What knuckles to run on a FW HP 44

[ChrisHowardMD]

I have restored an old Mustang, but this is my first Bronco and first post here! This place has been a ton of help and I have found answers to all of my questions except this one.

I bought a giant project that has been apart for 20 years so that I could do everything on it - its all about the journey on this one. I stripped it to nothing, blasted the frame and am working on completing the rolling chassis first. So far I have WH 5.5" lift springs, Tom's extended radius arms, f250 front shock mounts (not installed yet), WH adjustable track bar, Ruff Stuff 1-ton TRO Y-link, and a rear inboard shock mount. I want to run 37/12.50/17's and full widths. I bougt a cheap set of worn 37/12.50/17s mounted on some 2012 dodge wheels (5x5.5) for mockup. I found a set of 1973 F150 axles and am working on getting them setup. I wanted some disc axles, but they are impossible to find with the weld-on wedges. Far in the future I plan on doing a Siper'd 302/351, C4, and D20. Body lift TBD.

For the rear I stripped it and welded new HD perches (had to rotate them 12* to get a good pinion angle!) and will be doing the Ruff Stuff disc conversion.

For the front FW HP 44 I mocked everyhing up to get the correct pinion angle (12* up for my setup), and welded on new wedges at the stock width. I used the poly 4* bushings that came with the radius arms so I can go up to 6* or down to 0* in the future if needed. Then I cut-and-turned the C's to get 6* of caster. I cut the stock track bar mount off the original D44 and welded it onto the FW HP 44. Then I added the WH track bar riser. I probably should have just used an aftermerket track bar mount, but I had already ordered it and thought I might as well use it. So far so good, just a bunch of work, especially getting the wedges and C's off!

Now for my question - I plan on doing the standard chevy disk brake swap form one of the vendors, nothing fancy. What knuckles should I use? Bronco or F150?

I currently have the Bronco knuckles on there so I could get the higher tie rod position and the Ackerman would be right for a Bronco. However, the more I researched it I realized the equation for Ackerman angle has track width and wheelbase, so I guess neither knuckle will be perfect. Also, is there a camber difference between the two knuckles when installed on F150 C's? The C's ball joint surface was measured at 0* before and after the cut and turn. I have read that some need to use the shims with the disc knuckles on drum D44s, but I can't find any info on the drum knuckles. As I'm typing this I thought of another issue - Will the larger F150 U-joints even fit through the Bronco knucles?

Thanks in advance for the help,
Chris

 

[DirtDonk]

Some good questions.
I don’t really know if the drum brake knuckles from a 73 to 75 F150 will even work with the bronco disc brake kits. Hopefully someone here knows if they’re compatible. I would expect the main stumbling block to be the spindle and perhaps a different size fitting on the hard lines.
But the hard line issues should be easy to overcome.
But I am pretty sure that the axle shafts will have to be installed before the knuckles, because the F150, or aftermarket heavy duty U-joints are too large.
If you get a 76 to 79 F150 knuckle, or a 76/77 bronco knuckle, you can’t use the Chevy disc brake conversion, and would have to go with Ford parts.

One advantage to using F150 knuckles is that the tapered hole would fit the steering linkage you have. Whereas bronco knuckles would have to be reamed out to fit the larger Chevy “1-ton”rod ends.

Personally, have only messed with later disc brake stuff myself. So not really sure any of my answers hold weight or water.
So I will be just as interested as you to hear what others have to say.

 

[DirtDonk]

I meant to ask you about doing your set up. Did you mock it up so that the suspension was at the expected ride height after a 5 1/2 inch lift, before you cutting welded things in place for different angles?

 

[ChrisHowardMD]

I meant to ask you about doing your set up. Did you mock it up so that the suspension was at the expected ride height after a 5 1/2 inch lift, before you cutting welded things in place for different angles?

The Bronco knuckles bolted right up to the F150 C's. I put the spindles on the knuckles without brakes or axles so I could mount wheels. Everything looks like it should work. The wheels look like they maybe have some positive camber, but they are worn out pretty bad from a bad alignment from the guy I bought them from and I'm currently a little paranoid.

The disc brake kits with the chevy calipers for sale at all the Bronco vendors look just like the ones for the F150 (horsepowersales). I'm not sure if maybe the spindles +/= bearings are different because of the thicker axles? Are the outer shafts different diameter F150 vs Bronco?

I guess what I need to do Is try to assemble it with the axles and backing plates to see if it all goes together. I can measure the spindle angles for camber then. But if they both work, which one do I choose? I alreaty have the 1-ton steering and the reamer for TRO, so I can easily go either way.



