Guys,
I need some information and some help. I have a 2002 2500 CTD Shortbed with the auto and 4:10 rear gears (locking differential). I bought the truck used and didn't have much choice on gears but now I need to make a change.

I drive 98% of the time unloaded and a combination of highway and city and I do about 30K miles per year. You can imagine, the 4:10 is killing me!! When I do tow, it is a 31' Airstream Travel Trailer that tips the scales at 5800lbs LOADED. Needless to say, my Cummins NEVER works hard.

I want to swap to 3:54 gears in the rear and I don't want to lose my posi-track either. I know that under most circumstances there are better ways to increase mileage other than gear swaps, but in my case the 4:10's gotta go! I just don't need them and I drive TOO much highway to keep them.

My question is this (yes I read countless posts, but I need condensed info guys):

What do I need to buy and do to accomplish this swap? I know I need the gears themselves and I found them at ringpinion.com. What else will I need? I am pretty mechanically inclined, I did my own fuel injectors, my own HPFP lift pump conversion, my own draw straw and big line kit installation etc. I may not be a master mechanic but most times I can find the good end of the ratchet!

Is this a major job? I have been told that you have to pull the axles completely out and then replace all the bearings and seals etc. and then I have also been told that you can pull the axles out just enough to replace the gears and just support the axles with jack stands so as not to damage the seals etc. I don't know what to believe!! Any help is much appreciated guys!
-Don

 

Well you have half the battle done already, you have a 2wd truck!!!

Like you, my 02 came with 4.10's as well, and with a 6speed even!! It was wound pretty tight to make 70mph on the interstate even with 285 size tires. I will say this, if you plan to put 35" tires on with an automatic, keep the 4.10's. The auto's have a lower OD ratio and they really lug with 3.55's and 35's.

All that being said, I love my current setup with 3.55's and the 6spd.

To do the swap, you need to get the ring and pinion as well as a 3.55 sized carrier. Also needs to be posi if you want to keep that. You can just pull the axles out about 6" on each side and support with jackstands if you so desire. I pulled mine completely out. You will need to pay close attention to the markings on the pinion after it comes out. It will give you at least an idea of how to set up the new one and get it close enough to check with marking compound. I did it with the help of a longtime mechanic friend and it was done within about 3 evenings time span, although I did pull one all-nighter and about kill myself the next day by falling asleep at the wheel of a scraper. I dont reccommend doing that. Just be real careful with that carrier and ring, it gets really heavy really quick. If you can afford the time to do it, it would be much easier on you to remove the rear end from the truck and do the swap on the bench rather than on the ground under the truck. I did not require a case spreader to swap mine, I just used a big rubber mallet to whack the chunk into place. I had the chunk in and out about 5 times to get the backlash just exactly right. I am generally not a perfectionist, but I was really picky about these, forseeing how much torque I wanted to throw at them. Any more questions just ask. Do yourself a favor and get the factory service manual. It has good detail about changing the gears.

 

Thanks man. I forgot to mention tire sizes, I am running 285's and I don't plan to go any larger. Sounds like I do need the factory manual or a Haynes manual at least. I tried to find a complete rear end locally, but no luck. Thanks again.
-Don

 

You dont even need to swap whole rear ends, just take it out of the truck and take it to the bench, it will be so much easier. You will also want an install kit with new bearings and shims to make the job go smoothly. Mine probably only had 45K on it when I did it, but I put all new bearings in anyway. Dont waste your time and money on a haynes manual. PM me and I can help you get a factory manual.

 

If you have no experience setting up a rearend, I suggest getting someone who knows how to do it Perfectly. It does not matter how mechanically inclined you are, you want to do this one time and one time only. Is a few days of your time really cheaper than someone who can set it up right for you to start with?
FWIW, I simply swapped out a whole rearend, in about 2 hours, maybe less. A lot easier than missing the setup, and having pinion bearings roar, while grinding up my gears.

 

i agree ,,, find Good help with the tools to do it

 

A couple tricks to make this easier;

1. KNOW WHAT A GOOD PATTERN LOOKS LIKE and settle for no less.
2. Leave the pinion seal off (and the crush sleeve of course) while you set the pinion depth.
3. Have a bearing splitter and a hydraulic press at your disposal. The splitter must be high quality. No chinese junk on this one.
4. Know that you very likely will need to take the bearings off the pinion and carrier a couple times to change the shims, but about 40 to 60% of the time they set up with the original shims.

A couple other things to know, since you have the 4.10 gearset is that I believe you are on the split for the carrier size. I think your carrier will take the 3.55's. I think the 4.10 is the lowest you can go before a carrier change, so I think you have the tall ratio carrier.

I am assuming you have a Dana 70U. I suggest you check out www.accuautoparts.com

Crushing the crush sleeve will be fun. I would have a HUGE cheater, and do it with the axle in and the tires on the ground blocked and Ebrake on.

PS you can do this without even taking the tires off if you can keep the punkin' clean! Do your homework. This is a serious job first time around even for an experienced mechanic. It's doable, but I suggest you do your homework FIRST as you are apparently now. I would also avoid a cheap gearset- mainly because they often don't set up as easily, and this may play in heavily considering it's your first time. But also, well, quality is worth a little more money.

 

Thanks a lot guys. After researching and digging, I have decided to go with either Motive or Yukon gears but I am going to get my local mechanic to do this. He builds race cars regularly and thinks this type of thing is fun (sick) and he is really good. Any ideas on what this should cost me? He's usually pretty good on the cost, but I'd like to know in advance what to expect. Bear in mind, I am buying the gears and install kit. Thanks again for everything.
-Don

 

I'd personally be willing to pay up to $300 for a good R&P setup, but I don't know if that will buy you the job....

 

ok I have had this same question before the I read diesel power they did the same swap and found that by going to tall they lost MPG because the truck is working to hard I would go below a 3.73 although they offer a 3.42

 

Cminzey,
True, too tall will kill you. I had this same setup (285/75/16) Auto Trans and 3:55 gears on a 2001 CTD I had and it resulted in 24mpg on the interstate! Right now, I am getting no better than 18 on the big road and I drive unloaded too much to accept that. I can't go any bigger on the tires as I have a 2wd and I'd have to lift the front end about 3 inches to do it! The heaviest thing I pull these days is my 31' Airstream and it only weighs about 5,600lbs loaded and I never pull over 65. I found a guy who would do this swap for me for $700 including parts (yukon gears, not Dana). He's the best I have found yet.

 

I have an 04 dually did some up grades and went from 16.9 to 21 mpg just with exhaust,edge mileage max,airbox and banks intake you just need to figure out where the happy medium is I hardly pull a trailer either

 

I have a Van Aaken right now but I am thinking of going to the Quad Adrenaline and just using the lower power settings as my tranny isn't built right now. The Adrenaline also has the max mileage setting too. I want to get the AFE Bladerunner for my truck and I have a deal cooking right now for a set of Mach 1.6 injectors. I am also looking at a 4" turbo back kit with no muffler. Basically, I am looking at doing a lot of mods for power and mileage but I have to be careful with the tranny. I would love to get a meth kit but not right now...