1948 – 1958 Buick Roadmaster Convertible

The Roadmaster is an automobile that was built by Buick from 1936 to 1958.
Roadmasters produced between 1936 and 1958 were built on Buick’s longest non-limousine wheelbase
They shared their basic structure with entry-level Cadillac and senior Oldsmobiles.
Between 1946 and 1957 the Roadmaster served as Buick’s flagship.
It was resurrected for the 1991 through 1996 model years it was the marque’s largest vehicle.


The 1942 Roadmaster was:
Wider, and roomier than before.
This was due to it’s longer wheelbase.
There was also:
A new vertical-bar grille and “Airfoil” fenders that swept back all the way to the rear fenders
Both features became a Buick icon exhibited in one way or another for years to come
The 4-door phaeton was dropped and would never return.
Coupes adopted the appealing Sedanet fastback style that had been the sensation of 1941 on the Century and Special.
Effective at the beginning of 1942, new automobiles were available only to those in occupations deemed essential to the war effort.
By mid-January, cars with no exterior chrome trim apart from the bumpers were being produced.
By February passenger car production was shut down completely.
Despite the abbreviated model year a total of about 8,400 were sold.


Postwar automobile production resumed in the 1946 model year.
Features included:
Chrome more sparingly applied
Swept-back fenders were fitted to sedans as well as coupes
A war-inspired “bombsight” hood ornament was adopted.
Additional features included:
The instrument panel was two-toned with woodgrain facings except on convertibles which used body-colored panels.
Series identification was found on cloisonne emblems centered in the bumper guard front and rear. Compound Carburetion was eliminated
The compression ratio was reduced to 6.60:1.
As a consequence the 1946 Roadmaster’s horsepower fell from 165 to 144.
Torque on the other hand was hardly affected.
Nevertheless, Roadmaster’s I-8 still produced more horsepower than a top of the line Chrysler’s. Due to wartime inflation prices were substantially higher.
Roadmaster increased its share of Buick sales from four percent in 1941 to 20 percent in 1946, with a total of about 31,400 sold.


In 1947 a new stamped grille with a separate upper bar was used
The Roadmaster name appeared in red-filled script on a chrome button within the bumper guard crossbars, front and rear
All new was an Estate wagon body style
It sold 300 units and instantly became the top of the line in the station wagon market.

In 1948:

A series script appeared on the front fenders and the white Tenelite steering wheel that had been used previously was traded in for a black one
A new optional custom trim option was offered, consisting of cloth upholstery with leather bolsters with the robe cord cover and lower door panels trimmed in leatherette
Convertibles acquired power windows, seat and top as standard equipment.
But the biggest advancement was the introduction of Dynaflow, the first passenger car torque converter transmission.
Optional on Roadmaster in its first year, it was so popular that by the following it was standard equipment.
Overall sales were just under 80,000 in both 1947 and 1948, over four times greater than in any prewar year.

1949 Buick Roadmaster

The Roadmaster received its first major postwar restyling in 1949.
Its wheelbase and overall length were reduced but its weight was actually marginally increased
The biggest change was a much larger two-piece, curved glass windshield that the sales brochure described as like an “observation car.”
It was also in 1949 that Buick introduced “VentiPorts.” Four were displayed on each of the Roadmaster’s front fenders, with three on the fenders of the Super, Century, and Special.
The sales brochure noted that VentiPorts helped ventilate the engine compartment, and possibly that was true in early 1949, but sometime during the model year they became plugged. The idea for VentiPorts grew out of a modification Buick styling chief Ned Nickles had added to his own 1948 Roadmaster.
Ned Nickles Re-Styling
He had installed:
Four amber lights on each side of his car’s hood wired to the distributor so as to flash on and off as each piston fired simulating the flames from the exhaust stack of a fighter airplane.
Combined with the bombsight mascot, VentiPorts put the driver at the controls of an imaginary fighter airplane.
Buick chief Harlow Curtice was impressed and he ordered that VentiPorts be installed on all 1949 Buicks, with the number of VentiPorts (three or four) corresponding to the relative displacement of the straight-eight engine installed.