DirtDonk - I tried looking for angles on this site so I wouldn't have to mock it up, but no luck. I ratchet strapped my rear down to ride height - 11" (6" stock + 5.5" for the lift) between the axle and frame. For the front I suspended the frame 12.5" (7" stock +5.5") over the axle using a gantry crane. I bolted in my long arms and the stripped HP 44 with the new/unwelded wedges. Then I realized I had to install my engine/tranny/d20 and drive shafts. The front driveshaft fit perfect. Then I hit the nose of the pinion with a rubber mallet until the pinion angle was 1* less than the driveshaft angle which is basically pointed right at the end of the double cardan. With the pinion angle set I double checked that my wedges were correct left to right and then tacked them in. Then I measured my caster - it was neg 8* I think. You want positive 6-7*. After that I unbolted it and put it on the bench on jackstands. I burned in the wedges then cut and turned the C's one at a time so I could compare angles - ie make right 14* more positive then left, then move left to match right. It wasn't too bad, but I definately recommend just pounding the C's off after grinding the welds, then clean up the surfaces and pound them back on in the right spot. I tried to rotate them on the shaft and I hammered for so long my forearms were worthless for 2 days! I had a tiny gouge that was preventing them from rotating more than 2-3*. This was my first cut-and-turn and I learned everything here and on youtube. It was a little scary, but no so bad assuming you have a big enough welder.

I am years away from having a finished body, cage, tire mount, bumpers, etc. so I'm not sure if my ride height values are accurate, but I had to start somewhere. I hope that by going 1* below pointing directly at the transfer case will also give me a little bit of wiggle room if I end up a little lighter/higher.

 

[DirtDonk]

The Bronco knuckles bolted right up to the F150 C's.

Yep, Ford Bronco, F150, GM K5 and K10, and even some Jeep and Dodge offerings will bolt right up and use the same ball joint numbers.

The wheels look like they maybe have some positive camber, but they are worn out pretty bad from a bad alignment from the guy I bought them from and I'm currently a little paranoid.

Well, positive camber was what they were supposed to come with from the factory back then. Between 1 and 2 degrees positive.
Too much for our tastes these days and for good tire wear, but within spec so most alignment shops call it good if it's under 2 degrees.
Made tire rotation a very important part of old maintenance schedules. Still important, but if you ignored it back then you were lucky to get 20k out of a set of front tires.

The disc brake kits with the chevy calipers for sale at all the Bronco vendors look just like the ones for the F150 (horsepowersales). I'm not sure if maybe the spindles +/= bearings are different because of the thicker axles? Are the outer shafts different diameter F150 vs Bronco?

No. Same outer shafts and one will fit the other. They are larger in the u-joint yoke department, but the axle diameter of the outer stub shaft is roughly the same. Might be a bit different in the middle (never measured) but not the outer splined area. I'm sure someone will know all the details.
I used original Bronco outers with my F150 knuckles and brakes. The locking hub mechanisms are the same for all those previously mentioned trucks, so the diameter and spline count are identical at least at the outer end.

I guess what I need to do Is try to assemble it with the axles and backing plates to see if it all goes together. I can measure the spindle angles for camber then. But if they both work, which one do I choose? I alreaty have the 1-ton steering and the reamer for TRO, so I can easily go either way.

Are the F150 knuckles drum brake? I wonder if they're the same as the Bronco knuckles?
For the GM disc brakes, you need to use the spindles that come with the kit. You can compare spindles and knuckles, and if they're the same in the important parts, use whichever ones you want.
An F150 knuckle might have more beef in the steering arm for reaming? Look at the height of the steering arms (F150 should be lower and the Bronco higher) and see which one works best with your steering linkage and trackbar angles.
More mockups in your future it sounds like!

DirtDonk - I tried looking for angles on this site so I wouldn't have to mock it up, but no luck.

Too many differences between Broncos. And each setup might be different too. Yeah, after all these years you'd think that we would have compiled a true "if you have these parts, you need this size/shape/angle/part number" lists. But we've all been too busy changing, re-changing and modifying the changes to settle down on one thing.
Heck, we're lucky that Chuck posted up the "expected average approximate ride height values from a consistent point" all those years ago, or we wouldn't even have the 7" front and 6" rear that you got to utilize on this project!

I am years away from having a finished body, cage, tire mount, bumpers, etc. so I'm not sure if my ride height values are accurate, but I had to start somewhere. I hope that by going 1* below pointing directly at the transfer case will also give me a little bit of wiggle room if I end up a little lighter/higher.

Sounds like you set it up just right. Pretty much the only thing you could have done until it's all put together. But it's nice to be able to get all of this work out of the way long before the final assembly for sure.
Since the measurements of final height can only be approximated, going by the most commonly accepted approximation is a best practice. Even if your ride height ends up being half an inch one way or the other won't really make a huge difference. Sounds like you've got plenty of wiggle room.

Paul