Model A & B
Ford Garage
Rotating Engine Mass
The intent of this page is to compare and contrast the dynamic characteristics and rotating engine masses of different configurations of popular Model A and B engine, flywheel, and clutch combinations.
The Mass Moment of Inertia (MMI) of an object about a given axis is its inherent resistance to rotational acceleration about that axis. An object with a higher MMI will have a lower rotational acceleration than a body with a lower MMI for the same application of torque.
Dynamic Balancing of Rotating Mases
Refer to the two links below for a technical presentation on dynamic balancing methods utilized by the Ford Motor Company in the Model A era.
Gisholt (Precision) Balancing Machine
as used by the Ford Motor Company
Dynamic Balancing Simplified
Gisholt Machine Company, 1926
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An Elementary Textbook of Automobile Engineering
Model A & B Engine Vibration & Crankshaft Balancing
Textbook Published by the Ford Motor Company, 1935
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Table below is under construction
The weight of the individual engine components in the table below is given in pounds.
| Engine Configuration | Crankshaft (lbs) |
Crankshaft Gear |
Flywheel | Flywheel Starter Ring Gear |
Clutch Driven Disc(s) |
Clutch Pressure Plate |
Combined Rotating Mass (lbs) |
Rotational Mass Moment of Inertia |
|---|---|---|---|---|---|---|---|---|
| 1928 'Beavertail' A crankshaft Multi-disc flywheel Multi-disc clutch |
28.3 | 0.9 | 58 | 3.1 | 11 | 101.3 | tbd | |
| 1929-31 Standard A crankshaft Multi-disc flywheel Multi-disc clutch |
28 | 101 | tbd | |||||
| 1929-31 Standard A crankshaft Standard A flywheel Standard single plate clutch |
63 | 2.5 | 15 | 111.5 | tbd | |||
| 1929-31 Standard A crankshaft Lightened A flywheel (26 lbs) Standard single plate clutch |
26 | 75.5 | tbd | |||||
| Burlington (counterweighted) A crankshaft Standard A flywheel Standard single plate clutch |
37.8 | 63 | 122.3 | tbd | ||||
| Burlington (counterweighted) A crankshaft Lightened A/B flywheel (Stipe 37 lbs) V8 flyweighted clutch |
37 | 11.2 | 92.5 | tbd | ||||
| 1932 Standard B crankshaft Standard B flywheel Standard single plate clutch |
38 | 53 | 15 | 112.5 | tbd | |||
| 1933 Integral counterweighted B crankshaft Standard B flywheel Standard single plate clutch |
45.6 | 120.1 | tbd | |||||
| 1934 Pinned counterweighted "BB" crankshaft Standard B flywheel Standard single plate clutch |
56.8 | 131.3 | tbd | |||||
| 1942 Ford-Köln G28T German B engine G28T Integral counterweighted B crankshaft G28T Flywheel Single plate clutch |
needed | 40 | tbd | tbd | ||||
The dynamic response of the rotating engine masses is measured by the rotational mass moment of inertia (MMI) of all the components summed together. The calculated contribution of each component is the integration of its mass distribution and the distances from the axis of rotation.
A mass located 'farther' from the axis of rotation has a greater contribution to MMI than the same mass located 'closer' to the axis.
Summary:
As a general statement, the lower the MMI, the less rotational energy the system can store, and the faster the engine will be able to change its rotational speed. In other words, the faster it can spool up and down in speed.
The higher the MMI, the more rotational energy the system can store, and the slower it will be able to change rotational speed (spool up and down).
Pictured below for reference is the typical stock Model B counterweighted crankshaft introduced by Ford in December 1932.
More related information on Ford Garage:
- For more Model A & B related information, use the Site Search box at the top or bottom of this page.
- Model A & B Engine Vibration & Crankshaft Balancing
- Model A Burlington Forged Counterweighted Model A Crankshaft
- Model BB Ford-Köln G28T-6303-B2 Counterweighted Crankshaft
- Model A & B Stock and Lightened Flywheels
- Model A & B Flywheel Ring Gear
- Model A, B, & V8 Pressure Plates and Clutches
December 2012