Standard Equipment

Dynaflow was now standard equipment,
Engine horsepower was increased to 150 through a slight increase in the compression ratio.
This contributed in conjunction with the now standard Dynaflow in giving the new Buicks a top speed of 110mph.
In the middle of the year the Riviera, joined the body style lineup selling 4,314 units.
It featured:
Featuring power windows as standard equipment
The 2-door Buick Roadmaster Riviera,
Along with the Cadillac Series 62 Coupe de Ville and the Oldsmobile 98 Holiday, was among the first hardtop coupes ever produced.
The Riviera was also notable for it’s:
Popular optional “Sweepspear” chrome body side molding, which would soon become a Buick trademark.
This chrome-plated strip started above the front wheel, after which it gently curved down nearly to the rocker panel just before the rear wheel, and then curved around the rear wheel in a quarter of a circle to go straight back to the tail-light.
The “Riviera trim”, as it was initially called, was also made available on the Roadmaster convertible very late in the model year.
With a total of 88,130 sold, the all-time annual record for Roadmaster.
The model accounted for 27 percent of all Buick sales, a remarkably high proportion in light of its price, which was only slightly less than a Cadillac Series 61.

1950 Re-Styling

The 1950 restyling featured:
A grille so toothy that Consumer Reports commented that “a toothbrush for the dentures comes extra.”
The Sweepspear had proved so popular in its first year that it was made standard on most body styles at the beginning of the 1950 model year, and on the station wagon and the new long wheelbase sedan mid-year.
The long wheelbase sedan was stretched an extra four inches (102 mm). Like the convertibles, the Riviera and the extra plush long wheelbase sedan came with both power windows and power seats as standard equipment.
Overall Roadmaster sales fell to 75,034
Roadmaster’s share of total Buick output plummeting to 12 percent
In 1951 the long wheelbase sedan was also called a Riviera although it was not a hardtop. The Sedanet and regular wheelbase sedan were cancelled.
Styling changes were minimal in 1951 and 1952.


Power steering was added as an option in 1952 and horsepower climbed to 170 thanks primarily to a new four-barrel carburetor.
Sales continued to slide falling to about 66,000 in 1951 and to 51,000 in 1952.


By 1953 the Roadmaster straight-eight was 16 years old and had become seriously dated.
All of Roadmaster’s major competitors had shifted to short-stroke V-8 engines.
If Buick wanted to continue to be the paragon of longer, lower and wider, it needed one of its own.
The new engine was ready in time for 1953, Buick’s Golden Anniversary year.
Although the Nailhead (as it was popularly called) was nearly identical in displacement to the straight eight Fireball (322 versus 320 cubic inches), it was 13.5 inches (340 mm) shorter, four inches (102 mm) lower, and 180 pounds lighter.
With 188 horsepower, it was 11 percent more powerful.
The compact dimensions of the V-8 engine enabled Buick to reduce Roadmaster’s wheelbase by 4.75 inches (121 mm) across the line.
Buick also introduced a new “Twin-Turbine” Dynaflow as a companion for the V-8 engine.
Estimated to increase torque at the wheels by 10 percent, the new transmission provided faster and quieter acceleration at reduced engine speeds.
Standard and Options
Both power steering and power brakes were made standard.
Air conditioning was a new option
A 12-volt electrical system was adopted.
A new body style for 1953 was the Skylark convertible.
The Buick Roadmaster Skylark was one of three specialty convertibles produced in 1953 by General Motors, the other two being the Oldsmobile 98 Fiesta and the Cadillac Series 62 Eldorado.
The Skylark featured:
Open wheel wells
Drastically lowered belt line
Four-inch-chop from the standard Roadmaster’s windshield
Absence of VentiPorts and a new Sweepspear
Kelsey-Hayes wire wheels
A solid boot cover
At $5,000 only 1,690 units were produced.
It would become its own series built on a Century body.
This was the last year for the Roadmaster Estate, and it was the last wood-bodied station wagon mass-produced in the United States.
Its body was a product of Ionia Manufacturing which built all Buick station wagon bodies between 1946 and 1964
Priced at $4,031, 670 were sold.
Overall Roadmaster sales bounced back up to 79,137.


