D44 ALIGNMENT ISSUE

[Oldtimer]

I took my 68 Bronco to alignment shop to record actuals in preparation to do Cut & Turn of inner Cs.
77 D44 axle
2-1/2” WH suspension lift
0° rubber “C” bushings
0.8° Pinion/Drive shaft mis-alignment
TRO with track bar riser bracket on axle (Duff’s)

See printout below.
Caster is -1.9/-2.0, which was expected (Interesting driving).

Question: The SAI (steering axis inclination) is 21.3° driver side, and 11.2° passenger side.
Last alignment check (2007) it was 9.5° both sides.
I can’t find a spec that lists an acceptable range of SAI for D44 front axle, but I don’t think they should be this far apart.
What should I be looking for as I disassemble the front axle, or do I ask Wheel Works to remeasure?

 

[Yeller]

Something is not adding up. SAI that far out would be very obvious, the front end would look like a smily face. The tires would be cambered in like a lowered ricer.

 

[tirewater]

Optimum specification for King Pin Angle is 8.5 degrees (14-01-12 in the shop manuals). A search in the web eludes to Jeeps w/ Dana 44 having a 12.5 degree SAI.

As Yeller states, it's not adding up. Having near zero camber on the left wheel with 21.3 degree SAI is curious. Anything bent on the knuckle or axle housing? Camber shims between the spindle & knuckle? Caster/camber adjustment sleeves in the ball joints? I'd have them re-measure. Adjustment shims only give you a couple of degrees, so I don't see having .5 camber w/ 21.3 degrees of SAI being likely.

 

[Oldtimer]

No camber shims or caster/camber sleeves.
Nothing obviously bent, broken, or loose.
I just changed C bushings, springs and pulled all camber shims.
Drives as before, and as expected with negative caster.
I am leaning toward re-measurement.

 

[Speedrdr]

Don’t know if it would make that much difference, but were the bushings put on just before the alignment? If so, did you make sure you had them put on correctly? Don’t know if 0* bushings make a difference in installation.

Randy

 

[DirtDonk]

It does not. Zero degrees is 0° and you can put all four bushings in any position because they are all the same.

I’d be interested in seeing a remeasure as well. Unless you were out beating on it since 2007 and bent the tubes somehow. And the yokes too for that matter!

And it’s interesting about the caster. In our experience here on the forums “most“ 77 front axles had more caster built into them than previous years. Even with zero bushings I would’ve expected to see maybe 0 to 1° positive caster instead of over 1° negative.
Then, again… I did say most. And most does not mean all, so maybe you’re one of the lucky few with a low caster 77.
Are you the original owner so know that the axle has not been swapped?

Have you verified that your 2 1/2 inch lift is actually still 2 1/2?
It should be, because fronts are typically very consistent. But I figured I’d throw that into the mix as something to verify.

 

[BanditBronco]

I am pretty sure that since it is black in the read columns of the paperwork that it wasn't actually measured during your alignment. It has been a few years since I have ran a rack but with older rigs like these they usually turn off as much nonadjustable items as possible. I could be completely off base but at least worth the question.

 

[Oldtimer]

I’d be interested in seeing a remeasure as well.

Are you the original owner so know that the axle has not been swapped?

Have you verified that your 2 1/2 inch lift is actually still 2 1/2?

Remeasured, SAI looks good. Caster changed a little, but still negative.

I have owned 68 Bronco since 73.
I swapped in 77 D44 in 1983

New WH springs.
Front 2.25 lift (9.25-7)
Rear 2.50 lift (8.5-6)



Now for cut & turn.

 

[DirtDonk]

While I like rubber for C-bushing use, and you don't want to over-compensate with too much offset from poly bushings, how are you going to use this rig?
I ask because rubber C-bushings and off-roading don't always play nice together. So far only the poly bushings have the integrated retaining "collars" or edge flanges that keep them in place when twisting up.
The rubber may or may not last as long as poly, but they last plenty long enough for most of us. They just don't always stay in place.

