Hi all, I hope I'm not repeating a topic that's already been discussed in depth, my apologies if so.
i have a 1976 F150, 4 wheel dr with a 460.
This truck is my pride and joy.
Problem is kids had it and just beat her up so she's a work in progress.
At the moment I'm dealing with a wobble at about 35 mph. The truck has had the wobble since I got her, it's just become very much more evident now.
When I got her she's running 37x12x16.5 tires with a lift.
I've now got 40's on it, also 16.5's.
I've replaced ball joints, hubs steering stabilizer shock, balanced tires, new pitman arm and new steering box.
Now I'm being told bushings so I'm getting new bushings and track bar. As I said I don't mind because I know when all is said and done, I'll know what's been done and know it's been done right.
Any and all suggestions welcome!

 

Put tires something close to what it was designed for on it and I bet your problem will be cured.

 

So interesting set up a F150 (5 lug 1/2 ton) and 16.5 rims. That size is normaly a F250 8 lug rim size. And and OLD rim size to boot. With all the new parts, I hate to say but I bet is has a cobbled up lift installed on it, and that could the issue.

37"/40" tires on a 1/2 ton, I bet a lot of lift. I know 1/2 ton, because you said it has a trac bar and that is a 1/2 ton item ony, NOT used on a F250. With all the new parts, have you ever had a proper front end alighment (professionial shop) done to it?

New bushings as in radius arm bushings at the frame connection points or the "C" bushings? C bushings are the degree bushings installed where the radius arm clamp to the axle. You put different degree bushings when you put a large lift on it. Has that been done?

Bottom line IMO death wobble fix, I would go with a pro shop front end alighment 1st. Since you have a ton of other new parts on it.

Does it have radius arm drop plates?

 

Been through something similar with our 78. Although ours wandered at any speed. Really couldn't get above 40 until we did all of the following: I see some you have already done, but I'll list them anyway

Replaced front and rear shocks, stabilizer too
Replaced track bar bushings
New tie rods, ends, drag link
new front axle u-joints
New wheel bearings (even spindle)
New rotors
New calipers
Welded crack in cross member
Welded slight crack where steering box mounts
Borgeson steering shaft
New C-bushings and radius arm bushings

Non of this helped much, what got us to where we could drive on the highway was a Blue top steering gear

Last weekend we did the ball joints (they seemed to be good when we did the other stuff, but am sure they loosened up with use)

How much lift do you have?

Matching the degree of C-bushing to lift may help.

We pretty much new our main problem was the steering gear, but tried to dodge it by replacing the other worn out stuff first.

My advice when working on the front axle is if you have to pull the shafts, do everything that requires them being pulled. When we pulled the whole axle to do the C-bushings etc... we also replaced the inner axle seals. Needless to say they still leaked, so when we did the ball joints last weekend, we sleeved the axle shafts and replaced the seals again. So far no drips. (fingers crossed)


Hope this helps.

Be prepared if you do the u-joints, ours were original and had to be cut out with a torch. A press just couldn't get em to move.

 

Get in the truck not running and move the steering wheel left and right. See if the nose moves before the tires start to turn. If yes then c bushings and control arm bushings are going to be the best bet

Let's see this monster ☕

 

I dealt with this once on a 78 F150 4x4. Turns out all it was was bad shocks on front. I would hit a bump, and the coils would just keep boinging up and down with nothing to slow them. Add on bigger heavier tires and it's only worse. And yes...boinging is a scientific term LOL

 

Could have a cracked frame. Pop the steering box off and look at the frame behind it.

 

And when you get a new trac bar, prior to installation, insp the mount holes at each connection point (frame and axle). Alot of times the frame connection point (bolt hole) will get worn out/oblonged. And even a new trac bar and rubber bushing put in there will not fix that. #3B239 is the trac bar and the upper connection point # 3A093 is what I am refering to. Yea that is a 78 Bronco diagram, but same as a 4wd F150.

 

While you should go ahead and perform all of the checks and maintenance that has been mentioned before this post, the ovaled out trac bar axle mount should definitely be considered as well. I've seen this problem on multiple vehicles using the same exact axles. Here is an article that goes into detail about how to fix it: https://www.projectbronco.com/Techni..._mount_fix.htm

 

Are you sure the axles vent is clear ? If it's plugged up that could be the reason for the pumpkin leaking into the axle tubes.

 

Yes, the vent tube and hose were replaced when we replaced our brake lines. Judging by the grooves on the axle shafts, we are pretty sure the sleeves and new seals are the fix. Why on earth Ford didn't incorporate an outer seal like on some Jeeps, stumps me. I started a thread on that issue about 2 years ago.

But it never hurts to check the vent hoses occasionally.

Now back to the death wobble.

There are several threads on here that cover a lot of what has been mentioned.
Several on Bronco sites as well.

Keep at the wobble issue and the OP will figure it out.

 

track bar tight? do we have a crossover steering or the other y setup? do we have tight radius arm bushings ON BOTH ENDS? Are the wheel bearings packed and adjusted properly? Is the alignment been checked for loose/bent spindles? that much tire might mean wrecked or tipped over and now you need to put humpty dumpty back together. They are kindof known for that due to rubber front end stuffgetting worn. Have we balanced the tires? have we swapped tire from front to rear to verify out of round tires? That is a lot of tire. Do we have new/good/unbent rims? I agree first is swap tires to anything else known good and see how it does there. maybe tires. maybe balance. maybe rims. maybe front end. people seem all too eager to rebuild a car due to cheap junky tires. put on some michelins and I bet you minimize if not eliminate problems.

 

Thank you, I've been looking for something like this to help me eliminate as I go.

 

Thank you, I thought I'd done alot till I stated reading y'all's suggestions, looks like I'm in for a penny in for a pound

 

So this truck was owned by kids before me and they pieced it together, absolute Frankenstein truck.
I'm working my way they alot of what y'all have suggested, I appreciate all the suggestions.