i have a 01 2500 4x4 cummins w/ auto tranny it currently has 4.10's and i want to put 3.55's in it to get better fuel mileage. has any0ne swapped the ring & pinions in these trucks.never had the frontend apart so im not sure what to expect.
Swapping gears is more of an art than a science. Setting up the correct pattern can be a bit tricky, but these axles are really no different from any other full floater type or knuckle type as in the front. If you haven't done it before, do MUCH research first. It is a very big, and easy to foul up job. The gears need to be very carefully shimmed to set them up.
Having said that, the rear is pretty easy, and can be done with the truck on the ground. The front will be the fun part as you have to pull the axleshafts to get the carrier out. The other hard part will be crushing the crush sleeve that goes between the two bearings on the pinion after you have your pattern correct and are doing a final install. Those things are a BEAR to crush.
It is NOT a simple bolt in job. I have done many gear changes, lockers, etc, and in your situation, I would first see if you can source an axle swap. It might be more practical all the way around. (Maybe a gas engine truck who wants to trade you?)
If you do do it, I would recommend doing the front axle balljoints, and possibly the unit bearings. The timkens last forever, but getting the business end pinion bearing off is pretty tough, so buying new bearings will make it a lot easier. You still likely will have to split off the bearing to change the shim behind it if it doesn't set up right. (about 40 to 60% set up right at the pinion with the old shim depending on the axle type. If not, it's guess and check)
You MUST have a hydraulic press, bearing splitter, dial indicator, dial calipers at least or better, micrometers. A balljoint press is probably needed to get the front knuckle off. Some axles you can wiggle just enough from pulling the hub and spindle to get the axles out of the carrier, but not most. Oh and a horrendous large cheater to crush the pinion sleeve.
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