VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 Early vs Late Model Year 1931

Junkyard Dog, I read your posting about Bumpers: #17912 06/05/06-"The early 1930 Chevy bumpers were double face bars with black grooves. The late 1930 bumpers were double face bars with no grooves. The early 1931 bumpers were double face bars that were convex. The late 1931 bumpers had a single face bar." I have the double face bars on the 31 Coach. That makes it an early 31 model. What were the starting and ending months of the 1931 model year? Is halfway thru the model year the cutoff between early and late? Also, my engine number has the date code= C 2 1 (March 2ND 1931). Is there a way to figure out what date the Coach was made? The Cowl Tag shows: Body NO. O 3637 (Oakland Plant 3,637th Coach), are there production records to indicate what day it came off the assembly line? Knowing early vs late would help with other comparisons between same year cars besides the different bumpers. Thank You

The production for the 1931 model year started in October of 1930 and the production ended in September of 1931.

Actually, "early" and "late" are general terms used to kinda sorta mark various changes in production parts and accessories. However, those terms do not dictate that the changes were made exactly in the middle of the year since production changes occurred in various months throughout the year.

Usually the assembly of the vehicle took place within the same month of the casting date of the engine, that is if the vehicle still has the original engine from the factory.

There are production dates by the month as to when a car was manufactured but I haven't seen any records indicating the exact day a particular vehicle was made in a specific factory.

Thank You Junkyard Dog for this information. I guess knowing the actual day of production of the car isn't all that necessary, unless you wanted to read the history of that day in the newspapers. Knowing generally what month will work for me. As for changes made during the model year production run, I should know that it's a flowing process (phase in-phase out), and not a ridged stop start thing. Kinda mimics day to day life a little. I'm assuming that my engine is the original factory installation. Is there a way to verify this? I do appreciate everyone's help in my search for knowledge about "OLD BLUE".

Given the casting date of your engine I would say that it is probably the original engine.

Many of the part changes and etc. were listed in the Chevrolet Service Bulletins and sometimes they even listed the day of the change.

The date of changes also depends on when an individual factory implemented the change. Even after that it was possible for some of the stock of old parts to be used when the new ones not readily available.

Harry, a couple of other things on the EARLY 31's that I noticed on my early 31. Mine is a five window coupe. There is a small drain gutter on the top of the doors that the early cars did not have.There is information on this in the sevice news bulletin. My car also has upholstery fabric covering the rear and two side window garnish moldings were the later 31's had the metal garnish all the way around. I also have the two faced bumper and mine was also made in Oakland.

They're some different hoods also. Same number of louvers but in a different part of the hood. Early cars I've seen including mine have the louvers farther back..Joe

Harrys31coach, if you know the car number from the plate near the right front body sill, I can tell you the approximate production date.

Hey Junkyard Dog, I'll start reading the Chevrolet Service Bulletins for model year changes. Thanks

Chipper, Thank you for your observation regarding factory old stock and new stock availability. Could dealerships and repair shops have interchanged early and late parts, making it difficult to tell early and late production models? A kind of mixed new and old on the same car?

31 Sal, Yours is Oakland made? Good! Now OLD BLUE won't feel so alone. It sounds like the service bulletins keep people aware of the different changes within a model year.

Jiaccino, (JOE) Appreciate the heads up on the hood louvers. I have not compared any 31 hoods yet, but I'll measure mine from the aft louver to the back edge and keep watch. What model car/truck do you have?

d2d2, If this will help, the sill plate shows: 6 AE 22732
Thanks, But ya know, the more I know, the more I don't know.

Harry
I just sent you a picture. My car is an Oakland 31 sedan delivery....Joe

The early Chevrolet Service Bulletins (which are completely different than the Chevrolet Service News) are hard to locate and it may take years of collecting to develop a good library.

Junkyard Dog, Thanks again for correcting my mistake about the 'Chevrolet Service Bulletins'. I don't have any of those. The Chevrolet Service News for 1931 is what I have. With all the (want/need to know) questions being asked, It's good to know that there's a source to refer to. Appreciate you sharing your library with everyone on Chevy Chatter II.

6 AE 22732 was assembled on or about March 17, 1931.

5625 passenger cars were assembled at Oakland in March, 1931.

d2d2, I do appreciate your information of within a day or two of March 17, 1931, OLD BLUE was born. That would be right in the middle of the production year run: Oct 1930-SEP 1931 (Stated by Junkyard Dog). It's got the two bar front bumper, so if I had to guess between early or late model year, I'll go with early. That's until I discover other secrets OLD BLUE decides to reveal. Thank You

From my understandings, bumpers were extra & didn't come with the car. Depending on the size of the dealership, the car would probably got what was left on the shelf if the customer ordered bumpers. I don't have an exact date when single face bar bumpers came out....Joe

Yes, all bumpers were dealer added accessories.

Jiaccino and Junkyard Dog, Your information has spoiled my belief as to definitely having an early model year 1931 Coach. Well, that's OK. As I investigate further, I'll find out more and seek your opinions. I want it to be a driver, but a period correct driver. I also want the history knowledge to be an informed hobbyist. Without your help it won't happen. Thank You

I have a Canadian made '31 Coach, and they have the engine # included on the ID plate affixed to the cowl. Mine originally had engine #2315237 according to the plate, but when I bought it, the engine was T293779, date stamped H-16-0, or August 16, 1930. With an August 1930 date of manufacture for this engine, I suppose my replacement engine could have come from a late 1930 model, or an early 1931 model.
Mine also came with double convex bumpers, both front and rear (deluxe model).
A local Chevy enthusiast tells me the original engine would have been from about April '31, suggesting my car was manufactured in the spring of '31, close enough for me.

GM was still procucing engines in August for the 1930 model year, and the "T" prefix before your engine serial number indicates that your engine was from a truck.

Motor numbers 2300001 to 2350400 inclusive were taken from the regular US number series in January, 1931 and assigned to Walkerville.

JY-D, do you know if there was a difference between the truck and car engines at the time, i.e. in August of 1930? I was curious what the T implied, thought it may have been a reference to the plant where engine was cast.

The truck and car engines were the same. The only difference was that the truck engine had a "T" prefixing the engine serial number.

I had thought that the truck engines originally had different (smaller diameter) sleeves in the intake ports to restrict airflow?

Or am I off in la-la land again?

All the Best,

Chip.

The 1929 trucks used different manifold sleeves than the 1929 passenger cars. For 1930 and 1931 the sleeves were the same for both the passenger cars and the trucks. 1932 used a different manifold sleeve, but it too was the same for cars and trucks. However, for each year the basic engine was the same for both the car and the truck.