The Death Wobble

I was starting to consider a steering stabilizer on my A...then I went over the front end one last time trying to find something wrong. Then I found my pitman arm was just slightly loose. A quick tightening of the nut and everything was back to normal. The amount of movement was quite small, but apparently was just enough to cause a problem. From that, I would have to agree that a stabilizer would be just a band aid and not the real fix to the issue.
 
I agree with Jim,after dealing with this issue many times on modern trucks it is almost always too much caster.The problem is magnified by loose/worn parts and replacing those parts although needed only puts a patch on it for a while.
 
Snyder's sell a panhard bar for the front and rear. I had the "death wobble" on my 30 coupe and decided to try a panhard bar on the front. I had replaced virtually everything else that affected the steering of the car. The front panhard bar has a plate that is fixed under the driver's side shock absorber and the other end is on the passenger side shackle. The two are joined together with an adjustable length bar. The plate under the shock is very flimsy, but Snyders assured me that it would work.

I installed the bar and the "death wobble" was the same as before.

I eventually cured the problem by addressing the ball on the wishbone. The ball is supposed to be 1.5". Mine varied between 1.31 and 1.35". I finally shimmed the ball with the washers that are sold by the vendors and ensured that there was no back to front movement of the ball when the wheels were turned. That finally solved the problem, but I still need to bring the ball back to 1.5" and discontinue the use of the shims.

Dick
 
one more area to check in addition to the radius ball size are the steering box nuts. If the box is loose, the death wobble is sure to happen. Excess play in the worm/sector will do it too. Are the spring perch nuts tight?
 
King pins are the major cause of the death wobble. Do not forget about the string line test. The line from the king pins to the center of the rear end should go over the top of the tie rod end. This is the Ackerman theory. This will show you if you have something bent.

Charlie Yapp had an article about this in his Secretes of Speed Magazine. He has a web site and he might send you an e-mail copy.

Hot rod builders like to place the tie rod in front of the axle and then they like to complain about how poorly the car steers. They install steering stabilizers but the car still does not steer correctly. They never heard of the Ackerman theory and the car will bump steer and have the death wobble if this theory is not followed.

You try to explain the problem to hot rodders and they give you a dumb look and usually say that they have seen hunderds of cars with the same set up they have and I reply they probably all steer just as bad as yours.

My model had the same embarrassing problem and I called Burt's in Denver.
Steve or Phil said to screw the tie rod ends and drag link ends is as tite as they will go. I was screwing them in all the way and then backing them out a half a turn or so for the cotter key. I did like Burt recommended and the problem went away.


Be sure to tells all what fixed the problem.
 
Poor Ackerman will never be the cause of bump steer, but it will cause the "inside" tire on a tight turn to scuff around the corner. Ackerman needs to be correct because the tires turn on different radii going around a corner. Death wobble and bump steer are two different things, loose components and/or poor alignment can cause wobble, while bump steer is caused by the drag link and wishbone (or radius rods as on hot rod) swinging in different arcs. If a longer pitman arm is installed and the wishbone mount remains the same you may encounter bump steer.
 
I had the "death wobble" too. I put on the steering stabilizer from Snyders and have never had another wobble since. I'm sold on it.
 
After 29 posts and a heck of a lot of work the poor guys car still isn't fixed.. That shouldn't be.. This isn't [or shouldn't be] hard to find or fix.. If everything is tight and adjusted correctly the car should drive as intended.. Something is being missed.. It appears a fresh set of eyes and hands need to wander around that monster.. I'm beginning to wonder if there really is a problem.. A 'man-hole' was mentioned; after running over it does the vehicle really go into ' death-wobble/shimmy' mode or does the bump just cause a hard jar of the steering wheel ?? If someone thinks that caster is a concern then just put the ' spacer washer' under the ball which helps reduce caster a bit..
 
I put on a shortened Pitman arm and a steering stabilizer. It now works wonderful and not a shake, wobble or shimmy since installed 2 years ago 1
Hope it helps !
Wayne
 
Providing the ball is symetrical, or the wear can be taken up with a dished washer that is available from the various parts suppliers......you may find that the through bolt holes in the bottom of the clutch housing have become excessively worn. You may be able to machine a couple of steel bushings that will slide into the holes in the clutch housing, but will also slide over the cap bolts that hold the ball cover.

