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Joined: Jul 2017
Posts: 98
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Jul 2017
Posts: 98 |
I was asked today by the brother in law if it was possible to change the differential gears of a 37 Chevy 1/2 ton. Not certain what ratio may be in the truck at this time. To the best of our knowledge it is the original differential. Does anyone have any information on this topic?
Don't let a day go by that you don't attempt to learn something new.
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Joined: Dec 2016
Posts: 656 Likes: 3
Oil Can Mechanic
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Oil Can Mechanic
Joined: Dec 2016
Posts: 656 Likes: 3 |
I am building one of these differentials, and so far what I have been able to gather
The ring and pinion design is used in:
Late 35-36 Chevrolet Master
Late 35-36 Pontiac 6 & 8
Late 35-39 Chevrolet 1/2 ton
Ratios:
4.89 - Pontiac "mountain" gears (and probably an extremely rare Chevrolet option).
4.55 - Pontiac 8 default gears
4.44 - Pontiac 6 default gears
4.11 - Chevrolet default gears, Pontiac "plains" gears
3.82 - Chevrolet only fuel economy option (uncommon)
3.36 - Larry Jackson aftermarket Chevrolet gears (modern era, very few sets made)
Early 35 (and probably 34) are almost the same, but use a different pinion, pinion bearing, and carrier. It doesn't add any more ratios to the mix, so probably not much help.
The short answer is since its a Chevrolet it probably already has 4.11, and that is the most desirable ratio you are likely to find.
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
I agree. A 1936 Chevrolet with a 4.11 allows a crusing speed of 55+ MPH if in good mechanical condition. You can zip it up to 60 or 65 for fun. Low speed pulling power will be good and 2nd gear starts easy.
Chevrolet never offered a 4.44 or 4.55 or 4.89.
A 1937 1/2 ton truck had a 4.11 with a 3.82 option. With any ratio a 1937 truck sounds like it is going to take off at any speed over 50 MPH. Small cabin, no insulation or soft material inside.
Gene Schneider
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Joined: Jul 2017
Posts: 98
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Jul 2017
Posts: 98 |
Thanks for the replies gentlemen. I appreciate it. Both the 37 truck and the 29 car that we own seem to be 40-45 mph vehicles. I wont push the 29 any harder than that.
Don't let a day go by that you don't attempt to learn something new.
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Joined: Mar 2002
Posts: 1,739 Likes: 2
ChatMaster - 1,500
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ChatMaster - 1,500
Joined: Mar 2002
Posts: 1,739 Likes: 2 |
The gear ratio for 1929 was 3.84:1. They switched to 4.11s in 1930 to make the cars faster off the line They are not interchangeable though due to differences in the rear axle. Your 29 should go faster then 45 with good bearings and clean oil system.
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
I agree that 45 MPH is a COMFORTABLE crusing speed for both the 1929 car and 1937 truck.
Gene Schneider
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