D44 inner C cut & turn

[gtme1996]

I've had my '71 front axle out and stripped to rebuild for a while (too long, actually) and am considering rotating the Cs for caster correction. Since it's out, I don't have a way to measure what it was so I was wondering if anyone could recommend how much they need to be rotated or, better yet, offer a degree number relative to the center section being vertical. I read several threads and the consensus seems to be rotate 5-9° to get 4-6°. Lift will be 2.5", probably with a 2° C-bushing as is usually recommend, with a 1" BL to run 35s. Factory Bronco PS has been swapped in.

Any input is appreciated!

 

[DirtDonk]

I've got plenty of assumptions, presumptions, SWAG's and theories, based on my '71 and the many stories here over the years.
Unfortunately, just like in your case, most of the discussions here were only for caster measured after the fact. Most did not measure theirs "before" the teardown, or just bought a trailer of parts in the first place.
And there have been plenty of variations on the results over the years too. Pointing to inconsistencies in the manufacture of the front axle assemblies.
So we don't know exactly how much yours has/had.

Which makes your request for hard numbers and measuring points even more critical.
Guesses based on lots of intel are good. But because there is such a thing as too much caster (maybe), hard numbers are better!
Heck, I don't remember anyone here ever measuring the actual change in caster between the different spring heights!
Be nice to get a good digital angle-finder on a hard point and raise and lower the suspension on jacks or a rack, just to see if the old numbers still hold true.

Hoping someone with their Dana 44 with known caster can shed some light on the subject. Measuring from some easy to repeat locations for you to get to your goal.
I think James Roney had some hard numbers not long ago, but don't remember if they were something that could be transferred over to another rig without some head scratching.

good luck!

Paul

 

[Madgyver]

Because you don't have a baseline caster reading to start with before you tore it down. what you try to do will still have to be measured. What do you do if you miss your mark?
In my opinion, No good reason to rotate inner C's for just a 2.5" lift. Too much work and it will add more time to your build.

Taz and I encountered this dilemma when we needed to replace one of the inner C on his 77 FWHP Dana44 axle due to rust. Do both and rotate or just replace the bad side? Since we had long radius arms and only a 3" lift, It was decided to just replace the bad side.
Glad we kept it simple.

 

[DirtDonk]

Good decision. Likely would not have been needed in your case anyway.
The full-size, high-pinion differentials almost always had more caster built into them than their Early Bronco counterparts. So yours probably was already rocking 6 or 7 degrees positive right out of the gate. Add the long arms and whatever bushings you used, and you were likely good to go without any extra work.

Mad's right about a 2.5" lift though. Even with bad numbers, your Bronco likely won't have any u-joint bind. But if I had my druthers, I'd still want more caster than comes in a Bronco axle, and do the cut-n-turn in just about any situation with a stock '71 Dana 44.
My '71 drove great with just that 2 degrees of caster. But most don't seem to have that same luck.
If you're willing to go through the extra effort, I say do it.

Paul

 

[lars]

A data point:

When I did mine 20 years ago(!) I had 4-1/2" front coils yielding an actual 4" of suspension lift, 7 degree C bushings and so-called "caster corrector" upper ball joint sleeves yielding an additional 1-1/2 degrees. My fave local alignment shop measured about 2 degrees on the left and 1-1/2 degrees on the right.

Wandered like crazy. My goal was 5-6 degrees of caster, like my boss's 78 big Bronco that drove arrow-straight.

Knowing nothing and not knowing of anyone else who had done it, I did the job myself including fabbing my own alignment fixture. It was a lot of work. Now that I'm old and sore, I would definitely do it again though I'd pay someone else, especially since shops with the capability are more common now.

Anyway. Removed the caster corrector sleeves, replaced the 7 degree C bushings with 2 degree bushings figuring it would be good to have more uniform rubber (urethane) around the wedges. Rotated the left back 10 degrees as best as I could measure and rotated the right to match.

Reassembled, discovered my track bar riser was in the wrong place (axle rotated forward 5 degrees due to different C bushings) so had to fix that.

Then off to the alignment shop. It was obvious in that short drive that I had achieved my goal. Soooo much better- the "return to center" of the steering was vastly improved. Shop numbers confirmed it- 5-1/2 degrees on both sides. Well worth the effort.

As Mad rightly points out, with 2-1/2" of lift it may not be worth it. Unfortunately without being able to measure the built-in caster of your existing housing, it''s impossible to say. There has just been too much variation in the Dana 44 housings over the years. My housing was/is a 1977 vintage so it's obvious that the quality control didn't improve as the years went by.

 

[gtme1996]

Thanks for the input!! I am on the fence about pulling the trigger because I’ve been trying to lean into the RKG mantra of “don’t get it right, just get it running” but the engineer in me wants it right! That said, when I was driving it, I don’t really recall it having any unpleasant characteristics. Again, that’s been far too long ago so I probably don’t remember either way. I’ll keep doing some research and see where it takes me.

