that was available only on hatchbacks. An 84-horsepower four-cylinder engine was standard, but Monzas could be ordered with a 145-horsepower 305-cubic-inch V8 instead. The Monza dashboard contained round gauges in a brushed-aluminum instrument panel. The Towne Coupe Cabriolet was deleted, but a half-vinyl roof and opera windows could still be ordered. The Monza Mirage was produced by Michigan Auto Techniques, an aftermarket company contracted by GM. The Mirage is painted white, with red and blue racing stripes along the length of the car. It also features flared body panels, and a special airdam & spoiler. The vehicles were built in GM's St. Therese plant, and sent to MAT for modification, after which they would ship completed cars to the dealer. There were approx 4,097 1977 Mirages made from MAT, but there were also Mirages created by Chevrolet dealerships, as the body add-ons and stripes were available ordered through dealer parts. The 5.0 liter (305 cid) engine was the only V8 option for the 1977 model year.

The standard Vega 2.3 aluminum-block engine was discontinued at the end of the model year, replaced with the Pontiac 2.5 "Iron Duke." The 1978 Monza line expanded to include rebadged holdovers from the Vega line, which ended production after the 1977 model year. Chevy grafted a new Monza front end onto the previous Vega hatchback and wagon body-styles. The Monza 'S', marketed as the Monza price leader, used the Vega hatchback body. With production of only 2,000 units, it was speculated that this was simply an effort to use up a stock of leftover 1977 Vega bodies. The Monza wagon, was also offered in an Estate wood-trimmed version, used the Vega wagon body. The 1978 Monza line gained a new base coupe and 2+2 hatchback with round headlights in an upright front end with a crossbar grille. The Sport 2+2 hatchback and Sport notchback used a modified version of the previous quad rectangular headlamps, now above a full-width open-slot grill. The 151 CID (2.5 liter) inline-4 'Iron Duke' was standard for 1978, replacing the Vega inline-4 engine. Engine options were a Chevrolet-designed 3.2 liter (196 cid) V6 engine with a 2-barrel carburetor that produced 90 horsepower (67 kW) at 3600 rpm. Replacing the 3.2 liter V6 in California and high-altitude areas was Buick's 3.8 liter (231 cid) 105-hp V6 engine.

Four-cylinder engines and the 3.2 liter V6 were not available in high-altitude areas. The 145-horsepower 305-cubic-inch V8 remained optional in all but the "S" hatchback and wagon models. Discontinued at the end of the 1978 model year were the 'S' hatchback, Towne Coupe Sport option and the Estate version of the wagon. The 1979 Chevrolet Monza linup was trimmed to four models. Added standard equipment was added for 1979 including an AM radio, tinted glass, bodyside moldings, and sport steering wheel. Only one Monza model kept the sloped Euro-look front end, the 2+2 Sport hatchback. Others had a freshened grille. A more-potent standard 151-cubic-inch (2.5-liter) four-cylinder with a redesigned cross-flow cylinder head and two-barrel carburetor developed 90-horsepower - five more than in 1978. Three optional engines were available: the 105-horsepower 196-cubic-inch V6, 115-horsepower 231 V6, or 130-horsepower 305 V8. The Spyder performance package cost $164, the Spyder appearance package added $231. All Monzas had a color-keyed instrument panel, and all except the base coupe had a center console, and corrosion protection was improved. Discontinued at the end of the 1979 model year were the Monza wagon, the 196 CID (3.2 liter) V6 and the 305 CID (5.0 liter) V8. The 1980 model year lineup consisted of a base 2+2 hatchback and notchback and 2+2 Sport hatchback; the 151-cubic-inch (2.5-liter) four-cylinder engine remained standard; the only engine option was the 3.8 liter (231 cid) Buick V6. Chevrolet decided to shelve the antiquated design and let base models of the Chevrolet Camaro and the new Chevrolet Citation X-11 hold the division's place sporty-coupe market.
Chev Monza Sport
Chev Monza

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