1934–1935 LaSalle Convertible Coupe: Oldsmobile-derived straight-eight

Cadillac built the 1934 LaSalle Convertible Coupe as part of Series 350, powered by a 240.3-cubic-inch L-head straight-eight commonly rated at 95 horsepower. For 1935 the open two-door continued under the Series 50, also identified in marque literature and collector references as the 35-50, with an enlarged engine of approximately 248 cubic inches and a commonly published rating of 105 horsepower.

The change from Cadillac-derived V-8 power to an Oldsmobile-based inline-eight was central to LaSalle's survival during the Depression. It reduced manufacturing cost while the 119-inch-wheelbase chassis, independent front suspension and low, narrow grille gave the companion marque a visual identity distinct from both Oldsmobile and Cadillac.

Best known for combining Cadillac Art and Colour styling with a lower-cost straight-eight chassis, the 1934 Series 350 also gained national exposure when a LaSalle served as the pace car for the 1934 Indianapolis 500.

Collectors still value the Convertible Coupe for reasons that extend beyond open coachwork. It represents the sharp mechanical break between the V-8 LaSalles of 1927 through 1933 and the later Cadillac-powered cars, while its rumble-seat body, closely skirted fenders and low-mounted lamps capture General Motors styling at the point when upright formalism began yielding to streamlining.

Quick Facts

The basic distinctions are best understood by separating the factory series names. Series 350 applies specifically to 1934; treating every 1934–1935 example as a Series 350 obscures a genuine model-year change.

The Companion Marque Streamlined Era is an editorial and collector-era description rather than a Cadillac factory generation code. The dependable period identifiers are the LaSalle marque, model year, factory series, Fisher body information and the corresponding chassis and engine records.

Why the 1934–1935 LaSalle Convertible Coupe Matters

LaSalle sales had fallen sharply as the Depression reduced demand for medium-priced luxury cars. Cadillac responded in 1934 with a smaller and less costly LaSalle whose engine shared its basic architecture with Oldsmobile rather than Cadillac's V-8. The decision lowered the car's price and manufacturing burden without abandoning Cadillac assembly standards, dealer support or styling supervision.

The Convertible Coupe made that strategy unusually visible. Its folding top and rear rumble seat exposed the short passenger compartment, long hood and tapered tail more clearly than the sedan bodies could. A narrow radiator shell, integrated front-fender forms and lamps set low beside the grille reduced the tall, separate-component appearance of earlier LaSalles.

The 1934 Indianapolis 500 pace-car assignment gave the redesigned LaSalle a public role that had nothing to do with homologation or factory racing. No special competition version was required, and surviving pace-car-themed cars must not automatically be assumed to have been official Speedway vehicles.

Historical Context and Development

Cadillac, LaSalle and the Depression market

General Motors introduced LaSalle for 1927 as a companion marque produced under Cadillac. Early LaSalles used Cadillac-derived V-8 engines and styling directed by Harley Earl, but the economic case for such close mechanical kinship weakened after 1929. By 1934, Cadillac needed a LaSalle that could be sold and built at a greater distance from its senior cars.

Packard remained a formidable luxury rival, while Buick covered much of the upper-middle-price territory within General Motors. Chrysler's Airflow arrived for 1934 with much more radical aerodynamic packaging. LaSalle followed a less disruptive course: conventional front-engine, rear-drive proportions clothed in lower and more integrated bodywork.

The 1935 Packard One Twenty intensified competition by offering an eight-cylinder Packard at a lower price than the firm's traditional senior cars. LaSalle's straight-eight chassis therefore mattered commercially as well as mechanically. It gave Cadillac dealers a less expensive product during a period when established luxury manufacturers were searching for volume below their traditional flagship lines.

Styling direction

Cadillac's Art and Colour organization replaced the upright grille and separate visual masses of the early 1930s with a slim radiator treatment, flowing fenders and a body set lower over the chassis. The headlights sat close to the grille rather than standing high on a broad crossbar. On the Convertible Coupe, the low windshield and compact fabric top made the hood appear particularly long.

The rumble-seat deck tapers behind the doors, creating a cleaner profile than the more practical touring bodies. Running boards remained, so the design was evolutionary rather than envelope-bodied, but the car clearly anticipated the integrated proportions that would define later 1930s American design.

Engine and Drivetrain

The 1934 engine was a side-valve, or L-head, inline-eight of 240.3 cubic inches. Although built for LaSalle, it was derived from Oldsmobile practice rather than the Cadillac V-8 used by the previous generation. The 1935 unit retained the same general architecture but gained displacement and output.

