Caster and front driveshaft

[toddz69]

Assuming you have to cut the radius arm mounts off the axle too, in order to set the pinion angle?

Thx

No. You leave those alone unless you're doing something like Apogee where you're doing a full-width high-pinion axle and you'd like the radius arm wedges at an EB-like width.

Like Lars and others, I did the rotation (actually I paid a local machine shop to do it) of the outer C's such that I now run 2 deg. bushings and have 5-6 deg. of positive caster. I believe they were rotated about 10 deg. iirc. Just some fun math to get it right.

Todd Z.

 

[Apogee]

Assuming you have to cut the radius arm mounts off the axle too, in order to set the pinion angle?

Thx

Just to add to what Todd said, you can generally use the C-bushings to set the pinion angle where you need or want it, especially knowing that you can flip them go the opposite direction if needed. With Broncobowsher's trick for running one upside down and the other rightside up, you can achieve 0, 2, 4 and 7 degrees readily in either direction, clockwise or counterclockwise.

Since my wedges had to be cut loose anyway, I can pick the bushings I want to run and then set everything from there...although I think I will set it up with my 2 degree bushings zeroed out. I don't think I'd ever go back to rubber bushings, but you never know and luck favors the prepared.

 

[the74bronco]

Is this something someone with reasonable shade tree skills can do? I’m comfortable with the grinding down, but I’m concerned about getting both sides the same. I like the idea of pulling the axle, grinding, reinstalling, and then welding. Can I weld this with a 175 amp mig? What is the tuber thickness?

 

[bchesley]

Is this something someone with reasonable shade tree skills can do? I’m comfortable with the grinding down, but I’m concerned about getting both sides the same. I like the idea of pulling the axle, grinding, reinstalling, and then welding. Can I weld this with a 175 amp mig? What is the tuber thickness?

If you are patient setting them the same is just taking your time. An angle finder and level will be your friend. I welded mine with my Miller 185 and it has zero issues so the 175 should work too. The first one I did was on a dana 44 for a scout 10 years ago and I did it over a weekend taking my time. You can do it if you know how to grind and weld. Search and look over my post on the bronco axle.

 

[Apogee]

Tube thickness varies depending on the axle, however I used a 76-77 disc brake HP D44 from a F150 which has Ø2.75" X 1/2" tubes and are generally considered more desirable from a strength perspective than the 1978-1979 HP D44's with the cast-in wedges and thinner tubes, though I would argue that the 78-79 axles are easier to rotate the knuckles by cutting the tube where the castings are mated to the rest of the housing. There have been some decent write-ups on those by members here in the past if you do a little searching.

I think with proper weld prep, you could weld the C's back on with a 220V single phase MIG. Given the grooves I cut into my knuckle and tube removing the weld, they're pertty much already weld prepped and ready to go. I used a carbon-arc gouging rod to remove most of the weld, then finished with a grinder running a small-ish disc. I probably could have beat them off with an 8# sledge at that point, however in the interest of not hitting/breaking my ankle with a sledge hammer, I put it in the press and pushed them out. The long side was pretty easy to fit into the press, but the short side is pretty close to the pumpkin and almost didn't fit due to the depth of the bed on the press and thickness of the arbor plates, so if you use a press, keep that in mind.

Some guys don't even remove the C's from the tube, then just cut the weld and rotate them in place, but I wanted to remove any rust under the C's and clean everything up to get the best weld, so I took mine all the way off. When I reinstall them, I'll heat up the C's and drop them into place and let them shrink fit back onto the tube while I set the angles where I want them, but I'll wait until the axle is under the rig at ride height to do that.

 

[jamesroney]

Those things are on there. I did mine 16 years ago and I still remember sweating that. I also used 2 degree urethane bushings, based on the same logic. I checked them a couple of years ago, and since they were still in good shape I returned them to service.

I wound up with 6 degrees of caster and the pinion angle where it should be. What a difference. Cut and turn just puts the geometry where it would likely be if Ford were building that axle/lift combination now.

Hi Lars, I know what you mean...but I have to disagree. If Ford were building that axle today, they would put the same piss poor incorrect 4 degrees of Caster that they put in all of their trucks, to guarantee that they will wander, dart, and generally handle poorly. The closest recent example I could find was a 2015 Explorer Sport...and of course it specifies 4 degrees of caster. Anyone else building a live axle, 93 inch wheelbase, 4,000 lb 4x4 on 33's would call it a Jeep TJ and sure enough...7 degrees of Caster. Even the 2020 Mustang GT350 gets 7 degrees of caster. But you have to go to SVT to get that.

