I have a 2006 Durango Limited with 5.7L hemi engine, tow package and 3.55 differential. I would like to increase the tow capacity to pull a rv trailer and have heard I could swap out the differential for a 3.92. Is this a good idea? Has anyone done it? Who should do it, a dealer since it is still under warranty? Thanks.

 

VV:

How much capacity are you looking to gain?? Assuming you have a 4x2, the swap will run you in the neighborhood of $700-900 parts and labor.

It will be close to double those numbers if you have a 4x4.

Quite a few folks have made the swap, and reported good results. BTW, You might as well go with a 4.10 gear which will give you just a hair more oomph for the same money.

I agree that having a dealer perform the work will protect your warranty coverage, but you will need to find one that knows what they are doing.

This is the kind of work that you only want to do once, and do it right the first time. Things can get expensive quickly if it isn't.

Don

 

I was told the swap from 3.55 to 3.92 will gain 1500lbs in tow weight. I guess it would be a little more for the 4.10. The Durango I have is a 4x4 AWD. The Durango works great is my hunting and every day vehicle and I am wary about doing the swap but it would be less expensive than a purchase of another truck.

 

VV:

How much weight to you need to pull? If you will not be doing it very frequently, or very far, then as long as you are not way over the limit you should be fine.

OTOH, if your trailer has some serious poundage, then either an upgrade or even a swap to a different D might be to your advantage.

Since you have 4x4 or AWD for the Gen 2's, you would have to do both axles which will be a pretty good chunk of money.

Another tidbit to the equation is that DC decided to go with a reverse cut gearset for the 2nd Gen front axle. Another D owner found this out the hard way after his installer put the rear gear in first (4.56), then opened up the front to find that it was RC, and that no one makes a 4.56 RC gearset as of yet.

So, unless things have changed your option would be to have the factory 3.92 gears put in.

My friend that did the 4.10s has a 2wd, and there is no shortage of gearsets to choose from for the 8.25/9.25 axles.

Don

 

For our family of 8, the smallest trailers that would fit us all are in the dry weight range of 4,000-5100 lbs range but fully loaded could weigh between 5,000-7000 lbs range. I estimate that the Durango will all of in it weighs around 6,100 lbs so with the maximum of some trailers, it would put us over the GCWR of 12,500 lbs. That is why I would prefer to have the extra pulling capacity. I check with two shops and one said it wouldn't be a problem to switch both front and rear gears ($1,800), the other said he won't recommend it because the computer module is set for the 3.55 gear ratio and it could result in many problems.

 

VV:

With that kind of duty, sounds like you can justify the upgrade to 3.92s, or possibly even a different D already so equipped.

I would steer clear of that second shop. Their comments do not agree with experiences reported here and on other forums.

Since the 3.92 is a factory option, I any computer requiring a change will have that value listed as an option in its menu. Also, the speed signal is taken from the axle shaft as opposed to the tranny or driveshaft making it a moot point as far as what gear is in the axle.

Don

 

Thanks for the input. I am still interested in the differential swap and may have the first shop do it. The dealer's service was not open today but I will call Monday to see if they would do it and what would be the cost. That was a good idea to look for another Durango with the 3.92 axel. I could not find one in this area but will continue to look for one.

 

Here's an update, talked with the local Dodge dealer who I bought the Durango from. The service manager was not excited about the project but said he would talk to the differential technician. The message I got back would be they would do it but for $3300. It may be better to find a new D with the 3.92 gears but still no luck.

 

VV:

Sounds to me like they don't want to do the job. $3.3k is crazy. That almost sounds like they were quoting the install of new assemblies so they did not have to set up the rings and pinions.

Surely there is a dealer close enough to you that will perform the work without charging an arm and leg.

If you were not under warranty, a local 4x4 shop would be a good place to look into.

Good luck and let us know how things turn out.

Don

 

I think you are exactly right; this dealership did not want to do it and wanted to install new assemblies. Since the D is still under warranty I will check with other Dodge dealerships in the area. I will let you know how it goes and thanks again for your comments.