Have someone move the steering wheel back and forth, while you observe what is going on underneath.
 
I had the same problem on my coupe, the spring perch bolts were worn very little but I guess that is all it takes
 
Had the same problem. For other reasons I put on new tires, the old ones were 16 years old & somewhat stiff. Haven't had one shimmy since, that was 2200 miles ago.
 
I have been trying to help the original poster with his wobble problem. We have done all the things that he has mentioned. When the car goes into its death wobble, all the steering linkage moves an equal amount, both wheels wobble back and forth and the linkage moves clear back through the pitman arm. When it wobbles, the steering wheel does not seem to shake as violently as the rest of the steering linkage. He now has a gentleman helping him that knows Model As alot better than I do. They seem to be making some headway at correcting the problem a little at a time. There isn't much left but the steering gear box.
 
Fordors said:
Poor Ackerman will never be the cause of bump steer, but it will cause the "inside" tire on a tight turn to scuff around the corner. Ackerman needs to be correct because the tires turn on different radii going around a corner. Death wobble and bump steer are two different things, loose components and/or poor alignment can cause wobble, while bump steer is caused by the drag link and wishbone (or radius rods as on hot rod) swinging in different arcs. If a longer pitman arm is installed and the wishbone mount remains the same you may encounter bump steer.
Click to expand...


I disagree- .
 
Patrick L. said:
After 29 posts and a heck of a lot of work the poor guys car still isn't fixed.. That shouldn't be.. This isn't [or shouldn't be] hard to find or fix.. If everything is tight and adjusted correctly the car should drive as intended.. Something is being missed.. It appears a fresh set of eyes and hands need to wander around that monster.. I'm beginning to wonder if there really is a problem.. A 'man-hole' was mentioned; after running over it does the vehicle really go into ' death-wobble/shimmy' mode or does the bump just cause a hard jar of the steering wheel ?? If someone thinks that caster is a concern then just put the ' spacer washer' under the ball which helps reduce caster a bit..
Click to expand...

Why would you ask if there really is a problem? Of course there is or I wouldn't be posting here. Anyways Thursday we pulled both king pins and put everything back together. I ended up tightening the drag link a couple more turns. The car went out today and drove over every man hole cover or bump I could find and I'm proud to say it did not wobble or shake or anything. I also tightened up the bolt that holds the pit man arm on as well and that took some play away. So who knows if it's truly fixed but I did a lot of driving and it was so smooth. So maybe it was a combination of everything, but hopefully I am in good shape now. Thanks to everyone who offered suggestions, I think I did them all. Lol. Too bad it's October and the driving season is about over.
 
tdlmomowers said:
I have been trying to help the original poster with his wobble problem. We have done all the things that he has mentioned. When the car goes into its death wobble, all the steering linkage moves an equal amount, both wheels wobble back and forth and the linkage moves clear back through the pitman arm. When it wobbles, the steering wheel does not seem to shake as violently as the rest of the steering linkage. He now has a gentleman helping him that knows Model As alot better than I do. They seem to be making some headway at correcting the problem a little at a time. There isn't much left but the steering gear box.
Click to expand...

Franchise_24 said:
Why would you ask if there really is a problem? Of course there is or I wouldn't be posting here. Anyways Thursday we pulled both king pins and put everything back together. I ended up tightening the drag link a couple more turns. The car went out today and drove over every man hole cover or bump I could find and I'm proud to say it did not wobble or shake or anything. I also tightened up the bolt that holds the pit man arm on as well and that took some play away. So who knows if it's truly fixed but I did a lot of driving and it was so smooth. So maybe it was a combination of everything, but hopefully I am in good shape now. Thanks to everyone who offered suggestions, I think I did them all. Lol. Too bad it's October and the driving season is about over.
Click to expand...

i am confused wasnt shaking down the frt end , adjusting the alignment and cking for any slop at the pitman arm to box suggested in the first death wobble thread months ago??
 
Read 40 posts and nothing was mentioned about wheels. Had the same problem and sent the front wheels to wheel works in Denver. Tech said they were out of round. Wheels were fixed and no more death wobble.
 
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