Random but violent front end vibration

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evil 340

evil 340

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72 demon 340
73 disc brake setup on front. Other than that stock suspension setup. Cars been done for quite awhile but just not a lot of miles on it since restoration. Probably 200 miles over the past 3 years.
Vibration has happened twice in that span of miles. Comes on out of nowhere and shakes the dash pretty bad. Both times i slowed down and turned and it was gone. I m pretty sure the vibration started about a half mile or so after a stop. So i was leaning towards a caliper but there was no noticeable pull left or right. I ve had it up in the air and checked for loose nuts and bolts but all were tight except for the passenger side upper balljoint i got about another half turn on it where it bolts through the upper control arm. The wheel bearing nuts i put a little more tension on. Thats all i could find. I haven’t had time to drive it since then but I don’t think any of that is gonna fix it but its so random when it does happen god knows when it would happen again. If anyone has any suggestions i m ears. I ve got a 3 hour drive to Columbus coming up pretty quick. Thanks in advance

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My vote is alignment.

(With the possibility of tirod ends being warn)

Had a 63 econoline and when you hit a bump in the roadway at just the right speed the front would shake the chrome off a trailer hitch.

Stomping the brake would stop it.

Theory is the warn tierod ends allowed for the toe to go in and out under the right conditions, stomping the brake would reset things.

If your toe is 0 or real close to it. Then the tires could do the same thing.

Coupled that with warn parts?
 
My old Chrysler would do that with a worn Pitman arm (or loose mount). I'm sure any joint could do it tho.... they do love to find the most common speed the things been driven' at, like 70 mph etc.
 
Have your caster setting checked I have seen this cause the problem your having with many types of cars and trucks after jacking up the rear with new springs or suspension changes
 
Good suggestions so far...

May be a silly question, but you do have large ball joint upper control arms on there with those 73+ disk brakes yeah? Or tapered adaptors to go small ball joint UCA to large ball joint taper in the spindles?

Beyond that, alignment - marginal toe in or negative caster would be things to look out for. Then worn out parts, especially the pitman, idler, tie rod ends, ball joints, etc. And then there's always cracked welds, it's not uncommon at all for the LCA pivot tubes to break loose in the K-frame, or the steering box mount welds to fracture entirely leaving the steering box loose.

And since we're checking things- did the steering wheel shake? Or just the dash? You may also want to check over the u-joints, driveshaft, rear end etc, because if the dash shook but not the steering wheel there's a chance it might not be front end stuff.
 
Thanks for the help guys. I guess i should have stated that all the suspension pieces are new. Tie rod s every joint. It does have the big upper ball joints. The alignment sounds very promising as I can’t find anything loose or worn. The steering wheel did vibrate. It definitely felt front end to me. I m gonna do some more digging on it this weekend. I appreciate all your suggestions thank you all
 
Almost sounds like death wobble. I would jack it up and look for back and forth play in the steering linkage.
 
evil 340 said:
Thanks for the help guys. I guess i should have stated that all the suspension pieces are new. Tie rod s every joint. It does have the big upper ball joints. The alignment sounds very promising as I can’t find anything loose or worn. The steering wheel did vibrate. It definitely felt front end to me. I m gonna do some more digging on it this weekend. I appreciate all your suggestions thank you all
Click to expand...

Don't rule out parts just because they're new.
I've had two inner tie rods with less than 500 miles on them go to junk. I'm talking 1/4" play. Non-Mopar, but the point is that lots of new stuff is junk in a box.
 
I had a similar probem on my black 73 Dart 340 Sport. It would start randomly it seemed, rattling the steering wheel back and forth, and I would have to slow way down to get it to quit. Even though it only had 30K plus miles, I replaced ball joints, tie rods, idler arm, pitman arm, control arm bushings, etc. Nothing changed. I had factory Rallye wheels on front with reproduction Goodyear Poly-Glas E70 tires. Turned out it was the tires. I had them installed and bubble balanced.

After going through all that, I had the tires checked for trueness and then speed balanced, the problem was gone.
 
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I've never experienced tire balance to be "random" as the OP described. Loose nut on the ball joint is a big flag. I wonder what else was put together inappropriately? I'm thinking the loose balljoint nut is the fix.
 
