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Bronco II front TTB musings


Mechrick

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First, Howdy. Long time lurker, registered today, first post.

I currently own a Bronco II. After playing with full size Broncos for a couple of decades, decided to downsize. Was looking for Cherokee when the BII popped up on C/L as a roller. It's a 2.3L, TK5, BW 1350, with a '91 Explorer front, '03 Explorer Sport Trac rear.

I did an extensive post over at Fordsix.

https://fordsix.com/viewtopic.php?f=13&t=72863

It's mostly a trail vehicle. I want to ditch the Dana 35 TTB for something stronger. Have looked at the Dana 44 knuckle swap, the various SAS options, but I think my best course is swapping a Dana 44 TTB from a half ton. This will widen the front a bit to match the wider Explorer rear.

The four cylinder needs all the help it can get, so I think I'm going straight from 3.73:1 gears to 5.13:1 gears. Those with 33 inch tall tires should be about right.

Problems:

Dana 44 carrier break. To fit a 5.13 gear in a Dana 44 housing requires a 3.92-up carrier. I've never seen one.

Dana 50 center chunks supposedly swap in, and don't have carrier breaks.

If I use a Dana 50 center section, might as well use the bigger passenger side shaft/joints, since I have to alter a Dana 50 middle shaft to swap in the Dana 44 right axle.

Or just buy a locker for the front to ditch the stock Dana 44 carrier.

Comments? Any problems/tips for what I'm thinking?
 
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ford4wd08

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A 2.3 in a BII, you don't hear of that swap very often.
 

PetroleumJunkie412

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4x4junkie

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The D35 TTB is the same exact width as the Explorer rear (59.5").

You're not gonna break a D35 TTB with a 4-cyl on 33s... It's just about not possible, especially if you got the Jeep hubs and Spicer 760 u-joints on it (you'd have to do something pretty stupid to do it).

But if you're still itching to swap, then I'd certainly suggest dropping a locker in there if you need to ditch a 3.73/down carrier.


Welcome to TRS. :beer:
 

Mechrick

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It's got stock locking hubs.

I've never liked the Dana 35 TTB hub design. We were replacing those things under warranty shortly after the '91 Explorers debuted.
I'm currently running 31x10.50's. Knowing how these things evolve, when I buy gears, I want to buy them for the largest tire size I might eventually cram under there. My next tire purchase will probably be 255/85-16's. That means different rims, and the larger 5x51/2" pattern is appealing. I'll have to redrill the rear axles, no big deal.

I could see myself running 35's at some point in the future.

I do get into rocks on occasion (it's hard not to where I live). TTB is not the best setup for that, but I will do what I can.

Have a friend that runs lunchbox lockers in a Dana 60/Sterling-equipped Cherokee (nice rig). I bet a lunchbox locker in a Dana 50-swapped 44 would be pretty good.

When I did all the math on the axle swap, I came up with a couple of inches narrower in the front compared to the rear.

Whatever I do, I'm trying not to sacrifice the turning radius of this thing. It tuns sharper than any vehicle I've owned, including my Samurai.
 

4x4junkie

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It's got stock locking hubs.

I've never liked the Dana 35 TTB hub design. We were replacing those things under warranty shortly after the '91 Explorers debuted..
These are the Jeep hubs I mentioned above:

I'd put their strength about comparable to Warn's D44 hubs. I've not yet seen anyone on here report breaking one because they put too much stress on it.

As for effectively crawling rocks with a TTB axle, it's all in the suspension set up.
Many people bolt on crappy lift kits and then wonder why their truck handles like crap (steering all jacked up) or can't keep it's wheels on the ground (springs too stiff/shocks too short).
The key is setting the steering (tie rod) angles so that the linkage moves in phase with the axle beams (something lift kits almost never do out of the box), and then ditching the too-stiff TTB coil springs for something better (XJ or EB springs, or coilovers). I like the suspension mainly because it doesn't beat you up on the highway ride back home after you've had your fun like a solid beam axle tends to do (or if you just like to blast through the desert, TTB really shines in that environment). If you trailer your rig, then I s'pose this matters less.

Pic from Swamp Lake trail above Shaver Lake, Ca.
 

Shran

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4.10 gears were fairly common in a lot of old D44 equipped trucks... I don't know what your junkyard situation looks like down there but finding one of those would take care of your carrier situation. I had no trouble finding one when I was looking.

However I don't see you breaking your D35 if you put better hubs on it. They are pretty sturdy.

I'm not sure what measurements you're looking at for a D44 TTB swap but it's going to be quite a bit wider than what you have now.
 

Mechrick

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ditching the too-stiff TTB coil springs for something better (XJ or EB springs
I agree. Ford missed the spring rates big time. My full size Broncos were closer to optimum, and rode much nicer off road. The BII needs less rate and more damping.

