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Old 09-28-2012, 10:29 AM   #1
Franchise_24
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Default The Death Wobble

Refer to this long drawn out thread if you wish on what has been said thus far:
https://fordbarn.com/forum/showthread.php?t=79078

When I hit a bump just right (normally a man hole cover) the cars front tires shake back and forth violently. At first I had to come to a complete stop for it to stop, after things I've done I can somewhat steer out of it. Here is what has been done (so much it is not in any particular order)'

1) Replaced steering arms (both, balls were egg shaped)
2) Replaced bad tie rod end (other was fine)
3) Replaced guts on both ends of the drag link
4) Replaced guts on both ends of the tie rod
5) Used rubber ball and changed plate on the wish bone
6) All new wheel bearings and races for the front
7) King pins have been pulled - they have fairly new bushings that were reamed.
8) Tightened all perches and any castle nut under there.
9) Set the toe-in
10) Tried good tires from my Coupe on the Leatherback to rule out bad tires

Worried that it might be tracing back to the steering box. Tightened the pitman arm as well so there is no play there.

You can move the tires left and right slightly with the car jacked up and the steering wheel doesn't move

Just wanted to present the list of everything that has been done and see if anyone can offer any more suggestions.

Thank you,
Neal
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Last edited by Franchise_24; 09-28-2012 at 04:33 PM. Reason: Adding things I forgot...
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Old 09-28-2012, 10:41 AM   #2
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Default Re: The Death Wobble

I know this is a stupid question based on all the work you have done, but shortly after I completed my restoration I had the same problem and the only thing with mine was I didn't have the drag link tightened enough I just screwed it in several turns and the problem went away. If everything else is tight or new it is the only thing left. How is the toe in?
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Old 09-28-2012, 10:46 AM   #3
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Default Re: The Death Wobble

Quote:
Originally Posted by todd3131 View Post
I know this is a stupid question based on all the work you have done, but shortly after I completed my restoration I had the same problem and the only thing with mine was I didn't have the drag link tightened enough I just screwed it in several turns and the problem went away. If everything else is tight or new it is the only thing left. How is the toe in?
Todd
I forgot to add that the toe-in was set in. My concern is when you move the tires left and right there is that little bit of play with the pitman arm moving and the steering wheel isn't moving. Anyone think it might be something with the steering box?

And also, how much did you screw it in? Past the point that end end is flush with the drag link end?
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Old 09-28-2012, 11:04 AM   #4
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Default Re: The Death Wobble

If the pitman arm moves that is a good possibility mine is loose though and I don't have the problem but the winter project is to take out the steering gear and figure out why I can adjust it up with out having drag. My screws go past the end but I would refer to the service bulletins for proper amount, but they should be tight, to the point the spring has some tension on it.
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Old 09-28-2012, 11:13 AM   #5
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Default Re: The Death Wobble

Is the spring tired? The shackles shouldn't be horizontal but more vertical.
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Old 09-28-2012, 11:17 AM   #6
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Default Re: The Death Wobble

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Quote:
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Is the spring tired? The shackles shouldn't be horizontal but more vertical.
The spring is in good shape.
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Old 09-28-2012, 11:33 AM   #7
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Default Re: The Death Wobble

I had the same problem when I first got my coupe. Finally, the last think I did was to remove the rubber ball from the wishbone under the transmission. I went back to original set up. You will have to purchase the retainer kit because the original steel ball is smaller than the rubber ball. This fixed the problem and have not had a problem for 5 years now. The oversized rubber affects the caster in a negative way.
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Old 09-28-2012, 12:21 PM   #8
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Default Re: The Death Wobble

I think this was asked before, but, I don't remember the answer..I think you mentioned the steering box being OK.. How much steering wheel free-play is there ?? If there is more than about 1.5" then an adjustment may help if it is a 2 tooth box and there are 4 adjustments which should be done in proper order..
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Old 09-28-2012, 12:44 PM   #9
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Default Re: The Death Wobble

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Originally Posted by Patrick L. View Post
I think this was asked before, but, I don't remember the answer..I think you mentioned the steering box being OK.. How much steering wheel free-play is there ?? If there is more than about 1.5" then an adjustment may help if it is a 2 tooth box and there are 4 adjustments which should be done in proper order..
It's a 7 tooth box, and there is some play there. I think that is there are shims in the bottom by the light switch control that can be modified to tighten things up? The 1 adjustment on the side is as tight as it will go.
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Old 09-28-2012, 01:24 PM   #10
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Default Re: The Death Wobble

Neal, I would suspect both the 7-tooth box and the rubber ball. I had both of these situations on my '29 Tudor; getting rid of the rubber ball helped, but did not solve, the problem. My local Model A expert said the steering box needed to be rebuilt and adjusted and I needed to replace that wishbone with one that had a good ball. In the meantime, before I get to all that, I have installed one of the hydraulic anti-shimmy devices on the front axle, and that seems so have relieved the problem until I can get to the major stuff.
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Old 09-28-2012, 01:32 PM   #11
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Default Re: The Death Wobble

