Time to trail ready the Bronco and my first task is gears and lockers. After a bunch of research I've decided on 5.13s, ARB and axles in the rear and Detroit in the front.

I realize my freeway RPMs will take a hit with 35s and no overdrive but I'm rarely on it anyway.

What do you guys think?

5.13's are a bit steep if you drive on the street. when you jump up to 4.88's/5.13's the pinion gets small. Really small on a d44. may not what you want with a lot of ponies. But on the note I have 4.88's in my 79 with a healthy 460 and no issues. But the open diff and im easy on the go pedal too.

I'd go arb up front. With the steering issues you have already a detroit will make it impossible to turn when in 4wd. The rear is an important one. Another thing to look into for the front axle is an auburn ected.

With the amount of power you have you really don't need to go too low with axle gearing. My last Bronco was able to roast 42s with 4.88s with a non stroker but very healthy 351w. If I were you I wouldn't go any lower than 4.88s but likely stay closer to 4.56s. I would also recommend selectable lockers front and rear. A Detroit up front is going to be rough on your steering and axle shafts plus doesn't play nice on the street in the snow should you need 4 wheel drive. I agree with Rob, look at the Auburn ected or the Detroit electrac. I installed an ected in the rear of my uncle's full size Bronco and an electrac in the front of his. I was more impressed with the quality of the ected than the electrac. Either way I'd stay away from a full Detroit if there is any street use and/or no RCVs. Detroits like to self destruct when an axle breaks so I wouldn't consider one without the best axles out there.

Thanks guys...just the type of info I'm looking for. I had not hear of the Auburn ECTED before. Nice that it has limited slip capabilities. Actually, having one of those both front and rear would probably work well.

I agree that 5.13s may be to steep.....4.88 is probably a good compromise.

Eric,

I'm planning to go with 4.88 and ARB front and rear before Moab if I can swing the expense.

Rob mentioned the Auburn ected which intrigues me as well. Gonna check into it.

That grimjeeper gear ratio calculator convinced me to eliminate the 5.13 given my set up (OD with 33" tires).

I think you might do well with 4.56 ratio given your horse power.

Why do you want super low gears? You've got the power to turn higher ones, and you still have to drive to the trail. I was running 4.11 with 35s and was pretty happy with it. Going 4.56 with the regear for 37s. Wanted to go 4.88, but found screaming deals on gears. 4.56 is considered the norm for 35s and a 1:1 top gear.

My stroked 351w with ARB lockers works great with 4.56 gears. Plenty of power. Not concerned with horsepower as much as torque and these strokers are torque monsters.

I am going with 4.56 gears with 35's. I thought about 4.88 but thought it would be a little high. Just a question why not go with an arb front? You will already have the compressor for the rear.

It's worth it to spend the extra for a selectable locker up front. You don't really need a front locker much of the time. I'll roll around with the rear locked in (ARBs front and rear) for any trails that are moderate or higher, but will only lock in the front for tough obstacles. Being able to essentially spool the front at will gives predictability that you may not get with an auto locker. I can have it locked up 100% to clamber over something, then know that it's 100% open to make the really a really tight switchback. If anything, I'd run the auto locker in the rear and the selectable up front unless you're going to use it as a primary vehicle in the snow or drive distances to wheel in the winter, in which case I'd run selectable front and rear.

With the options out there I would only choose selectable lockers front and rear for a Bronco that is driven primarily on the street. The money spent now saves the money on tires in the future. Automatic lockers can be and usually are unpredictable on the street plus, with your torque, will pretty much stay locked in while turning at almost any speed or throttle input anyway killing tires almost as quick as a full spool. You will not regret the selectable lockers after you have them in for a while.

As always my preference and experience is a bit different from many. I wonder how many of you that don't recommend Detroit's actually ran them or had them correctly setup. I love Detroit's. Simple bullet proof no need for pumps lines and other bs... and when setup correctly they are made to unlock so you can turn. Ok, so they are not selectable but I have ran Detroits and welded difs, they are not the same. The Detroits are much much easier on turning. With that said, if you are going with a ARB in one axle, you might as well go ARB all around.

