Yrocmoto

Okay, I've probably read over 50 posts on this and I'm still a bit undecided. I have a unique situation. I know you think 4.10's from reading the title, but if you care to help, please read my concerns.

First, I have a 2004 (heritage, so 2003) CNG (natural gas) 7700 truck. It's a bit gutless on CNG (guessing 10% power loss?), and cannot find anyone to chip it, so I've done the intake and the exhaust, have electric fans on the way, and need gears bad.

So I thought I had 3.55's, everyone across the board told me to do 4.10's and I agreed. Went to the shop and found out I have 3.73's, now eveyone says it's not really worth the cost to 'only' go to 4.10's. I'd be psyched on 4.30's, but of course, no go for 4x4.

4.56's are a bit much, but I'm limited on mods with CNG and I do tow a 6000-8000 trailer 1 or 2 times a month (whichs SUUUUCKS right now). This is also my daily driver, not tons of freeway speeds, but I will drive on the freeway. I'm fine only doing 75mph and with 4.56's I should be about 2650rpms which is up EXACTLY 500rpms where I am right now, 2150 with the 3.73's. (this is overdrive).

So I know 4.10's are about back to stock, just a tad over, but with CNG power loss, it's too close for me. But, I don't want it to just totally suck when I travel empty and go 75-80mph. Is it going to just totally suck running those rmps?

Also, I realize MPG gets a little thrown out the window, and I really don't care about my MPG, except that I can only hold 12 gallons of CNG and stations are few and far between, so better MPG REALLY helps me get from station to station, so it is marginally more important to me since I have limited capacity.

I'm leaning 4.56's and dealing with it, but just nervous about hating that decision (which I'm equally feeling if I do 4.10's and wish I did 4.56's) If I could do 4.30's I'd feel it's the perfect compromise for me.

01f1502wd

Ive got 4.11s and im runnin 35s. IMO stay with the 3.73, when i had the 3.55s it was slow..now with 4.11s its back to about the same amount of power, any higher and u get to have high low end torque but on the highway at 70mph ull be at like 22-2400 rpms and kill your mileage, most ppl i know runnin 4.56s are guys on 37s or bigger.

Yrocmoto

I already have 3.73's and they SUCK!!!! hence the reason for re-gearing. I know that the sweet setup for 4.56's are lifted 35" and are fine for 37's as well.

I don't want to stay where I am just looking for reasons to go 4.10 or 4.56. Going 35mph up hills on an 80mph freeway got old FAAAST. But I don't want to put in 4.10's and wish I had gone 4.56, I already know it's little extreme, but am hoping someone has done 4.10's or 4.56 with 32" (as they measure, the are 285/75/16 mickey thompson's, which say they are 33" on their website).

Thanks

Foxhound_22

i would go with 4.10, but are you going to do more with your truck down the road?! if so what, i personally think 4.10 are good for 33s and 4.56, 4.88 good for 35s

01f1502wd

yea what do you want to eventually do with your truck? depending on that...it wouldnt be worth it to go with a smaller gear, then get 40s and have to change gears again, isnt worth the money.

Yrocmoto

Not really planning to do anything else as far as larger tires. So if I had 35's 4.88's would be okay but not 4.56's with 32's? This would be about the same scenario wouldn't it?

I know that 4.10's get me back to stock, but that might not be good enough for me as I want a little more, but is 4.56 too much?

I really want 4.30's is this a joke??
4.30 reverse cut 8.8

Yrocmoto

Actually Foxhound, I just realized I read your entire 'green machine' post and I'd like to do that to my truck!! I'm a desert rat for sure and sometimes dream of flying through it in style, but the reality is, it's cheaper to do it on my dirtbike and leave my truck alone.

Foxhound_22

in that case would go 410s, maybe!!! 4.56s but i think the rpm will be to high on freeway speeds, 4.88s if you like to do a little mild crawling on rocks, its hard to tell cause i dont know anything about cng, theres a guy on here thats pretty knowlegdable bout trucks i think his name is ax7 not sure tho

Yrocmoto

...actually I have $12K into my bike, maybe I need to rethink all this, your rig just looks like toooooo much fun!!

here's my thinking, I do want to lean towards getting my junk to the desert and playing in the desert, so I know the 4.56's will be funner for that, I know it won't be geared for the freeway, I just don't want to be pissed everytime I'm on the freeway.

My truck came with 3.73's and 245/70/16's which is 2400rpm's at 75mph. 4.10's with 285/75/16's is 2400 rpm's at 75mph. So what have I gained? 4.56's with 285/75/16 is 2650 at 75mph. So 250rpm's more just doesn't seem that crazy, but for some reason 2650 seems like a lot???

FYI ford offered 4.10's with the 245 stock tires as an option, which comes out to 2650rpms at 75mph, so maybe I'm 'tricking' myself into thinking it's okay since ford offers this as a towing option???

ak_cowboy

4.10s

4.56s will kill your mileage and top speed.