Packard Forum Index » Pre-War (1899-1942)

Does anyone know where I can find the gear ratio info for the 1937 115C?

Check the 1937 Shop Manual and 1937 Service Letters here on the website. It should be listed in those.

Also the owners manualhttps://www.packardinfo.com/xoops/html/downloads/1937_SixOwnersManual.pdf

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4.36 was the most common rear axle ratio but I believe there were two optional ones. If no one beats me to it, I'll post them before I go to bed.

EDIT - 4.36 standard, 4.54 and 4.09 optional.

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AgentX66X, one easy way to ascertain an excellent approximation of gear ratio regardless of who has changed what over the last 73 years is to jack up one wheel leave the other on the ground (or so it will not turn) and mark the wheel and driveshaft. Note the position of both marks. Rotate the wheel two full revolutions and count the turns of the driveshaft.

If you turn the wheel twice and note the driveshaft turns approx 4 and 1/3 turns, it is likely as O-D points out the standard 4.36:1 ratio. 4.5 turns, then it is the 4.54:1 ratio... you get the picture.

Why one wheel of the ground? The Spider gears are a 2:1 reduction. axle:pinion

Of course if for some reason the third member is out of the axle housing presently, count the number of teeth on the ring gear and divide by the number of teeth on the pinion (driven / drive) and you will have the gear ratio.

This combined with the info provided above should help verify the ratio presently in your car.

Jim

The ratio number is usually stamped on the front flange of the "pumpkin", should be upper left if facing the "pumpkin" from the front.

There was a thread in the PAC Forum about this subject recently.

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Thanks everyone for the info. I will try to find the stamp and if not I will do the age old jack and spin trick