slced123

does anybody have any experience switching out the 4.10 gears going down to 3.73 gears to improve mileage / lower engine RPMs? I don't want to totally screw up towing, but it seems like I can afford to give up a little "low end". This is with a 48re tranny. How much $ am I talking? How much hassle? Thanks for any feedback...

NDanecker

I went from stock 3.73 to 4.10 to compensate for 35" tires. Then I went back to pretty much stock height and back to 3.73 (long story but that is the jist of it).

Had a local shop (www.xtremediesel.com) do the 3.73 to 4.10 and cost me just over 2k, and they screwed up the rear end. They lied saying they knew how to do gears. I ended up doing the 4.10 to 3.73 myself and found damage to my front axle shafts threads (from trying to bang them out where you don't need to. They come out when pulling the bearing assembly ). They also didn't put cotter pins back on on the axle nuts and screwed up the pinion seal (leaked oil from pinion seal). SO between a constant hum from the rear end that they swore is normal with 4.10 (yea, whatever guys) and messing up the front axle I learned a valuable lesson - make sure you do your homework on who you have do your gears.

Can't help with mileage as the final ratio was about the same because of increased tire size with the 4.10. If you have stock tires and 4.10 you should see a nice improvement going to 3.73....but a loss when towing heavy. Trade off I guess.

Good luck!

jpsawyer

i went from 4:10 to 3:73. Overall not worth it. RPM's went down maybe 200 at 75mph. I just switched over from nitto 295 tera grapplers to 285 Dura grapplers and tow 10000 lb TT. I saw no legitimate improvement in fuel mileage to warrant $2k cost to switch. (my cost). But if you do switch over, my truck pulls trailer just fine with 3:73. I need to get the overdrive lockout so i can keep it in 3rd on small roads.

I have the 05 2500 48re. When i figure out how to do the sig line, i won't have to write this sentence

cgmorgan06

The sig option is under the user cp button on the left side on the page, and then from there go to edit signature and there you are.

jpsawyer

Thanks 4 the help. Dodge owners are great people

jpsawyer

I still have 4:10 gears 4 sale. Seems nobody wants them.

HOHN

With the auto trans I'd keep the 4.10s and slow down and/or put on bigger tires.

jmo

Megaramasaur

If your close to San Antonio, I'll swap my 3.73's for you 4.10's. It's easier to swap complete axles.

jpsawyer

i h 3:73's now. i switched from 4:10 a while back. I admit it was a mistake but u make ur bed and have to sleep in it. From my experience on this end, the swap was not worth the cost.

Valv

Why the swap was not worth it ? I am interested doing it too for mileage purpose, I drive many miles and any little improvements it helps.

Why it's not worth it ?

jpsawyer

I get around 17mpg. The only time i got better was with 4:10 and stock tires. The cost of install to me is not worth it. I saved about 200 rpm with the swap. As long as i run 1800-2000 rpm, mileage is 17.

nsxt

My mileage improved between by about 8% going from 4.10 to 3.73. I would have done 3.42 if that was available then.

The rear is not a technically difficult job to DIY, but a few tools are needed. 12 ton shop press, bearing separator, dremel, 250ft-lb 1/2 inch torque wrench, 3/8 torque wrench which reads down to 15 or 20 inch pounds, and the special tool Flange Wrench 8979 or equivalent which holds the pinion flange from turning while the nut is removed/installed. Everything else is pretty much common hand tools, various hammers (get a plastic headed one) and drifts.

Get an installation kit with new pinion bearings, nut and shims. New carrier bearings are not needed. To make pinion depth setup easy, dremel a few thousandths out of the old rear pinion bearing so it slides on and off the new pinion shaft without the need for pressing.

I already had torque wrenches, but borrowed a press and separator and made a crappy flange wrench out of 3.5 ft of angle iron. Total install cost was about $450 with a used gear set. This means I recover my costs in fuel savings after about 26000 miles. That alone wasn't motivation enough, I personally like less buzzing of the engine at 75mph.

Rednecktastic

Best to find someone with similar miles/wear as you and swap them axles assemblies if they have 3.73s. I tried at one time but could only find people with high milage wanting to swap.
I'd like to have the 4.10s.

Bart1001

I have a 04.5 with 40K on them with 4:10s that I would like to swap for 3:73 or 3:42 if anyone is interested.

blacksmoke

BarT1001, I have 2004 with 373 rear end are you still interested in making a trade? Where in OK. are you located? I live in AR.

THANKS
blacksmoke