Nothing Special's '71 Bronco

[Gary Lewis]

Man, that looks like a lot of WORK!  (I'm seeing Maynard G. Krebs.)

It took me a while to understand what all you did, but I think I have it now.  But that's a lot of cut off wheels, so that must have taken a lot of time.  And the concern of how to do it w/o cutting too much of the tube.  

I'll bet you are glad that is done.  On to the fabrication!  

[Nothing Special]

It was a lot of work, which was why I was dreading it!  But as to cutting into the tube, it's 1/2" thick so it can stand a few nicks!

[Nothing Special]

In a project like this, that creeps off in so many different directions, it's important to know what you're doing so you don't go and do something stupid.  And right now I really wish I knew what I'd known what I was doing so I wouldn't have gone and done something stupid.  But I'm getting ahead of the story...

On Saturday I ground down the welds I'd cut on the high pinion axle housing.  I also cut the housing to the correct length (6" off the passenger's side, 5/8" off the driver's side) and cut the track bar mount off one of the wedges (where the F-150 has it, on the Bronco it's on a bump stop mount).

That let me put the new axle in!  The wedges weren't welded at all, just being held by the radius arm caps.  That's where I left things Saturday evening.  I figured finishing on a high note was a better idea than try to get a little farther and maybe finishing on a different kind of note.

So on Sunday I put the axle on stands to get the Bronco sitting on its front suspension, and I installed the transfer case and front driveshaft so I could see how things looked at ride height.

If you recall from a month ago I had clocked the transfer case from the lowest position to the second position to get more clearance under the transfer case.  To do that I had to notch out the frame, and I only gained 1/2" of clearance.  I wanted to try to go higher, but before going to a lot of work to do that I thought it would be a good idea to see if I'd be able to take advantage of it.

Good thing I waited, because it turns out my limiting factor is the operating angle of the double Cardan U-joint at the rear of my front driveshaft.  At ride height it's at 26*.  I let the axle go to full droop ad the U-joint still wasn't binding, but it looks really close.  I don't really want to run it there, and definitely no higher.

Every time I find that I don't know what I'm doing I usually end up laying on my back under the truck staring up at things.  Doing that I realized that if I raised the transmission mount I'd gain more ground clearance and improve my front U-joint angle.  I couldn't go any higher with the transfer case clocked in the second position, so I put it back in the lowest position and started jacking.  Turns out I was able to get another 1/4" of clearance under the transfer case (so 3/4" over where I started) while reducing my U-joint angle by about 3*!  A win-win!  So where's the problem?  With the transfer case in the first position it doesn't try to share space with the frame, so if I'd known what I was doing I wouldn't have had to cut the frame at all

So I modified my current trans cross member to hold it as high as it can currently go, and I might end up running it this way.  But right now the limiting factor is the top of the front driveshaft hitting the bottom of the trans crossmember.  If I rebuild the crossmember to go under the front driveshaft I can eliminate that interference,  So next weekend I'm going to pull the crossmember out and see if I like what that lets me do.  But that's a project for another day.

[Gary Lewis]

Brother, I fully understand!

Did you save the piece that came out of the frame?  Or, did it come out in one piece?  I'd think you could put it back and maybe fishplate some of the joints for insurance.

And, can you somehow use the lowered crossmember to support the skid plate?  Another win-win?

Last, where are the pics?  

[Nothing Special]

It's not all one piece, but that's not a big deal.  I can patch it together with new metal well enough.  It's just too bad that I have to.

The skid plate was always going to be awfully close to the trans crossmember, so attaching them was always a possibility.  My main concern is that I don't want any bolt heads on the bottom of the skid plate.  I want it smooth to slide over rocks rather than grab them.  So if I attach it all of the access to fasteners will need to be above the skid plate, where there really isn't much access.  Again, I don't really know what I'm doing, but I'll make it up as I go!

Pictures?  They're all in my head right now.  By the time I had my hands clean enough to handle a camera I had stuff put away too much to be able to get pictures.  And there's not a lot to show right now since the axle is back out anyway.  I'll try to get some next weekend.

[Gary Lewis]

The part may look like Frankenstein but it should go back in fairly well.  And I know what you mean about it being a shame that you have to.  Still, it'll work out.

On the skid plate, can you use countersunk screws to hold it on?

[Nothing Special]

We'll see about how I end up mounting the skid plate.  I figure I'll end up laying under the Bronco for a while again when I get to that point!

[Gary Lewis]

Yes, that's the way I figure things out as well.  Stare at them, doodle a bit, go away, sleep on it, and usually something comes to mind.

Speaking of which, will the skid plate be flat?  If it is curved up on the right and left ends I wonder if you could put the bolts that secure the skid plate up on the ends, out of the way of rocks.  But in order to ensure the plate isn't moved fore/aft put pins on it that go through holes in the crossmember.

[Nothing Special]

The goal is to have it as flat as possible, tight up against the bottom of the frame rails, with the front and back edges turned up so they can ride up over things rather than act like a grader blade biting into everything.  It will need to dip down lower to get under the transfer case at least, so it won't actually be flat.

In the foggy picture in my brain it's attached to the outside of the frame, but I need to spend more time under the Bronco before that will clear up.

[Gary Lewis]

If it attaches to the outside of the frame and has turn-ups front and rear then the bolts to the frame might be enough.

[Nothing Special]

So this weekend I took the trans crossmember out so I could try lifting the transfer case higher.  I was able to get another inch!  So that's a total of about 1.75" additional clearance under the transfer case and about 4" under the radius arm mounts!

