Hey guys, I'm new here and looking for info on swapping my rear axle in my 02 ram 1500. It has the corporate 9 rear with 3.55 gears. It actually has a cummins in it with a getrag 5 speed manual with no overdrive. It is my daily driver and my rpms are way to high at normal cruising speeds. Taller tires are an option but will start to look goofy. I believe swapping to a 3.08 would be ideal. I know the 90s f150s 8.8 had these gears and very similar bolt patterns. Anyways, I wanted to get some opinions from some of you to see if I,m looking in the right direction or way off. I don't know much about axles so fill me in. It's not a high horsepower machine so I don't need anything extreme. It mainly gets driven to and from work carrying my tools and will pull a trailer to haul firewwod or Atvs at times. Thanks

 

WAY OFF, ( just my opinion ). Even if you retro fit a Ford 8.8 ( these are also the same axles as the 4.0 Rangers have ) the torque of your Cummins will tear these axles up, even if using as a daily driver. Maybe you can see if you can have an overdrive installed in your tranny.

 

Why not just swap gears, I'm pretty sure you can go all the way to a 2.76 in a 9.25.

 

If you have a Cummins in a 1500 then you should probably try to go a 10.5 rear end first in order to handle the torque better

 

You will break the 8.8 they are border line even for a small block ford.. The 9.25 should handle the power unless you get stupid with the gear shifts or pretty heavy loads. The torque that those motors make will twist axles if you get on it too heavy with a load.

 

I just can't believe he would want a numerically lower gear ratio than 3.92. I mean a Cummins can't rev past 5K anyway so what kind of RPMs do you consider to be high during cruising?

 

i wound say no. bacause in the first years of the cummins, dodge used the one ton axle and were tearing them up un till a new axl set up was made to handle the new motor.

 

He is wanting to gear up like having another over drive the 5 speed he has must not have much overdrive in it or really short tires.. So he is trying to go to Higher gear ratio as in faster or from a 3.55 to a 3.00 to keep the diesels RPMs in the range it was designed to run in at highway speeds since he is running 1900 now at 60 I am guessing he will be around 2300 at 70mph a bit high for good mileage on a diesel they like pretty much just off Idle for best MPG. My son is wanting to do the same thing to his 06 so it will run 1600 to 1800 at 75 mph cheaper to put on bigger tires for him since he needed tires any ways..

 

I know I have a gas motor but with 5 speeds, 2 ODs, 3.92s and 34 inch tires I turn 1750 at 70

 

My dads 99 with cummins at 70 turns about 1700 or so and it sound fine.it does that because a diesel should do that at 70