Front axle geometry / driveshaft binding

[77bronocman]

I need some advice on finishing my 77 Bronco. I'm running an Explorer 5.0/NV4500/D20 powertrain with a 3.5" Cage Lift and the longer radius arms. The truck will be used for trailriding, but primarily on the road. 2 problems:

1) Alignment results:
Camber (spec 1 - 2) Left -1.6. Right 0.1
Caster (spec 2.8 - 4.3) Left 4.8. Right 5.3
I'm not sure why my camber is low only on the right side? Is there anything besides the C-bushings that would cause this? What should I look at? Is the Caster close enough or is there a way to correct it?

2) My front drive shaft is binding at the pinion yoke. The pinion angle looks severe, but I don't think there's a way to rotate it. My shaft doesn't have the double cardon in it which I understand is not stock. A local driveshaft place said that adding the double cardon to it would eliminate the binding issue. They can do this for about $125. Does this sound right or should I invest in a high angle shaft?

Thanks for the help

 

[Broncobowsher]

There is a lot going on here. The caster numbers make for a great driver. But with that much caster, and that much lift, the front U-joint angle is ugly. The CV is used at the transfer case, not the axle side. So that can fix the binding at the transfer case but won't fix the binding at the pinion.

The front axle is considered a beam axle. Left side is connected to the right. To change caster you typically have to rotate the complete housing. That is what offset bushings and built in offsets in extended radius arms do. But left is fundamentally connected to right. changing bushings on one side won't do anything. There are a couple possible fixes. Camber can be shimmed with tapered spacers behind the spindle. I thought I recently heard that the big bore spindle spacers are back out again, they had been off the market for years. Another fix is an offset eccentric that goes in the upper ball joint. This can be used to dial caster and/or camber. So there are a couple of simple caster/camber fixes. If you really wanted to dial the front end in there is another angle, SAI (steering axis inclination) which is sorta like caster with the imaginary line but in the camber plane. Deals with scrub radius. The shim does not change SAI where the balljoint eccentric does.

That's all fine for dialing in the wheel alignment, but doesn't do much for driveshaft angles. The CV at the transfer case will fix that fine. Only 3½" lift shouldn't even need high angle. But you are still screwed at the pinion. The only way to fix that is to rotate the axle housing. For your case, change the C-bushings to a lesser angle or possibly even put them in backwards. Now you can rotate the axle housing to fix the shaft and the front driveline will all run nice and happy. But that totally kills caster and it will track horrible. herding cats will be easier then trying to drive on the highway. Yes, there are the balljoint eccentrics that can give a little back, but not as much as you would need. Now we get to the labor intensive, but good fix. Cut the outer Cs off the housing and rotate to get caster back. Now you can have a non-binding driveshaft at the pinion. CV will prevent binding at the transfer case. And the outer Cs will have the caster dialed in to track good.

Too much work? Try just changing the C bushings and dial out 2-3° of caster. still positive which is good. Won't track as good. But will pull a few degrees of U-joint angle out of the front driveshaft U-joint at the pinion. The compromise fix, but a lot easier.

 

[Apogee]

My '77 had the same issue when I installed my CAGE 3.5" lift and long arms. The easy solution is to add a high-offset Tom Wood's "Super-Flex" u-joint at the pinion with the double cardan at the t-case. Fix the camber issue on the passenger's side and drive it. Your caster numbers are fabulous for a rig with power steering and pressumably 33-37 inch tires IMHO.

Otherwise, you can cut and rotate the c-wedges on the axle housing to put your pinion where you want it and they cut and rotate the outer axle "C's" to put the caster where you want it, as that's the only way to address both issues without compromising one or the other.

Tobin

 

[treihesse]

I will be installing a offset u joint soon on my front shaft as well.
It will correct a lot of the bind issue
I can also adjust my pinion angle easily so that helps

 

[welndmn]

I have to ask, it's full assembled right? As in you're not dealing with the front driveshaft with the motor and body off it.

