A Wisconsin builder combines a Greeves frame with a Triumph T100S engine to create a road-legal street tracker.
1962 Greeves/Triumph “Grumph” Special
1962 Greeves/Triumph “Grumph” Special
Engine: Triumph 500cc OHV parallel twin, 69mm x 65.5mm bore and stroke; 9:1 compression ratio, 41hp at 7,200rpm
Top speed: 105mph
Carburetion: Two Amal 626 Concentric
Transmission: 4-speed, chain final drive
Electrics: 12v, Pazon electronic ignition
Frame/wheelbase: Greeves 24SC Hawkstone single H-section cast aluminum downtube w/special lower engine mounting plates/52in (1,321mm)
Suspension: Greeves 24MCS motocross leading-link fork front, dual Koni shock rear
Brakes: 5in drum front and rear
Tires: 3.5 x 18in front, 4 x 18in rear
Weight (dry): 290lb (638kg)
Seat height: 30in (762mm)
Fuel capacity/MPG: 2.5 gal (9.5ltr)
Marrying a Greeves frame with a Triumph engine makes for an interesting motorcycle with an interesting name: Grumph. According to the Merriam-Webster dictionary, grumph is actually a word, defined as “to grunt” — and that turn of phrase is entirely applicable to the machine in this article.
Not in a hurry to get to the altar, it was a nearly three-decade long engagement before builder Greg Lawless of Wisconsin got this particular Greeves/Triumph combination together. In 1981, a co-worker offered Greg a tired old desert racer. The machine was a 1962 Greeves Hawkstone 24SC powered by a 2-stroke, 250cc Villiers 34A engine. Although mostly complete, all was not well, as the transmission was locked in gear. “He was cleaning out his garage,” Greg recalls. “He didn’t want any money for it, but I turned it down as I had no pickup or trailer to take it away. He countered with free delivery, and the deal was done.”
For 10 years the Greeves languished as Greg focused on family and other projects. But in 1991, he and a friend visited the Isle of Man TT races. In a parking lot he saw his first road-legal Grumph, a Greeves Scottish with a Triumph 3TA engine. “Gobsmacked,” is how Greg says he reacted to the combination, and he knew what he wanted to do.
“I had to figure out how to put a Triumph motor in the Greeves frame, and I thought at first it would be an enduro-style special,” Greg explains. After some initial research, Greg learned he could fit a 500cc unit-construction Triumph engine in the frame, but prior to the days of the Internet, he had difficulty locating a donor engine.
Time passed slowly until 2008, when he connected with an eBay seller who had a 1970 Triumph T100S bottom end mixed with a variety of other Triumph engine parts. It was a Frankenstein engine, but it suited Greg’s purposes and he bought it. Build direction changed, though, when Greg saw a Greeves that had been set up for short-track racing — he quickly decided his Grumph would be a road-legal street tracker.
Before we get into the particulars of Greg’s Grumph build, here’s a little background on Greeves. According to Colin Sparrow’s book, Greeves: The Complete Story, the British motorcycle company got its start when Bert Greeves built a motorized wheelchair for his cousin, Derry Preston-Cobb. Disabled from birth, Preston-Cobb could not walk and his left arm and hand did not function. In 1941, Greeves refined his concept for disabled transportation and built a three-wheel “invalid carriage” for Preston-Cobb powered by a small-displacement Villiers 2-stroke engine. The pair could see they had a commercially viable product, and in 1946 they set up Invacar Ltd. in a small factory.
Fast forward to the early 1950s. Greeves decided it wasn’t sound business to rely solely on government contracts for the large number of Invacars his company was selling. A lifelong motorcycle enthusiast, Greeves turned his attention to engineering a machine that would feature Villiers engines for power.
One of the first steps Greeves took was to design a unique front suspension system using rubber torsion bushings in a trailing-link design. The prototype fork was installed on a tired-looking Norton 16H, and the concept was proven. Early in 1951, a full-fledged Greeves offroad prototype motorcycle was constructed.
Tests found areas of fault, but with remedies, Greeves introduced the machine to C.P. Read of Motor Cycling magazine. According to Sparrow’s book, Read said, “ … the appearance of the front end of the Greeves somewhat shook my rather conventional outlook.” To that, Sparrow adds, “Which is a polite way of acknowledging that it was actually pretty hideous.”
Greeves production started in 1953, with machines featuring a rugged cast alloy H-section beam in place of the standard front downtube and revised forks, now in a leading-link format but still with rubber torsion bushings for suspension. Roughly half the motorcycles built were for competition use, including motocross, trials and road racing. Updates over the years included larger engines and eventually telescopic forks. Greeves machines proved popular from 1959 to the early 1970s, but an influx of lightweight and powerful Japanese offroad machines helped put a nail in the coffin of the English company. Already suffering from slow-selling, dated products, a factory fire in 1975 spelled the end of Greeves and within a few years the company was gone.
Greg’s 1962 Greeves Hawkstone scrambler was a lightweight machine built for offroad use, and machines like it were competitive in California desert races of the day. In fact, Greg confirms the previous owner’s uncle did in fact campaign his Greeves in the desert. Part of a Greeves’ appeal was the Villiers 2-stroke powerplant, but Greg was determined to build a Grumph so he sold his tired 34A engine with Greeves square barrel to Dan Vitalleti of Vitalleti Racing and Restoration in Richland, Washington. Greg mentioned to Dan his plan to fit a Triumph twin engine in the Greeves frame, and Dan happened to have a set of Triumph/Greeves engine mounting plate templates.
