Play causing front end shake? *UPDATED 8-23-12*

[Franchise_24]

On my '28 if I hit a bump just right my whole front end starts to shake real bad. So much so that I pretty much need to come to a complete stop and start going again. My wife saw it happen the other day and the front tire she saw she said looked wobbly like it was going to fall off. I jacked the front end up and checked it all out. Kingpins appear good, everything is tight, but there is a tiny bit of play in the steering box. Could this play be causing what I am describing?

[mass A man]

No, I don't think the problem is in the steering box. I have play in my old truck's steering box and I never get "the wobbles" in my front end and I hit plenty of bumps up here in New England. Maybe a broken or worn out spring assembly in the drag link ends or tie rod ends, if you are sure the king pins ARE OK. I guess you found the front wheel bearings in proper adjustment when you were checking the king pins. Proper front end alignment needs to be verified along with a good original angle of support at the wish bone ball under bell housing.

[BRENT in 10-uh-C]

I would agree with Mass A Man that everything is not tight, ...and I too would begin at the front radius rod ball. As to answering your question about it being the steering box, a sharp turn in either direction should temporarily remove any slack in the steering gear box and should eliminate the wobble for the moment.

[Mike]

I had the same problem, it was loose spring perch nuts.

mike

[mmindling]

Had the same problem with by '28. Uncontrollable shaking when hitting a bump just right. Put new Firestone tires on and never had the problem again. The old tires were aging and the rubber was hard. Had been stumped because I couldn't find any loose mechanical parts.
Another possibility is the Pitman arm, where it bolts to the steering box shaft. This can come loose and cause wobble.

Regards,

[email protected]

[Not George]

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I had this problem on an O/T car, balanced the tires and it was fine

[ora masters]

Originally Posted by BRENT in 10-uh-C

I would agree with Mass A Man that everything is not tight, ...and I too would begin at the front radius rod ball. As to answering your question about it being the steering box, a sharp turn in either direction should temporarily remove any slack in the steering gear box and should eliminate the wobble for the moment.

thanks brent on the steering gear box now i know why my 32 pick up shimmeys

[oldmanandakid]

I found a cracked bearing race on second inspection as I missed it when first checking the bearings.

[tdlmomowers]

I am trying to help Franchise 24 diagnose his wooble. It does appear that the nuts may not be tight on the spring perches at the ends of the spring. They have castlelated nuts on the spring perches, but there are no cotter pins installed. We will tighten these up and install cotter pins and then see what it does. This car was the victim of a lot of jury rigging before Franchise 24 got it. We have corrected a bunch of problems and it would appear we still have work to do.

[Loyd Nix]

My 30 tudor would start to shimmy if I hit a bump at low speed. I tightened the drag link set screws and that was that. Easy and cheap--my favorite kind of fix.

[BRENT in 10-uh-C]

Originally Posted by tdlmomowers

I am trying to help Franchise 24 diagnose his wooble. It does appear that the nuts may not be tight on the spring perches at the ends of the spring. They have castlelated nuts on the spring perches, but there are no cotter pins installed. We will tighten these up and install cotter pins and then see what it does. This car was the victim of a lot of jury rigging before Franchise 24 got it. We have corrected a bunch of problems and it would appear we still have work to do.

Just a thought or two to ponder, the spring hanger (shackle) nut(s) really are not supposed to be 'that' tight. IMO, by tightening them you can mask another problem but that really isn't correcting the root problem. Think of it this way, ...if the spring does not have the proper arc, then the eye-to-eye measurement is not correct. This allows the spring hangers (shackles) to rock back & forth on the perches. While this generaly will not cause a shimmy, it can create an issue when a severe bump is encountered as it allows the frame/body to sway affecting the drag link position in relation to the steering arm. The results are usually the vehicle will dart when a bump is encountered.

I must be real honest in that we could write a book listing all the possibilities that you two should be looking for. Steering arm balls that are worn, or incorrectly pre-loaded can cause a shimmy. The same mindset applies to the drag link. Truthfully, I cannot help but think someone who grabbed one of the front wheels at the 9 & 3 o'clock position and violently shake it back & forth should allow someone else to see where the slack is.

[1931 flamingo]

IF strg box is good and mounted to frame tight, start with the pitman arm and work forward. Also ck the wishbone mounting and the ball for not being egg shaped. Wheel brgs correctly adjusted.
Paul in CT

[Franchise_24]

Thanks to all for the great replies. Hopefully we can get it looked at this week and report back with some findings.

