1960 Triumph 5TA Speed Twin

Triumph’s Edward Turner initiated the design theme of the bathtub rear metal enclosure and the deeply valanced front fender. First seen early in 1957 on the 350cc 3TA “Twenty One,” the conservative styling was then introduced for the 1959 model year on the 500cc 5TA “Speed Twin.” It didn’t go over very well here in the U.S.

According to Triumph Motorcycles in America co-authors Lindsay Brooke and David Gaylin, the bathtub design was met with disdain, and dealers had to contend with the bodywork into the mid-1960s. “Turner’s failure to accept America’s love of the ‘naked’ motorcycle cost Triumph incalculable lost sales in its biggest market,” Brooke and Gaylin note in their recently revised and expanded book. They continue: “Many U.S. dealers had to remove the factory-fitted bathtubs from the 500s and 650s just to sell the motorcycles. This was especially true in sunny, dry California, where dealers often stripped the bathtubs as soon as they uncrated the motorcycles. At the larger dealerships, including Bud Ekins’ shop in Sherman Oaks, it wasn’t uncommon to find piles of bathtub enclosures stacked up behind the shop.” In 1959, American East Coast distributor the Triumph Corporation, or TriCor for short, released their dealer catalog announcing Triumph’s lineup. In it, TriCor refers to the new 5TA as the Speed Twin Streamliner.

“A completely new 30.5 cu. in. (500cc) OHV ‘over-square’ vertical twin engine 69mm bore x 65.5mm stroke model replacing the earlier version Speed Twin, and embodying a new conception of comfortable, clean and modern motorcycling,” TriCor’s copywriter wrote of the Speed Twin. “Provides high performance with turbine-like smoothness and exceptional mechanical silence with extremely easy starting and proven reliability.”

Of the bathtub bodywork, TriCor said, “The enclosed streamlined rear seat sets a new standard of cleanliness for rider and passenger alike. Extremely generous front fender is employed and the whole machine is of modern advanced design, beautiful appearance, low comfortable seating position, most economical to operate and easy to keep clean. This fine new Triumph model looks to the future and will appeal not only to experienced motorcyclists but to newcomers to the fun and economy of motorcycling.”

From Tiger to Speed Twin

It was a different look for the Speed Twin model, which was first introduced in July 1937. But the Speed Twin wasn’t the company’s first twin. In 1913, Triumph developed an experimental 600cc side-valve vertical twin engine that never saw production.

In the 1930s, Triumph designer Val Page created the parallel twin 6/1. It was in the company’s catalog from 1934 to 1936 before motorcycle magnate Jack Sangster, who also owned Ariel, purchased Triumph and in 1936 installed Edward Turner as chief designer and managing director.

Turner’s first exercise at Triumph was to dress up three Page-designed overhead valve single-cylinder machines, creating the 250cc Tiger 70, 350cc Tiger 80 and 500cc Tiger 90. These motorcycles had a definite sense of style, and were equipped with polished alloy primary chain cases, chrome-plated gas tanks with silver-sheen painted panels, and purposeful, high-level exhaust systems. The engines were housed in rigid frames driving a separate transmission and were equipped with girder forks.

With the Tigers complete, Turner began a new project and sketched out a twin-cylinder engine with a vertically split crankcase housing a single, central flywheel. The 498cc engine featured 63mm bore by 80mm stroke and had its crankpins “in line,” with both pistons rising and falling simultaneously. The cylinders fire alternately, with power impulses spaced evenly at 360 degrees. Early Speed Twin engines were fitted with a six-stud cast iron barrel. The cylinder head was also cast iron, with separate alloy boxes housing rockers and valve adjusters. Camshafts sat high in the crankcase and were gear driven through an idler gear turned by a crankshaft pinion gear in the right hand timing chest. Separate pushrod tubes ran fore and aft of the cylinders, and ignition was supplied by a combo magneto/generator mounted on a cast platform at the rear of the engine.

The 5T Speed Twin was born when Turner placed this parallel-twin engine into the heavyweight Tiger 90 single-cylinder frame, with cycle parts painted Amaranth Red. A popular seller, the Speed Twin was updated with a new eight-stud cylinder design before production stopped in 1940 due to World War II. When the Speed Twin returned in 1945 for the 1946 model year it was updated with hydraulic forks, the generator was moved to the front of the engine and the magneto gained automatic ignition control.

Triumph continued producing the Speed Twin with minor variations in design, introducing the optional sprung-hub rear suspension system in 1947 and an enclosed headlight with a nacelle in 1949. In 1953, Triumph gave the Speed Twin an alternator for power generation and the engine cases were altered to delete the generator. In 1955 Triumph finally brought swingarm rear suspension to its range and the Speed Twin was so equipped. In 1957, new tank badges were installed, as was a full-width, 7-inch cast iron front brake hub.