 

[Broncobowsher]

2½" of lift in old school numbers takes 4° bushings to restore the caster.
Trying to guess without a starting point. I would guess 1° of positive caster at stock ride height.
With 2½" lift that should get you -3° caster.
I would run 2° bushings. But flip the front bushing (fat part on the top of both bushings), this will zero out the correction.
Aim for 6° caster, so rotate 9°.

When done you have an easy 2° of adjustment either way by flipping the existing bushings around different ways.
If you want more lift later, go with more bushing.

This way you can get the hard part taken care of now, and fine tune with wrenches when done and have final numbers.

 

[jamesroney]

Hoping someone with their Dana 44 with known caster can shed some light on the subject. Measuring from some easy to repeat locations for you to get to your goal.
I think James Roney had some hard numbers not long ago, but don't remember if they were something that could be transferred over to another rig without some head scratching.
Paul

It's a straight sine function. The radius arm is fixed length at 32 inches. At static ride height, (zero lift) the arm is nominally horizontal.

So, for caster correction, the numbers are as follows:

1 inch lift = 1.8 degrees
2 inch lift = 3.6 degrees
2.5 inch lift = 4.5 degrees
3.5 inch lift = 6.3 degrees
4.5 inch lift = 8.1 degrees
5.5 inch lift = 9.9 degrees.

The total angle between the caster axis and pinion inclination is 12 degrees. It's always 12 degrees. In the dozens that I have measured, its 12 degrees. Lots of people tell me that it isn't 12 degrees, and that all Bronco's are different. Yet, when I get them in the shop, and I measure them...they are all 12 degrees. 8 degrees on the pinion, and 4 degrees of caster.

The reason why this becomes an argument is because of the caster specification. The 1969 Ford Truck Service Specification Manual on page 3-26 states that the target caster is 3.5 degrees. That is for a manual steering, bias ply, 6 cyl station wagon on a ranch. The notion that the same spec is correct for a 70 mph highway cruiser on 33 inch radials with power steering is just plain silly. But I have seen it countless times, and will no doubt see it again on this thread. SOMEBODY will say that the factory caster was 3.5 degrees, and then someone else will say how 3.5 is adequate. And the debate continues.

Since no one is handing me an ice cold beer, and since I am not sitting by a warm campfire, I am reluctant to enter the debate. But I will say this:
1. 3.5 degrees of caster is the WRONG spec for a 93 inch wheelbase live axle bronco on 33's with radial tires.
2. I don't give a hoot about how much angular deviation (u-joint angle) you think is acceptable. Dana Spicer, Neapco, Precision, etc...all indicate that 1 degree of misalignment is preferred. For high speed, continuous operation, it's 1 degree max.
3. Every Bronco that ever left the factory and drives over 50 MPH needs more caster.
4. You can certainly get by with caster correction by installing c-bushings, and living with a kink in your driveshaft. If you never put your Bronco into 4WD on the freeway...it will work just fine right up until it binds. Lots of people do this.

@gtme1996 your specific answer is as follows: (and BTW, I like the 2 degree poly bushings, because they have shoulders and don't squirt out like the factory rubber ones.)

For a 2.5 lift, 35 inch radials, power steering...needs 6 degrees of caster. Factory was 3.5, -4.5 for the lift, +2 for the bushings, = 5 degrees of additional angle.
For a 3.5 lift, the answer is 7 degrees of additional angle.

 

[lars]

(snippped) SOMEBODY will say that the factory caster was 3.5 degrees, and then someone else will say how 3.5 is adequate.

Won't be me. Cue what I wrote above. Love my 6 degree caster angle. Yup.

And since you mentioned pinion & u-joint angle I should mention that I got lucky there. Between the 2 degree urethane bushings, extended radius arms and NV4500 that moved my clocked-so-it-barely-clears-the-frame Atlas, I magically got the desired 1 degree of u-joint angle. Would love to say that I planned it that way, but it was a fortunate accident. Nice to be able to go 70 in 4-hi without a bunch of vibration. Or bound-up u-joint on rocks in 4-lo.

 

[TheLimeRanger]

i have 2.5" of lift and 7 degree c bushings. that netted me 1.6 degrees and 1.8 degrees of caster. if i had the axle out and had a way to do it, id totally cut and turn. maybe someday that will be in the cards for me.

 

[Wild horse 75]

Now you’ve got me thinking. I’m about to rebuild my front diff so now would be the time to fix this before powdercoat.

 

[gtme1996]

your specific answer is as follows: (and BTW, I like the 2 degree poly bushings, because they have shoulders and don't squirt out like the factory rubber ones.)

For a 2.5 lift, 35 inch radials, power steering...needs 6 degrees of caster. Factory was 3.5, -4.5 for the lift, +2 for the bushings, = 5 degrees of additional angle.
For a 3.5 lift, the answer is 7 degrees of additional angle.

Thank you very much!! I'd been checked out for the past week or so and had pretty much convinced myself to let it be but your response as well as the others have convinced me it's the right thing to do! Now to find someone who can weld it up after I do the cut and turn...

 

[jamesroney]

Thank you very much!! I'd been checked out for the past week or so and had pretty much convinced myself to let it be but your response as well as the others have convinced me it's the right thing to do! Now to find someone who can weld it up after I do the cut and turn...