 

[surfer-b]

How are the ball joints? This want do anything for the d-shaft binding but the reason I ask is I have never seen a Bronco with a neg camber #, what you have for the lft, unless the joint are worn out.

 

[77bronocman]

How are the ball joints? This want do anything for the d-shaft binding but the reason I ask is I have never seen a Bronco with a neg camber #, what you have for the lft, unless the joint are worn out.

I'll check them, thanks.

 

[77bronocman]

I have to ask, it's full assembled right? As in you're not dealing with the front driveshaft with the motor and body off it.

Yes it's fully assembled.

 

[77bronocman]

My '77 had the same issue when I installed my CAGE 3.5" lift and long arms. The easy solution is to add a high-offset Tom Wood's "Super-Flex" u-joint at the pinion with the double cardan at the t-case. Fix the camber issue on the passenger's side and drive it. Your caster numbers are fabulous for a rig with power steering and pressumably 33-37 inch tires IMHO.

Otherwise, you can cut and rotate the c-wedges on the axle housing to put your pinion where you want it and they cut and rotate the outer axle "C's" to put the caster where you want it, as that's the only way to address both issues without compromising one or the other.

Tobin

Thanks. Can you send me a few pictures of your setup?

 

[77bronocman]

Any recommended threads on the cutting and turning process for the front driveshaft C's?

 

[allenfahey]

Keep in mind with the offset u-joint you can't drive in 4wd over 30-35 miles an hour. It will violently vibrate, 2wd you will be fine.

 

[76Broncofromhell]

Any recommended threads on the cutting and turning process for the front driveshaft C's?

Here's how I did it in mine. It was a pain in the ass, but my axle had abysmally low caster from the factory, and there was no way to get the desired caster with just c-bushings.

http://classicbroncos.com/forums/showthread.php?t=144532&page=3


I would not run the super flex u-joints for a couple reasons:

• They are expensive
• They cause vibration because they move the centerlines of the two axis of the u-joint
• They don't increase the max angle of the driveline that much.

I would recommend buying a new transfer-case yoke from high angle driveline to adapt the Toyota 100mm mini truck CV driveshaft to the t-case (http://www.highangledriveline.com/early_bronco_conversion.html ), and a Dana 44 to Toyota yoke ( http://www.wfoconcepts.com/pr/Dana-44-30-300-Toyota-Flange-Dual-Pattern-26-Spline/3210/3310/3322 ).

Then buy a used driveshaft from a Toyota 4x4 (84+) from Craigslist and you are good to go. They have up to a 41* range of operation. They are as strong as 1350 joints, are plentiful and will allow you to operate your Bronco in 4wd at speed.

 

[tmbuehrer]

I don't have the specs in front of me, but I do alignments everyday, and 1-2 degrees of camber is way too much for any vehicle other than a road and track car. on a typical straight axle you want you caster as close to 0 as possible. the -1.6 camber will cause extreme inside tire wear. now in theory, for the right to be correct(in my book) and the left to be off the only probable causes would be worn or bent ball joints, or bent outer c's or knuckle. I can get alignment specs off my alignment machine on Monday if needed.

 

[DirtDonk]

I'd be interested in seeing what your machine says. You'd think they would all be the same, but I've seen different ones posted up from different sources over the years.

Bent yokes and a very possibly sloppy installation in the first place, could be causing some of that, but since the spec is 1-2 degrees positive (according to my old Chilton's too), and he's showing negative, I'd suspect 40 years of bouncing around or a few good curb-feelies or rock close-encounters.
I'd love to see that .1 on mine!

Paul

 

[77bronocman]

Yes please send me the right information. Thanks!

 

[77bronocman]

Anybody got a print of what the dimensions of the front driveshaft are supposed to be on the 77 Dana 44? It seems like I should be able to measure and see if something is bent without an alignment machine?

