Dakota Durango Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
1,525 Posts
Discussion Starter #1
Not sure where to put this as I dont see an axle forum and search didnt pull up much.

I am ordering gears for my jeep and thinking about doing some 4.56s for the dak. I have 3.92s now I believe (SLT, QC, 4x4 w/ tow package), just looking for some more get up and go when towing. I tow about 5,000lbs regularly. I have some 265/75/16 LRE tires for hauling but the 33s are on when its un-loaded and daily driving. I take the freeway to work and at 65mph with no head wind, it sits around 1500rpm. But if there is a headwind, the golden spot it seems is around 2k rpm and then im, doing 70. I worry that with the 4.56s, I will be sitting around 3k rpm on the freeway to work. I am usually just doing 65mph to work and back but when we go up north every month, speed limit is 70 so I dont want to be running at 3k for 3 hours on end.

Thanks in advance
 

·
Registered
Joined
·
1,135 Posts
http://www.grimmjeeper.com/gears.html
This one will give you a gear by gear breakdown of what rpm you will be running. With 4.88s and 35s I am running about 2200 in OD at 65 mph with my NV3500.
 

·
Don't be "That Guy"
Joined
·
7,400 Posts
Sounds like you have 3.55s without crunching numbers. my quad cab is a 4.7 auto, (5-45RFE) and I also have 265/75/16 tires. 30.5" tall. at 70mph I'm also right at 2,000 rpm. 4.56s will send you up to 2600-2700 with that size tire...just a guess off the top of my head without doing any math. I think 3.92s will get you where you want...a couple hundred RPM increase and more oomph out of the hole.
 

·
Registered
Joined
·
1,525 Posts
Discussion Starter #5
Hmm I thought the daks with towing packages came with 3.92s(?) If thats the case maybe I will look at 3.92s. I will have the dealer run my VIN and see or maybe ill just do it the good ol fashion way.

Thanks for the charts and help guys
 

·
Registered
Joined
·
49 Posts
Look on the inside of your glove compartment. there should be a little tag in there that tells you what gears you have among other info like limited slip and paint codes. Im betting 3.55s. My old 04 545rfe 4.7 ran about 1600 at 65mph with 265 70 16s. tow package just includes the class IV receiver,hd cooling, tranny cooler, and a harness for hooking up a trailer brake controller. Nice truck by the way yours is one of my favorites.
 

·
Registered
Joined
·
1,466 Posts
My truck runs like 2,200 at 65mph and it only has 31s on it. What the hell!
 

·
Registered
Joined
·
1,466 Posts
My truck has a reflashed TCM in it, I'm not sure if its the equivalent of the 545 or not.
 

·
Registered
Joined
·
1,525 Posts
Discussion Starter #10
Look on the inside of your glove compartment. there should be a little tag in there that tells you what gears you have among other info like limited slip and paint codes. Im betting 3.55s. My old 04 545rfe 4.7 ran about 1600 at 65mph with 265 70 16s. tow package just includes the class IV receiver,hd cooling, tranny cooler, and a harness for hooking up a trailer brake controller. Nice truck by the way yours is one of my favorites.
I will take a look and report back, and thanks man, hopefully soon to have a couple more goodies :D



Your truck has thew 45rfe. He must've done the 545rfe mod to his truck so he as an extra overdrive gear.
I have yet to do the grand cherokee TCM but I am assuming its because of the 33s but maybe the PO could have done it? Me and a friend did the shift kit but thats all I have done transmission wise so far.
 
1 - 11 of 11 Posts
Top