I was not saying that detroits aren't quality products. I went with a Grizzly locker rear and an aussie front. That being said if money was no option I would run arbs front and rear. Selectable lockers are the best of both worlds. My 2 cents.

I have run just about every type of locker out there. Properly set up Detroits are still a handful on the highway with power. You never know which way it's going to pull when you step on the gas. Same when you let off the gas. It may not have as big of an effect in a longer wheelbase rig, but in a short wheelbase with a lot of power it is unpredictable. Been there more than once. I don't see why you should have to change your driving style because of an unpredictable locker. My last Bronco had a bit of power and it got embarrassing when trying to turn on a street in downtown Denver. If I was on the gas at all it would lock up and chirp the inside tire. I could cater my driving to make it not chirp but, again, why should you have to change your driving style to accommodate a locker? An ARB or ected is not much more $ than a Detroit and a way better option for a street driver.

I would never be embarrassed with burning a little rubber on the street. I also never felt the on gas off has was a big deal when a ran mine many miles on the street. But I always drove junk so I was use to a loose drive. At street air psi a Detroit won't always unlock. But at wheeling psi on the rocks it sure will. To each his own but an arb has pnumatic pumps and air lines electric wires and solenoid to go wrong. A Detroit has.... A spring that I guess could break. AND! Every damn jeep runs arb's and I hate jeeps!

Dang....this is getting complicated. So as far as drivability. ARB front and rear?

Hard to argue that one. Can't beat a selectable for street manners.
Or maybe look at an eaton E-locker. I have one in the back of my 93 and it woks well. Price wise pretty comparable to arb and Detroit.

ARB front and rear

I ran a Detroit for 12 years, now a Lock-Rite in the back. I drive daily, and in the snow (but only around town, rarely above 35 mph). They will chirp around turns and can "snap" the truck a little. The Detriot was very predictable, compared to the Lock-Rite.

I've decided against the ARB because of all the stuff to break, pumps, hoses, etc. I watched someone in Ouray get a leak in one line, shutting down their ARBs completely (this can be avoided by setting up the system differently). He wasn't sure he'd get back home from where we were,without his lockers.

I'm thinking Ox locker for the front, even if the cable breaks, there is a small fitting that can be screwed into the diff that will "lock" the diff in an emergency. I'd like a selectable locker for the rear, but it won't be an ARB, and Ox doesn't make one for the 9". I'll probably go back to a Detroit in the rear, when/if I start upgrading it.

I'm not huge on ARB's due to their inherent issues with always having to be airtight. If you have a leak in the air tubing, you don't have a locker. If a seal inside gives out, you don't have a locker. More often than not, I have seen the air system for these fail during a snow bashing run. Maybe the lines are brittle in the cold and shrink, or crack?? The locker itself seems ok, but I know of 4 guys who had seal problems.

Selectable lockers are great, but there are other options out there to explore. Electric ones are a good alternative.

gearing - 4.56 gets my vote. If you want/need deeper gearing, do that in the t-case. That way you are not sacrificing street manners. Yes, that's another big chunk of change, by I LOVE my atlas and it is the best mod I have ever done on my bronco. And when you finesse over an obstacle, you are less likely to damage your rig and look good doing it.

Gunni beat me to my points!

I also ran a detroit in the rear of an F-150 and "torque steer" was something you have to get used to. Mainly just let it do it's thing as it'll come back, but that's hard not to feel the need to correct it.

I think the 4.56 is the gearing if changing the gears.

I am locked, front and rear, with a Grizzly up front and a Detroit in the rear. Only time I'm locked up front is when the hubs are in, so when I get off road they are locked. I like the simplicity, if we can call it that, of the Detroit. I have had several, and the limited is squirrelly no mater what so I locked it with the Detroit out back. Then I went with the Aussie up front for a while and its good and works well, just a challenge when you approach a rock step and don't want the skinny pedal. The Grizzly makes me smile.
I obviously use the twin sticks if required but will usually just shift the front out if it is a switch back or really tight turn.
My heavy Duty WH PS pump makes it pretty darn easy though I have to admit. Way better than when I have a stock Sag pump and the Aussie.
I do agree it all depends on what you use your rig for and what you want to do with it.

Any input on 4.29 Ring and Pinion... am also about to dive in and was considering 4.29 instead of 4.56