I have done many things on this old F100 that would be considered difficult jobs, but nothing compares to the simple afternoon job that is replacing the radius arm and axle pivot bushings. Everything that could go wrong went wrong.
The General Steps
If you attempt this job, be very liberal with rust penetrators like PB Blaster, WD-40, or Kroil. I also recommend you do this one side at a time and have an impact driver with the appropriate sockets. These steps apply to 2WD Fords that use the Twin I Beam suspension system; it was a sort of primitive independent suspension they used until 1996.
- Jack the truck on the frame far enough behind the radius arms that you can access the castle nuts safely.
- Remove the front wheels.
- Remove the front disc brake calipers so you don’t risk damaging the brake hose. Compress the pad with a C-clamp, remove the 9/16ths bolt, and use a hammer and chisel to remove the spring-loaded key between the rotor and caliper. Get the assembly out of the way.
- Now to remove the front coil springs: using a bunch of extensions and probably a breaker bar, remove the 1" 1/8th nut down the middle of the coil springs. Remove the oddly shaped washer as well and don’t lose it. Next, remove the two 9/16ths bolts from the top that hold the coil to the upper frame. With a little man-handling, it should pull out; set it aside.
- Now to actually perform the bushing work: remove the 1" 1/8th nut and bolt that connects the “I beam” to the frame of the truck. These are directly underneath the motor. If it is jammed in there, pry on it with a crowbar. Now you should see the axle pivot bushing. You will need to hammer and chisel and sawzall the old one out most likely.
- Rent the most aggravating tool on earth, the ball joint press, in order to press the new bushing in. My new bushings were extremely stubborn, so I lightly beveled them to fit the void in the “I beam.” Use the impact driver on the ball joint press or you’ll be exhausted. This is much easier if you just pull the whole axle.
- Now that the axle pivot bushing is replaced, let’s do the radius arm: remove the cotter pin from the rear of the radius arm, and remove the 1" 1/8th castle nut. You may need to pry the rear bushing off if the radius arm won’t slide out nicely. If it is particularly stubborn like mine, you’ll need to use a come-along to pull the radius arm out of its frame shackle. Once the arm is out, how to replace the bushing becomes obvious.
- To finish, do the steps in reverse. Replace all removed cotter pins.
Doesn’t sound too bad right? Time-consuming, but not agonizing right? WRONG!
Everything Goes Wrong
I did the driver’s side first which wasn’t horrible, but I did somehow ruin the threads on my radius arm. Considering the importance of this part, and the price of a new one, I had to fix them. The bolt size is 3/4" 10 thread. Luckily, my father borrowed a specialized tool called a thread chaser from his workplace which made short work of the fix. I placed it over good threads, clamped it down, and ran it counter-clockwise in order to fix the bad threads. It took me about 20 reps.
The passenger side is where things went horribly wrong. I disassembled it as written above, but when the time came to line the radius arm back up to its shackle with the axle pivot in place, it refused to move. I even used the come-along to force it inwards to line it up with the shackle; instead of that it nearly pulled the truck off of the jackstands! I couldn’t get the come-along to release, so for safety’s sake, I cut the come-along loose so the truck would stay on the jackstands.
It didn’t take me long to realize that the radius and “I beam” must be able to pivot off of each other, but were not, making it impossible to line both up at the same time. So, I disconnected the drag link from the steering knuckle using a pickle fork, and removed the bolt from the axle pivot again, and pulled the whole passenger side axle into the shop.
At the suggestion of a friend, we heated the “I beam” with a torch, and attempted to remove the bolt that connects the “I beam” to the radius arm with the impact driver. No such luck, it was seized that badly. So, in desperation, I flipped the son-of-a-gun over while still hot, and wailed on it with a hammer like a madman until it finally broke free. I thought for sure I was going to have to take it to the machine shop to be pressed out. The next day, my father cleaned and thread-chased the old bolt so I could reuse it because it was damaged from the hammer wailing (we did this because the bolt is an unusual length not readily available). Once the refurbished bolt was installed, wouldn’t you know, the radius and “I beam” do pivot, they were just severely frozen together. Now that the two can pivot, I easily put the radius arm into its shackle and had enough play in the “I beam” to line it up with its bolt hole on the frame then tighten the pivot point down.
One last wrinkle: I couldn’t get the drag link reconnected like this so I disconnected it entirely from the pitman arm below the steering box (again, pickle fork) to get some play in it and connected it to the passenger’s steering knuckle first. Of course, it then would not line up with the pitman arm so I just turned the steering wheel enough to line it up. This probably slightly fricked up my alignment, but I just wanted it to be drivable before getting it dialed in. Once this wrinkle was dealt with, I put it all back together in reverse in about an hour and a half.
I seem to have written this in such a way that it seems as if this were just minor hiccups, but I assure you, this job has left both my IQ and vocabulary in the bottom percentile. If I knew I were getting into this much trouble, I would have paid for a shop to do it, but my understanding was that this wasn’t a big job. It took me nearly two weeks!
Learn from My Mistakes
Instead of just the general steps above, let me give further advice on how to make this a little easier. All of what I have written is applicable to Fords using the Twin I Beam suspension system.
Firstly, just pull the front axle entirely. Pull the axle pivot, the drag link/tie rod, and radius arm out entirely. Do this in order to make sure the “I beam” and radius arm are properly pivoting, and so you can use the ball joint press on the axle pivot bushing without cursing gravity sideways. This will make it much easier to reinstall.
Secondly, if possible, avoid removing the metal sleeve that surrounds the axle pivot bushing. There are axle pivot bushings from some manufacturers that actually reuse the sleeve which totally obviates the use of the ball joint press. Spend the extra cash on them; it is worth avoiding the trouble I went through.
Well, the truck could definitely use an alignment. I can feel it pulling to the right when driving which is a job for an actual mechanic with the right tools and know-how. However, I am not in a hurry to get it aligned because I probably should replace the tie rod ends, they’re looking a bit rough. This will definitely screw with the alignment, but I see no need to get my ageing parts aligned instead of getting new parts aligned.
At some point, I need to consider a new gas tank because I continually find rust in my fuel filter. Further, there’s some kind of breather hose that snapped off long ago that makes the tank leak if you try to fill it up. I never fill above 3/4 tank as a result. I have been dreading this for many months, but after the trauma described above, it can’t be that bad.
A small but annoying issue lies in the carburetor; even once up to operating temperature with the choke off, the fast idle cam doesn’t fully disengage. It just barely catches the fast idle screw causing the truck to idle at 1100 RPM when it really doesn’t need to. Once warmed up, it will happilly chug at 750 RPM, but that cam keeps snagging. Sometimes I can get it off by punching the accelerator real quick, but that’s hardly a solution. Also, it can be embarassing to have the truck “diesel” in public.