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Gear Ratio Advice Needed (currently have new 4.11 front, have to build rear) OD trans

fordguy

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Jan 23, 2005
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I am "conflicted" on gears. My plan is to button up my frame over Christmas holidays and get the body on the frame. Unfortunately i built the front end first. I have a 4R70W and will run 33 inch tires. So should i build the 9 inch with 4.11s and see how i like it. I am in the hole and do not want to keep digging. I really wanted 4.88s, but I will lose big time if i sell the 4.11 dana. It is completely built with trac loc, dana gears, new axles, disc brakes, etc. the only thing not new is the housing and the knucles. Conflicted in Mississippi, classicbroncos to the rescue. I will most likely run a trac loc in the 9 inch, but not sure what i currently have. I have a thread going on my rear end code. I have two rear ends, one in the truck that is supposed to be a 9 inch, will get that checked out tomorrow and report back. I guess if it is really a nine, then the smart money would be run and see what happens?
 

bax

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Aug 22, 2005
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4.11 with 33's and a 4r70w will work fine. I am running that same combo. The first gear is low enough to get going without much effort. The high gear is fine at 70 MPH. If anything a 4.30 or a 4.56. I think 4.88 is a little too much. I am happy with the 4.11
 
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fordguy

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Roger, if you are good with 4.11s then i think i will give it a whirl. i hope the nine inch i bought as 4.11s is such. I will find out tomorrow. my rig is going to be a driver, that can make the trip to Hot Springs (250 miles), ride some mild some trails and drive back home. Doing local shows in a hundred mile radius with my street rod buddies is on the agenda also.
 

Broncobowsher

Total hack
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Jun 4, 2002
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34,874
The good thing about Mississippi is that it is flat. Flatter than Kansas. Really it is, grew up in Kansas, worked in Mississippi, spent time in both places.

If you have a 9" with 4.11s (4.10, 4.09, whatever), run it. It's a starting point, and you already have it. While higher then I would normally recommend, but in your location it might work out just fine.
 

sykanr0ng

Bronco Guru
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Aug 11, 2014
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If you find that don't like the gears you could put on smaller tires.
It is a very old hot-rodder trick to get the same effect as lower gears.
 

needabronco

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Jul 2, 2004
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6,411
Loc.
Prescott/Farmington
Don't fear the gear! I run an AOD with 4.88s and 315/75/16s which are basically 34"s. I'd much prefer to have 5.13s in my truck, but live in the Mountains at elevation. Gears aren't that expensive especially if take the time to learn to do the work yourself.

I suggest you see if someone in your area has a similar drivetrain/gear combo and go drive it to see if you like it...
 

englewoodcowboy

Lick Creek Restorations
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Jul 25, 2010
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4,200
I think 4.11 will be ok as well if you are primarily a driver. I myself in that combo have gone 4.30 and 4.56 for customers all who have been happy but if the motor is healthy and strong I see no issues just might not be as peppy off the line but we aren't building drag cars.... are we? LOL
 
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fordguy

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Don't fear the gear! I run an AOD with 4.88s and 315/75/16s which are basically 34"s. I'd much prefer to have 5.13s in my truck, but live in the Mountains at elevation. Gears aren't that expensive especially if take the time to learn to do the work yourself.

I suggest you see if someone in your area has a similar drivetrain/gear combo and go drive it to see if you like it...

i dont fear the gear, i fear the cost of re-gearing
 
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fordguy

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I think 4.11 will be ok as well if you are primarily a driver. I myself in that combo have gone 4.30 and 4.56 for customers all who have been happy but if the motor is healthy and strong I see no issues just might not be as peppy off the line but we aren't building drag cars.... are we? LOL

that is what i think, not a drag car. my motor is 2001 explorer with fuel injection. I have had a peppy motor in this bronco,
 
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fordguy

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if the other 9 inch i have proves to be a 4.11, i will be time and money ahead for now. I could use more of both lol. my goal is to get the frame buttoned up so i can put the body on the frame.
 

Nothing Special

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Nov 25, 2016
Messages
804
I've got 4.10s with 33" tires and an NV3550 5 speed manual with OD. I like the combo for street driving. I can start in 2nd most of the time, and can cruise in OD as low as 35 mph. With a load, or if I'm in a hurry I start in 1st and I don't upshift nearly as early, but it still works out well (although I don't use OD much when I am driving in the mountains).

You've got an auto trans, so it'll react a little differently. It'll always start in 1st, and along with the torque converter you should have decent (if not really exciting) off-the-line performance. You might end up wanting to lock it out of OD at times if it ends up hunting between gears, but that's not hard to do.

You also say you're planning on TracLocs in both axles. I know this thread isn't asking about that, so I'll butt out unless you want to discuss it. But I don't see any benefit to TracLocs. I'd go with open diffs if it was pretty much street only, and Truetrac or locker if more traction was needed.
 
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fordguy

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I've got 4.10s with 33" tires and an NV3550 5 speed manual with OD. I like the combo for street driving. I can start in 2nd most of the time, and can cruise in OD as low as 35 mph. With a load, or if I'm in a hurry I start in 1st and I don't upshift nearly as early, but it still works out well (although I don't use OD much when I am driving in the mountains).

You've got an auto trans, so it'll react a little differently. It'll always start in 1st, and along with the torque converter you should have decent (if not really exciting) off-the-line performance. You might end up wanting to lock it out of OD at times if it ends up hunting between gears, but that's not hard to do.

You also say you're planning on TracLocs in both axles. I know this thread isn't asking about that, so I'll butt out unless you want to discuss it. But I don't see any benefit to TracLocs. I'd go with open diffs if it was pretty much street only, and Truetrac or locker if more traction was needed.

i plan on going to OCBR and doing mild trails, the dana is already built with a truetrac, i would consider a locker on the 9.
 

DirtDonk

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Nov 3, 2003
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Even as a "don't fear the gear" kind of guy, with the Explorer EFI setup I would not hesitate to "settle" for the 4.11 combo myself.
I have 4.56's and 31" tires with the same engine and I bet it would pull 3.50 gears just perfectly.

Only the added weight and potential rolling resistance of the larger tires could work against you in the overall acceleration department. But general drivability should be sweet.

Make sure to give us the final rundown and your feelings when done. Sure, you may end up wanting some lower gears for those off-roading excursions eventually, but here's to hoping you'll find the 4.11 a nice compromise.

Paul
 

Broncobowsher

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Jun 4, 2002
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34,874
15 years ago my realtor had a 5.0 Explorer he used to drive clients around at to tow a race car. While it has better rolling resistance and better aero then a Bronco he was still a bit of a hot rodder. The Explorer would make passes down the drag strip if the race car wasn't running.

It was originally equipped with 3.73 gears (32" 265/75R16 stock size tires). He regeared it to 4.30s. Made it quicker, tow better, and didn't kill fuel economy. Ran it hard past the 200k mark. Sold it when it started getting too ratty to run clients around in.

I wouldn't have picked 4.11s for this build. But given the combo I think it will be okay. Not great but still functional. It will likely drive a little soft. Explorer EFI and low elevation really help. The flatness of the land is another reason I give a pass. Out west with mountains, different gears. Even running someplace like Tennessee has a lot steeper highway grades and would make me pick a deeper gear. But Mississippi it will likely be good.

The nice part is 9" gears in 4.11 can be sold used fairly easy. Good demand from off-road crowd to the hot rod crowd all use it.
 
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