4x4x2 PS Box - which pitman arm and what mounting height

[MnCampNHunt]

We are in the process of mounting up a 4x4x2 PS box to the frame using a 1/2" thick adapter plate - similar to the old West Coast Bronco plate. This is a body off resto. And currently the frame just had the axles/suspention installed (no body now, and only 1-1/2" SL).
Have two questions:
1) Which Pitman Arm should we use? The arm from the stock manual steering '71 Bronco? Of the longer arm (~3/4") from the '79 full size Bronco?
2) Any suggestions on how high to mount the box? Currently thinking has low as we can, such that the hoses will just clear the frame (WH #2111 and 2113)

 

[Madgyver]

I'll share some pics of what we did.
1st pic is before the FireBronco smash. all other pics are the repairs and after.

 

[thegreatjustino]

1) Which Pitman Arm should we use? The arm from the stock manual steering '71 Bronco? Of the longer arm (~3/4") from the '79 full size Bronco?

The drag link end of the '79 arm has a different angle to it than the EB arm due to the '79 arm facing forward in the stock application.

 

[toddz69]

I have the arm from an EB manual box on mine and it works great.

Todd Z.

 

[MnCampNHunt]

ToddZ - do you remember if you had to file the "key" bump out of the orginal pitman arm?

 

[Apogee]

I'm not sure what pitman arm I have with respect to application, but it's a keyed 6.5" center to center unit and it provides a little over 8 inches of travel on the drag link, which I'll knock down to 8 inches with the steering stops in the knuckles and hydro-assist cylinder. It's a mostly flat pitman arm (with keys) mated up to a GM TRE steering linkage (tie-rod over on F150 knuckles) mounted as high as I could get it on the frame with my custom adapter plate. FWIW, my axle is pushed forward by ~1.5", so my box is well into my body mount and radiator support and doesn't reuse any of the factory frame holes. I made the adapter plate out of 3/4" steel and tapped the holes for box directly into the plate...I also run the original fasteners through the frame into tapped holes on the plate with a 3/8" thick reinforcing plate on the inside of the frame as well. All plates are welded to the frame.

 

[DirtDonk]

Are you gonna be painting your body before you put it back on the frame? If so, I would make sure that the new, bigger and non-stock location box clears the inner wheel well first.
That way you don’t have to go through the stress of “reforming“ or otherwise modifying your newly painted sheet metal.

 

[toddz69]

ToddZ - do you remember if you had to file the "key" bump out of the orginal pitman arm?

I don't remember doing anything like that. But to be fair - the conversion was done over 20 years ago and I've forgotten a lot since then.

Todd Z.

 

[MnCampNHunt]

Thanks All.

We will pull the pitman arm off the orginal manual box and give that a try before anything final.

The body is an older fiberglass one that will be repurposed onto this build. Being Fiberglass, will make it easier in some ways to modify. Frankly the fiberglass core support is in need of significant reinforcement. We might repurpose some/most of the orginal steel core support.

We tried a TRO configuration but the WH F-150 tie rod came too close to the track arm stud on the axel at extreem turn. It has the F-150 knuckles and disc brakes. It is almost entirely going to be on streets so not a big loss. Had to get a TRO bushing to use as one of the knuckles holes had a very large taper (were purchased unsed and off the donor truck).

Currently the plate has been drilled and tapped is bolted to the frame, we are waiting on the feed and return lines to ensure that they will clear the frame. Think we will drop the newly rebuilt motor in as well before committing to tapping the holes for the box - measure twice/cut once.

 

[DirtDonk]

How much lift? If any?
If enough to justify a riser plate instead of a drop bracket, maybe that’s your answer to the TRO dilemma. Get the track bar bolt up just enough to clear the tie rod.

 

[SteveL]

What tie-rod set up are you running? If still using the inverted y set up you're gonna need the 77 pitman. If you have any other tie-rods the stock 77 pitman has the wrong diameter hole for the drag link. I run the 4x4x2 box, 3.5" suspension, and a tro set up with stock pitman arm. Had a drop pitman until I went tro.

 

[MnCampNHunt]

We have installed the WH 1-1/2" SL kit and will not have any BL. We have the WH F-150 double adjustable tie rod (2380) and there stock adjustable drag link (2379). Stock track bar without any drop or riser brackets. Currently frame only (no motor or body weight).

With the TRO configuration and at full right turn the tie just touches the large stud on the axel for the track bar. But TRO isn't a big deal for us with the usage almost entirely being roads. Mostly wanted to do this to keep the drag link as parallel as possible.

Have not checked out the fit yet of the stock '71 Bronco Pitman arm. Next step will be to drop the motor/trans/t-case.