Both engines used a detachable cylinder head, a single downdraft carburetor and conventional coil-and-distributor ignition. Pressure-fed lubrication served the engine's working bearings, while a belt-driven fan, water pump and radiator handled cooling. Exact carburetor models and detail calibrations should be verified against model-year parts books because restored cars have frequently acquired later or substitute units.

A single dry-plate clutch fed a three-speed manual gearbox and rear axle. Synchromesh eased shifts in the upper ratios, although first gear remained a ratio best selected at rest or nearly so. Rear-axle ratios could differ with equipment and intended service, making the build record and physical gear count more useful than assumptions based on model year.

The most consistently documented engine figures are summarized below. Period references are not uniform on the exact decimal displacement of the 1935 engine, so it is commonly described simply as the 248-cubic-inch unit.

Factory publications did not emphasize torque or engine speed in the manner of later specification sheets, and reliable model-specific torque and redline figures are not consistently documented. Those numbers should not be inferred from later Oldsmobile engines merely because the LaSalle unit shared an engineering lineage with them.

Chassis, Suspension and Braking

The Fisher body was mounted on a separate steel frame with substantial cross-bracing. As with many open cars of the period, the absence of a fixed roof placed greater demands on the body sills, door openings and timber used in structural and trim-supporting areas. A restored body can look straight on stands yet reveal weak door alignment once its full weight returns to the chassis.

Independent front suspension was a major feature of the 1934 redesign. General Motors promoted its enclosed coil-spring arrangement as Knee-Action suspension. The rear remained a conventional live axle supported by semi-elliptic leaf springs, a layout that balanced improved front-wheel control with proven rear-axle durability.

Steering was manual, with a large wheel providing leverage at parking speeds. Four-wheel mechanical drum brakes were appropriate to the period but require careful adjustment so that all wheels contribute evenly. Hydraulic brakes did not define these 1934–1935 LaSalles, a point sometimes missed when later components have been installed during an older restoration.

The table concentrates on chassis facts that materially affect identification and restoration.

Correct setup matters more than the apparent simplicity suggests. Worn front-suspension joints, tired dampers, loose steering components and unequal brake adjustment compound one another, producing wandering and long stopping distances that are not representative of a properly sorted car.

Driving Experience and Road Manners

The straight-eight's strongest quality is smooth delivery rather than high engine speed. Closely spaced firing pulses, a heavy flywheel and modest compression allow the LaSalle to pull progressively from low road speeds, provided the driver does not ask top gear to cover every gradient. The 1935 engine's additional output gives it a little more flexibility, but neither version rewards sustained high revolutions.

First gear gets the car moving, second handles town work and hills, and top serves as the cruising ratio. A deliberate hand and a pause through neutral suit the gearbox. Worn linkages, tired synchronizers or incorrect lubricant can make an otherwise sound transmission appear much less cooperative.

At speed, the independent front suspension isolates sharp road disturbances better than the beam-axle arrangement of many earlier luxury cars. The rear axle still communicates ridges and broken surfaces, especially when the car is lightly loaded. Body roll is evident by modern standards, yet a well-rebuilt chassis should settle after a single movement rather than continue floating.

Steering effort is substantial while parking and becomes more natural once rolling. Response is measured rather than quick, with the narrow tires and large wheel feeding road texture back through the rim. Mechanical brakes offer usable progression when correctly synchronized, but they demand greater anticipation and pedal effort than later hydraulic systems.

Identification and Originality

Series, chassis and body evidence

A genuine 1934 car should be documented as a Series 350, while a 1935 example belongs to Series 50 or 35-50. The Fisher body-data plate, chassis or serial identification and engine number should be examined together. No single loose plate should be treated as conclusive proof of body style or model year.

Exact number locations and sequences should be checked against the applicable Cadillac-LaSalle shop manual, parts book and LaSalle club records. Published internet decoders often combine Cadillac and LaSalle ranges or treat an engine number as though it were a modern standardized VIN. These cars predate the 17-character VIN system by decades.

Matching numbers also require period-appropriate interpretation. The engine carries a production or unit number, but the modern expectation that every major component bears the same complete vehicle serial does not apply. A credible original car instead presents numbers, casting features and components that correspond to its model year and documented production sequence.

Body, trim and finishes

The Convertible Coupe should retain the correct rumble-seat body structure, folding-top mechanism, windshield arrangement and open-car doors. Converting a closed coupe into an open body involves far more than removing the roof, and discrepancies in sill reinforcement, cowl structure, door tops and rear deck construction usually expose such work.

