Reprinted with permission The FV Newsletter, June 1992
One of the seemingly difficult things when buying a car is trying to figure out the true gear ratios in the transmission. Here is an easy way to figure this out.
Start with one rear wheel jacked up and the other firmly o the ground. Put the transmission in the gear you want to check. If the engine is in the car, it will be easier if the spark plugs are removed. If there is no transmission, then and old clutch disk on the input shaft will work fine.
Make a mark on the top of the tire and on the pulley or clutch disc. Rotate the tire 3 times and count the number of rotations of the engine (clutch disk) to the closest 1/8.
Divide engine count by axle then multiply by 2. Convert this figure to a decimal and look for the closest value in the chart below.
Gear Ratio |
Long | Short | |||
Fully Syncro |
4.13 | 4.38 | |||
| 1 | 10 | 38 | 3.80 | 15.69 | 16.64 |
| 2 | 17 | 35 | 2.06 | 8.50 | 9.02 |
| 3A | 22 | 29 | 1.32 | 5.44 | 5.77 |
| B | 23 | 29 | 1.26 | 5.21 | 5.52 |
| C | 23 | 28 | 1.22 | 5.03 | 5.33 |
| 4A | 27 | 24 | 0.89 | 3.67 | 3.89 |
| B | 28 | 23 | 0.82 | 3.39 | 3.60 |
For example:
Engine (8 2/8) / axle (3) x 2 = 5.50 = 1.26 third / short box
Engine (5 7/8) / axle (3) x 2 = 3.92 = .89 fourth / short box
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