John Walters
Member
Looking in various publications I have seen AA trucks pulling heavy loads. What was the engine in the AA? A heavier duty 4 cylinder?
AA engine
- Thread starter John Walters
- Start date
Chris Haynes
Well-known member
Exactly the same engine that cars had. Just lower gearing.
As Chris says...it is the same engine;
HOWEVER...the difference was that the clutch in the "AA" was equiped with heavier springs and had a slightly wider disc than that used with the "A" (Refer to page 351 of the Ford Service Bulletin).
There was a short time in early 1928 I think that FORD dropped the "AA" designation for the trucks because they went back to using the same clutch spring as the "A" but found out that they needed to revert back to the heavier clutch so the "AA" was reinstated.
Pluck
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Refer to page 351 of the Ford Service Bulletin...you be the judge!
The engine could have had an “A”
(Fig. 5) or “AA” (Fig. 4) associated with the
Pluck
number and the engine itself. An “A” usually meant that the engine was for a car
or a light commercial vehicle. The “AA” usually meant that the engine was
associated with the heavy duty trucks. This concept remained the same
throughout the production of the Model A/AA Ford except from starting with
engine number A26268, a February 16, 1928 engine, the “AA” prefix was
dropped due to the fact that all truck clutch springs were the same weight as the
car and commercial vehicles.
On May 15, 1928, the Indianapolis Ford Service Letter indicated that all the truck
engines were now being equipped with a 455 pound spring and that the engine
numbers on such motors were being prefixed with the letters “AA” again. The
cars and commercial vehicles retained the 420 pound clutch spring and the prefix
“A”. These heavier truck clutch springs were painted “red” to distinguish between
the two. Not sure of the engine number that this change occurred with.or a light commercial vehicle. The “AA” usually meant that the engine was
associated with the heavy duty trucks. This concept remained the same
throughout the production of the Model A/AA Ford except from starting with
engine number A26268, a February 16, 1928 engine, the “AA” prefix was
dropped due to the fact that all truck clutch springs were the same weight as the
car and commercial vehicles.
On May 15, 1928, the Indianapolis Ford Service Letter indicated that all the truck
engines were now being equipped with a 455 pound spring and that the engine
numbers on such motors were being prefixed with the letters “AA” again. The
cars and commercial vehicles retained the 420 pound clutch spring and the prefix
“A”. These heavier truck clutch springs were painted “red” to distinguish between
Pluck
Me to...maybe the next time you go to the FORD Archives, you can research it out and report back! That would be the best place to find out your question.
In the mean time read what it says in the Ford Service Bulletins.
Pluck
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James Rogers
Well-known member
Vince, I have tried to find verification of a wider disk and only could find some flywheels that had a marking of wear the disk made that is 9 1/4" instead of 9". I have also found a couple of pressure plates with the same wear pattern. This would indicate, the AA disk was 9 1/4" diameter instead of 9" but, I have no real proof.
Kurt in NJ
Well-known member
I have a28-37 parts book, it lists "AA", and "BB" clutch disc as being 9-3/4 " outside diameter ----and in my used clutch disc pile I have at least one non spring hub 9-3/4 disc---it is also listed for "Taxi" use
2 different pressure plates--A,B,18,40,46 and AA/BB
In the service bulletins it says the truck clutch can be easily identified by the red paint mark and the grey enamel springs--page 351
all the multi disc parts have "A" except the spring which has "AA" and is listed for A also (AA truck with 3 speed trans)is in all the listings
2 different pressure plates--A,B,18,40,46 and AA/BB
In the service bulletins it says the truck clutch can be easily identified by the red paint mark and the grey enamel springs--page 351
all the multi disc parts have "A" except the spring which has "AA" and is listed for A also (AA truck with 3 speed trans)is in all the listings
Tom Wesenberg
Well-known member
I always thought of the A and AA discs as 9" and 10", as that's what I read years ago. I guess the measurment could have just been rounded off to the nearest inch. Anyway I bought an NOS 10" disc at a swap meet for the 1930 AA I worked on, and recently I found an excellent slightly used 10" that I'll use sometime. The 10" does overlap the square openings in the pressure plate, but that doesn't matter.
Kurt in NJ
Well-known member
The book I was looking in was published july 1945 --it is interesting to look at the differences in the same year span book published different times---and how it changes in the green book
Chris Haynes
Well-known member
I prefer to use the later disk with the shock absorbing springs in the center.
Kohnke Rebabbitting
Well-known member
If your disk is 10 inches Tom, it won,t do you any good, as the flywheel surface is only 9-3/4's, all my pressure plate cores are in the warehouse, so I can't tell what they are now.
We have always used the 9-3/4, in cars, and trucks.