I have not cut or welded anything on the front axle since I bought the Bronco in 1998. This vehicle has been off-road many times in its life: mud, rocks, potentially some jumping even (previous owner). It is very possible that something is slightly bent or damaged. But nothing I can see is obviously damaged. I don't think there is much if anything wrong with it.

 

[Broncobowsher]

Jumped, that isn't good for axle housings
Doubt you will be able to find what's bent on an alignment machine. It's hard to tell if an axle is straight when it is out, stripped and clean much less while still in the truck. Could be a bent tube, bent C, bent knuckle. Or a little of all the above. And by only a small amount it is hard to tell. Add in sloppy build tolerances on the 70s.

About all I can recommend for narrowing it down is to look at SAI (kingpin inclination).
If they vary side to side like the caster does the housing or C is out. If they match side to side, knuckle. The shop should have the specs already, even if they don't all that really matters is the difference side to side anyway.

 

[tmbuehrer]

with out looking at the specs, I can tell you where I would have mine. camber .0 +/-.3 degrees. caster at 2.0 +/-.5 degrees, and total toe .1 to .2 degrees. that's what my ideal specs would be. but I will get ford specs tomorrow at some point. by the way I am a ford master diesel technician and have been doing alignments for years.

 

[DirtDonk]

Have you ever made note of what changes in attitude (driving attitude that is) larger tires make when using the degree-method, rather than the older inch-method?
In other words, a vehicle that should have a toe-in setting of .2° with 28" tall tires is going to have more toe-in (as measured with an inch scale) with 36" tires at the same degree setting.
Since many here have said they like a little more toe with larger tires, I wonder what the actual relationship is.
I'm sure it has been figured here with high-school geometry, but I don't remember what any results might have been.

Just wondering if you've been doing it long enough to have played with those numbers.

And I think some will argue for more caster than you specify. An original early with manual steering, yes. That 2 degrees seems to work ok enough. Especially with smaller tires. But anyone with power steering on an EB likes something a little closer to the factory spec of +3.5 to +4° caster. With many here putting as much as 8 degrees positive into their custom builds. That much might not be strictly necessary, but they seem to like it.

Paul

 

[Broncobowsher]

I do alignments at times for a living. I'm often the guy the other techs come to as I understand alignments. I will do things that are not in the book. For giggles one day I set a car up that drove perfectly normal, no pulls, nothing weird, but would oversteer turning left and understeer turning right. That was a fun car to drive hard.

Anyway, back to setting toe on an alignment machine. The machine goes off angles no matter what. It has no idea what size tire is on the vehicle. The toe dimension is based off a standard tire diameter (I thought it was 29"?). Yes, for a taller tire with the exact same alignment, the toe will measure different. But the angle is exactly the same. That angle is a slight scrub that the tire will have with the ground. Diameter means nothing to that angle.

But the vehicle may respond better or worse with more/less toe. This is usually due to sidewall/tread block flex. Adding toe can load the tires so they bind a bit and act more stable. Or it can cause a wander as one tire bites better and causes the other to slip more and that relationship drifts side to side. It doesn't always follow the rules.

My preference that usually works, the stiffer the tire the closer to no toe. The more flex in a tire, a little more toe often can tighten up the front end but not always. Lots of other factors to rule out first. Toe is one of those last ditch fixes.
With new front end parts (ball joints, tie rods) run less toe. As they age, add a little more toe.

Never, ever, trust tire molding lines, tread blocks, or even the edge of a rim for setting toe. They are never true to the bearings axis of rotation, and that is what you are setting. It isn't the toe, it is the alignment of the wheel bearings. It is just easier to understand when it happens to be toe.

I understand it is an angle, but I always use the standard inches or mm as read by the alignment machine. I don't know toe readings as an angle, and few techs would either. Doing it at home in the driveway, it really doesn't matter. You will never get an accurate fraction of a degree in order to set the toe, but you can get a fraction of an inch which will work just fine. After you get the measurements you can go figure the angles, but that is just too much work.