Did you install new upper control-arm cam-bolts?
If yes, my experience with those is that the new ones do NOT have enough threads on them to properly clamp the bushings. I ran into this a number of times with customer cars.
The solution is to grab a handful of thick hard washers and put one on each end of the new bolts, making sure the Eccentric washers still have enough engagement, then bolting it all back together, and resetting the alignment.
If there is Not enough Eccentric engagement, then put both washers on the nut side.

The first time I ran across this, I was backing a car off the 4-Post drive-on lift, and when I hit the brakes I heard a hard clunk, which I knew shouldn't be there. So I drove her back on, and as soon as I hit the brakes, there it was again. A little detective work found that the Upper Control arms were almost Loose. I put the wrenches on them, and they were tight as could be, which led to the discovery of the not-enough-threads.
After that I kept an eye on supplier's bolts, and every one had the same problem.
Here's the deal;
when the control arm moves, it takes the caster with it. When the caster changes, so does the camber. When the camber changes it yanks the toe-setting way out, and then the car becomes unstable, steering itself. When that happens, so does the "death-wobble" .
If I'm right, the fix is cheap and easy.
 
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If the car has sat for a while, I would check the tires for flat spotting. That happened on my Barracuda.
 
Happened to me on about my third test cruise with the Bee after restoration. Slowing from 60 into a 30 and the wheel damn near ripped my hands apart. Inner balance weight gone on the drivers front wheel. Knocked off by the uca.
 
I hope that you have some help on the ground trying to sort this out. Having someone else to jerk the steering wheel around and move the tires while you watch can reveal things that you can't find alone.
 
Bodyperson said:
I've never experienced tire balance to be "random" as the OP described. Loose nut on the ball joint is a big flag. I wonder what else was put together inappropriately? I'm thinking the loose balljoint nut is the fix.
Click to expand...
I'm know the out of balance part wasn't random but maybe each opposing side cancelled the shaking sometimes. Then maybe a bump or dip in the road woud set it off and I would have to slow down to make it stop. Anyway, after the tires were speed balanced, it never happened again.
 
I would do what I've ALWAYS DONE, and just did a couple weeks ago with my 2-4WD converted Cummins. Get a friend, or in my case I used an old video cam wired to a monitor---to closely look at EVERY thing under there that moves and or IS NOT SUPPOSED TO MOVE

Start at top and work your way down.
1..Determine FOR CERTAIN that there is NO PLAY from the steering wheel to the steering coupler. Then wiggle the wheel and..........
2...Look at the joint between the column, the coupler, and the shaft into the box. Look for ANY differential movement when wiggling the wheel.
3...Next watch the shaft into the box and the pitman shaft. Look for rotation, up and down, and side to side play. Move to the tapered joint at the pitman shaft, look there

4....Look at all 4 tie rod ends, look for play

5...Look for play up and down and bearing side play, and tapered end play in the idler arm

6...If you do not have, go to MyMopar.com and download a service manual, for free. Look in there for PROPER bearing adjustment, not just tighten them up

7...Also in the manual is procedure for checking ball joints. Lower arms MUST be supported ON the ARMS to check lower balls.

8....Obviously, also look at upper arm bushings. LCA bushing is tricky, so look that over REALLY good. Strut rods can be tough to check as well crowbar, etc may be needed.

9...STEERING BOX!!!! They can come loose at the box to K mounting bolts!!! Look CAREFULLY for ANY box movement.

10... You might spin the wheels and check runout, for bent rims or other problems. Other than the wheels, "the usual" bad tires, internal tire damage, balance, etc. Might consider trying different front wheels / tires

11... Check disc rotor runout.
 
Ok i drove it to work the other day and got it to do it. With some extra eyes and steering wiggling we caught the geerbox moving a bit. I didn’t check that the first time i jacked it up. Then found a little play in draglink to pitman arm. Steering better. I took it down death wobble road (chattery backroad) and it faintly started again. This time without the added wobble thru steering i could feel it better and notice to me feels like a brake hanging up a little almost like a warped rotor. Could feel it the brake pedal as well. Slight pull to the left. I m going back into it today. Thanks again for every single suggestion.
 
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