Cummins
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Description
The 1994-1997 Powerstroke equipped F-250 and F-350 trucks featured a Dana 60 assembly up front and either a Dana 80 or 10.25" out back. The 10.25's were reserved for single rear wheel (SRW) applications, where the larger 80 was used in all duallies (DRW). From the factory, these housings were stuffed with either the popular 3.55 ratio, or the 4.10 most commonly used for heavy duty towing, as it delivers higher RPM's at lower speeds in comparison to the 3.55 ratio.
Over the years, these assemblies have proven themselves relatively reliable on moderately used trucks running stock, or close to stock tire size and power output. For those of us that demand substantial power increases and larger tires, there is room for improvement to improve the reliability and performance that they can afford. One of the best upgrades we can recommend for anyone that has increased tire size, is that of a ring and pinion ratio upgrade. As previously stated, most of these trucks came factory with a 3.55 ratio, designed to have a proper run out with a stock size tire (roughly 31" depending on model year). But as soon as you upgrade to a 35" or larger tire, all of a sudden your RPM vs. speed are effected, even causing a disruption of the shift pattern on automatic transmission equipped trucks.
Lets give the example of upgrading to a 37" tire. By using cross multiplication, we can determine that in order to have the same RPM vs. speed as with the factory tire size, you would want to install a 4.23 gear ratio (3.55/31*37). Unfortunately, in this scenario there is no such thing as a 4.23 ratio, but the closest would be a 4.10 that is readily available. Or, you can also opt to go with a slightly lower ratio of 4.56 that would give you a higher RPM vs. speed compared to stock.
Besides replacing the ring and pinion, we also offer numerous other upgrades, such as ARB Air Lockers, rebuild kits, and so much more. As always, if you have any questions about which product is right for you and your truck don't hesitate to give us a call and we would be happy to help.
Over the years, these assemblies have proven themselves relatively reliable on moderately used trucks running stock, or close to stock tire size and power output. For those of us that demand substantial power increases and larger tires, there is room for improvement to improve the reliability and performance that they can afford. One of the best upgrades we can recommend for anyone that has increased tire size, is that of a ring and pinion ratio upgrade. As previously stated, most of these trucks came factory with a 3.55 ratio, designed to have a proper run out with a stock size tire (roughly 31" depending on model year). But as soon as you upgrade to a 35" or larger tire, all of a sudden your RPM vs. speed are effected, even causing a disruption of the shift pattern on automatic transmission equipped trucks.
Lets give the example of upgrading to a 37" tire. By using cross multiplication, we can determine that in order to have the same RPM vs. speed as with the factory tire size, you would want to install a 4.23 gear ratio (3.55/31*37). Unfortunately, in this scenario there is no such thing as a 4.23 ratio, but the closest would be a 4.10 that is readily available. Or, you can also opt to go with a slightly lower ratio of 4.56 that would give you a higher RPM vs. speed compared to stock.
Besides replacing the ring and pinion, we also offer numerous other upgrades, such as ARB Air Lockers, rebuild kits, and so much more. As always, if you have any questions about which product is right for you and your truck don't hesitate to give us a call and we would be happy to help.