1979 4x4 F150-front end ViBrAtIoN

[eliteman76]

OK, so I brought my '79 4x4 half ton back online.
Been driving as a daily driver for around a month now.
My problem is serious, and can't seem to pin point it:
at any speed over 45-50 mph, if I hit a section a wash board road, a decent dip, bump or other problem on the road, the front end shimmys and shakes like a...well, it's bad. I'd rattle your fillings out of your teeth bad.
It makes me cringe driving the truck on the highway or interstate, and it was never like this before.
I slam the brakes, slow the truck down, and it goes away.
My dad owned the truck since 1991, it got a full frame off of sorts, rebuilt 400.
I redid the heads a year and a half ago after a blown head gasket, and put on a 4 barrel edlebrock intake and carb.
I am debting a few things:
I knew the shocks were junk, they were installed in 1993. Because this was a hunting/work truck for my dad, and not his driver, he was fine with it.
I put new shocks, last summer I did radius rod bushings.
Front end was rebuild years back, had alignment bushings installed.
This is a plow truck, aswell, but the tires do not wear odd at all.
A shop installed a new steering box 3-4 years ago.
The steering feels a little loose, but I can't seem to find a problem with it in the air.
At this point, I am debating tie rods or an issue with the castor.
The tires are still balanced, if on a smooth road, this thing rides nice, no tire shake. Tires are a 6 ply stock size 235/75/15.
Anyone out there, HELP!

[eliteman76]

Oh, sorry, forgot the picture of Old Blue!

[dbu8554]

sounds like it might be king pins if your car has them if not ball joints

[FEandGoingBroke]

I am willing to go out on a limb here and suggest a steering shock be installed onto yout center link.

Also, the Trunion bearings (AKA: knuckle bearings) could be crap as well.

Thirdly, any vehicle with more weight on the front than the factory prescribed will act funny if you hit a bump going that fast...

Lastly, what happened to you is known to me as the 5-Ton Shuffle, or the FJ death Rattles, or the Willy's Shimmy.... Happens on a lot of vehicles but mostly bias ply wheeled or big 4X4's...

Suggsestions: Tighten the nut's on the radius arms. The bushings were new recently and they may have settled and gotten a bit sloppy on you.
Install a steering stabilizer. I'll bet those two things will cure your issue.
Also, remove the shocks and get waranty replacements. so everything is perfect again.

Finally: Stop driving through bar ditches at 55 mph

_________________
I'm so depressed... My doctor refused to write me a prescription for Viagra. He said it would be like putting a new flagpole on a condemned building...

<font size=-1>[ This Message was edited by: FEandGoingBroke on 4/14/07 12:26am ]</font>

[eliteman76]

Fe, thanks for the info;
It has a single stabilizer on the front, and while it's a little old, the unit is still pressurized and functional.
I plan on replacing it anyways, but right now $$$ are tighter than I prefer, and I am getting my Torino street legal next week.
I am going to work on inspecting the entire front end again this weekend, I am almost betting maybe the driver's tie rod is partially to blame.
One other thing, I have noticed a popping up front, at first I thought maybe a brake caliper, but now I got to wondering about your thought of the radius rods.
Thank you for bringing that up.
Will try to update later this weekend.

[eliteman76]

Well, I did the track bar bushings, they were completely rotted.
No more popping, slop in the steering, and I can actually drive over 60 mph.
For the $22 it cost for the kit, I can't remember it driving this nice for so long.