Motor Division in World War Two / WWII
Rest in Peace!
This page updated 11-14-2017.
The Pontiac Motor Division emerged from the
original Pontiac Buggy Company, founded in 1893 by Edward
Murphy. In 1907 it became the Oakland Motor Car Company, which was
acquired by General Motors in 1909. In 1926 Oakland introduced its
Pontiac line of automobiles. They became so popular that the Oakland was discontinued. A new Pontiac Plant was built in 1927.
within this plant that the Division produced the war products described
The new Pontiac Plant in 1927. The
Fisher Body Plant is across the railroad tracks. The overhead
conveyor transported the finished bodies from the Fisher Body plant to
Pontiac final assembly plant. This was long before GM combined the
managements of the body and final assembly plants into one.
Today's automobile plants have both functions under one roof.
Photo added 12-25-2016.
Pontiac's Plant #4 was the first auto
manufacturer to win the Navy "E" award on January 20,1942. Pontiac received
this award for delivering 20mm Oerlikon anti-aircraft guns to the Navy ahead of
schedule. Pontiac Plant #4 did not convert its Navy "E" award when
it became a combined Army-Navy "E" Award, as it could have
This Navy "E" award was not noted by the War Department's Army-Navy "E"
award public relations release dated
December 5, 1945. There is no mention of Pontiac being one of the
original war plants to receive the Navy "E" award, nor that is
was one of those that did not convert.
As of November 1943 Plant #4 had added four stars and would add a fifth
for a total of six awards..
This clip from the November 1943 "Pontiac at
War" booklet shows the Pontiac Oerlikon Plant
receiving the Navy "E" award for the third time. It is
also noted on the "E" for Excellence page of "Pontiac at War" had received
four stars for the Navy "E" flag.
Pontiac's Plant #11 won the Army-Navy
"E" Award one time for the manufacture of the Mark XIII aerial torpedo.
Pontiac's Plant #14 won the Army-Navy "E" Award one time.
Pontiac Motor Division of GM
World War Two / WWII Production Numbers / Statistics: 20mm Oerlikon anti-aircraft cannon, 40 mm Bofors anti-aircraft
cannon, Mark XIII aerial torpedoes, 155mm artillery shells, tank axles for the M-5 Stuart
and M24 Chaffee tanks built by
Cadillac, parts for Detroit Diesel to include fly-wheel housings,
connecting rods and cylinder liners, truck engine castings for GMC to
include six cylinder blocks for all GMC 270 engines, some but not all engine heads for GMC 270 engine, oil pump housings, bearing caps.
Pontiac's first war job was building
20mm Oerlikon anti-aircraft cannons for the US Navy. This
particular weapon, along with the stand and gun sight, were all built by
Pontiac. This weapon is serial number 223843. Author's photo
from the 2016 Virginian Museum of Military Vehicles Open House.
Data plates on the Mark 10 20mm gun stand.
The serial number on the middle plate is 267182. This matches the serial
number on the bottom plate. Author's photo.
The serial number on the Mark 4 gun breach
is 223843. Author's photo.
The brass Mark 4 gun sight assembly was also
manufactured by Pontiac. Author's photo.
It has a weight of 12 pounds. Author's
This twin 20mm Oerlikon anti-aircraft gun is on the destroyer escort USS
Slater in Albany, NY. The weapon closest to the camera was
built by Pontiac. Author's photo added 11-14-2017.
The serial number is 4919x. Author's photo added 11-14-2017.
Pontiac began work on the 40mm Bofors anti-aircraft gun in January 1942.
Pontiac cleared 217,000 square feet of the sheet metal plant space to
manufacture the weapon. The Bofos could fire 130
rounds per minute, and the two pound projectiles had a range of 5,420
yards. The 40mm Bofors was also produced by Chrysler and
Firestone. Author's photo.
On March 12, 1942 Pontiac began work on the
Mark 13 aircraft torpedo. The thirteen foot long weapon contained
5,222 parts and 1,225 assemblies. The gyro, which guided the
weapon to its target, turned at 9,000 rpms. It had a diameter of
22.5 inches and weighed 2,216 pounds, of which 600 pounds was the Torpex
explosive. The internal steam turbine propelled the Mark 13 at 33 knots
for a maximum range of 6,300 yards. The Naval Torpedo Section,
Ameritorp Corporation, and International Harvester also produced the
Mark 13 during WWII. The four companies built 17,000 torpedoes.
