05-05-2021, 09:56 AM | #1 |
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Join Date: Aug 2009
Location: Ft.Collins, Co.
Posts: 103
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Gear change ?
This is a continuation of an earlier thread (Swap Meet Score) . Can I run a 3.42 gear ratio with a 4 series carrier via a shim etc ? I picked up an Eaton true-trac #913A315 at a swap meet with a 4.10 gear set on it . I would prefer not to go that crazy with the gears as I dont have overdrive . Can I use a 3 series gearset on this unit or am I going to have to use the 4.10s ?
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05-05-2021, 10:52 AM | #2 |
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Join Date: Sep 2016
Location: Ozark, MO
Posts: 567
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Re: Gear change ?
Assuming it is for a 12 bolt, You can use 3.73 gears on a 4 series carrier. That is as numerically low as you can go.
If I recall correctly from my jeep days, you can shim a 4 series gear to work on a 3 series carrier, but not vise versa (The pinion gear is a small diameter on 4 series gears, so the carrier is thicker, to move the ring gear towards the pinion). The jeep vendors actually sell "thick" 4 series gears for this vs a shim. |
05-06-2021, 09:50 AM | #3 |
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Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,722
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Re: Gear change ?
Spacer, not shims. Shims are on the outside of the bearings to adjust backlash and preload. But a higher numeric gear can be run on a lower carrier with a spacer. But I would not recommend it.
3.73 is the carrier break for the truck "4" series carrier as mentioned above, 3.07-3.42 for the "3" and less than 3.0 for the "2" series carrier. For cars, you can get a thin gear to run 3.73 on a 4 series carrier (car break is 3.90 and up for the 4 series) I did not find a thin 3.42 gear for the trucks when I Googled FWIW.
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