I have a '78 F150 Supercab 4x4 with a 351M. In the last 2000 miles, I've changed all the ball joints and front U joints. I've also replaced the steering gear (new/refab). I had an alignment done after all of this. This weekend, I put a new steering shaft in. When I installed the new shaft, I put alignment marks on the splines of the steering column and steering gear. When I started driving to work this morning the steering wheel was centered. By time I got to work (24 miles) it was about 30° of to the right. I checked the marks I put on the spines, they were good. The pitman arm like good too. I put an alignment mark on that for the ride home. The steering wheel became more off centered but all of my alignment marks were still good. Have any of you seen ot heard of the steering gear input skipping?

 

Something is wrong then, I wouldn't drive it until you figure it out.

it's not in the gear box that's almost certain.

 

Yeah, seems suspiciously like your steering arm, or perhaps the drag link are the possible culprits because that's the last area you messed with.
Why change the arm by the way? Is the suspension lifted so you put a raised arm on? Or was there wear and tear on the old one?

Maybe have someone turn the steering wheel back and forth about a half-turn in each direction while you watch all the steering and suspension components under the front end. Do this while the full weight is on the ground and if anything is loose it will show up clearly.

Paul

 

X100 do not drive it until you figure out what is wrong, loose, broke or causing it. So was the (steering gear refab/rebuild) from a big box auto parts store? What condition is the "rag" flex joint coupler (3A525) where the steering shaft connects to the steering box in the engine compartment? I would start the truck and go full steering lock left (to the stops) and put a little more pressure on the steering wheel and see if it skips. Then go full right and ck for the same thing.

Then insp steering wheel to steering shaft splines, steering shaft itself, splines of shaft in engine compartment where the rag joint mount plate and all connections going to steering box.

Also if you do not a rag joint connection, you can have a bell (3B676) shaped like setup, where the end of the steering shaft connects to the steering box input shaft. The inside of that can get worn. You have an unsafe condition for sure.






The 2 square blocks slip on to the pins on the shaft. And they slip into the square grooves in the bell. That is a sliding joint. Get it figured out and I would not drive it until you do.

 

Sounds just like what mine was doing before the pitman shaft sheered off in between the pitman arm and box. There isn't much room between the two so I never noticed what was coming. I was lucky, it broke off in a parking lot.

 

I miss spoke last night, I was tired after work. It was the steering shaft that I change this weekend. I changed it due to a ton of play in it. I checked the tie rod, drag link, center link (all of those are new with less than 6000 miles on them) and the pitman arm. I didn't see any sign of damage.
This morning, I started the truck and turned the wheel all the way left and right, starting from the wheels being centered. After completing a full left swing (to the stops)and coming back towards center the wheels would visibly shutter. The same thing happened in the same manner when swinging from the right. It only happens when when I go all the way to the stops. If I swing right or left but stop about an ½-¾ inch shy of the stops, it doesn't happen at all.

 

77&79F250,
​​​​​​ I bought the steering gear from National Parts Depot. The old one was clicking bad from inside the steering gear and I wanted to change it because I use the truck as a daily driver. The one I received from NPD said it was a refab, but I work with refab aircraft parts all the time and this thing looks brand new. My steering shaft (replaced this weekend), goes straight from the column to the steering gear. I did pull both ends of the shaft of last night and the splines are in pristine shape, no signs of being rolled over. I did like you recommend and turned the wheels to the stops and give it a little extra pressure. There was no skipping. The wheels did visibly stutter after a few degrees of turning back towards center. I marked all my splined connection with torque stripe (witness marks) and non of the splined connections have jumped. I'm wondering if I should put a bit of a partial or full turn in the adjustment screw in the top of the steering gear and see if that stops the shutter/skipping and if the wheel alignment stays put.

 

The problem may not be in the steering at all. Check your rear axle perches where they connect to the springs. The spring center bolt or u-bolts may have broken, and the axle shifted back on one side. That would put your steering off.

EDIT: Just noticed it's a 4x4. Check the front springs the same as the rear. Front axle could have shifted on one side also.

 

Personal experience - replaced nearly all front end stuff on my 96 Chevy 4wd. Took it to get aligned (I got close but was having a similar issue). They must have put it on the alignment rack 4 times after driving it. Tech finally noticed I had left the cotter pins out of the castle nuts on either center link or idler and pittman (been a few yrs don't remember) and they were slowly backing off as it was driven.

And yeah, tech shoulda seen it sooner, but I shouldn't have forgotten them either.

 

I would not do that unless someone says that the skipping could be caused by a preload adjustment issue and/or until you have a full shop manual that tells you how to adjust it. Sure, on an old box you can tighten it up just slightly (sometimes) and have good luck with it (sometimes) but it's a very specific adjustment for when the box is being set up, so is not to be taken lightly.
You may already have known all that, but I had to say something because the world of old cars and trucks is littered with buggered gearboxes due to turning that screw too far and not verifying the work. After awhile, it'll wear out your nice expensive sector and input shafts.
that said, I've done it. but I also felt the binding and backed it back off. It was not sufficient to tighten up the worn out box though, so eventually I had to replace it anyway.

Nothing says you can't experiment. Just know what's going on inside there first.

Paul

 

This might help you determine if it is the box or something else.

Before you start driving and the wheels are straight and the steering wheel is centered, you should be able to turn the wheel a certain number of times to the left then back to center, and also to the right and back to center. Should be the same number of turns for each side. That way, you know the steering box is in the center position. Somewhere around 2 turns for each side.

Now, after you drive it and your steering wheel is 30 degrees off center but the wheels are straight, do the same test to determine if the steering box is still in the center position. If the steering wheel still turns the same amount in both directions, your steering box is not the issue most likely.

If it isn't the box, I can only think it is something slipping but the shafts/splines would show that and it sounds like you checked. Another person mentioned the axles moving, that is where I would focus if none of the splines are slipping. Good luck.

 

I have seen a loose/worn track arm bushing at the frame cause something similar to this. Steering wheel shifting from center. Have you checked this?

 

Good idea. Loose track bars can really cause some interesting things. I've seen Jeeps you could push on the fender and move the body back and forth two or three inches.

 

Normally a 4wd F150 has radius arm front suspension, but it being a SC 4wd F150 it should have a leaf spring front suspension. Correct? Since you got the refab box from a generally better parts source, the chances of it being a better quality rebuild are at least... better. BUT NOT always. Is the shimmy just seen in the wheels of felt in the steering wheel?

I am still thinking about what or where the original problem can come from.....Does the new steering shaft you put in have a u joint or a flex joint connection? Is it a Borgeson shaft with the steering damper built in?

 

Thank you for the help. Sorry for the delay in responding, I was in the process of moving into a new house. I ended up centering the steering wheel and verifying the number of turns to get to the stops. I drove some back roads (about 30 miles total) and the count from center to the stops was off a about a half turn. I was able to email NPD and get them to warranty the steering gear. The new gear is in and the steering is no longer shifting. That was some weird stuff.