Need Gearing Advice, esp if you had stock 4.10s

[Alec]

Hey all,
It's time for me to regear again. For various reasons I don't have my high stall torque converter anymore, which was helping me turn my 33" tires. The truck feels mismatched again and I need to regear.

I have 3.73 gears now, which are about equal to the 3.27 stockers I had. However, the larger tires and rims are much heavier and create more drag so the truck feels like a dog.

Putting in 4.10s would put me close to a stock 3.73 ratio,
and 4.56s would put me close to a stock 4.10 ratio. So my question is to those with 4.10s stock with stock sized tires, or those with 33s and 4.56s: how does the truck feel on the highway? I often go fast on the highway and don't want to be pushing really high RPMs. I want to be able to cruise at 80 mph comfortably, but still be able to go up to 100 or so without redlining the motor. The lower gears would obviously make wheeling and city driving easier, but I'm just concerned with pulling too many RPMs on the highway. I'm guessing I'd pull around 3200 in OD at 80 mph which isn't too bad. However, faster than that and I'd be ragging on the motor. I guess I need to ask myself, "How often do you go 100?" not very much I guess, though I pass people at 90 all the time. But at 90 the RPMs would still be bearable.

So did I just type this long post and answer my own question? Lower is always better, right?

But I'd like to hear your opinions on this. Thanks!

 

[Jefe]

My 4.88's and 35's make it close to 4.10's with stock tires. I love it that way 4x4ing, around town, and on the highway at 65-70. But at 80, its a little under 3000, and if I try to climb a hill at that speed, it'll drop out of overdrive and unlock the torque converter and it'll sometimes hit 4500, which is no good.

Also remember that since you're 2wd you could go with 4.27's so you don't have the big gap between 4.10's and 4.56's.

 

[Alec]

Hmmm, forgot about the 4.27s. I guess you're right. Everyone always says 4.10 or 4.56 because of the front diffs, but I don't have that matching problem

 

[Robert]

Alec, your overdrive ratio must be a bit lower than my 5R55E (actaully a lot lower). My '97 came with 30" tires and 4.10 stock. I've made a couple trips across the U.S. when my Explorer was completely stock. With my cruise set on 80 MPH I was turning 2800 RPM. I had no noise or mileage concerns. If I was to put 33" tires on mine, the 4.56 would put my RPM back as close to stock as possible. The only two OD ratios that I am aware of Ford putting in the V6, 4-speed transmission are .72:1 & .75:1. I know mine has a .72:1 OD ratio. Even if yours has a .75:1, your RPMs will only be 3% higher than mine. So with 4.56 gears, 33" tires and .75:1 OD ratio I wouldn't think you would be turning over 2900 RPM at 80 MPH. Maybe your torque converter was never locking properly due to the added load from your taller tires?

 

[Alec]

Hmmmm.....

Since Jefe mentioned the 4.27s I've been leaning towards those. That way I know I wont be going too low. Robert, also remember that the OHV doesn't like to rev as high as the SOHC. Also, according to to charts at both 4WP and 4lo.com, 4.27 would be a good "middle-ground" ratio for me.

From the feel of my motor and tranny, I only need to kick up the RPMs about 300. 4.10s would do that, 4.27 would do about 450, and 4.56 would do about 600.

 

[TarHeel085]

with my 32's i can run 80 at right around 3000 RPM and i have the 4.10's.

 

[yob_yeknom]

Originally posted by Alec
but still be able to go up to 100 or so

Have you checked to see what speed the tires are rated for?

 

[TarHeel085]

Re: Re: Need Gearing Advice, esp if you had stock 4.10s

Originally posted by yob_yeknom
Have you checked to see what speed the tires are rated for?

thats why i dont go above 80

 

[Digger196]

how fast can i go w/ BFG m/t?

 

[Alec]

Mine are rated for either 100 or 108.

 

[Crankcase]

Originally posted by Digger196
how fast can i go w/ BFG m/t?

I wouldn't suggest going above 80 with mud terrains...unless you want lugs flying out from the wheel wells.....

 

[Digger196]

dang i thought i could go faster! oh well!

 

[Paul Gagnon]

No such thing as 4.27 gears for the 8.8", the ratio is 4.30.

 

[Rx4phun]

100 or 108 on X-terrains, thats interesting. How much pressure are you running in the tires. I know splat is a unique X but becareful I dont think any of us, especially you what to have to load it on to a wrecker

 

[Alec]

Thanks Rx4phun, I don't want to have to do that either. I'm running about 34 psi cold. It feels great on the highway. No shimmy, shake, or nothing; just wind noise and movement from gusts of wind (which I'm always careful of).

Thanks Paul, I was unaware of that. 4.30s it is

I'm calling up the tranny shop today to see if they can make me a deal. This'll probably happen between Dec 16th and 20th.

 

[Rx4phun]

what are you tires rated at and how are they wearing. I have 33x12.5 procomp ATs and Dont want them to get all worn in the middle but I could use some mileage. I'm running 28-29 cold
Gary

 

[Alec]

What rating do you want?

They're wearing faster than my BFG ATs did, but they have about 6-7000 on them and basically look new. They don't even have stretch marks from when I smoke 'em.