Please update your profile to include your location. You will have a better chance of getting a local resource if we know where you are.

If you are in NorCal, I am happy to volunteer. Nothing I like better than someone doing all the work, and bringing me a clean axle that's fully prepped.

If I were you, I would go ahead and buy the cheapie Harbor Freight MIG 170 machine for $499. Add the smallest bottle of 75%/25% you can find. Practice on your track bar riser, and your shock mounts. Then weld it yourself. Then you just need someone with expertise to watch you and help.

...and then you can wear that cool t-shirt that says: "look, I welded it myself..."

 

[gtme1996]

That'd probably help, wouldn't it? I'm in Savannah, GA so almost as far away from NorCal as CONUS allows. Anyway, I know a few people who could do it for me, one of which is a welding instructor at the local career academy. I've been hoping to take some lessons from him anyway since work can never get it together to offer the training I've been asking for. And thank you for offering to do it as it is greatly appreciated!

 

[bigmuddy]

i have 2.5" of lift and 7 degree c bushings. that netted me 1.6 degrees and 1.8 degrees of caster. if i had the axle out and had a way to do it, id totally cut and turn. maybe someday that will be in the cards for me.

Its on my list one day. I am getting by as I don't offroad much anymore and never have been into high speed mudding and snow.
I run a 2.5" lift with 35's, using Cage long arms and I think a 4 degree poly bushing, of course the cage arms have I think 4 deg castor built in?
It steers like a champ at any speed, but my pinion angle is virtually parallel to the ground which causes me to run a weird u-joint on the front shaft to get it to mate up.
Maybe get to it over the winter and the truck is still in need of hanging all the parts back on it... we shall see!

 

[toddz69]

Won't be me. Cue what I wrote above. Love my 6 degree caster angle. Yup.

And since you mentioned pinion & u-joint angle I should mention that I got lucky there. Between the 2 degree urethane bushings, extended radius arms and NV4500 that moved my clocked-so-it-barely-clears-the-frame Atlas, I magically got the desired 1 degree of u-joint angle. Would love to say that I planned it that way, but it was a fortunate accident. Nice to be able to go 70 in 4-hi without a bunch of vibration. Or bound-up u-joint on rocks in 4-lo.

Your note got me curious as well - finally got a chance to check mine a few evenings ago. I knew mine was "good" but didn't know the angle. Sure enough, it's right around 1 deg. between yoke and driveshaft too.

Todd Z.

 

[nvrstuk]

Like Lars mentioned and Mr. Rooney stated WHY the need for more caster than the Ford manual suggested. NOBODY ever seems to point out the bias ply & manual strg factors which are HUGE when comparing old skool factory #'s but running pwr strg and bias ply tires . I deal with this all the time with my HR guys that pull out a book and say "Hey, the book suggests caster #'s of... "

Dial in 6-8% caster and you will never regret it- ever. There is a noticeable difference between 3.5 and 7.5 deg caster and if you're doing it, dial in the numbers that will help you the most. I run 7.5deg on my D60 HP with 40"s. Cruise at 70mph all day like you want it to.

I dialed in 1.5deg Ujoint at ride ht and everything was great... for 4 yrs until I put in a different engine. Everyone is right when you all just now under your breath said "... the engine makes no difference for ujoint angle" and you're all correct-again!

It's just that the torque & power of the new engine finally allowed me to not need a doubler anymore so (yup- you guessed it) the lack of a doubler shortened my front driveshaft and now my much hyped 1.5deg pinion angle has vanished. lol
The back was easy to dial in again with the 4 link.

It's still fine with the wheels spinning 70mph in 4WD but my build now looks like I did it wrong (at least it was right once).

 

[Madgyver]

when you say numbers,
what caster degree is ideal at ride height?
and what should the pinion angle be in relation to driveshaft? I've always followed 1*-2* for the rear under load guestimate.
my guess is that long arms would make a difference than short arms?

 

[nvrstuk]

6-8deg caster at ride ht.

1-2 joint to shaft/flange angle. Tom Wood's has always told me 2 deg. This is important so the needles in the caps rotate/move a little.

 

[jamesroney]

6-8deg caster at ride ht.

1-2 joint to shaft/flange angle. Tom Wood's has always told me 2 deg. This is important so the needles in the caps rotate/move a little.

With soft flexy leaf springs in the rear, you need to add enough extra angle to get you to the magic 1 degree from @nvrstuk WHEN THE BRONCO is being pushed down the highway at freeway speed. A 9 inch pinion will climb about 2 degrees with 3.50’s and 33’s at 65mph. This is why the vendors sell a 6 degree tapered wedge for the rear on a 2.5 lift. The 4-link guys are lucky, because they don’t get uncontrolled pinion climb, and they can dial in the pinion angle as it cycles.

I would think that you could get away with a little less caster on 40’s, but most 40’s have pretty aggressive tread, thus wanting more caster. All other things being equal, bigger diameter needs less caster. But when has “other things” ever been equal?

It’s funny that when you ask whether a mountain bike is more stable than a road bike, everyone comprehends caster. (“Look ma! No hands!”) But as soon as you bury it under a fender, it becomes a great mystery.