1,500 were used in combat. Author's photo from the Liberty
Aviation Museum in Port Clinton, OH.
This Mark XIII is on display at the National
Aviation Museum of the US Air Force. Author's photo.
This is the warhead section of the torpedo
that would have the detonator and 600 pounds of Torpex explosive, 1.5 times
more powerful than TNT. Author's photo from the USS Silversides
Museum in Muskegon, MI.
This area would contain the alcohol fuel and
compressed air to power the steam turbine. Author's photo.
The steam turbine is at the rear of the Mark XIII. Author's photo.
The primary aircraft to carry the Pontiac
Mark 13 torpedo was the TBM Avenger. It was built by the Eastern
Aircraft Division of GM in Trenton, NJ. Author's photo taken at
the Liberty Aviation Museum.
The Mark 13 was also carried by US PT boats.
One of 21,147 DUKW amphibious trucks built by GMC
and Chevrolet during WWII is next to the PT boat. Pontiac supplied the engine blocks for the
GMC 270 cubic inch engine used in the DUKW. Author's photo
taken at the Liberty Aviation Museum.
Pontiac built the front differential and axle for the Cadillac built M5
light tank. Cadillac built 1,824 M5 and 3,530 M5A1 Stewart tanks
in Detroit. It also built 1,778 M8 which had a 75mm howitzer
rather than the 37mm cannon. Author's photo.
After Cadillac ceased production of the M3,
it produced the M24 Chaffee light tank. Pontiac supplied
the front drive axles for it. Author's photo taken at the Ropkey Armor Museum.
Pontiac cast all of the engine blocks for
528,829 GMC 6x8 and 24,910 6x4 trucks. This was the
270 cubic inch, six-cylinder engine. Pontiac also disassembled and
crated GMC trucks for overseas shipment. This saved valuable
shipping space on transport ships. Author's photo.
Pontiac supplied the Detroit Diesel Engine
Division of GM with fly-wheel housings, connecting rods, and
cylinder liners for its diesel engines. Author's photo.
The Detroit Diesel engine was used in 19,353
LCVPs or Higgins boats. Detroit Diesels were also used in many
other types of landing craft for the US Navy. Author's photo from
the 1st Division Museum in Wheaton, IL.
Two Detroit Diesel 6046 engines powered
10,968 M4A2 Sherman tanks. Author's photo.
Pontiac at War
A Special Report to Employees of
Pontiac Motor Division
This booklet has a wealth of information
about Pontiac's contribution to the war effort, starting in March 1941 up
through its publication in 1943. The three main war products; the
20mm Oerlikon, the 20mm Bofors, and the Mark XIII aerial torpedo all
have several pages dedicated to them. It includes an excellent history of
Pontiac up until the start of WWII. This rare booklet is a primary source
document that allows a look back at Pontiac from its inception
There is no date on the booklet.
However, presumed original owner wrote the date on the cover when he or
she received it. The date November 3, 1943 is documented on the page discussing the suggestion program. The booklet must have been published, then, by the end of
The history of Pontiac Motor Division
from 1893 until WWII, as written by Pontiac, is included in the next
In the next two pages Pontiac gives more
information on its manufacture of the 20mm Oerlikon anti-aircraft cannon
for the US Navy.
In the next three pages Pontiac gives
details on its manufacture of the 40mm Bofors anti-aircraft cannon for
the US Army.
Below are five pages on Pontiac's
manufacture of Mark XIII aerial torpedoes and their use by the US Navy.
Below is information on Pontiac's
manufacture of tank axles for the M5 Stuart light tank.
Pontiac's manufacture of diesel engine
parts described below was an important contribution to the war effort.
These engines were used in a variety of landing craft and tanks.
Pontiac's casting of engine blocks for
GMC trucks and DUKWs is described below.
Pontiac and GMC were both located in
Pontiac, MI. Pontiac was able to assist in the war effort by
crating for overseas shipment the 2-1/2 ton 6x6 GMC trucks. This allowed
GMC to focus on the important assembly of trucks for the war effort.
The above page gives more details on the
continued awarding of Navy "E" award, and the four stars
added by November 1943. These would be for manufacture of the 20mm Oelikon anti-aircraft cannon. This would imply that the awards for
the Torpedo Plant and Plant 14 came later. These would have been
the combined Army-Navy "E" awards.