 

[DirtDonk]

Drag link parallel to what? To the ground or to the track bar?
If you are only lifted 1.5 inches, it’s good that you won’t need a riser because that’s an awkward height.
But if you were planning to go TRO and not modify the track bar angle, you would very likely have not been parallel to the track bar.
In fact, in many installations, the larger steering box alone hangs down low enough to begin with, to skew the angles.
Meaning that just installing the staring box might necessitate the need to modify the track bar mounts.

At this stage, everything needs to be marked up together. You don’t necessarily have to compress the suspension to ride height, but it’s still a good practice to do in order to ensure everything is where it should be when it’s all said and done.
Meaning the distance between the top of the axle tube and the bottom of the frame rail should be about 8 1/2 inches.

Speaking of which, anybody reading this have a Dana 30 and a running Bronco that can take a measurement?
Just wondering if the measurements we’ve been using all these years can be skewed by the different tube diameters between the 30 and the 44.

 

[Oldtimer]

Before installing track bar riser bracket, I trimmed the threads on track bar bolt and use a thinner castle, nut so that tie rod cleared at full right turn.

 

[MnCampNHunt]

Donk - I assumed that having the drag link as parallel to the ground, axel & tie rod was a good thing for the steering geometery. To reduce wobble or bump steer effect.

?? Should we be trying to keep the drag link and track bar parallel??

If so we should look at raising the steering box - right now we were thinking nearly as low as we can get it.

Thanks too for the 8-1/2" distance that could be helpful too!

OldTimer - I like the idea of a thin pattern castle nut!! That might be a good option.

 

[Oldtimer]

I think I redrilled cotter pin hole.

 

[jamesroney]

Drag link parallel to what? To the ground or to the track bar?
If you are only lifted 1.5 inches, it’s good that you won’t need a riser because that’s an awkward height.
But if you were planning to go TRO and not modify the track bar angle, you would very likely have not been parallel to the track bar.
In fact, in many installations, the larger steering box alone hangs down low enough to begin with, to skew the angles.
Meaning that just installing the staring box might necessitate the need to modify the track bar mounts.

At this stage, everything needs to be marked up together. You don’t necessarily have to compress the suspension to ride height, but it’s still a good practice to do in order to ensure everything is where it should be when it’s all said and done.
Meaning the distance between the top of the axle tube and the bottom of the frame rail should be about 8 1/2 inches.

Speaking of which, anybody reading this have a Dana 30 and a running Bronco that can take a measurement?
Just wondering if the measurements we’ve been using all these years can be skewed by the different tube diameters between the 30 and the 44.

Hi Paul. I'm around today, so I can measure anything you want from my Air Force Bronco. But your intuition is correct. The ride height is constrained by the radius arm / coil bucket relationship. The Dana 30 and D44 (and the Hybrid) center-line are all located EXACTLY the same within the radius arm C-cap. And yes, the Dana 30 is always skewed by 1/2 of the tube diameter.

If I take my existing stone stock Bronco with the D30 and 2.5 inch tubes, and install a Dana 44 with 2.75 tubes, it will ride at exactly the same height. But the top of tube to frame rail dimension will always be 1/8 inch longer for the D30.

 

[DirtDonk]

Thanks, James
Luckily, when dealing with Broncos in general, an eighth of an inch in either direction doesn’t really skew results by enough to matter. So that’s good to know that it’s a minimal difference and that we can still use the 7 inch front and 6 inch back as a “general approximation“ or thereabouts.

 

[DirtDonk]

Before installing track bar riser bracket, I trimmed the threads on track bar bolt and use a thinner castle, nut so that tie rod cleared at full right turn.

I think others have done that as well. That was one of the relatively simple cures over the years, but more people preferred to use the riser.
However, those were accompanying higher lifts. So the shorter stud is still a viable alternative.

 

[DirtDonk]

Donk - I assumed that having the drag link as parallel to the ground, axel & tie rod was a good thing for the steering geometery. To reduce wobble or bump steer effect.

Very logical, but only partially correct with a bronco.
It’s important to do both. Keeping the track bar and drag link as parallel as possible, and as long as possible, and as much the same plane as possible, and as level as possible.
Sometimes they are all achievable, sometimes only one or two are achievable.
It’s a compromise, but it’s worth pursuing to get at least close to perfection.

?? Should we be trying to keep the drag link and track bar parallel??

Always. Or at least as close as you can make them.

If so we should look at raising the steering box - right now we were thinking nearly as low as we can get it.

Not necessarily raise it up. Just make it all work together.
Lowering the steering box is not necessarily a bad thing, unless you go too far. That’s why I said mocking up was important.
Don’t permanently weld anything until you know that you’ve done as much as you can to get everything to play nice together.
Track bar and drag link location are the equation. It’s up to you to make everything work together.

Thanks too for the 8-1/2" distance that could be helpful too!

That’s the standard 7 inch stock, plus your expected 1.5 inches of suspension lift.
Body lifts don’t alter the equation directly.

OldTimer - I like the idea of a thin pattern castle nut!! That might be a good option.

Certainly keep it on the list!