With the front axle in and sitting at ride height I again pointed the pinion up at the drive shaft.  I ended up with the pinion pointing up 11*, the driveshaft angle also at 11* and the transfer case pointing up 4*, giving me a 15* total angle in the double Cardan, a lot better than the 26* I had last week with the transfer case 1" lower.  That's so much better that it seems unbelievable.  So maybe I had something wrong in my measurements last week, but I'm pretty confident in today's.

Of course lifting the transfer case also changes the rear U-joint angles.  Back there the transfer case is pointed down 4*, the driveshaft is at 17* and the rear pinion is pointing up 21*.  The 13* in the double Cardan doesn't worry me at all, but the 4* in the single Cardan at the diff is far from ideal.

However, raising the transfer case would have increased the driveshaft angle and not affected the pinion angle.  So that means even though 4* seems like a lot, it's got to be less than I had before.  If I do experience vibration I might change something, but I'm not going to worry about it now.

Thinking about how I could have got to this point, I set the pinion angle with a different transmission and transfer case.  The AOD was longer, so the driveshaft was shorter, with a steeper angle.  When I went back to a manual trans I never corrected it.  And I never noticed any vibration so I never second-guessed myself.

Well, it is what it is.  And like I said, I'm going to run it and see what happens.

And Gary was asking for pictures.  Here's one from before with the transfer case and radius arm mounts where they were at the start of this process.


Now here's one from today with the transfer case 1.75" higher and the radius arm 4" higher.


And just for fun, here's a pic of the front axle with the come-along "track bars"


Next step is to make a new crossmember so I can take out the jack that's holding the trans up.

[Gary Lewis]

That is a HUGE difference!  And the angles look good, at least the front ones do.  But if you have problems with the rear shaft can you change the pinion angle fairly easily?

[Nothing Special]

It'd sure be easy compared to everything else I'm doing!  It'd mean cutting off the spring perches and welding them back on.

[Gary Lewis]

That’s what I thought. So IF you have a problem you have a fairly simple solution. 👍

[Nothing Special]

It's been a long time since an update.  Life has gotten in the way of a couple of weekends, so I've had to make do with the evenings I could work in.  Combining that with making a couple of mistakes made things go pretty slowly.  But now it seemed like time for an update.

I started off making a new transmission crossmember that wasn't in the way of the new transfer case and front driveshaft location.  Here's what I ended up with.


Installed (viewed from the rear)


And viewed from the front


This third view shows the problem (although poorly).  I angled the front tube up as it went out toward the frame, and I shouldn't have done that on the driver's side .  The driveshaft hits it, even at ride height.

The smaller problem sort of shows up in the second picture above.  While I angled the front tubes up for more clearance I left the rear tube straight.  While that wasn't as bad an error as the front tube on the driver's side, it did give up some ground clearance on the passenger's side.

So I did a little surgery on my new crossmember.  The front tube is now straight on the driver's side and the rear tube angles up on the passenger's side.  Now I have all the clearance I can get under the crossmember and I've got plenty of clearance for the front driveshaft.

[grumpin]

Nice job!

[Gary Lewis]

Looks good, Bob.  

I'll bet it feels really good to be making progress,

[Nothing Special]

Thanks!

Busy summers are why I always think I'm going to do big projects like this in the winter and spring.  But Minnesota winters are why I always end up doing them in the spring and busy summer!  I am looking forward to wrapping this one up, but I've still got a ways to go.  Hopefully I'll make some more obvious progress this weekend.

[Nothing Special]

Pretty good progress this weekend.  Not quite as far as I'd hoped, but not bad.

With the transfer case in its forever home I could finalize the position of the front axle.  It was a lot like the accordion in the song by the Who, with the axle going in and out and in and out.  But I didn't have to play all night, and the music was all right...  Oh well, I've ridden that a lot farther than it was worth.

Anyway, with lots of repetitions I got the axle centered in the frame at ride height and tacked the track bar bracket in place.

Then I got the diff pointed at the transfer case, for a 12* up angle on the pinion and a 12* angle on the driveshaft.

With the wedges tacked in place I took the springs back out and cycled the suspension.  Full droop was fine, but when checking full stuff I added to my bouquet by picking another couple of whoopsie daisies.  I had checked where I wanted the bump stops to be and had built standoffs to put stock bump stops at the right height.  But I didn't take into account how much the bump stops would deflect, and I hadn't checked it with the driveshaft in place.  The front U-joint hits the exhaust crossover.  Oh well, not a big deal.  I can buy some aftermarket bump stops that are 2" taller than stock.  That should work well.

Finally I put the inner Cs on, rotated them to 7* caster and tacked them in place.

But I had hoped that that wouldn't be "finally" for this weekend.  I pulled the axle out and started to weld everything up, but didn't get far.  My welder, plugged into 120V, just doesn't get hot enough for metal this thick.  I knew it would be marginal at best, but it's not even that.  It's just too cold.  So I loaded the axle into my truck and I'll try welding it up at work tomorrow.

So pictures!  Here is a side view showing very little of the radius arm mounts or transfer case!  You can also see the driveshaft coming straight off the pinion and tucked up nicely, as well as the C on the driver's end of the axle.


And here's a front view


Still a lot more to do, but this feels like a big step!

[Gary Lewis]

That is excellent progress, Bob!  That's a really BIG step.  

And it is all tucked up under there very nicely.  Good angles, good protection, and lots of clearance.