04 Dodge Ram....a little at a time..

dropped the rearend off today.

I think I'm going to go ahead and have the whole rear re-built. put a shorter gear so I can pull a trailer with it.

---------------------------------------------Originally posted by FCKNLOWI think I'm going to go ahead and have the whole rear re-built. put a shorter gear so I can pull a trailer with it.---------------------------------------------4.56s & 295/35/24 turn nice. i actually picked up a few mpg as long as i keep it under about 72mph on the highway. AND because of the 0.67 overdrive gear in out transmissions, its only up 300 rpm @ 70mph.

will it matter that my truck is a 5 speed and has the little V8 in it? the 4.7 (i think)

check out dodgetalk.com. do some searches & see if you can come up w/ the final ratio for 5th gear. plug that into the calculator for transmission, use a 1:1 ratio for the transfer case. use this calculator to play see whats best. http://www.4lo.com/calc/gearratio.htm 

TransmissionNV3500 - Manual, 5-Speed Overdrive45RFE - Automatic, Multi-Speed Overdrive5-45RFE — Automatic Five-SpeedAvailabilityStd. — All with 3.7- and 4.7-liter enginesOpt. — All with 3.7-liter enginesOpt. with 4.7-liter, Std. with 5.7-liter enginesDescriptionSynchronized in all gearsThree planetary gear sets, one overrunning clutch, full electronic control,electronically controlled converter clutchThree planetary gear sets, one overrunning clutch,full electronic control, electronically controlled converter clutchGear Ratios     1st4.043.03     2nd2.331.67 — upshift1.67 — upshift1.50 — kick-down1.50 — kick-down     3rd1.391.001.00     4th1.000.750.75     5th0.73-0.67Reverse3.553.02.20Overall Top Gear2.59 w/3.55 axle2.66 w/3.55 axle2.38 with 3.55 axle2.86 w/3.92 axle2.94 w/3.92 axle2.63 with 3.92 axle

I believe it has the 2.59 w/3.55 axle.

so punch in your stock setup. tire dia: ?diff ratio: 3.55 or 3.92 (should be a tag on the axle)transmission ratio: 0.73transfer case: 1.0mph: i typically use 70 you'll know what rpms you'll be spinning down the highway. obviously you can punch in other speeds to get around town rpms, just adjust the transmission ratio to the gear you think you'll be in. to calculate your new setup, leave everything the same except for the diff ratio. most common ratios for a 9.25" chrysler rear are the 4.10 or 4.56 you'll gain mechanical advantage to get your truck / trailer up & moving w/ gears, but this calculator will tell you what you engine will be doing & help you make the right decision. you don't want to be turning 6500 rpms everywhere you go lol. 

what I came up with:  (stock 245/70/17)TIRE SIZE - DIFF -  MPH = RPM30"              3.55     70        2031.730"              4.10     70        2346.6  30"              4.56     70        2609.8 30"              3.55     75        2176.930"              4.10     75        2514.130"              4.56     75        2796.2  (new tire 295/35/24)TIRE SIZE - DIFF -  MPH = RPM32"              3.55     70        189832"              4.10     70        2199.932"              4.56     70        2439 32"              3.55     75        2034.432"              4.10     75        2349.632"              4.56     75        2613.3

i'm assuming you verified your stock diff gear is a 3.55? 3.92 is a factory option, but probably not likely since you have 17s from the factory. by looking at your chart, you on stock tires & gears @ 70 mph your engine is turning 3,032 rpms. w/ your 24s & 4.10s at the same speed you'll be turning 2,200 rpms. thats less than 200 rpms more, hardly overworking the engine IMHO. 4.56s are tempting, but its definately going to be more noticeable at highway speeds. when i was deciding, i also took a mental note while driving how much 200, 300, & 400 rpms more sounds like while driving.