Alas, though...Ford Chassis Engineering seems to like that "I'm lying down on top of a giant beach ball" feeling. I am sure that there is a documented study in the Ford archives from 1920 that concludes that the ideal caster angle is 4. Been stuck with it ever since. After 100 years, maybe someone will fix it. (2021 Bronco???)

 

[toddz69]

Alas, though...Ford Chassis Engineering seems to like that "I'm lying down on top of a giant beach ball" feeling. I am sure that there is a documented study in the Ford archives from 1920 that concludes that the ideal caster angle is 4. Been stuck with it ever since. After 100 years, maybe someone will fix it. (2021 Bronco???)

Well, they did have 6-9 deg. of caster in the '78-'79 trucks - does that count?

Todd Z.

 

[jamesroney]

Well, they did have 6-9 deg. of caster in the '78-'79 trucks - does that count?

Todd Z.

I keep hearing that, but every book I can find says that 78-79 f150 + Bronco is 3.5 degrees caster. I’ve never measured a cast wedge housing...so I cannot confirm. But I can guarantee that the 77 F150 High Pinion has 4 degrees of caster, at 4 degree pinion inclination.

(Actually, most books say “caster not adjustable”...but when I can find a number, it says about 4.)

The only other numbers that I can find in my old Chilton's book publishes 6-8 degrees, but puts a big asterisk on the 78-79 Bronco because the 6-8 degrees is measured at 3.5 inches of ride height. At normal ride height...the number is 4. They go on to tell you that you get 2 degrees of reduced caster for every inch of ride height.

Some guy on the internet quoted an old Mitchell manual and said the spec was 6-9 degrees. I've seen that re-posted a LOT. It would be nice if someone with a cast wedge could measure the angle of the wedges, the caster and the pinion yoke. I have it for the Bronco 44, and the 76-77 F150 Welded wedge axle. I'll bet its the same for the cast wedges.

I'm not sure that it's fair to say that a truck has 7 degrees of caster, but only when you have a snow plow, and 3 fat guys sitting on the hood...but I do know how a Sunbeam Tiger wheel alignment is performed, and strangely enough...they require adding weight to achieve a specific ride height when making adjustments.

 

[lars]

Hi Lars, I know what you mean...but I have to disagree. If Ford were building that axle today, they would put the same piss poor incorrect 4 degrees of Caster that they put in all of their trucks, to guarantee that they will wander, dart, and generally handle poorly. The closest recent example I could find was a 2015 Explorer Sport...and of course it specifies 4 degrees of caster. Anyone else building a live axle, 93 inch wheelbase, 4,000 lb 4x4 on 33's would call it a Jeep TJ and sure enough...7 degrees of Caster. Even the 2020 Mustang GT350 gets 7 degrees of caster. But you have to go to SVT to get that.

Alas, though...Ford Chassis Engineering seems to like that "I'm lying down on top of a giant beach ball" feeling. I am sure that there is a documented study in the Ford archives from 1920 that concludes that the ideal caster angle is 4. Been stuck with it ever since. After 100 years, maybe someone will fix it. (2021 Bronco???)

James-

Ha. I should’ve been more clear. Yeah, what’s up with the fixation on 4°? When I did mine my boss had a 1978 big Bronco that stayed arrow straight with great return to center. At some point before I modded mine he had his alignment checked. I remember well that caster came in at 6° with no side to side differential. That became my goal, and if I recall correctly that was in spec for the 78-79 model years. So when I wrote that mine is now how Ford might’ve done it, that’s what I had in mind. 4 degrees. Ugh. Before I modded mine I had a real gem of a D44. 3-1/2” of lift, 7 degree C bushings plus “caster corrector” ball joint sleeves and I had a rockin’ 2° of caster. Basically the quality control on my housing was non-existent. I removed the caster correctors, installed 2° C bushings, then drove gingerly to an alignment shop to get a baseline. With that information I determined how much I needed to rotate my knuckles. The rest is history.

 

[lars]

I keep hearing that, but every book I can find says that 78-79 f150 + Bronco is 3.5 degrees caster. I’ve never measured a cast wedge housing...so I cannot confirm. But I can guarantee that the 77 F150 High Pinion has 4 degrees of caster, at 4 degree pinion inclination.

(Actually, most books say “caster not adjustable”...but when I can find a number, it says about 4.)

