The MG TD
Brave men of all ages from Bangor to Burbank rallied around to buy MG TC's and drive them with great joy over the nation's back roads. All exports of this Nuffields branch, still relatively small, were spoken for. From the coldly analytical viewpoint of the sales executive, though, there was still a very big something missing.
For a variety of reasons TC's seemed to be driven by movie stars and wives of racing drivers. In a country where women are reputed to have a majority vote in all big buying decisions, this just wasn't a solid share of the potential market.
The Abingdon analysts looked over the situation and decided that they needed a better-riding, lighter-steering, and altogether more modern Midget, but they acknowledged that the classic looks were an invaluable sales point and vowed to drape them over any new chassis. In this way the TD came upon the earth, to become the most convincing missionary for driving fun since the War.
The Y-Series
The
monoposto MG R-Type had what the new MG needed, independent suspension. The connection between the R and TD series was tenuous but significant, both cars declaring independence by means of parallel wishbones. There was a more solid link in the form of the Y series, also termed the "One and a Quarter Litre" for prestige advertising purposes.
Introduced in 1947, this line included a staid four door sedan with a one-carb XP AG engine, and a four-seater open tourer with the TC engine and left-hand drive specifically for the D.S. market. Not too many V-Types actually caught the west- bound boat, but an occasional Tourer was sometimes seen fleetingly, like the Flying Dutchman.
More important to the maintenance of the breed was the chassis of the YA MG. At the rear it was underslung like the TC, though with longer springs and a Pan hardrod, but up front the frame rails joined a big cross member which carried the IFS. A coil spring acted on the lower wishbone, whilst the shorter top arm was pivoted directly from a hydraulic shock absorber. Rack and pinion
steering was mounted ahead of the hubs, linked to forward-facing
steering arms. Identical in most details, the same layout ws found in the MGB, not to mention the TD. It was simple, cheap to build, and accurate.
Once the TD was seen in action, most of the diehards admitted that there might he something to its new independent suspension, which paid off in precise
steering and steady braking. The Stock MG Race became an institution which revealed that any technical differences between TC and TD could be overshadowed by careful preparation. Also the more modern chassis of this was better suited to engine swaps and to the construction of all-out racing specials.
The MG TD's Engine
As mentioned above, the TD's engine was a virtual twin to that in its predecessor, with the same output and general characteristics. It was the power plant that was used in the YB Tourer, which was dropped when the TD was introduced on January 15, 1950. Detail differences included an updated air cleaning system, a replaceable element oil filter, and a stamped instead of cast oil pan which now held less oil. Further development had made the XPAG engine tougher than ever. This was fortunate, since many TD engines were unwittingly badly treated by owners who had forgotten the joys of shifting gears.
The MG TD's Transmission
If skillful cog-swapping had become a lost art, the TD's box was calculated to bring about a renaissance. It resembled the TC transmission in general layout and
synchromesh type, but has a slightly wider ratio spread to compensate for extra poundage in the later car.
The TC's countershaft was heavier in section and better supported, and its gears were selected by a remote control integrated with the main gearbox cover. This newer box differed in having the control, and extensions of the shifting yoke bars, which were housed in a long tail shaft casing bolted to the back of the main case. A later refinement was the addition of outrigger bushings to support the extended yoke bars.
Thanks to the compact shift pattern, handy lever, and effective but non-blocking cone synchromesh, a TD driver could slash ruthlessly from gear to gear without making an appointment with his mechanic beforehand. When you first tried tossing a fast one from second to third, though, you had to beware of a weak blocking spring in the reverse gate which was an embarrassing spot to be caught while the rest of the cars off the grid were playing "crinkle-fender" around you.
The MG TD's Frame
A lot of the TD's added weight was well-placed in the frame, which in every direction was infinitely stiffer than the old TC beams. This was a must to provide the rigid alignment of components needed to keep an IFS car from being a "floppy dog" in the
steering category. Side members were deep channels boxed on the inside and joined by tubular cross members plus a big pressed bridge between the two sets of wishbones up front.
There was also a strong tubular hoop inside the cowl, stiffening and supporting the dash and
steering column. Modified rollbars like this should have been part of every open car. Thanks in large part to this hoop; we have seen TD's rolled on and off the race track without the slightest damage to the occupants. Rugged through and through, the TD gave the lie to the misconception of "dangerous little cars."
