More on low axle gears for Dodge Dakota Quad cab 4x4

From : jason purcell

Q: i think everyone is misunderstanding my question... my overdrive is fine...70mph at 2000 rpms but that is with the 3.55s. my question is what is rpms at 70mph in a truck with 3.92 gears what is the actul difference in gas milege/drivability between two trucks with the exact same setup but 1 truck has the lower gears i got a quote today from a 4 wheel drive shop for having the gears changed. he said $1300 parts and labor. high cost i realize but cheaper than trading in truck and spending 3-4 more ears paying t off. not to mention the local dealers dont have any 04 dakotas on the lot with the 3.9 gears anyway. and its probably too late to order one. its almost time milege wise to change the differential fluid in the axles anyway so i have to decide soonif this is worth doing... will it make the truck more fun to drive but at what cost to drivability / gas milege etc. that is my dilema. jason jason purcell wrote if you have a dakota quad cab 4wd 4.7l auto with the 3.92 rear axle ratio please tell me what rpms you run at 70mph. what gas milege do you get the best i ever got was 18.7 on a long road trip from tennessee to missouri i am considering an axle swap and am trying to decide whether or not to do the swap or just trade in before the dakota remodel comes out this fall but i dont want to routinely be running 3000 rpms either. thanks jason that just doesnt sound right. it sounds like your od is not kicking in. the dodge aod has a .68 or so od. with a 31 tire and 3.93 gears 3000 rpms puts you over 100mph. but a 11 4th gear puts you right at 70 mph at 3000 rpms. before swapping differentials take a close look at your transmission. -- ------ .bob 1997 hd fxdwg - turbocharged! 2001 dodge dakota qc 5.9/4x4/3.92 1983 gmc jimmy - mountain beater 1966 mustang coupe - daily driver 1966 ffr cobra - ongoing project .

Replies:

From : philr

jason purcell jepneonrtnospam@earthlink.net wrote my overdrive is fine...70mph at 2000 rpms but that is with the 3.55s. my question is what is rpms at 70mph in a truck with 3.92 gears 3.92 / 3.55 = 1.104 1.104 x 2000 rpm = 2208 rpm @ 70 mph with 3.92 gears phil live oak fl 04 ram 2500 quad 4x2 ctd 600/48re .

From : denny

i think everyone is misunderstanding my question... my overdrive is fine...70mph at 2000 rpms but that is with the 3.55s. my question is what is rpms at 70mph in a truck with 3.92 gears what is the actul difference in gas milege/drivability between two trucks with the exact same setup but 1 truck has the lower gears i got a quote today from a 4 wheel drive shop for having the gears changed. he said $1300 parts and labor. high cost i realize but cheaper than trading in truck and spending 3-4 more ears paying t off. not to mention the local dealers dont have any 04 dakotas on the lot with the 3.9 gears anyway. and its probably too late to order one. its almost time milege wise to change the differential fluid in the axles anyway so i have to decide soonif this is worth doing... will it make the truck more fun to drive but at what cost to drivability / gas milege etc. that is my dilema. jason i have a 95 1500 4x4 auto 5.2l that started life with the 3.55 gears. i would get about 10-11 mpg just driving around and maybe 17-18 at 75 mph. i changed to 3.92 a few years back and now i get 11-12 just driving around and about 15 at 70-75 mph. i dont take the truck out on the highway much so it doesnt bother me much. as far as the rpm difference figure about 200 rpm higher. i can check mine tomorrow to see what mine is i have 33 inch tires and the speedo corrected to them but it should be close to yours. as a side note on my dana 44 in the front i had to change the carrier also due to the offset of the ring gear. the 3.23 and 3.55 took one carrier the 3.92 and the 4.10 took another one. im not sure if yours is the same but check the part number of the carrier to see if it is the same one for both ratios. denny .

From : trey

philr wrote jason purcell jepneonrtnospam@earthlink.net wrote my overdrive is fine...70mph at 2000 rpms but that is with the 3.55s. my question is what is rpms at 70mph in a truck with 3.92 gears 3.92 / 3.55 = 1.104 1.104 x 2000 rpm = 2208 rpm @ 70 mph with 3.92 gears phil live oak fl 04 ram 2500 quad 4x2 ctd 600/48re im getting the same numbers. 10% lower ratio and 10% higher rpm. would help in the city but hurt pretty bad for a long road trip i would think .

From : tom lawrence

i got a quote today from a 4 wheel drive shop for having the gears changed. he said $1300 parts and labor. high cost i realize but cheaper than not really. probably about $500-$600 in parts two sets of r&p two install kits possibly two carriers and its darn near an all-day job with the majority spent on the front axle. .

From : trey

tom lawrence wrote i got a quote today from a 4 wheel drive shop for having the gears changed. he said $1300 parts and labor. high cost i realize but cheaper than not really. probably about $500-$600 in parts two sets of r&p two install kits possibly two carriers and its darn near an all-day job with the majority spent on the front axle. or $1300 to have it done by someone that knows what they are doing so i dont fubar the whole thing. side note if you do have to get new carriers you may want to look at getting a locking siff at the same time since everything will to taken apart. provided you want a locking diff. anyone here have front and rear arb lockers .

From : tom lawrence

or $1300 to have it done by someone that knows what they are doing so i dont fubar the whole thing. no i wasnt suggesting he do it himself - i was trying to point out that the $1300 wasnt an unreasonable amount since the parts alone are almost half that with the rest paying for the 6-8 hours of labor. apart. provided you want a locking diff. anyone here have front and rear arb lockers hes not looking to build an off-road truck - he wants more power and better driveability on-road. theres a big difference between an $80 carrier and a $350 lsd or $500 air locker times 2. .

From : tbone

or $1300 to have it done by someone that knows what they are doing so i dont fubar the whole thing. no i wasnt suggesting he do it himself - i was trying to point out that the $1300 wasnt an unreasonable amount since the parts alone are almost half that with the rest paying for the 6-8 hours of labor. apart. provided you want a locking diff. anyone here have front and rear arb lockers hes not looking to build an off-road truck - he wants more power and better driveability on-road. theres a big difference between an $80 carrier and a $350 lsd or $500 air locker times 2. but if he is going to tear down the rear axle anyway he should consider putting in a limited slip diff. it does offer better drivability on wet road once you get used to it and adds nothing to the labor costs if he does it during the gear swap. i also see no real advantage to putting a lsd or locker in the front axle for a street truck. -- if at first you dont succeed youre not cut out for skydiving .

From : thumper

if you want the scat ....you gotta pay for it....it aint free ! philr wrote jason purcell jepneonrtnospam@earthlink.net wrote my overdrive is fine...70mph at 2000 rpms but that is with the 3.55s. my question is what is rpms at 70mph in a truck with 3.92 gears 3.92 / 3.55 = 1.104 1.104 x 2000 rpm = 2208 rpm @ 70 mph with 3.92 gears phil live oak fl 04 ram 2500 quad 4x2 ctd 600/48re im getting the same numbers. 10% lower ratio and 10% higher rpm. would help in the city but hurt pretty bad for a long road trip i would think .