MODELS

CMP

IDENTIFICATION

Last update 12 March 2007

Although Ford and General Motors built the CMP to a common design, there are many minor detail differences apart from the more obvious such as the different cab styles and engine configuration. The vehicles may look the same but there are a great many differences between the two makes. This page is designed to help identify that mystery CMP sitting in the back blocks near your home or those CMP parts that are gathering dust behind your back shed.

FORD vs CHEV

WHAT'S DIFFERENT

The Canadian DND designed the CMP and then tasked the two manufacturers, Ford and General Motors to manufacture them to their standards. The DND aimed to keep the vehicles as standard between the manufacturers as possible but they allowed them to use components that they already had in production such as engines in the vehicles they manufactured. Consequently, there were many differences which distinguish the Ford from the Chevrolet and vice versa.This list attempts to detail some of those differences, both obvious and subtle. I have also included some of the changes made in Australia by both Ford and General Motors on their locally produced versions.

BADGES …Fords have a Ford badge on the grille, Chevrolets have a Chevrolet badge.

BADGES…No 11 and 12 cab Fords have a small Ford script chrome badge below the instrument panel. These badges must have been highly desirable souvenirs since I have only ever seen one still in place and that is on the panel of my Rover armoured car which is based on a No 12 cab F60L chassis.

BUMPERS…Ford F8 and Chevrolet C8, C8A and C8AX all were fitted with 5" wide front bumpers. All other CMPs were fitted with 6" wide bumpers. Chevrolet C15s have the slot for the crank handle cut into the bumper itself. I'm not sure if the C8 is the same but I suspect it would be. All other CMPs have the crank handle guide on a small post bolted to the top of the bumper. The holes in the front face of all bumpers near the ends are for the forward facing green reflectors which were mounted behind the bumper. These reflectors can be found on Nos. 11, 12 and early N0. 13 cab trucks.

CAB…For more detailed information on cab styles, go here.

CAB…One of the quickest ways to ID a No 13 cab is to check the gap between the bottom of the headlight recesses and the steel angle frame below it. Fords have a gap "two fingers" wide while Chevrolets have a very small gap, less than one finger or no gap at all. In fact, I have an Australian Chev cab which has a one finger gap on one side and no gap at all on the other. You can date a late model Ford here too. 1944 models had "FORD" stamped in this space under the left hand headlight while in 1945, "FORD CANADA" was stamped there.

CAB FLOORS…The cab floor on Fords is made of tread plate or diamond plate. Australian built Ford cabs have thicker floor plate than Canadian cabs (1/4" vs 3/16"). Australian Ford cab floor plate is actually locomotive tread plate. On Australian built Chevrolets, the floor is made of smooth sheet steel and "anti-slip" strips are welded to it in both driver's and passenger's footwells. Canadian built Chevrolets have a similar floor to the Fords.

CAB VENTS…On No. 12 cab vehicles, there is a cab ventilation inlet on either side of the radiator. On the Fords, this inlet is through four louvres punched into the sheet metal, on Chevrolets the inlet is a round hole covered with a small metal mesh grille.

CAB VENTS…The side air vents on Australian built Chevrolet No 13 cabs are rectangular in shape. The vents on Canadian built Chevrolet cabs and all Ford cabs are rhomboidal.

CHASSIS…Ford and Chevrolet chassis are similar in design. The easiest way to tell them apart is to look at the hangers at the rear of the front springs. On the Ford, this is a cast horn shaped bracket riveted to the chassis rail. The rear of the spring actually is positioned between this bracket and the chassis. The rear shackles of the front springs on the Chevrolets are attached directly below it's mount on the chassis rail. Another way is to check the gearbox mounts. The Chevrolet gearbox is mounted on a cross member which passes under the gearbox. The Ford has a cross member which mounts to the rear of the gearbox and which has a hole in it for the gearbox output shaft to pass through.

The Chevrolet C15 chassis is substantially different to the 4X4 versions. This chassis is probably a North American pick up truck chassis adapted to take the CMP cab, running gear and right hand drive. It is 36" (915mm) wide compared to 34" (864mm) on the 4X4 vehicles and only has a single section throughout.

DASH JEWEL…Most Canadian built Chevrolets had the renowned General Motors Canada "jewel" attached to the dash. I don't know if any Australian built trucks had this but it is nice.

DATA PLATES…Like most military vehicles all Ford and Chevrolet CMP vehicles were liberally adorned with a variety of data plates. Follow the links above for some help in interpreting what the data on the data plates actually means.