To give plenty of bump and rebound room, the TD frame, like that of the first M-Type, kicked up over the rear axle. Seven-leaf semi-elliptic rear springs were hung well outboard and damped by Luvax-Girling lever-type shocks. Probably to simplify the supply problem within the Nuffield organization, a hypoid rear axle was used, lowering the drive shaft one inch, but making very little difference in a two-seater sports machine.
The MG TD's Brakes
Diameter of the Lockheed
brakes remained at nine inches, but two leading shoes at each front wheel gave added stopping per pound of pedal tromp. On the TC the fly-off handbrake lever was placed on the floor next to the
gear lever, like most Jaguar two-seaters, where it was well out of the way. The MG crew placed it between the seats of the TD, where it was perhaps easier to operate but constituted an obstacle to full and efficient use of the interior space.
The MG TD's Wheels
Much of the uproar over the TD was caused by the adoption of disc wheels, which must have been done with much soul-searching by the designers. Forgetting the discs fitted to the great Frazer-Nash cars, and unable to see the Halibrand, Dunlop, and Borrani lightweight racing disc wheels of the future, English and American purists resented this affront to their tastes.
Since few other than 32nd-degree MG enthusiasts would put up with the maintenance curse of the big wire jobs, though, it was an excellent long-term decision. The first cars came through with solid pressed discs, but later in
1950 Cord-like holes were punched through to sharpen up the styling and provide token air flow over the brake drums.
Someone once remarked that a sports car should be judged not by what it does, but how it does it. Only by the latter criterion can any distinction be made between the TC and TD, which on paper and in race results stacked up dead even over the years. A choice between the two depends entirely on personal preference. One of the TD's most impressive features was the solid, rattle-free feel of the chassis and body. This one-piece willingness encourages hard driving on bumpy surfaces-unthinkable to most TC chauffeurs. Limits are set by the solid rear axle, of course, which was usually the first end to pop loose at the limit.
Behaviour of the front wheels was exemplary at all times. Traction was high, wheel angles moderate, and braking firm and sure. When drivers first tried the all-independent R-Type MG, it rolled so much on corners that they cried: "Take it away and clamp on a pair of half-elliptics." Initial reaction here to the TD was the same if not stronger. Certainly the TD canted over more than twice as far as its predecessor, and if you don't care for it, that's all there is to it. Don't be deceived, though, for this lowered roll stiffness, working through the wider contact patches of lower-pressure tyres, kept sheer cornering power at a high level.
The MG TD's Steering
The one feature of the TD openly coveted by TC owners was the rack and pinion steering. Mainly because of mechanical and production limitations, it didn't have the shatteringly high ratio of that infamous worm-and-peg box, but it was so light and precise that the most bitter hearts were won ever. It’s only vice, common to all such gears, was its high reversibility, which caused a lot of "kickback" at the wheel. This did give a lively feel of the road, enjoyable to most drivers, and was not annoying if the rim was held lightly on bumpy surfaces.
MG TD Refinements
Through its three years of model life many refinements were made to the TD. Magnetically driven instruments with redesigned faces and rheostat-controlled lighting replaced the erratic chronometric units, and a water
temperature gauge was added. Headlight dimming was also done by foot instead of hand. The faithful XPAG engine was given a new head with revised ports and longer reach plugs (NA-8 instead of L-lOS), new rockers, specially-hardened tappets, and a less harsh cam with more scientific lobe contours. Oil circulation was further developed, and clutch size was up to 20 cm from 18.
The MG TD Mark II
Lasting after the first outburst was a persistent clamour that the TD just wasn't that masculine. The boys at Abingdon couldn't take this long and finally came up with the Mark II or "TDC" Type, a moderately rodded TD. An impressive brace of SU pumps dump fuel into 4 cm carbs, up from previous. Stiffer springs and bigger valves admitted the mixture to a higher-compression chamber.
These tacked on a half-dozen horses which went to work through a higher rear end cog (bringing revs per km back to the TC level). Andrex friction shocks added to each wheel are adjustable and a boon to
handling predictability. Availability and size led to the use of many TD chassis as bases for competition cars - from Johnny Von Neumann's aluminium bodied pseudo-TD to Dave Uihlein's twin-cam-converted Noviesque race car. There were special bodies by Bill David, Motto of Turin, and Bertone (the very handsome Arnolt-MG's).
Also see: MG Heritage |
MG
Performance Chart 