And that brings us to 1959 when Triumph brought out the 5TA Speed Twin, based on the unit-construction platform of the 350cc 3TA. The 490cc engine of the 5TA featured a much shorter stroke than the original Speed Twin and had unitized construction, with the transmission mainshaft, layshaft and gears carried in a cavity cast into the rear of the alloy engine crankcases.

The front and rear wheels of the 5TA were the same size as those on the 3TA, 17 inches in diameter each, and 2 inches smaller than the 19-inch wheels found on the Speed Twin of the previous year. And the Speed Twin was no longer Amaranth Red — the TriCor catalog lists the color as Continental Red, a deep ruby hue. Triumph persisted with the bathtub enclosure until 1964, when an abbreviated “bikini” version appeared that lasted a single year, through 1965. By 1966, the Speed Twin was once again naked, but the model was at the end of its road and the 5TA was dropped. There were, however, other 500cc Triumph models available, including the Tiger T100 followed by the sporty Daytona models of the late 1960s and early 1970s.

Finding a bathtub

And that brings us back to Gary’s 1960 Speed Twin. Obviously, Gary likes something a little unusual, and says his riding career started when he was about 8 years old aboard a Whizzer-powered bicycle. His dad ran an automotive machine shop in Green Bay, Wisconsin, called Athey’s Garage, so Gary was no stranger to engines and gears. He says in his early riding days, he could buy a 1930s Harley-Davidson for $35, fix it and ride it, but he always wanted a bathtub Triumph.

He didn’t get one until early 2012. That’s when he asked Randy Baxter of Baxter Cycle in Marne, Iowa, to help him find one. “The bathtub Triumph turned me on, but they were really hard to find in complete condition,” Gary says.

Randy found the 1960 bathtub Speed Twin in Arkansas, where the seller had picked up the Triumph with the intention of simply flipping it. As a result, nothing is known of the bike’s previous history, but the most important thing to Gary was that it was all in one piece and the rear enclosure was in place. “I’ve been attending motorcycle swap meets for years and I’ve never seen a bathtub — on its own — for sale,” Gary tells us. “This Triumph was worn out, and was just a plain, old, tired machine. But I don’t like to buy anything in a basket, so it was ideal. I like to make my motorcycle projects as perfect as I can, and will always look for new-old-stock parts to make them that way.”

For this Speed Twin, Gary had a tremendous amount of help from Randy at Baxter Cycle, who had or found many of the new-old-stock (NOS) components required to bring the machine to the level it’s at now. Included on that list of parts would be the 17-inch rims, correct spokes, fork tubes, wiring harness, taillight, headlight, seat, Smiths speedometer and all of the replacement rubber parts. If something wasn’t NOS, such as the exhaust pipes and mufflers, it had to be near perfect for Gary to accept it.

As Gary proceeded with restoration he found no surprises. The frame was straight and true, with no cracks or previous repairs. The forks were good, but were rebuilt with NOS tubes and all new internal components. Original front and rear wheel hubs were cleaned and painted red before new bearings were installed and the NOS rims and spokes laced into position with Avon tires finishing the wheels.

Bodywork was minimal, as there were no major dents requiring attention. As a matter of course, however, Gary properly cleaned the inside of the gas tank and lined it for protection. “I’ve used two or three different brands over the years,” Gary says of tank lining products. “I’ve never had trouble with any of them, and if somebody does I’d suggest it’s because the tank wasn’t cleaned as well as it should have been.”

Paint and more

All the red parts on the Speed Twin, including the frame and associated brackets and stands, hubs, fork lowers, headlight nacelle, chain guard, brake pedal, gas tank and the bathtub, were painted by Gary’s friend John McHugh.

Where Gary likes to spend his time is in the engine, because that’s his area of expertise. Gary bought his dad out of Athey’s Garage in 1970, and although now retired, he still likes to perform all of his own machining. When he disassembled the top end of the Speed Twin engine he found it had plus-0.020-inch pistons.

Gary cleaned up the crankshaft and turned the journals to accept new shell bearings. He sent the connecting rods to Baxter, who had the big ends “cleaned up” to bring them back into spec. Gary fit and honed new small end connecting rod bushes before reinstalling the complete assembly in the crankcase, with fresh crankcase bearings.

The cylinders could have been lightly honed and new rings installed on the existing pistons, but Gary bored it to plus-.030 inch, using NOS oversized pistons and rings from Baxter Cycle. Gary re-cut the valve seats in the alloy cylinder head and finished it with fresh valve guides, valves and springs — all NOS, of course.

Into the freshly painted cycle parts Gary installed the meticulously detailed 490cc engine, using the Triumph hardware that he’d cleaned and had either cadmium or chrome plated, as per original. New-old-stock ignition points and coils were used in the rebuild, too, as Gary doesn’t like to veer from factory specifications. Remarkably, he says it was a straightforward restoration, with no surprises.

The 5TA is in his personal collection, and while it satisfied Gary’s itch for something different, it’s been joined by its smaller sibling and bathtub-wearing 1958 3TA, which has also been similarly restored. “The bathtub Triumphs caught my attention all those years ago, I enjoy having them around now.” MC