Shifting Front Axle

CatMan1

Senior Member
For some time now I've had the 'Death Wobble' when driving my '28 Sport Coupe. I have noticed that when parked, and someone turns the steering wheel left to right some, that the front axle moves. I would imagine that's not correct? (I know it's not) How much of that could come from a worn Radius Ball? Maybe something else is loose? Maybe this is why the car steers so hard?
 
Check all of the front suspension including:
> Loose / cracked front frame cross-member;
> Broken / worn-out front spring;
> Broken front spring attachments to the cross-member;
> Play in king pins;
> Loose wheel bearings;
> Bent front wheel rims;
> Wheels out of balance;
> Loose / out of round drag link & tie rod ball joints;
> Loose steering connection to the frame.

I doubt that the front radius rod ball joint can cause the wheels to shimmy.
 
Jack up front end and put jack stands under front frame. Axel should now be hanging free.

You now should be able to see any loose areas that need attention.

Keep us informed.

Enjoy.
 
It only wobble when I'm driving around town and hit a bump. I can drive down the highway and it never does it then, thankfully. I'll check all that while I'm working on the axle. How do I inspect the Radius Ball to see if it is worn?
 
I’ve never seen a shimmy on a Model A that wasn’t being caused by a few different things on the front end.

That being said. I have never, after rebuilding a front end, had any shimmy.

A little ware here and there, now you could have a shimmy.

Enjoy.
 
I had the same problem with the entire axle shifting when turning while stationary. The radius rod had been changed to the rubber ball type, which was badly deteriorated and half missing. You could move the back of the radius arms just by laying under the car and giving it a shake. Replaced the rubber ball and problem solved. I’m sure most people on here would tell you to replace it with the original style cup if your car has the rubber ball though.
 
Probably isn't your problem but while you are checking, make sure that the spring center bolt is not broken and that the square head is in the proper position in the front crossmember. I had one break one time and the entire spring would shift sideways taking the axle with it and affecting the overall steering geometry.
 
Start out with the wheels on the ground to add resistance and watch what moves when someone turns the wheel; watch the shackles, pitman arm fit to sector shaft, drag link & tie rod ends, wishbone ball, steering box mount bolts, spring U-bolts, and check that the axle is tight on the thrust bearing with minimum clearance under the axle.

Next put it up with the axle on jack stands and check the kingpin bushings by tipping the wheel in and out at the top, check the thrust bearing by lifting the wheels with a bar. Verify and ID the location of motion found when it was on the ground.

Next put the stands under the frame, let the axle hang, check that the perch bolt is tight in the axle and that there is no play in the wishbone eyes. See if anything else is loose on the frame and crossmembers, sometimes a trace of rust can be an indicator.

These check should provide you with all the information needed to evaluate the condition of your front end.
 
I may have found the issue. I’m a little embarrassed to say that after three years of ownership I just now caught this. I discovered that the previous owner neglected to replace the springs and spacers for the radius ball. That must be why the axle is shifting. Wonder if it’s causing the ‘Death Wobble’ and heavy steering?
 
Pay attention to the radius ball mounting bolts where they go throught the bell housing mine had alot of play would allow the whole thing to move around even with a good ball and new springs
 
Also check the toe in. If that is excessive, or non existant you will surely get the death wobble. I set mine at about 3/16" or less and it seems to track great. I also put on radial 600 X16 tires and tubes and the car doesn't want to follow small grooves in the road like it used to do.
 
Here's what I'm up against. My wife drove to Birdhaven yesterday afternoon and picked up the springs and spacers. They won't work. When I put the cap back on the spacers covered up the threads on the bolts. That's when we realized that we must have the wrong cap. It's bigger, thicker and has a adjuster nut on the bottom. I guess. She's going back up today for the proper cap. How far down can you drop the radius rod to install the top part? (I wanted to post a picture, but it won't let me.)
 
Is this what you bought at Birdhaven?
 

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With your hand you can pull the radius rod down and put a 4x4 block of wood between the rod and oil pan. The original spacers and springs will not fit with a rubber ball over the radius rod ball . There is a cross pin that holds the special bolts in place, with the radius rod down look up in the hole and or feel around see if the cross pin is holding the bolts
 
Did the cap that you have look like this? The thick cast caps are for the rubber ball type mount and won’t work with springs.
 

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Did the cap that you have look like this? The thick cast caps are for the rubber ball type mount and won’t work with springs.


No, not like that. Another member is going to help me post a picture soon. It was an aftermarket adjustable one the likes of which Birdhaven had never seen. The two pieces were so thick that by changing them out we probably changed the angle of the axle! We were so frustrated that we forgot to do the one thing we were in this to do......install one of the washer shims.... :(
 
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