| Topcot | -- 11-16-2016 @ 1:32 PM |
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Can anyone tell me what the rear end ratio would be for a 1940 Mercury (coupe)? Were there various ratios offered? Are there any markings on axle or differential that might tell me? Would doing the jack up the car and turn the wheel and watch the drive train turn (count revolutions) method work?
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| ford38v8 | -- 11-16-2016 @ 3:57 PM |
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Topcoat, Yes to all those questions. Your Merc would likely have left the factory with a 3.78 or 3.54 ratio. As you must know, these gears may have been changed out at some point over the 76 years of your Merc, but the original set would have been identified as hand stamped numbers on the bottom forward rib of the differential. (Large number divided by the small number gives the ratio.) To confirm the set you think you have, Jack up one rear wheel only, remove the spark plugs for ease of turning the engine. In high gear, two revolutions of the wheel will equal the ratio as seen on the crank pulley. (If turning both rear wheels, only one revolution.) An easier method would be to drain the differential, mark the ring gear with a marking pen, and while in neutral, turn the wheel while counting the ring gear teeth, which would be the large number stamped on the differential. Alan This message was edited by ford38v8 on 11-16-16 @ 3:59 PM
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| TomO | -- 11-17-2016 @ 9:56 AM |
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Alan gave you the correct information, but I would like to add that the 3.54:1 was the most common ratio for the 40 Mercury and that it is very likely that the ratio stamped on the differential is the current ratio. The Mercury differential is different from the Ford in 1939 and 40, in that the pinion gear is pressed on the drive shaft and there is no sleeve connecting the drove shaft to the pinion gear. This makes it more difficult to change the ratio. Tom
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| Topcot | -- 11-17-2016 @ 2:51 PM |
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Thanks to Alan and Tom. I'm going under car this weekend too see what I can find out.
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| ford38v8 | -- 11-17-2016 @ 3:09 PM |
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Thanks, Tom. I'd forgotten about the Pinion/Driveshaft on the Merc. Alan
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