Original wood patterns are especially valuable during restoration. Door fit, top-bow geometry and the relationship among the rear deck, rumble-seat lid and quarter panels depend on body structure that may have deteriorated invisibly beneath upholstery or metal skins.

Wheels, hubcaps, lamps, instruments, carburetors, distributors, generators and brake components are frequently replaced with visually similar GM parts. Similar does not mean correct. A serious restoration should use dated factory literature, period photographs, body-tag information and surviving untouched cars rather than relying solely on catalog descriptions.

Paint colors and upholstery combinations must be verified from model-year Cadillac-LaSalle color and trim references. Modern color names or generic formulas cannot establish authenticity, and an old repaint may preserve useful evidence inside the cowl, beneath door hardware or behind interior trim.

Variant and Trim Breakdown

For this body style, the meaningful variant division is by model year and factory series. There was no homologation model, production racing derivative or separately cataloged high-performance Convertible Coupe.

Exact Convertible Coupe production totals are not consistently presented across surviving references, particularly where body-style totals and model-year totals are conflated. Claims of extreme rarity should therefore be supported by factory records or recognized marque research rather than an uncited registry figure.

Performance and Dimensional Specifications

Factory literature supplies chassis dimensions and rated power more reliably than modern-style acceleration data. Model-specific 0-to-60 mph, quarter-mile and independently measured top-speed figures are not consistently available for the Convertible Coupe, so they are omitted rather than reconstructed from sedan tests or later recollections.

Published vehicle weights can differ according to whether a source quotes shipping weight, curb weight or an equipped car with sidemounts and accessories. The same caution applies to overall length, which may reflect bumper and spare-wheel arrangements. A build-specific appraisal should use factory body data and direct measurement.

Compared With Related LaSalle Models

Versus the 1933 LaSalle

The 1933 model belongs to the earlier Cadillac-derived V-8 lineage and carries more upright body architecture. The 1934 Series 350 is not merely a facelift. Its inline-eight engine, smaller chassis, independent front suspension and new body design make it a distinct mechanical generation.

Versus the 1935 Series 50

The 1935 Convertible Coupe is often advertised casually as another Series 350, but its proper series designation and enlarged engine separate it from the 1934 car. Much of the visual concept continued, so body tags, mechanical details and documentation deserve more weight than a seller's model description.

Versus contemporary Cadillac models

Cadillac retained V-8 power, larger dimensions and a higher price. The LaSalle did not simply use a shortened Cadillac chassis with fewer trim pieces. Its Oldsmobile-derived straight-eight was the key cost-saving distinction, even though Cadillac manufactured and marketed the complete car through its organization.

Versus the 1937 LaSalle

The 1937 LaSalle returned to Cadillac V-8 power with a 322-cubic-inch engine and introduced another major styling and engineering change. Buyers who want the streamlined straight-eight chapter must therefore concentrate on 1934 through 1936, while collectors seeking the later Cadillac-powered experience generally begin with 1937.

Ownership and Restoration Notes

Mechanical parts availability is uneven. Routine ignition, bearing and brake materials can often be sourced or reproduced by specialists, but correct engine castings, suspension housings, trim, instruments and Convertible Coupe body hardware are much harder to replace. A complete but worn car is usually a better restoration foundation than a cosmetically attractive example missing model-specific pieces.

The cooling system deserves close attention. Sediment in the block, restricted radiator tubes, a worn water pump and incorrect ignition timing can combine to produce overheating. Before rebuilding the engine, a specialist should inspect the block and head for cracks, measure the crankshaft and bearing clearances, assess valve-seat condition and confirm oil-pump performance.

The gearbox should be evaluated for bearing noise, jumping out of gear and weak synchromesh. Clutch chatter can arise from contamination, distorted components, worn mounts or poor alignment rather than the friction disc alone. Rear-axle noise requires inspection before assuming that a lubricant change will cure worn gears or bearings.

Structural restoration is the greater financial risk. The lower cowl, door posts, sills, rear quarters, rumble-seat gutters and floor-to-frame mounting areas can conceal corrosion or failed wood. Top irons may be bent or assembled from unrelated parts, and reproducing a correct-fitting fabric top is specialist trimming work.

Mechanical brakes need equalized cables, sound drums, correctly arced linings and free pivots. Lubrication schedules in the original owner's and shop manuals should be followed because the chassis contains many service points that later cars eliminated. Long storage periods make inspection of fuel, cooling and braking systems mandatory before road use.