So we need to either have someone make rubber bushings with retaining flanges, figure out a screw-on solution involving some kind of thin metal plates for the sides of the radius arm caps, or maybe even just a small "set-screw" setup where you drill a hole all the way through a cap and insert a screw to act as retaining pin for the bushings.
None as easy as just getting rubber bushings made up with the update, or just (the whole purpose of this rambling discussion on my part) use 2° poly C-bushings.

So the question again is, how will you use your Bronco?

Paul

 

[Oldtimer]

At my age I am not about to take on the Rubicon trail.
I (reluctantly) went with rubber C-bushings because that is all that comes in 0° offset.
My front pinion now points at transfercase and misalignment of pinion to driveshaft is 1/2°.
If I don't like how the vehicle responds in emergency braking*, or my moderate trail driving causes the rubber bushings to squirm out of the caps, I will go to 2° poly and mount half of them upside down to maintain pinion alignment.
Paul, I have seen your comments about retention plates screwed to radius arm caps, and may explore that option.

Maybe one of our favorite vendors could be encouraged to market a 0° poly C-bushing, but I suspect the consumer demand is not sufficient.

*I will keep the poly bushings at rear of radius arms. I changed to poly bushings because, in panic stops the rubber bushings compress differently, allowing front axle to twist right or left, causing rear axle to swap places with front axle. I have not stopped sideways in a crosswalk since I installed poly bushings.

 

[jamesroney]

At my age I am not about to take on the Rubicon trail.
I (reluctantly) went with rubber C-bushings because that is all that comes in 0° offset.
My front pinion now points at transfercase and misalignment of pinion to driveshaft is 1/2°.
If I don't like how the vehicle responds in emergency braking*, or my moderate trail driving causes the rubber bushings to squirm out of the caps, I will go to 2° poly and mount half of them upside down to maintain pinion alignment.
Paul, I have seen your comments about retention plates screwed to radius arm caps, and may explore that option.

Maybe one of our favorite vendors could be encouraged to market a 0° poly C-bushing, but I suspect the consumer demand is not sufficient.

*I will keep the poly bushings at rear of radius arms. I changed to poly bushings because, in panic stops the rubber bushings compress differently, allowing front axle to twist right or left, causing rear axle to swap places with front axle. I have not stopped sideways in a crosswalk since I installed poly bushings.

Or you could install some 7 degree poly bushings, bring your caster to 6, allow your front driveshaft to have a 7 degree kink in it, and just drive it.

I could give you the bushings for free. If you like the way it handles, then we could do the cut and turn later. (or never) There's an awful lot of Bronco's out there running that way.

 

[tirewater]

I think the question is how often you'll be in four wheel drive in places that front drive shaft angle will become an issue.

I'd do what Jamesroney suggests and put 7 (or 4) degree bushings in and live with any front driveshaft vibration, which probably wouldn't be noticeable when driving off pavement. To me, a steering wheel that returns to center, and a vehicle that tracks stable on the road is more important than perfect front drive shaft angle.

Tom Wood's page has a nice tech & video on drive shaft angles - only because I had to reread it, lol...
https://4xshaft.com/blogs/general-tech-info-articles/driveshaft-angles

Chris

 

[DirtDonk]

Oldtimer mentioned in post #8 doing the cut-n-turn.
With the intended use, I’m guessing that running rubber bushings will be fine. Probably never have one come out.
Now just making sure you “get ‘round to it” is the next step!

 

[Oldtimer]

Or you could install some 7 degree poly bushings, bring your caster to 6, allow your front driveshaft to have a 7 degree kink in it, and just drive it.

Drive it? My neighbors will confirm that I prefer wrenching over driving.
Also, the drive shaft kink will not play nicely with locked hubs at 70mph.

Oldtimer mentioned in post #8 doing the cut-n-turn.
Now just making sure you “get ‘round to it” is the next step!

And I am pushing on!

 

[jamesroney]

Text me. I need you to make a measurement before you pull the inner C's.

I was pretty confident that you were committed to doing it "right." But since this is a public forum, I wanted to leave the other option published (the "null hypothesis?")
Group think is a real thing.