moneyman

I am thinking about changing my stock 355's to a 373 rear end. Who out there has done this and are they glad that they changed? Also what happened to your fuel economy?<br><br>

BigBlue

If I'm correct, no one makes a 3.73 for an 01 Ram. Otherwise, I'd definately have a set. That would be the perfect gear ratio. The new one's come with 3.73's from the factory.

ARAcummins

I would like to do the same, but I have never found a 3.73, and I have 4x4 so I would have to change both, I guess I talked myself out of it befor looking into it to hard.<br>Heath

OlBlue

3.73:1 are available for both Dana 60 and Dana 80. The Dana 80 gear split is 4.10 and up, 3.73 and down. In order to keep the RWAL use a 3.73 thin set ring gear on the factory 4.10 carrier in the rear. Front gears and install kit runs $230. Rear thin set with install kit runs $415. These prices do not include labor. These are average prices from two different online vendors (I don't know if I'm supposed to post names).<br><br>I'm going with the &quot;new and improved&quot; Detroit locker in the rear, but still trying to decide on traction device for the front. It looks like Truetrac is not available so Detroit Powr-Lok or Trac-Lok may be the only options. Anyone have experience with the front and our wonderful half locked half unlocked axles?

Rally2

OlBlue FWIW I would stay clear of a limited slip or full-time locker in the front, a selectable locker like ARB or OX would be my only 2 considerations. Here's my reasoning:<br><br>In 2wd mode the driver side axleshaft spins the left side gear in the diff but the right side gear is stationary (or moving very slowly) because it's disconnected from the passenger side wheel. If you install a LSD in the front the slutches will constantly be dragging the right side gear and halfshaft around, probably the front driveshaft as well. This may not cause any drivablility problems but fuel mileage would drop a bit and the LSD will wear out fast I bet.

BigBlue

I have LSD in my front axle. ??? You can get a set of hub disconnects if you want to go to manual hubs and completely unlock the axle from the tire.

OlBlue

I asked this question of the techs I called. They indicated that the force on the clutch disks to turn the unlocked half was so small it wouldn't matter. What they did say was that (depending on the rig), the drivers side tire would be spinning the front drive line and this might cause enough drag to feel as a constant pull to the left.<br><br>Big Blue, does your pull to the left? Did you go with Trac-Lok or Power-Lok?<br><br>Sorry about sorta changing the subject of this thread. I'll start a new one if this continues much.<br><br>Thanks

OlBlue

I should know better than to crunch some numbers....what can I say, I'm an engineer.

Anyway with 3.73 vs 4.10 gears it seems like most agree that a 2mpg fuel increase could be observed. At $1.97/gallon, it would take 190,936 miles to pay back the $2,329.42 it will cost for gears, carriers (Powr-Lok front and Soft Locker rear) and installation. :'(

Somehow I need a number for the driveability or &quot;fun&quot; factor

Rally2

Big I know a few guys are running them but haven't heard much feedback. What model did you go with and is it completely unnoticeable in 2wd?

BigBlue

Mine came factory. I bought mine brand new. It pulls slightly right but that is because of the tires.

Smokee

HMMMM, instead of changing gears, why not change tire sizes?

moneyman

what tire size would that be?

BigBlue

You'd have to go with smaller tires to increase your gear (numerically speaking). If you go with larger tires, you will numerically decrease your gear.

OlBlue

I've created an excel spreadsheet that will show you engine rpm from 5mph to 120mph with tire sizes from 245-75 to 305-85 (includes 315-75). You can change one cell for gear ratio and see the engine speed differences. This is for an NV5600 with .73 overdrive and 1.0 direct. If you've got the 4500 or... you only need to change the overdrive ratio (.75???).<br><br>Sounds complicated, but it's really really easy and informative.<br><br>Anyway, if someone wants a copy, let me know. This way you can tell what tire sizes would do vs. gear sizes.