The only other numbers that I can find in my old Chilton's book publishes 6-8 degrees, but puts a big asterisk on the 78-79 Bronco because the 6-8 degrees is measured at 3.5 inches of ride height. At normal ride height...the number is 4. They go on to tell you that you get 2 degrees of reduced caster for every inch of ride height.

Some guy on the internet quoted an old Mitchell manual and said the spec was 6-9 degrees. I've seen that re-posted a LOT. It would be nice if someone with a cast wedge could measure the angle of the wedges, the caster and the pinion yoke. I have it for the Bronco 44, and the 76-77 F150 Welded wedge axle. I'll bet its the same for the cast wedges.

I'm not sure that it's fair to say that a truck has 7 degrees of caster, but only when you have a snow plow, and 3 fat guys sitting on the hood...but I do know how a Sunbeam Tiger wheel alignment is performed, and strangely enough...they require adding weight to achieve a specific ride height when making adjustments.

I'll have to ask my hangar neighbor about Tiger alignment. He's had his for about 40 years so he should know. Maybe.

 

[toddz69]

I keep hearing that, but every book I can find says that 78-79 f150 + Bronco is 3.5 degrees caster. I’ve never measured a cast wedge housing...so I cannot confirm. But I can guarantee that the 77 F150 High Pinion has 4 degrees of caster, at 4 degree pinion inclination.

(Actually, most books say “caster not adjustable”...but when I can find a number, it says about 4.)

The only other numbers that I can find in my old Chilton's book publishes 6-8 degrees, but puts a big asterisk on the 78-79 Bronco because the 6-8 degrees is measured at 3.5 inches of ride height. At normal ride height...the number is 4. They go on to tell you that you get 2 degrees of reduced caster for every inch of ride height.

Some guy on the internet quoted an old Mitchell manual and said the spec was 6-9 degrees. I've seen that re-posted a LOT. It would be nice if someone with a cast wedge could measure the angle of the wedges, the caster and the pinion yoke. I have it for the Bronco 44, and the 76-77 F150 Welded wedge axle. I'll bet its the same for the cast wedges.

I'm not sure that it's fair to say that a truck has 7 degrees of caster, but only when you have a snow plow, and 3 fat guys sitting on the hood...but I do know how a Sunbeam Tiger wheel alignment is performed, and strangely enough...they require adding weight to achieve a specific ride height when making adjustments.

Funny - I was digging through my old Chiltons too and saw those numbers. What the heck do they even mean "3.5" of ride height"? I also looked through an old SAE paper I have that I thought might have some info but it only listed it for the TTB front end, saying it was 6 deg. when fully loaded. Not real specific!

I also have an old magazine article around here somewhere that talks about the greater caster numbers for '78 but I have no idea where it is - would take a lot to find it and dig it out.

Todd Z.

 

[jamesroney]

I'll have to ask my hangar neighbor about Tiger alignment. He's had his for about 40 years so he should know. Maybe.

This is the “right” way. I have the gap gages around here somewhere.

 

[garberz]

When I set up my HP44 from a 79’ F150, with the cast wedges. It has the same relationship of the wedges to the “C’s” as my 76’ low pinion 44. Duff long arms with 7* bushings gave me 10* of caster.

Mark

 

[blubuckaroo]

I keep hearing that, but every book I can find says that 78-79 f150 + Bronco is 3.5 degrees caster. I’ve never measured a cast wedge housing...so I cannot confirm. But I can guarantee that the 77 F150 High Pinion has 4 degrees of caster, at 4 degree pinion inclination.

(Actually, most books say “caster not adjustable”...but when I can find a number, it says about 4.)

The only other numbers that I can find in my old Chilton's book publishes 6-8 degrees, but puts a big asterisk on the 78-79 Bronco because the 6-8 degrees is measured at 3.5 inches of ride height. At normal ride height...the number is 4. They go on to tell you that you get 2 degrees of reduced caster for every inch of ride height.

Some guy on the internet quoted an old Mitchell manual and said the spec was 6-9 degrees. I've seen that re-posted a LOT. It would be nice if someone with a cast wedge could measure the angle of the wedges, the caster and the pinion yoke. I have it for the Bronco 44, and the 76-77 F150 Welded wedge axle. I'll bet its the same for the cast wedges.

I'm not sure that it's fair to say that a truck has 7 degrees of caster, but only when you have a snow plow, and 3 fat guys sitting on the hood...but I do know how a Sunbeam Tiger wheel alignment is performed, and strangely enough...they require adding weight to achieve a specific ride height when making adjustments.

Please correct me if I'm wrong, but moving the wedges won't correct the pinion angle any more than changing "C" bushings.
To fix the pinion angle, you have to cut the axle tube and reweld it.

