M201, Willys MB and Ford GPW Differences

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Handbrake Drum

The handbrake on the M201 operated like a normal drum brake with the brake shoes on the inside of the drum. Willys and Ford Jeeps  had an external contracting band brake, 'though late war Jeeps had internal shoes like the M201.

Batteries

The MB and GPW started life on 6 volts, although late in the war, I believe there were some 12 volt Jeeps. The early M201's were also 6 volt, but evolved to 12 volts. From 1960 onwards, M201's were upgraded to 24 volts, the NATO standard. This was achieved by fitting a second battery behind the first, displacing the voltage regulator from the fender to the firewall. This then forced the air filter to be moved to the left side of the engine bay.

For the early M201 12 volt conversions, an additional 6 volt battery was installed between the two front seats. The mounting points and cable position can be seen on this M201. Lights, gauges and other electrical systems would have to be upgraded to 12 volts at this point too.

The M201 later used a single 12 volt battery before the 24 volt conversion placed two 12 volt batteries in the engine bay. 

Willys and Ford Jeeps may have had this conversion if they were used by the French Army after World War 2.
Air Filter

As a result of the second battery, the M201's air filter was moved to the left side of the vehicle. On the MB and GPW, it was mounted on the right side of the firewall, next to the fuel filter.

Voltage Regulator

With the fitting of a second battery to the M201, voltage regulator was moved from behind the battery to the firewall, next to the fuel filter. It is also a different style case to the MB and GPW version. On the MB and GPW, the regulator was fastened to the right fender.

Dynamo/Alternator

The M201 had a large powerful alternator fitted. The MB and GPW had a much smaller dynamo, but late in the war, there was a 12 volt alternator conversion fitted, as seen on the GPW.

Water Pump

On the M201, the water pump had an extra pulley and drive belt fitted compared to the MB and GPW.

Distributor

The distributor, coil and ignition leads on the M201 was completely sealed and watertight, using positive pressure from the air filter intake. The MB and GPW had a standard distributor and points, with a separate coil mounted on the block behind the distributor.

Spark Plugs and Leads

The M201 plugs were also sealed and shielded to work with the watertight distributor. The MB and GPW Jeeps used standard rubber insulated push on leads. These were sometimes fitted with a 'witches hat' rain cover, but these can lead to shorting.

Horn

The Willys and Ford vehicles had various horn styles. An early design featured a long trumpet on the front. This was replaced with a flat round design. The M201 horn was similar to the flat type, but with a different slot pattern and converted to 24 volts where necessary. 

Carburettor

The M201 uses a Solex Carburettor, but the MB and GPW use the Carter or Zenith carburettors.

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