hmm why would you think that with bigger tires (he has said he is running 37's) that changing to a numerically higher set of differential gears wouldn't affect increase MPG, i agree that any savings that you will get will be offset by the costof the swap but i don't understand how you can clame that changing to a numerically higher set of differential gears with bigger tires wont increase MPG, what evidence do you have to support this? I'm not slamming you because i have read many of your posts (the really long ones lol) and find them informative I'm just curious?, i know people here have re-geared there trucks when they went to bigger tires, what were your findings in relation to MPG....i haven't changed mine yet (due to cost of the gears ant the fact its -10*C outside where id be doing the swap now) so i don't know one way or the other first hand....

 

Howdy again.

Checked the gears today, there at 3.55, and from the sounds of it should be a bit higher with the lift/tires im running on. What would you all suggest changing them to?Someone said 4.56 or 4.88 earlier.

Anyone have experience in this? Would like to know the difference I would see from 3.55 to 4.88, and if it would be worth spending the money to see the gas milage increase.

Any advice on changing the gears / cost / increases would be very helpful!

 

A gear swap will cost you about this much

450 2 sets of rings and pinions (4X4 must match gears front and back, or you'll be paying $2500 for axles swaps)
+2002 sets of master install kits
+ 50 in gear oil(about 5 quarts total)
+500 for the labor (this obviously fluctuates depending on the shop, but this is probably a good or average cost)
+ ??? for a new carrier for the Dana 44 axle up front.(I don't know how much one of these costs,I have a 2WD).The 9.25 corporate in the back doesn't need a new carrier.
1200 total+plus the carrier.

now you're gonna have to drive a while to get that back, but your truck won't drive like a hippopotimus any more.

with 37" tires, you'd definitely want to go with 4.88 gears. It'll probably feel like you put a damn supercharger on the thing after that swap.

The alternative is to go back to a225/75/16 stock tire and then you'd know what the swap would feel like if you stayed with the 37" tires, but did the gear swap.

 

Wow, 1200 not including the carrier... Any idea what the increase in milage would be?

 

you dont need to get a new carrier for the dana 44, you can get a special ring made for the dana 44 that can use the 3.73 and lower carrer

ex of a think ring and pinion in 4.88 http://www.ringpinion.com/ProductDet...px?ProdID=3318

not only will you be getting back some MPG (wont be as goot as it was before the bigger tires because you still have more rotating mass to move) but it will also give you more power
but aim is pritty close on his price, hight help if you or a buddy can do the swap then itll be $700ish

 

Shouldn't he need a carrier for 9.25 Axle. I thought the carrier was only good upto 3.96?

 

I've got 4.10's in mine now with out a carrier swap.

 

Thanks again everyone for the advice, im gonna sit on it for awhile, 700+ bucks is a lot of money, will definately ask for advice when/if I do decide to do the upgrade. Will also suggest anyone looking for answers towards there truck to come here.

If I could findout how much it could increase, even a ballpark, for miles to gallon, it would definately help me make a decision. If I never upgrade the gears, is it bad to continue running the truck as is?

 

It's harder on the tranny and rear diff to push that much mass with abig ring like that,the tranny might giveout sooner.The MPG on agood running engine with stock gearing and tires is around 13~14 MPG, but is really subjective tovehicleaerodynamics (raising is bad for MPG), terrain being driven over (hills, flat, etc)wind, and the foot-to-lead ratio the driver possesses.

 

DodgeFan01honestley your not gonna see a huge mpg increce maby 2MPG however your other diveline parts will thank you there will be less stress on them (like aim4squirrels
said) also its going to be a substancial performance increce


ICEMAN_CHthe carrer in the 9.25 will be fine, there is a lot more room in there than a dana 44