Dave Degens, Dresda main man and all-round font of Triton knowledge
Dave Degens may not have invented the Triton but he made them famous. After 50 years building Dresda Tritons, he has a lot of knowledge to share
Dbike,ave Degens vividly remembers the first Triton he ever saw. “It was around 1955. It belonged to one of our crowd, Johnny Gray. He was an engineer and had fitted an iron Tiger 110 engine into a very early Manx chassis. When I finally blew up my first
a tuned-up G3L Matchless, Johnny Gray towed me home behind the Triton and it left a lasting impression.” Moving up to a BSA Gold Star, Dave turned his café racing ability to the track, where the Triton came back into his life. Racing success with the Triumph-engined Norton hybrids prompted the acquisition of Dresda Autos, where he built and tuned road and racing bikes. Although Dresda later moved on to tuning big Hondas for the Japauto race team, when Dave returned to classic racing in the 1980s, the Triton side of the business started all over again. Officially Dave retired 14 years ago, but Dresda is still going because, as he says: “Our customers rely on us.” In conversation it’s clear that the racer’s determination to win is still there, even if these days it’s from the tuning bench more than the saddle.
Dresda’s principal specialities are the tuning and rebuilding of a variety of engines, and chassis builds and repair, mainly undertaken by Dave’s assistant Russell.
“We still build our own Dresda lightweight chassis,” says Dave. “There’s a Honda one in the jig, but we also do a lot of repairs and modifications to Featherbeds. Most probably weren’t right from new; the right-hand tank tube is usually higher than the left; they are prone to cracking across the downtubes so before we start building a Triton there’s a lot to do. We weld up any surplus holes, generally fit a rear loop and a sidestand lug and check that all the brackets are in the right place for the engine to be fitted.
“Designing engine plates isn’t just a matter of superimposing a Triumph engine plate over a Norton one to get an outline. Most commercial engine plate sets don’t attempt to find the best position for the engine. We’ve seen plates that, at full suspension travel, leave about four inches slack in the rear chain. We’ve fitted all sorts of engines to Featherbeds: Vincent, Rudge you name it; to do the job properly often the frame needs to be altered slightly. To fit a Triumph Trident, we spread the lower rails to lower the engine; that gives space to remove the rocker boxes, but also because the Trident rear sprocket is much larger than a Norton, it stops the rear chain wearing a groove in the frame strut beneath the oil tank. When it comes to engine tuning, Dave says it’s important to know what you want. “Some of our modifications I only offer to racing customers. Most people don’t want a race engine in a road Triton – fitting Thunderbird cams and softer pistons makes a much more pleasant bike to ride, with enough performance for most people. Many of our modifications are worth having for reliability as much as speed. Take the lightened valve gear. We lighten, balance and polish the rockers and fit much lighter valves with 6mm stems (5/16in is standard) in special Colsibro valve guides. The weight reduction means we can drop the spring rate by around 100lb; this enables higher revs on a racing engine, but also takes a lot of wear and tear off the cams.”
“With the pre-unit engines, we start by reinforcing with weld around the drive side (left) main bearing. Flex in the bottom end is a problem in tuned engines and the more rigid the crankcase, the better. Everybody thinks the one-piece Triumph crank is the best, but it’s too rigid for the pre-unit crankcase. I’ve never had a boltup crank break but, as performance increased, the one-piece
‘MANY OF OUR MODS ARE WORTH HAVING FOR RELIABILITY AS MUCH AS SPEED’
ones started going across the timing side big-end. Replacing the ball main bearing that side with a roller, like the drive side, helped – and Triumph later did the same thing. For racing we reinforced the timing chest, adding vertical beads of weld as buttresses to prevent cracking across the camshaft and breather holes where the power was trying to rip the barrel off!
“I’ve always stuck with Triumph plunger pumps, I’m not a big fan of rotary ones. In the early days I used to sleeve the plungers oversize and bore the pump bodies to suit. Nowadays we use T140 plungers to achieve the same effect. I always took the view that since standard Triumphs rev to 60007000rpm and the standard valve releases at around 60psi, you need about 10 psi per 1000rpm. Once I got the ignition sorted, my Triumph was revving to 10,000 and I wanted more pressure; I’ve found you can get 150psi out of a Triumph plunger pump.
“Also on the lubrication side, we use a pressure feed to the rockers instead of picking it up off the scavenge. It comes off the blanking bolt on the front of the timing cover and we find that the increased oil coming down the pushrod tubes reduces cam wear by about 30%. We also uprate the rocker spindle seals with two O-rings instead of one and a cap over the end. We use thick, preunit-type bottom pushrod seals and it’s important to check tube length and the depth and also angle of the machining in the cylinder head. These often need to be corrected to compress the seals correctly. We do special O-ring-type tappet covers, too.
“When we started racing the unit Triumphs we always had a mysterious misfire at about 6800prm. The factory thought it was ignition, but looking down once I saw petrol coming out of the tickler as a vibration patch hit the carb. Since then, I’ve used rubbers to isolate the carb from the engine. We make our own from radiator hose material which seems to work best. We also make the adapters for the different heads. “We run greater piston-to-bore clearance these days, because the fuel burns hotter. A two or three thou running clearance needs to be more like five or six now and we’d recommend eight thou for an 11:1 piston. The squish on a Triumph piston wants to be about 31 thou; you know you’ve got it right if there’s just a black stain around the edge of the piston with no carbon build-up.
“Belt drive has made a big difference. Running the clutch without oil means you can back off the springs to give much lighter action. We do a special sealed mainshaft nut to prevent oil running up through the shaft into the clutch. We keep a selection of fractionally different size front pulleys so that when we set up a unit engine we can get the tension perfect.
“Norton gearboxes were in fashion for a while, but I was never convinced. There was always trouble with them; I remember turning up for a 24-hour race; Gus Kuhn was there with three Nortons and said: ‘I wouldn’t bother getting out of the van, Dave!’ But in the race all three dropped out with gearbox trouble. When you look at it, Triumph gears are much meatier; besides Triumph used to make close-ratio sets so I stuck with them. We fit sealed bearings to back up the oil seals and we’re often asked to fit five-speed internals into pre-unit shells; it only takes a few simple modifications to clear the camplate etc, but there are variations in five-speed sets – that star-shaped dog/washer comes in varying thicknesses, so I always set the gears up in a dummy gearbox with windows to check engagement. We usually replace the bronze layshaft bushes with needle rollers, too. “When we were racing the big-bore engines with Norton cranks, we were up to about 800cc and did have a few gearbox shells crack. We reinforced them with weld between the shafts, but they’re usually strong enough. Those engines had so much torque you could win a race without revving over about 5000!”
So many Featherbed specials have been built that it’s easy to assume there’s nothing to it. A talk with Dave Degens soon makes you realise that it’s not quite so simple, so maybe it’s as well that Dresda is still around.
‘WE RUN GREATER PISTON-TOBORE CLEARANCE THESE DAYS, AS THE FUEL BURNS HOTTER’
Dave’s ‘retired’, but Dresda keeps going...
Weslake engine nestles neatly in one of Dresda’s own Lightweight frames In Dave’s racing days beads of weld were used to reinforce the crankcase weak points Dresda’s lightweight valves and softer springs increase rpm and reliability
Rubber mounting keeps the fuel from frothing Special tappet covers are machined to accept O-rings