[Brobrian]

One of my A's wobbles and the other doesn't. This is a famous A problem. I've bee tracking this down for years. Thought I had it licked a bunch of times.


Here are some of the things I've done with little lasting effect:
Check wheel bearings and axle nuts.
Replace wishbone ball cup & springs, add robber ball sleeve.
Decrease air pressure in front tires for less jarring
Rebuild worn gear and sector bearings
Tighten pitman arm
Check for play at the king pins.
Increased toe in (actually made the biggest change).

Probably any one of these could have produced the wobble or something similar and should be checked on a car that wobbles. But, after replacing the worn steering parts on the 31 pu I've decided that there is likely wear on the coupe's tie rod ends. That's what I'll replace next.

In the mean time my grandson gets a kick out of it when I turn hard back and forth to get the wobble to stop.

[Louis]

Originally Posted by Franchise_24

On my '28 if I hit a bump just right my whole front end starts to shake real bad. So much so that I pretty much need to come to a complete stop and start going again. My wife saw it happen the other day and the front tire she saw she said looked wobbly like it was going to fall off. I jacked the front end up and checked it all out. Kingpins appear good, everything is tight, but there is a tiny bit of play in the steering box. Could this play be causing what I am describing?

I had the same problem on my 31 coupe, I gave up and put on some 16" 35 ford wheels and a set of 6.50 X 16" tires, problem gone, I really think some of the org. wheels are so far gone [no matter how pretty they are] that they are a big part of the problem, JMO.

[FL&WVMIKE]

I had that "jitterbug" problem on my 34. I tightened my tie-rod ends, one half turn, and it hasn't happened since. This was about ten years ago.
I was lucky. It can be soooo many things.
MIKE

[Tom Wesenberg]

Originally Posted by FL&WVMIKE

I had that "jitterbug" problem on my 34. I tightened my tie-rod ends, one half turn, and it hasn't happened since. This was about ten years ago.
I was lucky. It can be soooo many things.
MIKE

Tightening the plugs will change the toe-in, so I wonder if the change in toe-in was the fix, or was it the tighter springs on the steering balls?

[Marco Tahtaras]

One of the things that have helped so many Model A's survive all these decades is the fact that they are so forgiving. Nearly every system on the car can function seemingly "normal" with multiple deficiencies. For example your ignition system can have numerous weaknesses such as a weak coil, slop in the distributor shaft, and play in the upper plate, but it will run acceptably. The points may close up very slightly and the car then develop a "miss". However, fixing any one of the other three things may "fix" the problem enough for it to seem "normal" again.

A couple weeks ago Jim Boehmke found an article where what you describe was coined the "death wobble". This is much more severe and not the same as a shimmy although they do share similarities. It's been my opinion (as it was the author's of that article) that death wobble cannot occur without slop in one or more places within the steering and suspension linkages. It's VERY important to note that includes the ball and cups at the back of the front radius rod (wishbone).

With all that in mind, descriptions such as "new tires" or "adjusting toe-in" as a solution obviously worked for folks. However that type of change would simply be enough in those particular cases to make the symptoms lay dormant. As with Brent, I also believe proper investigation WILL locate one or more areas of slop. 10-12 years ago I posted about the pendulum effect at the shackles (spring hangers) with an excessively flat front spring as Brent mentioned but I believe that would also require other contributing factors.

The single most effective way to locate slop requires two people. The car must be on the ground. While one person lays under the front the other person grasps the steering wheel and forcefully rotates the steering wheel back and forth through it's free movement. Spend some time staring at EVERYTHING under there. You will likely see things like the Pittman arm and steering sector shaft moving up and down in the sector housing. If you don't that means either the steering had been at least partially rebuilt or you are NOT looking close enough!

It sounds like you've already checked front wheel bearings and king pins. These are the only checks I can think of that are done with the front end off the ground.

[Franchise_24]

Marco,

Great reply, and thank you for the advice. I hope to get it looked at sometime this week. Working and trying to get 2 peoples schedules to match up is sometimes hard, but as soon as I know something I will post back findings. Thanks again for the great reply.

[tdlmomowers]

We took a quick look at Franchise24's Model A, last evening. There seems to be some play in the rear drag link joint. When you would crowd the steering, you could see some movement at the rear joint. We are going to dissassemble the draglink and check out the parts in the joint. Acts like the spring is either weak or broken. The plug at the rear joint seems to be threaded in too far.