4.10 gears were fairly common in a lot of old D44 equipped trucks
I'll have to visit the pick a part and see what they have.

I'm not sure what measurements you're looking at for a D44 TTB swap but it's going to be quite a bit wider than what you have now
In order to fit the larger tires and keep the turning radius, I'll have to go wider.

The key is setting the steering (tie rod) angles so that the linkage moves in phase with the axle beams
I'll buy the correct taper reamer and move the tie rods to the top of the steering arms. Then it's just a matter of picking the correct drop pitman arm.
 

Shran

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Aren't the tie rods already on top of the steering arms...? All of mine are.

As far as the width of a D44 TTB, I'm just not sure how your math works. The D44 is 6-7" wider than the D35, which by itself is already wider than your current rear axle. I get that a wider front and a narrow rear turns sharper but you're going to be a LOT wider in the front unless you use a full width axle in the rear too, and it's going to look weird if you don't. I've got a mental image of 6" of tire outside the body on the front and almost tucked in on the rear.
 

Mechrick

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Aren't the tie rods already on top of the steering arms...?
I need to be more clear, I was referencing the Dana 44 TTB.

The D44 is 6-7" wider than the D35, which by itself is already wider than your current rear axle.
The axle pivot points in the BII are closer together than the 1/2 tons. The width difference ends up about 3.5".

I'm going from memory, I'm pretty sure I got a bit over 60" WMS to WMS for the rear.

My rear axle is out of an '03 Explorer Sport Trac. The Sport Trac's are a bit different. Regular Explorers were IFS by then.

When ordering brakes for this axle, I was surprised to learn the Sport Trac rotors were larger in diameter. Everything else appears the same as a disc brake rear Explorer.
 

Shran

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OK, that makes sense... but... the hole is tapered, if you run the reamer in from the top, you just get an hourglass shaped hole and only half of the TRE shaft is touching anything. At that point I'd rather just drill it out and run heims and a 3/4 bolt or a much larger TRE if Nevada doesn't allow heim joint steering linkage.

Gotcha on the Sport Trac rear axle. I was thinking they were a bit narrower than that.

How do you deal with the axle beams being closer together? One custom length shaft, I assume? Forgive my ignorance on that subject, I haven't researched it a whole lot but several details about the D44 TTB swaps have kinda turned me off to them. Heavy, wide, spring perches further out than they should be. D44 knuckles on a D35 or D44 spindles out on a D35 (the mappyjack method) seem a lot more better and easier to me... D44 TTB swaps seem like a lot of work for not much gain.
 

Mechrick

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I might go with just 44 knuckles.

Aussie and Spartan lockers are available (and cheap) for the 35. I need to figure out how much tire I can get under there before they hit the frame rail or radius arms.

On the Dana 44 swap, the left axle ends up full length. The right axle shaft has to be shortened. Dana 50 TTB axles are shorter, a good place to start.
 

scotts90ranger

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I've been running a turbo 2.3L with a D35 up front (open) and stock junkyard hubs for near a decade with 35" tires and 5.13 gears... did the full circlip mod on the joints, clearanced the window, external C clip eliminator (spring in the boot) and the only thing that has gone wrong on mine are one side wheel bearings from rust, bent the drivers side beam hitting a rock with the bottom lip of the pumpkin which I fixed in the vehicle... The rest is just alignment issues... I'm running the FA600 pitman arm and it handles pretty decent. Roughly 6" of lift, probably less by now, tires rub on the radius arms some but not a big deal. I don't beat on it but don't take it easy either, try not to put a bunch of torque on the front while turned, been a bit harder on it in the last couple years and it just keeps taking it...
 

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I don't think D50 shafts would be usable, they have bigger u-joints that likely won't fit at the steering knuckles of a D44 (the D50 center shaft & slip yoke part can be used on the 44 though).

If you lengthen each D44 beam 1" next to the pivot, this would then eliminate the need to swap or modify the shafts (this compensates for the difference in the brackets and preserves the axle's OE width).

In order to fit the larger tires and keep the turning radius, I'll have to go wider.
Not necessarily... The radius arms you use will impact this more than anything. James Duff (and I believe Skyjacker) extended radius arms should clear a 35x12.50 tire on an 8" wide wheel w/3.75" backspace at full steering lock. My radius arms are home-built, the tire just barely touches them at full steering lock but still does not reduce my turn radius. I can drive circles in the middle of an average suburban residential street with my BII.


On the Explorer 8.8 axles, I'm not aware of any differences as for width goes... AFAIK, they all are 59.5" wms-wms, '91-'94 being drum brake, '95-'01 ('95-'03 Sport & Sport Trac), disc brake. Of course in another thread here I now seem to be learning some new things about OEM D35 carriers, so maybe I shouldn't swear to it ( :dunno: ).
 

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