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Neal, I would suspect both the 7-tooth box and the rubber ball. I had both of these situations on my '29 Tudor; getting rid of the rubber ball helped, but did not solve, the problem. My local Model A expert said the steering box needed to be rebuilt and adjusted and I needed to replace that wishbone with one that had a good ball. In the meantime, before I get to all that, I have installed one of the hydraulic anti-shimmy devices on the front axle, and that seems so have relieved the problem until I can get to the major stuff.
Ray,

As far as the ball goes, does it just get out of shape like the steering arms do? I heard something about taking the rubber ball part off and adding a washer or something under the metal ball, anyone hear of that before?
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Old 09-28-2012, 01:37 PM   #12
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Default Re: The Death Wobble

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Originally Posted by Franchise_24 View Post
Ray,

As far as the ball goes, does it just get out of shape like the steering arms do? I heard something about taking the rubber ball part off and adding a washer or something under the metal ball, anyone hear of that before?
Yes, it just wears out of round. I haven't tried the washers. I found a good original wishbone with a round ball for $25 at a swap, and I will eventually install that in my Tudor. I don't think they're hard to find, but I've been told even an odd one can be built up and ground back to proper size and shape.
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Old 09-28-2012, 01:44 PM   #13
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Default Re: The Death Wobble

Don't take me wrong (and I know you have already heavily reflected on this), but with less time and effort than you've already expended, you could have removed the front axle assembly including brakes, spring and wishbone and done a precision rebuild of every little component. With the excellent and extensive advice you've gotten on this thread, you could now do a superb and comprehensive job. Your A deserves this, and so does your driving experience. IMO, the A was a finely built machine and when carefully and properly restored to specs there is just nothing like the driving pleasure. IMO having an A "adequate" is not the same as "excellent". Two different worlds, and you should be enjoying the "excellent".
Too much caster has been mentioned as a contributing factor and can be measured on the car with the plumbob method or an angle finder. Do this with the size tires, tire pressures and spring heights you're going to run. If the front spring is de-arched too much that will increase caster. Frame sag, normally concentrated near the rear motor mount and front body mount area, will also increase caster a slight amount. Look at your gap between the front body mounts and frame and your hood fit for indications of frame sag, sideways bending or diamonding. It is easy to measure the axle on the bench for bends and twists and should be done while it is out of the car. There was a recent thread about axles. Also, look for a crack or break on the radius rods where they attach to the axle. While you have the spring out, clean the heck out of the front crossmember top and bottom to inspect for cracks there. There is an easy way to make a close guess on frame twist and spring lopsidedness with a floor jack. Thanks for getting this interesting thread started.
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Old 09-28-2012, 01:49 PM   #14
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Default Re: The Death Wobble

I have had the " death wobble " on cars over the years and IF the balls are ROUND I bottom out the spring and then back the screw out 3 turns . No more death wobble . If the balls aren't round you need to set this at the worn point otherwise it will bind when you turn it due to no clearance . This is on 33-34 cars but as far as the tie rod & drag link go they are Model A's .
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Old 09-28-2012, 01:50 PM   #15
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Default Re: The Death Wobble

I thought we talked about the wishbone before,, maybe not though.. I thought we did because it can certainly be part of a shimmy.. There are two types.. The original is all metal and the ball is 1.5" dia. and when the ball wears the old fix was a fender washer 'warped' into a cup.. It works.. But, now the vendors sell such a washer.. I think most install the washer on the bottom,, but,, I install it on the top because I'd rather increase the caster a bit [ it probably doesn't make any difference though].. The second type is a later style that uses the rubber ball.. The housings for the 2 are different and the rubber ball is only supposed to fit the later type [from what I know, I've never used one],, but,, anything can be forced to fit I suppose..
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Old 09-28-2012, 03:39 PM   #16
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Default Re: The Death Wobble

To conqueror our wobble we did everyone of your steps except we replaced the rubber ball with a washer and we also had the spindles/king pins machined, installed new thrust bearings, replaced the stock pitman with the new shorter arm and replaced the front spring. I wish I could tell you which step stopped the wobble but I can't. It was a process of addressing every problem we saw as the work progressed before the car ever went back on the road. That old front end wasn't just dangerous, it was a death trap, on many levels. Keep us posted on your progress.
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Old 09-28-2012, 04:00 PM   #17
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Default Re: The Death Wobble

I had the woble in my A ,it got worse and finally got so bad I was scared to use the brakes.
Tried all the above,none got rid off it completely,
NEW tyres and tubes DID.
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Old 09-28-2012, 08:38 PM   #18
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Default Re: The Death Wobble

Improper tire pressure can cause the death wobble, at least it did on my car.
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Old 09-28-2012, 09:08 PM   #19
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Default Re: The Death Wobble

Sounds very much like "bump steer" I had on my 1941 Ford. The entire front end, drop axle, spindles, etc were brand new. Everytime I would go over a bump, railroad tracks, man hole cover, etc, it would cause the front end to shimmy.

After my friend that owns a front end alignment shop checked it, told me I needed to put a panhard bar on the front. I ordered a panhard bar from Speedway Motors, installed it and the "bump steer" went away.

I've never seen a panhard bar on or heard of anyone putting one on a Model A, has anyone installed one on a Model A?
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Old 09-28-2012, 11:16 PM   #20
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Default Re: The Death Wobble

What do people think of the steering stabilizers?
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