Heavenly Heckflosse – Andrew Atwood’s W112 1963 300SE Heckflosse | MBCA

Andrew Atwood with Gary Anderson

For the past two years, club member Andrew Atwood’s W112 1963 300SE Heckflosse – or Finback – has been restored step-by-step in the pages of The Star. Now it is time to share the stunning result.

Heavenly Heckflosse

Article by Andrew Atwood with Gary Anderson | Images by Norbert Guthier

As the glorious pictures in this article attest, my nearly 10-year project to restore a 1963 W112 Heckflosse (Finback to most Americans), as reviewed in The Star in the last 12 issues, is now complete: I couldn't be happier.

The result is everything I had hoped it would be, but there were lots of possibilities for missteps along the way. In the interest of explaining what a full restoration can entail, let me summarize the project.

In the beginning

Every classic-car enthusiast dreams of finding and restoring a desirable version of a favorite marque, an old family heirloom or fondly remembered automobile from childhood. For me, from the time I owned my own 1963 220Eb when I was a teenager back in Sydney, Australia, I dreamed of building a pristine 300SE W112-chassis Heckflosse.

In 2006, I finally found one of these models, though it was in sorry shape and had been sitting outside unused since 1987. Also, I didn't have any place to work on it - my wife certainly wasn't going to move our cars out of the two-car garage for three or four years this might take to restore.

So chalk up two mistakes I warn hobbyists about:

I bought the first one I found, despite its condition and...
I bought it before I was ready to start work - meaning it would sit outside for several more years.

During the three years it took me to build a workshop behind my house, I hatched my plans. The 300SE was the top-of-the-line for Mercedes-Benz in 1963.

With copious amounts of chrome, the 300SE is easily distinguishable from its lower class cousins.

The graceful fins accentuated its elegant lines and the wood-and-leather interior was the epitome of luxury. The smooth-riding air suspension that set the W112 chassis apart from the otherwise identical W111 made driver and passengers feel like royalty.

But the model proved to have issues. The M189 6-cylinder engine was way ahead of its time and quite powerful for the period, but still not very responsive; the 2-piston-style fuel injection was not reliable; and the car was not cost-effective to repair. In addition, the air-suspension system would lose pressure if not driven frequently, leaving the car resting sadly on its axles, which were also complicated to repair and restore.

So, inspired by my favorite World War II German aircraft, the Messerschmitt Me 262 Swallow, which today can only be flown and displayed at airshows by fitting a modern Garrett turbojet engine, I decided to find a better engine and air-suspension system.

Most restoration specialists don't recommend extensive modifications because they can detract from classic originality, make repair by anyone other than the original restorer more difficult, and reduce its market value. As I was building this car for myself and not for sale, I built it to my personal tastes.

Power train

During the teardown, I followed tried-and-true advice: Take lots of photographs at every step in the project; digital computer technology makes this easy. Document every step in a logbook, complete with diagrams. Carefully package and label each component and its related pieces. Store everything in an orderly fashion where it will be easy to find when needed again.

Regarding the engine, I wanted to be true to the breed, staying with a fuel-injection system and using an engine that would look as if it came from the 1960s. Wanting more power, I opted for a V-8.

Those criteria left me with several choices among the 1969-1980 M116 and 1981-1989 M117 engine families, which I then narrowed down to two: the 3.5-liter M116 introduced in 1969 or the later 5.6-liter M117. Weighing the plus and minuses, I chose the M117 5.6-liter with its reliable continuous injection system and lighter-weight aluminum block and head. With a Euro continuous injection system and steel air-filter assembly, it would have the old-school look I wanted.

For the transmission, I had several choices. I went with one from a Euro 500SE, as it was engineered to start in first gear, unlike most U.S. versions that started rolling in second gear.

I decided to stick with my original 3.91:1 limited-slip differential, with anti-dive brake compensators that gave the 300SE amazing handling for its size and year. I did use the larger diameter wheels from a W100, which gave it slightly lower engine rpm at highway cruising speeds. But with the power of the new V-8, I found I'm now getting wheel spin in first gear at anything over half throttle. I have managed to find a 3.27 limited-slip differential with oil cooler and anti-dive compensators that I am going to convert to a 2.82 differential and install soon.

Suspension

Rebuilding the original air suspension would have been expensive and it still would have been unreliable and high maintenance; with the availability and variety of modern electronic air-suspension systems in the aftermarket, I decided to use an AccuAir 4-corner adjustable suspension kit.

To maintain period appearance, I installed the tank, control valves and compressor behind a panel in the trunk under the rear package shelf, fabricating air cans in which to mount the airbags. Installation required drilling only a few 1/8-inch holes for sensors; I can return the car to the original form at any time, if I wish.

Of course, the suspension and undercarriage components were completely overhauled and powder coated a stock semi-gloss black to ensure the car would offer impeccable handling and ride as well as look good. Testing it before finishing the restoration, I couldn't have been more satisfied.

Finishing the job

The power train was certainly the highlight of this restoration for performance-minded cognoscenti, but the remaining restoration was by the book. Given the number of years the car sat out in the weather, there was an extensive amount of rust repair that needed to be performed in the rocker panels and rear quarter panels. But bodywork is my strong suit, so that was a pleasure to work on for relaxation after hard days at the shop.

For the paint, I made two very good decisions. First, I decided on DB162 blue-grey for the color, a gorgeous and infrequently seen color that varies in hue depending on the light. Second, I had the sense not to try to do the panel work and paint myself, contracting it out to a local paint shop that does work for high-end collectors as well as the area Mercedes-Benz dealership.

Of course, I had the chrome refurbished by a specialist with experience that could meet all the new environmental restrictions. The work was expensive and had to be carefully worked into the schedule; it was worth the time and money.

For the interior, I wanted new red leather on rebuilt seats, so I replaced the pads and springs and ordered leather kits from a specialist company that offered period-correct patterns in the original coverings' perforation and pleating. Door cards, carpeting, and steering wheel were items I could handle; a friend who restores antique rifle stocks refinished the wood.

After that, completing the job was just a question of careful reassembly as I checked every fastener for correct tightness and every hose and wiring connection for functionality.

Polishing the smudges out so my photographer friend Norbert Guthier could get the best shots for me.

After a succession of increased-distance test drives - and 10 years after first acquiring the car, I have finally finished. I couldn't be more proud. Look for me - and my Heckflosee - at club events and on the road.

1663 Mercedes-Benz 300SE (W112)

TYPE: Four-door sedan
ENGINE: M117 V-8 5,600cc fuel-injected
TRANSMISSION: Euro-spec 722.4 4-speed automatic
HORSEPOWER: 300 (DIN)
TORQUE: 350 lb-ft
LENGTH: 192 in
WIDTH: 70.7 in
HEIGHT: 57.3 in
CURB WEIGHT: (after power train swap and with air suspension) 4,575 lb
FUEL EFFICIENCY: 17-22 mpg
PERFORMANCE: Zero - 60 mph 7-8 sec