Caster Correction - Cut and Turn the knuckle

I know the title sounds scary, but it will potentially fix your steering and front driveshaft woes. I unfortunately was forced in to addressing it on my rig with a busted front driveshaft. I broke on the first trail this year at the LEBC Round-up, and it ended my weekend of wheeling. I had to do something and I can’t afford a new custom front end. The only thing I knew to do was to cut and turn the knuckles. I have owned two International Scouts that I have done this too, but I had not seen or heard of this with Broncos. Here is my cut and turn project.

The front end setup prior to the turn was Duff long arms (has built in caster), Wild Horses 5.5 coils and 7 degree bushings. This netted me 7 degrees of caster per alignment shop. It drove like a dream at 70 as long as my tires were balanced. I really wanted to maintain the way it drove at speed and maintain that 7 Degrees. So out came the axle.

First is to remove knuckles from the axle via angle grinder. Grinding the weld off is a little slow because you need to be careful not to cut into the axle tube. Once the welds are ground down a big sledge hammer is your preferred tool to remove. I have about 3 total hours on removing mine and cleaning up the old welds.

Next, reinstall the axle with the correct pinion angle. Once the new pinion angle is set you reinstall the knuckles at desired degrees. The vehicle must be at ride height before you weld them permanently in place.

The bronco was a little different and it presented a little challenge. When you have a leaf spring style suspension there is only perches to rotate. Broncos have a track bar and mount that have to stay aligned too. The track bar bracket presented a challenge because I didn’t want to remove and rotate those brackets also. I had previously installed a Wild Horses track bar riser and it would be way too much to take it off.

I decided I would just order several sets of bushings and play with it too see what I could get and keep all things aligned. In all of the photos below I reinstalled the axle with a 2 degree bushing backwards to spin the pinion up a total of 9 degrees. This was a little of a compromise because of the track bar bracket limitations. My main concern was if I had enough clearance for my steering over knuckle. Next step was to mock up my steering with the knuckles only hammered in place. This allowed me to make changes if it would not clear. It barely cleared so that told me that’s as far as I can rotate the pinion. I then triple checked the steering again for clearance to make it permanent and welded them in place.

A fresh coat of paint and some new stainless brake lines to finish off the project. It drives just like it did before, but now I have a much improved pinion angle. I just need to order a new driveshaft to get back on the trails.

Also one last public service announcement on adjustable track bars. My Wild Horses TB that I have been running for 6 years seized up and it would not rotate. Use anti-seize on the threads if you ever think you might want to adjust it. Mine would not line up with the new rotated axle and housing. The bushing was now rotated 9 degrees and would not line up the holes for the bolt. I ended up ordering one from BC and I really like the Heim joint end. I put tons of anti-seize on the threads.

I have a few more photos I will add to the post. I hope that I have inspired someone to just do it. It fixed every issue with my front end and my bronco drives great.

More photos

I am surprised that you didn't have to cut the wedges off too. Good that you found bushings to bring the pinion angle up. It is a good upgrade, looks like you're all set.

Awesome write up!
I have been waiting to do the exact same project even down to your track bar selection.
What degree radius arm bushing did you go with?
According to my math the knuckle needs to be rotated 1/4" back. Do you know how far you rotated yours?

FYI... I installed an adjustable track bar (Performance Unlimited) way back in '97 or so and it lasted till about 2014 with heim joints... I needed to replace the heim ends and with a 3' cheater bar on a 24" pipe wrench I could NOT rotate the heim...wow... the FYI is this-- use anti-seize on almost any bolt you don't use locktite on!

Nice writeup! A number of us have done this over the years and I agree that it's a great mod. I don't have the Duff arms - I rotated mine about 10 deg. and run 2 deg. bushings and I have between 5-6 deg. of caster.

Todd Z.

I started and stopped with a 2 degree bushings, and I actually have my 2 degree bushings backwards. I had to negate some of the built-in caster on the long arms. I don't remember exactly how much they have but I know I am still at least of couple of degrees positive from factory.

If I ever decided to go with a 4 degree backwards I would go down to 5 degrees caster which is still acceptable. That would be the factory pinion angle for a stock height truck. It gives me some options to dial it in. If I ever decide to go fast in 4wd I might try a set to get closer to perfect alignment.

JohnJohn said:

Awesome write up!
I have been waiting to do the exact same project even down to your track bar selection.
What degree radius arm bushing did you go with?
According to my math the knuckle needs to be rotated 1/4" back. Do you know how far you rotated yours?

Click to expand...

I don't know distance I only know degrees. I rotated the axle exactly 9 degrees. I might have been able to go 10, but my steering ram and larger tie rods were to close to hitting. Do a mock up is my best advice. Cycle everything 4 or 5 times to make sure it works. Then weld them on.

I did this in 2003. Hard to believe it's been that long. I started the job by swapping the 7 degree bushings I had for 2 degree bushings. Then drove gingerly (steering was unstable, to put it politely) to an alignment shop to get an accurate "before" caster measurement. With a 3.5" lift I wound up rotating the knuckles 10° to get a net result of 5-1/2° positive caster. Picked up another ~1/2° when I installed extended (by 6") radius arms. What a difference. As in, unsafe to safe. Oh yeah, as a bonus, no more damaged pinion u-joints on the front driveshaft. It's a lot of work but the best way to get good steering geometry.

I remember reading your post about how dramatic the improvement was when you completed it waaaay back when...

I have a little update with some trail time. Last weekend I had a chance finally install the driveshaft and lock in the hubs. First, you can see in the photos that the front pinion and driveshaft are just a few degrees out of being in perfect alignment. I knew this was the case, but seeing it puts it in perspective. I can live with this not being perfect. If I needed high speed four wheel drive for an extended period I could easily get the two degrees needed to make it perfect with a bushing change.

With everything locked in I ran it through its paces and it worked flawless. Smooth was an understatement. I am extremely pleased with how it worked out. It was well worth the effort, and I am mad I didn't do it sooner. It would have saved me from buying a new driveshaft. Now I just need to get ready for OCBR.

bchesley said:

I have a little update with some trail time. Last weekend I had a chance finally install the driveshaft and lock in the hubs. First, you can see in the photos that the front pinion and driveshaft are just a few degrees out of being in perfect alignment. I knew this was the case, but seeing it puts it in perspective. I can live with this not being perfect. If I needed high speed four wheel drive for an extended period I could easily get the two degrees needed to make it perfect with a bushing change.

With everything locked in I ran it through its paces and it worked flawless. Smooth was an understatement. I am extremely pleased with how it worked out. It was well worth the effort, and I am mad I didn't do it sooner. It would have saved me from buying a new driveshaft. Now I just need to get ready for OCBR.

Click to expand...

There is apparently some benefit in not having the pinion directly in line with the driveshaft. It works the u-joint needle bearings a little bit, so the grease gets moved around. Or so the story goes...

Congrats!

I run about 1deg (close as I can measure) to get the rotation that Lars is talking about... must work...I put about 60K miles on a 20 1/2" long rear driveshaft without replacing a ujoint... lot of carnage around the driveline but not it!!