DIFFERENTIALS…Chevrolets have conventional banjo type differentials, the Fords have a vertically split differential which looks similar to the Timken differentials found on many US military vehicles. However, some Fords used Chevrolet differentials. I do know that some Ford F60Ls used Chev axles. There seems to be several reasons for this. One is that some of the ships carrying Ford axles to Britain for assembly of trucks there were sunk and the GM axles were used to keep the assembly lines open. The other reason was that Ford Canada could not keep up with production of this type of axle for the CMP and many other vehicles such as the Universal Carriers. Some early build Ford F15As such as this No. 11 cab truck were fitted with GM axles.

DOORS STEEL…There are also minor differences in the Ford and Chevrolet steel doors. Both have a reinforcing cross pressed into the inner door panel, however the Ford cross meets in a small circle in the door centre. The Chevrolet reinforcing cross does not have the circle.

DOORS CANVAS…Quite a number of CMP trucks in Australian service were fitted with canvas doors in place of the steel doors. These were fitted for ease of maintenance rather than comfort although they did improve that as they were easily removed and stowed in hot conditions. Go here for a page about these doors.

ENGINES… Fords have a side valve V8 engine, Chevrolets have an overhead valve inline 6 cylinder engine.

FRONT AXLES… All CMPs of both makes were until sometime in mid 1944, fitted with the small, about 4.5" diameter, steering ball and swivel housings on the front axle. After that time, some but not all were fitted with the larger heavier duty, approximately 6" diameter, steering ends. All C60X vehicles had these heavier steering ends fitted as did most of the late war CMP based armoured vehicles.

FUEL TANK… All vehicles except gun tractors and the C60X are fitted with dual left and right 12½ Imperial gallon (57 litre) fuel tanks. The gun tractors and the C60X have dual 20 Imperial gallon (91 litre) fuel tanks. The tanks are handed left and right with the filler tubes usually mounted to the front of the tank. The filler tubes on the larger tanks are also much longer than those on the smaller tanks.

On some Australian vehicles such as the Chevrolet C15 6 seater utility, the tanks have been modified by removing the filler tube and the holes patched over. A new flush mounted filler is fitted to the top of the tank. The tanks are filled through a small removable hatch in the wooden floor inside the rear side doors. This tank is fitted to an Australian C15 wireless van and has a small tube in front of the original filler tube. Supposedly, this is for a fuel pickup for a generator set.

GEARBOX INPUT SHAFT…Chevrolets may come with two different gearbox input shafts. Some have a large ¾" spigot on the input shaft while others have a smaller 15mm spigot. There does not seem to be any pattern as to which vehicles were fitted with which shaft. Of course, different crankshaft spigot or pilot bearings are required depending on the shaft. Both shafts have the same clutch spline size.

GEARBOX…Vehicles of both makes are fitted with four speed non-syncromesh gearboxes. Ford gearboxes have a PTO position on the right hand side of the gearbox, Chevrolets have it on the left. Most of the four wheel drive vehicles of both makes have power tyre pumps are fitted to the gearbox PTO positions.

GRILLE…Chevrolets have a radiator grille made of stamped steel sheet in a diamond pattern, Fords have a woven metal grille with the weaves running vertically and horizontally.

GRILLE GUARD…The Ford radiator or grille guard is supported by two leaf spring like uprights attached to the rear of the bumper using "U" bolts which also attach the towing eyes to the front of the bumper. The Chevrolet guard has two uprights on either side of the radiator, two attached to the rear of the bumper and two attached to the front. This guard is wider than that on the Ford, being mounted outboard of the towing eyes.

GRILLE BAR…Chevrolets have a horizontal bar behind the grille. Fords do not.

HEADLIGHTS…Chevrolet headlights have a plain bezel ring whilst Fords have a bezel ring with two raised rings rolled into it.

HORN…Fords have their horn attached to the rear of the bumper just outboard of the left-hand chassis rail and in front of the radiator overflow tank. Chevrolet horns are mounted on the engine's inlet manifold.

INSTRUMENT PANELS…No 11, 12 and early No 13 cabs from both Chevrolet and Ford used their respective companies generic commercial vehicle instrument panels. In 1943 both manufacturers introduced new instrument panels which used the round United States military type gauges although they still used their own switches in the new panels. Brian Gough did some detective work here and has narrowed the time down to July 1943 in the Chevrolet C8A Heavy Utility models. I think it would be safe to assume that Ford changed around the same time. This is an early No. 13 cab Chev dash and this is a late No. 13 cab Chev dash. The late Ford dash is almost the same as the Chevrolet one. Both manufacturers still continued to use their own switches on these panels.