1955 Buick Roadmaster Riviera coupe
In 1954 Buick Roadmaster and Super shared with Cadillac and Oldsmobile 98 the new General Motors C-body, adopting:
The new “ponton” appearance
The addition of “Dagmar bumpers” to the front.
These were large, roomy cars, as much as five and a half inches longer in wheelbase and more than nine inches (229 mm) longer overall than in 1953.
Roadmaster script was found on the rear quarters and within the deck ornament.
New Features Included:
Rear fenders had a blunted fin at the rear edge
Dual “bullet” taillamps below.
A new panoramic windshield with vertical side pillars was used
Seats had chrome bands on 2-door models
Rear seats had an armrest on 4-door models
The front suspension was refined and Roadmaster’s horsepower was increased to 200
The pillared coupe and the Estate wagon were no longer offered as body styles
Overall sales dropped to 50,600.

1955 Features

In 1955 the new features included:
Broad lower rear fender bands
Gold-colored Roadmaster deck script and hood ornament
Bars on the hubcaps
Gold-accented grille added to distinguish Roadmaster
Horsepower jumped to 236
A new variable-pitch Dynaflow, in which the stator blades changed pitch under hard acceleration, provided quicker off-the-line getaway.
Back up lights were now standard.
Overall sales were 64,500.

In 1956 Roadmaster had a:

Shallower Sweepspear that did not dip all the way to the rocker panel as on other models.
Twin chrome strips graced the decklid with Roadmaster spelled out between them
Roadmaster script now appeared on the doors beneath the vent windows
Fender tip dual bombsights were standard
Two stator wheels were adopted as an improvement to Dynaflow
A brand new 4-door Riviera hardtop, proved to be the most popular Roadmaster, with 24,770 units sold.
Overall sales were 53,500. A padded dash became standard.

1958 Buick Roadmaster 75 Riviera
1958 Features
The 1958 features included:
A lower body graced the 1957 Roadmaster
An even more panoramic windshield equipped with reverse slanted pillars
A red-filled Sweepspear lined the bodyside
A chromed rear fender lower panel filled the area between the wheelhouse and the bumper end
“Dagmar bumpers” at the front.
New centered fuel filler was found in the rear bumper
The ends of which the single or optional dual exhaust passed through
Roadmaster script was found within the deck and grille emblems
Two door models had a trio of chevrons on the rear quarters but the four door models had a Roadmaster emblem nestled within the Sweepspear dip
Interiors featured a padded dashboard and were broadcloth and nylon in 4-doors
Nylon in 2-doors and leather in convertibles

New Engine

There was a new 364-cubic-inch engine, developing 300 horsepower
A new ball-joint suspension system improved handling
The pillared sedan was dropped entirely from the model lineup.
Also, new was a mid-year production ( March 1957) Roadmaster designated as Model 75 which was distinguished by:
Standard power seats and windows
Carpeted lower doors
A one piece rear window
Deluxe hubcaps and a Series 75 script found on the rear quarter body panel of the R.M.
Coupes and the rear door panels on the R.M. 4-door sedans replaced the standard 3 chevrons found in the same location on the standard full model year Roadmaster model lines
Roadmaster sales plunged to about 33,000.
However, this “sales plunge” was not an isolated occurrence found only at GM but was one shared by all manufacturers to one extent or another due to a capital market recession.


For 1958, GM was promoting their fiftieth year of production.
Anniversary models were created for each brand; Cadillac, Buick, Oldsmobile, Pontiac, and Chevrolet
The 1958 models shared a common appearance on the top models for each brand:
Cadillac Eldorado Seville
Buick Roadmaster Riviera
Oldsmobile Holiday 88
Pontiac Bonneville Catalina
All-new Chevrolet Bel-Air Impala.
In 1958 the Roadmaster could only be ordered as the well-equipped Roadmaster 75
It’s body was adorned with bulkier more heavily chromed styling.
It included:
A new “drawer pull” grille made up of rectangular chrome squares.
No distinguishing VentiPorts on the front fenders.
On the rear deck the Roadmaster name was spelled out in block lettering beneath a Buick emblem housing the trunk lock keyway
The Wheelhouses had bright mouldings
Rocker panels had an ebbed moulding and a large rear fender bright flash with ribbed inserts
Four headlamps were standard
New brakes, with cast iron liners in aluminium drums, proved to be the best in the industry
Sales fell further to about 14,000.
There was a complete restyling for 1959, but this time the names of the various series were changed.
Not until 1991 would there again be a big Buick known as the Roadmaster; the largest Buick models were renamed the Electra.

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