 

[lars]

Please correct me if I'm wrong, but moving the wedges won't correct the pinion angle any more than changing "C" bushings.
To fix the pinion angle, you have to cut the axle tube and reweld it.

Either way works. Think about it. If the wedges are no longer connected to the axle tubes, you can rotate the axle housing inside the wedges until the pinion angle is where you want it. Then weld them back on. Or, disconnect the tubes from the center section and rotate the center section to point the pinion where you want it. Then weld the tubes to the housing again.

Neither approach fixes the caster issue though. Separate problem.

In my case, my stock 1977 housing installed in my arguably modified radius arms wound up pointing the pinion about where I wanted it, so there was no need. So cutting the inner C's off and repositioning them, a non-trivial task, solved my wandering issues. Or at least the wandering issues that my Bronco had.

 

[Seventee]

I don't know exactly what the factory '78-79 relationship is, but I never had any drivability issues with either my '79 Bronco or F-150 at stock suspension height.

In my '70 Bronco, at 3.5" lift, my HP 44 has 4 degrees castor using 4 degree bushings. My front pinion actually points slightly high. So I believe 7 degree bushings should yield 7 degrees castor, and the pinion would be real close to in-line with the driveshaft.

 

[Rustytruck]

I am just asking because I don't know isnt the face of the yolks on both the front yolk and the face of the transfer case front yolk supposed to be parallel within 1/2 degree? Rear driveshafts use to be that way until they went to CV joints then they say the rear yolk and the rear part of the driveshaft are inline and the front CV joint accommodates the out of alignment at the transfercase rear yolk. anyone ever measure the angle of the front yolk at axle and the front yolk at the transfer case on a totally stock Bronco?

 

[jamesroney]

I am just asking because I don't know isnt the face of the yolks on both the front yolk and the face of the transfer case front yolk supposed to be parallel within 1/2 degree? Rear driveshafts use to be that way until they went to CV joints then they say the rear yolk and the rear part of the driveshaft are inline and the front CV joint accommodates the out of alignment at the transfercase rear yolk. anyone ever measure the angle of the front yolk at axle and the front yolk at the transfer case on a totally stock Bronco?

Sure, I can measure that for you. But don't forget that the 67-77 Bronco dana 20 uses a double cardan CV joint on both ends. So the front driveshaft also has a CV joint at the transfer case.

Your 1/2 degree parallel requirement is for a single cardan shaft. As soon as you put a CV joint in, then you want the non CV end to be perfectly co-axial to the differential yoke.

My stone stock U13 Roadster Dana 30 sits at 5 degree pinion inclination. My 3.5 inch lifted U15 with low pinion D44 was at 12 degree pinion inclination.

So you pick your poison. 7 degrees of caster, and the ujoint is bent, or 4 degrees of caster and the ujoint is kinda bent, or straight u-joint, and it won't steer, or cut and turn the ends.

 

[Rustytruck]

Yes the Bronco came with the double cardigan joint at the transfer case on both ends but from my viewpoint the factory didn't aim the pinion yolk up the shaft on either end. they more or less left it horizontal to the transfer case yolk. I just have never measured a stock one.

 

[DirtDonk]

In the rear it is definitely not horizontal between the yokes. Or if any were from the factory, I never saw it.
Even if they were though, then I say that after modifications to the suspension are made, the correct angle becomes even more critical.
So basically for a double-cardan joint you don't go by the output yoke of the transfer case, you go by the driveshaft itself as your reference line.

As James said it would optimally be inline with the driveshaft, but in the rear on our leaf spring vehicles and lots of "axle wrap" we've typically seen the best results from a rear pinion angle that's just below the centerline of the driveshaft. About 1 to 2 degrees down seems to work best.
Any more than that and you get vibrations under deceleration. Any less than that and you get vibrations under heavy acceleration.

If you have a 4-link suspension, or a semi-rigidly located setup like our radius arms in the front, then just aim the rear pinion right up into the shaft.
Although I've always heard that just a little offset gave the grease and needles just a little workout that kept them happy. Seems to not be needed here I suppose, since the book said zero degrees. In the case of leaf springs too, without any anti-wrap device, your rear-most joint still gets that "angularity workout" under normal use.

My stone stock U13 Roadster Dana 30 sits at 5 degree pinion inclination.

Just to be clear, that means that your front pinion is pointed 5° below the driveshaft centerline, correct?
And did you happen to check the rear while you were under there?

Thanks.

Paul