Buyer and Inspection Points

A pre-purchase inspection should establish identity and structural completeness before evaluating paint. The following checks address the failures most capable of turning a viable LaSalle into a stalled restoration.

Documentation has direct practical value. Old photographs, ownership records, restoration invoices, engine work orders and body-tag images can explain apparent deviations and prevent the removal of genuine period equipment.

Collector and Market Relevance

Open two-door bodies draw the strongest attention within many prewar American model lines, but the LaSalle's appeal is not based on body style alone. The 1934 Series 350 records Cadillac's response to an economic crisis through a new engine source, a smaller platform and markedly lower body design. The 1935 Series 50 shows how quickly that formula was refined through added displacement and detail development.

Collectors generally reward complete cars with sound original structure, coherent numbers, correct instruments and hardware, and documented restoration work. Authenticity matters particularly on the Convertible Coupe because closed-car components, later hydraulic brakes, replacement engines and fabricated open-body trim can produce a visually convincing but historically confused car.

The 1934 pace-car association adds recognition, but it must be handled carefully. An ordinary production Convertible Coupe does not become an official Indianapolis car through paint and lettering. Documented Speedway history, if claimed, requires a chain of evidence substantially stronger than resemblance to period photographs.

Cultural and Motorsport Relevance

A LaSalle paced the 1934 Indianapolis 500, placing Cadillac's redesigned companion marque before one of the largest American motorsport audiences of the period. This was a promotional and ceremonial role, not evidence that the Series 350 was designed as a racing or homologation model.

LaSalle also retains a dedicated club and preservation culture shared with Cadillac. That network is particularly important for straight-eight cars because factory literature, patterns, used components and knowledge of year-specific details are often held by long-term marque specialists rather than broad aftermarket suppliers.

The 1934 styling has broader historical weight within General Motors design. Its low lamps, slender grille and integrated fender forms offered streamlining without the radical packaging of the Chrysler Airflow. That visual vocabulary proved easier for conservative luxury buyers to accept and soon appeared, in evolved form, throughout the American industry.

Frequently Asked Questions

Is every 1934–1935 LaSalle Convertible Coupe a Series 350?

No. Series 350 is the correct designation for 1934. The 1935 car belongs to Series 50 and is also commonly identified as the 35-50 in year-series form.

What engine is in the 1934 LaSalle Series 350?

It uses an Oldsmobile-derived 240.3-cubic-inch L-head inline-eight, commonly rated at 95 horsepower. It is not the Cadillac-derived V-8 fitted to the preceding LaSalle generation.

How does the 1935 LaSalle engine differ?

The 1935 Series 50 retained the L-head inline-eight layout but increased displacement to approximately 248 cubic inches. Published output rose to 105 horsepower.

How can a genuine Convertible Coupe be identified?

Inspect the chassis or serial identification, engine number and Fisher body-data plate together, then compare them with the correct model-year factory references. The body should show purpose-built open-car reinforcement, correct door and cowl structure, a folding-top mechanism and an integral rumble-seat compartment.

Did the 1934 LaSalle have hydraulic brakes?

No. The Series 350 used four-wheel mechanically actuated drum brakes. Hydraulic conversions may improve convenience for some owners, but they are not original equipment and should be disclosed.

What are the most expensive restoration problems?

Failed open-body wood and sills, incomplete top hardware, damaged Knee-Action suspension components and a worn or cracked straight-eight can dominate a restoration budget. Missing trim and instruments are also costly because demand is small and reproduction coverage is limited.

Why is the 1934 LaSalle associated with Indianapolis?

A 1934 LaSalle served as the Indianapolis 500 pace car. The role gave the redesigned model substantial publicity, but it did not create a regular-production racing version, and pace-car provenance must be documented individually.

Collector Takeaway

The 1934 Series 350 Convertible Coupe matters because Cadillac changed nearly every assumption that had defined LaSalle. It replaced Cadillac-derived V-8 power with a smaller Oldsmobile-based straight-eight, adopted independent front suspension and wrapped the chassis in one of General Motors' clearest early expressions of streamlined design. The 1935 Series 50 then sharpened the same formula with greater displacement and output.

The best surviving examples are not simply glossy open cars. They retain coherent factory identity, sound Fisher body structure, the correct straight-eight drivetrain and the difficult small hardware that restorers cannot order from a generic catalog. Preserved on those terms, the Convertible Coupe documents how Cadillac kept LaSalle viable during the Depression without disguising it as a cut-price Cadillac.