MARKER LIGHTS…Chevrolet marker lights are positioned nearer to the outside edge of the front mudguard than Ford marker lights.

MIRROR BRACKETS…Chevrolet external rear vision mirrors are mounted directly onto the upper door hinges. Ford mirrors have their own brackets positioned between the upper and lower door hinges.

OVERFLOW TANK…Until about mid 1943, all Chevrolets had a cylindrical radiator overflow tank attached above the left front mudguard. After that date, it was relocated under the passengers floor. All Fords had their tank located here on top of the front of the left chassis rail.

PEDALS…Ford brake and clutch pedals are round in shape. Chevrolet pedals are rectangular.

ROOF HATCHES…There are some differences in the roof hatches when fitted. Australian Chevrolet hatches have square corners and the hatch coaming is fabricated from angle iron and is bolted or spot welded to a flat section pressed into the cab roof. Australian Ford hatch corners are rounded and the coaming is pressed out of the roof sheet metal itself. Chevrolets have a single grab rail running the full width and in front of the hatch, Fords have two small hand grips in front of the hatch.

Early Canadian vehicles, both Chevrolet and Ford, had a similar hatch to the Australian Ford hatch described above. Indeed, Ford built a large number of the cab roofs for Chevrolet in Canada. Some time in 1944, Canadian production vehicles of both makes appeared with round hatches similar to those found on most US sourced military vehicles.

SHOCK ABSORBERS…Both Fords and Chevrolets are fitted with lever type shock absorbers. However, Ford shock absorbers are of a rotary vane type whereas the Chevrolet shock absorbers are of the opposed piston type. Both shock absorber types are rebuildable.

STEERING BOX…Chevrolet steering boxes are mounted on a cast bracket beside the right hand front chassis rail. Ford steering boxes are mounted on the top of the right chassis rail at the extreme end.

STEERING WHEEL…Chevrolets have a four spoke steering wheel. Prior to July 1943 the wheel was made of a hard black plastic, after that date it was wood rimmed. All Fords have a four spoke hard black plastic wheel. It's spokes are slightly curved, Chevrolet ones are straight.

TOWING EYES…Chevrolets C8, C8A, C8AX and C15 all have their front towing eyes mounted to the front bumper so that they swivel in a horizontal plane. All other CMPs have them mounted so that they swivel in the vertical plane.

TYRE PUMP…Many CMPs, mostly the four wheel drive versions, are fitted with a power tyre pump driven off the side of the main gearbox. On Fords the pump is fitted to the right side of the gearbox, Chevrolets to the left.

The tyre pump outlets were usually positioned on the chassis rail adjacent to the tyre pump although some were fitted in the cab floor near the transfer case lever. A flexible air hose was included in the truck's equipment kit.

WHEELS…For information on wheels and tyres fitted to CMP vehicles, go here.

WINCH…All gun tractors and many other four wheel drive CMPs were fitted with winches. The winches are PTO driven via a short drive shaft off the rear of the transfer case. All the winches are of a Ford design, no matter what vehicle they are fitted too. The winch is based on the Ford vertically split differential and uses the same crownwheel and pinion as used in the F15 differential (6.666 to 1 ratio). The winches can be operated in both directions under power and will also freewheel. There is a small hand brake drum with a set of external brake shoes attached to the front of the winch input pinion shaft.

The winch rope is a 125 foot (38.1 metre) 5/8" (15.87mm) diameter hawser laid steel wire rope. It has an advertised breaking strength of 29000 lbs (13182 kg). A hard eye is woven into the free end of the winch rope and a short length of chain and a hook was often attached to the eye.

In the cab, vehicles with winches can be easily identified by a winch hand brake lever mounted to the left of and to the rear of the drivers seat. Externally, vehicles fitted with winches can be identified by the winch rope fairleads fitted above the pintle hook in the rear and to the left of centre and below the front bumper. Two or sometimes three 'pigtail' shaped winch rope guides are bolted to the outside of the left hand chassis rail to guide the winch rope if it is being used at the front of the vehicle.

Winches are operated via the transfer case selector lever. Forward and reverse is selected by the main gearbox. When the winch PTO is engaged, the transfer case is positioned in neutral, therefore the vehicle can not be driven when the winch is in operation.

If you see any obvious mistakes then please email me and I will correct them. I do not pretend to be infallible. If you don't tell me, I may never know what is wrong.

I have to thank a lot of people for their assistance with this page but especially Brian Gough, Mike Cecil, Keith Webb, Rod Lewis and Bob Dimer.