Need your opinion.....gears

[Tulsa76bronco]

Ok got a new EB....told the wife it was for my kid, I think I’m addicted! The Kid is 8. here is what I have 302 with C4, 3 1/2 lift 1” body put 35 tires on currently has 3.5 gears.

Not going to redo it for a few years since the kid is still young figured we would wheel it a little

I want to wheel it some so want to have some fun nothing extreme and I won’t take it on highway no need to

I was thinking 4.11 gears or should I go 4.56? I have a option to get a Detroit locker with 4.56 already in so really cheap and I wondered would that be overkill should I just go with 4.11 so that it rides better on streets?

 

[bronconut73]

If no overdrive,....

4.11 for 33's

4.56 for 35's

4.88 for 37's

Etc....

 

[okie4570]

I drive a lot of highway just to get to a town, so I'd go 4.11 with that setup. If you're city driving mostly, then I'd definitely go 4.56.

 

[broncodriver99]

I always thought 4.11 was just enough for 33's. I imagine the 4.56's would be better for 35's.

 

[Tulsa76bronco]

So what about putting in the Detroit locker? My mechanic didn’t think I had posi why would I not have it and how would I check?

Also bronconut my other eb is a 302 with AOD with 33” tires and has 3.5 gears should I move that to 4.11

 

[ared77]

I know with 60's/70's Mustangs you raise the rear end, have trans in neutral. Then turn one tire by hand, the other will turn in same direction if "posi". Will spin in opposite direction if it's a non-locking differential. I assume same for EBs.

 

[bronconut73]

So what about putting in the Detroit locker? My mechanic didn’t think I had posi why would I not have it and how would I check?

Also bronconut my other eb is a 302 with AOD with 33” tires and has 3.5 gears should I move that to 4.11

Depends on which OD.
The AOD has the tallest OD and therefore requires more gear than an AX-15 or 4R70W.

AOD with 33's could probably go 4.88 which seems really low but I "believe" that is what you need with the AOD and 33's.
Could likely get away with 4.56 with a more typical overdrive.


I love my rear Detroit. I highly recommend it if you're going off road.

 

[01JLH]

With what you have now, go 4.56 and be real happy with all of your driving needs. Later go with pretty much any OD trans and go to 33” tires and be even more happy with highway performance. I will say that Detroit lockers are hard to beat for traction devices. What you will have to get used to is the twitching feeling you get when turning back straight after making a right or left turn. Some times you will have a popping sound when the locker unlocks after a turn. If the Detroit is working properly you will hear a clicking sound as you make the turn. That is normal and it is the locker ratcheting as you turn. If you accelerate at all during the turn, the Detroit locks and you get the twitchy feel and sometimes the pop when it unlocks. These things are hardly noticeable on a long wheelbase vehicle but on a short wheelbase like the bronco, it can be unnerving if you are not use to it.

 

[Tulsa76bronco]

Thanks guys I should probably be more clear I have two broncos. I will go with the 4.56 on my 77 with 35 inch tires and a Detroit locker, will drive in town and off road

As for my 76 that has a Ford AOD and 33” Tires which I drive all the time in town and highway so I want it to perform well. I have always been told to go with 4.11 but are u guys saying that is not enough I will rarely if ever go off road with it just want a smooth on road truck
Thanks

 

[englewoodcowboy]

For your AOD and 33’s I would go 4.30 or 4.56.

 

[661buster1963]

Kind of jealous, two broncos good for you.
I have about 75% of a 68 bronco, but have some friends that have schooled me on gear options and being a somewhat retentive engineer I have looked at options ever since I took my 68 down to the bones to basically replace every nut and bolt on it.

I would think moving from 3.5 gears in a AOD ride and 33" tires to a 4.56 or 4.88 is going to feel like you dropped a bunch of money in bolt on horsepower and seat of the pants acceleration. As was already mentioned the AOD is one seriously over driven transmission with a 0.667 OD gear so with 33" (assuming a more typical 31.5" dia) and 3.5 gears your 302 is only turning 1600 rpm at 65mph, maybe a little faster with some torque converter slippage. The 302 is barely off of idle at 1600. With 4.11 gears it will be close to 1900 rpm, with 4.56 close to 2110 rpm, with 4.88 close to 2300 rpm (again each of these rpm may be alittle higher with converter slippage)

I might be wrong but I dont think there is an early bronco compatible OD gear any more over driven that the AOD so to best enjoy it and use it a 4.88 would be hard to beat. If you plan to run it at 80 mph it only gets up to 2800 rpm. If you ever want to go to 35" tires you will want 4.88 as well, just my humble opinion.

I plan 4.88 as well for mine, 35" tires, with ZF 5 speed (OD is a mere 0.76). Dont ever plan to exceed 65 mph I expect a 2400 rpm speed on the 351W.

 

[Rustytruck]

So what about putting in the Detroit locker? My mechanic didn’t think I had posi why would I not have it and how would I check?

Also bronconut my other eb is a 302 with AOD with 33” tires and has 3.5 gears should I move that to 4.11

Problem with "I have a 302" is a 40 year old 302 with 170 HP when new and a stripped down Bronco is a far difference from a modernized 302 with close to 270 HP Add allot of weight with roll cage, bumpers and big heavy tires makes a big difference on whether you can pull a set of gears or not. Peak torque is where the sweet spot is and keeping the rig properly geared so that sweet spot is just above your cruising range so you have power to pass.

Bronconut73 gave you good numbers for a stock Bronco 302 going to larger tires and maintaining reasonable torque at highway speed. Stock Bronco 302 engines didn't leave allot of meat and potatoes on the plate.

 

[jmangi62]

I have 35s with 4.56 gears but I have a NV3550, seems perfect for this combo. Just sayin.

 

[Tulsa76bronco]

Both of my 302’s are modern the one with the 302and AOD has been rebuilt 4years ago with Windsor Jr. Heads and now has a fitech efi

 

[Tulsa76bronco]

Is there a thread on here on how to change the front and rear gears

 

[okie4570]

The rear 9" is pretty straightforward and not bad at all. The Dana 44 was a trickier imo. Lot's of how-to videos out there.

 

[centex77]

With the 3spd, 35's and 4.10's were plenty and I could chirp the tires if I wanted. I'm curious how the new 5spd is going to be with the 4.10's and 35's.