Touring with a Classic
Tech Tips for Cars from the ‘50s
 
by Richard Simonds
Image Fred Smits
 
Past issues of The Star have featured New Zealanders Fred and Elisabeth Smits traveling in their 1957 220S Ponton sedan with a Zambezi teardrop trailer they modified for the trip. Not surprisingly, along the more than 18,000 miles they have driven so far, the Smits had to deal with some technical and mechanical issues. Although some of those problems are specific to their car, there are several relevant to any vehicle from the 1940s or ’50s – not just a Mercedes-Benz vehicle. Based on their experiences, here are some tips that anyone with a car of this vintage may want to be aware of in preparation for a long-distance tour.

Brakes

A rumbling sound that wouldn’t go away after six months of travel, despite the efforts of several shops to find the cause, was eventually found to be caused by the brake shoes having high spots that rubbed on the brake drums, causing glazing on the drums and a harmonic vibration that transferred to the car as a rumbling sound. By “arcing” the brake shoes, the high spots were removed and rubbing on the drums stopped. The glazing also had to be removed from the brake drums.

Infrequent brake-fluid changes can cause the wheel cylinders to become pitted. When this happens, seals can leak under the pressure of braking and the car might pull to one side or – even worse – the brake pedal could go all the way to the floor, leaving the driver with no braking capability.

Brake hoses eventually lose their firmness and can expand under the pressure of braking, causing the car to pull to one side or – another even worse scenario – rupture, causing a loss of brake fluid and braking capability.

Shock absorbers

Pontons and other Mercedes-Benz models that have an early swing-axle rear suspension are vulnerable to having the right-side shock absorber break if the car hits an obstruction, such as a pothole or pavement crack, which can cause the right shock to bottom out. Carrying a spare rear shock absorber saved the day for the Smits when Magno Restorations removed the broken shock and replaced it with the spare.

This was a particularly nice gesture because Henry Magno’s shop is a restoration facility – it’s not really in the repair business. By the way: It’s always a good idea to replace both left and right shocks at the same time (as recommended when replacing tires on the same axle) to avoid inconsistencies in wear that can affect a vehicle’s handling.

Panhard rod

Cars with independent rear suspension require a rod or series of links to limit side-to-side movement. In the early swing-axle design, a Panhard rod, which Mercedes-Benz referred to as a “cross-arm shackle,” connected the frame of the car to a mounting point on the axle. A loose bolt on the Smits’s car caused this component to break when they hit a pothole. Again, Magno came to the rescue: He sent the needed part to the shop that fixed the Smits’s Ponton when they made their next stop.

Fuel system
Before setting out on a major trip, it is advisable to inspect the fuel tank and fuel lines for rust, and have everything cleaned and sealed to prevent rust from getting into the mechanical fuel pump and carburetor float bowls. If possible, having a return fuel line from the carburetor(s) to the fuel pump can help keep a supply of cooler fuel from the tank to the fuel pump and carburetor(s), minimizing the risk of vapor lock. Mercedes-Benz typically used high-volume, low-pressure fuel pumps in cars with carburetion, rather than fuel injection: Be sure your fuel pump is working properly and is of the right specification.

Other items

For anyone contemplating a long-distance tour, it is advisable to plan on taking along sufficient spares of these items:

Spark plugs
Points and condenser parts for the distributor
Fuses (most are ceramic in 8-, 16- and 25-amp capacities) – are not SAE sizes
Fan belts of each size needed – M-B fan belts are metric dimensions and most auto-part shops only carry SAE sized belts
Spare tire(s) – 1940-1980s Mercedes-Benz vehicles used 13-inch, 14-inch or 15-inch wheels; tires in the correct sizes are very difficult to find at a typical tire shop
Coolant – an extra gallon of M-B-approved coolant for engines with aluminum components
Brake fluid – one quart with the correct DOT-rating for your vehicle – to be used in the brake master cylinder (and clutch master cylinder if your car has a hydraulically operated clutch)
Special tools needed for tune-ups and other routine jobs.

The Smits hope that you’ll find these simple tips useful for carefree travel behind the wheel of your classic Mercedes-Benz.
 


Ouch! This was the really big one: The deadly combination of a loose bolt and the shock of hitting a deep pothole caused a fracture (arrow) in this cross-arm shackle, which was designed to stabilize the rear axle.