“They were Triumph engine plates to fit a Greeves TCS trials bike, which has a very similar frame to the Hawkstone,” Greg says. “I took a chance and had the templates digitized, then took them to a water-jet cutting firm.”
Before committing to metal, Greg had the company cut sturdy plastic plates and mocked up the Triumph engine in the frame. The fit was close, but a couple of holes to locate the front alloy beam had to be lowered slightly. Greg also altered the plate design so he could weld on tabs to mount the oil tank, and finally had the pieces cut in 1/8-inch 17-7PH (precipitation hardening) stainless steel. Greg is a metallurgist and spent his working career in the aircraft industry, so he knows his way around steels and alloys.
“That metal is so hard that the mounting holes were water-jet cut, as a drill would have little chance of going through, especially one in a hand-held hole shooter,” Greg says. “I may dump the bike someday, but those plates will remain flat to 0.005 inch.” He used the same 17-7PH steel to make other brackets, including the battery mounting plate.
Greg kept the stock leading-link Hawkstone 24SC forks, but modified them by using a larger diameter and stiffer 24MCS (motocross model) rear loop. The Greeves frame was slightly altered, as the tubes under the universal fiberglass seat pan had to be cut out and welded back in a lower position. To fit the special alloy oil tank — which looks as though it were made for the project — a bolt in the seat downtube had to be repositioned. The tank came from Chris Quinn at Wheel Works in Hayward, California, and is a period accessory, although it’s not known who made it.
Greg also relied on Chris to build up the wheels. These consist of the original Greeves “paddle hubs” (so named for their large cooling fins, or paddles) fitted with new bearings and brake shoes from the late Frank Conley, a Greeves expert and well-known U.S. parts specialist (parts sales are now under the direction of Ken Sykes). Chris laced the hubs into Akront shoulder-less Al rims, 18-inch WM2 front and 18-inch WM3 rear, with stainless spokes. Rebel Gears in Crossville, Tennessee, machined a flat aluminum 42-tooth sprocket with 530 teeth to match the Triumph front sprocket (the Hawkstone had a 420 chain).
“I figured by rudimentary measurements that the sprockets would line up,” Greg says. “I held my breath when I mounted the rear wheel and checked the sprocket alignment with the Triumph engine, and the alignment was perfect! Sometimes you get lucky.”
Speaking of the Triumph engine, Greg says it’s a 1970 T100S bottom end with a 1974 T100 barrel, a “push-in exhaust” cylinder head, and rocker boxes with valve adjuster covers. The outer transmission cover is from an early T100 with a helical (not three-ball) clutch actuator. Twin T100R intake manifolds feature a pair of Amal 626 carburetors topped with K&N air filters. The exhaust is a set of Triumph TR5T headers with custom bent and chromed pipes capped by chromed SuperTrapp offroad mufflers. Fitting the exhaust was a real challenge “because there’s only about 1/8-inch clearance on the primary side to exit outside the frame between the primary, chain, chain guard and brake pedal,” Greg notes.
Greg selected an aluminum gas tank from a Triumph TR25T Trailblazer. Because the tank was meant to fit over Triumph’s large diameter oil-in-frame backbone, it was also a perfect fit for the large diameter Greeves top tube. He stripped off the red paint and polished the alloy. Nestled in the notch at the front of the tank Greg managed to fit an oil pressure gauge where the oil cap in the frame would have been located. Greg also plumbed a MAP Cycle oil filter into the oil return line, placing it above the swingarm pivot.
Greg selected many of the other components, including the new-old-stock Bates 5-inch chrome side-mount headlight and bracket, Ron Wood Racing stainless flat track handlebar, Tomaselli levers, SuperPractic throttle, Lucas-style handlebar switches and Dunlop K70 tires, for their period-correct authenticity. “I wanted it to look as if someone made it in the late Sixties or the early Seventies,” Greg explains.
Speed is monitored with a small 2-inch white face Smiths speedometer mounted in a Greeves Anglian trials bike housing. The speedo sits just below the right front side of the gas tank and Greg says that to read it he almost has to be standing, like a trials rider would be, or else duck down and to the right.
A gray face Smiths tachometer sits in a Greeves Ranger fork top nacelle, which is where the speedo would have originally been on the Ranger model.
Greg had the frame and brackets powder coated U.S. Postal Service blue. While it matches any USPS mailbox, it’s a deeper shade than the Moorland Blue of the original Hawkstone. The seat cowl was paint matched to the USPS blue, and graphics include the lettering “Hawkstone Tiger” and “Made in England, Mixed in America” hand painted under a crossed British and American flags decal. Everything was clear-coated to preserve the finish.
Even though Greg has a stable of machines and he could choose to ride any one of them, he keeps the Grumph nearest the garage door. “It’s light, it starts easy and it rides like a dream,” he says. “It’s geared for 105mph at 8,000rpm. The first time I got it up to around 80mph it started wiggling, so I fitted a hydraulic steering damper from an old Kawasaki, similar to those on the Greeves Silverstone road racers.” The Triumph engine was built to T100R Daytona specs, and it produces 41 horsepower at 7,200rpm. That’s more than double the 19 horsepower at 6,000rpm produced by the stock Villiers 34A engine.
“It likes to be turned like you’re riding in the dirt; you sit up and push the bike down and through a corner,” Greg says. “The Triumph engine has lots of low-end torque, giving the bike plenty of grunt, too.” Now that just makes sense, seeing it’s a Grumph. MC