Technical Violent front end shaking

Is there a wear pattern on the passenger tire?

 

I forgot to mention when I was adjusting the steering I noticed there is in and out play on the steering box

 

Steering arm on spindle is scary. Go back and look at pics on post 83. That is how it should look.

 

The adjustment of that backside screw should eliminate all in/out play of the shaft that the pitman bolts to, That is called the sector shaft.

are you saying that the shaft still has in/out play after you adjusted that side screw?

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Both front tires have excessive wear on the first layer of tread on the inside. Has to be 1/16th to 1/8th of an inch. When my wife gets home I will measure the wheelbase on both sides.

 

F&J, I'll bet the box is bad, has been wearing and caused initial problem. Then the alignment guy isn't old enough to understand how these front ends are set up, so hasn't got it set correctly. Lastly he needs to find a shop that can fix the steering arm. Actually replace it and get drag link in better alignment and box centered.

 

I totally see where you are going, suspecting a worn out worm gear...right at the former high spot. I agree it could explain what has changed with more miles of wear.

How can this guy get help out in the boonies of PA?

I still want to know why the camber "looks" real bad. I can't just ignore that .Is that brand of axle really that bad?..or something else throwing camber off?

I also wish a member was nearby to verify the box adjustment, the true center, and if the outer sector bushing is worn out. Too many unknowns here over the net.

Being there in person gives a true view of all the angles and geometry in just moments, rather than guessing on camera angles.
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The wheelbase on the passenger side is 116 7/8 while the drivers side is 116 5/8. 1/4 inch difference. I am ready to go by a Subaru.

 

I don't use aftermarket axles for that reason. The quality control is just not there as with most offshore parts. He really needs a good hot rod shop to look at his car, and they are not easy to find.

 

Any body in the Pittsburgh area, I am about an hour from there near Johnstown, Pa.

 

Call Posies tomorrow, 717.566.3340. They may know of someone near you.

 

Hang in there. There is a solution. Not the end of the world...it's a car, it can be fixed.

That is why I questioned the camber. It may be a simple answer like the axle KPI angle was bored on spec and the company that made the spindle was slightly off on the KPI bore angle. "We the unwashed" with the old parts, would put a Ford spindle on just to know which part is wrong, or which one is bent.

Good thought as I thought they once ran a rod build shop.

Back to just the box; if a F100 ran 20 years with unbalanced front tires, the worm gear will have a divot at dead center. If you run the sector screw into the divot with zero lash, all "in/out" sector movement will cease completely ...but as soon as you turn the steering wheel slightly left or right, the sector will bind on the good parts of the worm immediately adjacent to the former as-designed high spot.

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The wheelbase difference is a red herring. You have split bones with (I guess) adjustable ends. You could adjust it if you wanted to, but it probably isn't worth worrying about.

You don't adjust the drag ling to make it more level, you change or modify the steering arm like in my pics. You might have a knock-on problem, though, where the steering arm/drag link may foul the shock absorber. You may have to relocate the shock slightly.

Don't go out and get the Subaru yet, plenty of people here that can advise you. The steering arms are cheap from speedway, it might be easier to just get a new straight one and have it so the drag link fits from underneath. This may improve things enough. If not the extra joggle needs to go in to get it a bit lower.

Looking at your photo's, the drag link angle is definitely a bump steer inducer.

There may be some play in the steering box, both rotationally and in and out, if the steering is not in the straight ahead position.

Mart.

 

From the very first post,it sounded like it had been Ok,but now its acting up=What changed is the first thing to take note of !
Tires? anything other then that new?
I've fixed more then a few in the pasted. Sometimes a changes comes slowly,but shows its head only when it got bad enough.;
Like a front cross spring sagging tell it's inaffect too long,making the shackels hang too far down=that can start showing up as deathwabbel or even wheelbearing getting bad. Tires that are new can have a number of things wrong with them,even though they look fine,from out of ture too out of round,out of balance in two ways,singelplan or dinamic* {* that one is often over looked. Another seeming little thing is a new tire just a little wider then old ones/can change forces on front end enough to start wobble,even more so if the rims used are actully out set too far from kingpin;making tread contact patch have greater scrub.

 

To reverse the idler arm I would have to notch the gear worm for the bolt. I just really need to get it to someone. While I had the idler of I checked the steering box and there is a tight spot at dead center. I just don't know!

 

Maybe I'll cut it off and put a Subaru front suspension on it, or what would really be a sweet ride an SD suspension. Wow that would be great.

 

Frustration setting in as the car sits another weekend.

 

He already said he checked it and thats not his problem but that was the EXACT cause of my violent shimmy.

 

Get the car to a shop that can checkout everything and knows early Ford hotrod geometry and front-ends. In looking at the axle from the front - really don't "see" a camber issue - but that is just my old eyeballs trying to determine what is "normal" via just a picture.

I do not like where the upper steering arm is located (height above the king pin top ) and the resulting steep upward angle of the drag link. To me, it appears to be installed "upside down" so as to miss the shock. The drag link should be as close to parallel with the ground as possible (and close to the angle of your bones). Outside of potential wear issues (which I can't guess about), I can see where your setup can contribute to bump steer, which then might be initiating the DW situation. (May be other issues as well - like a worn steering box???)

See my attached picture of a 32 spindle that has been setup for a dropped heavy axle and stock 32 bones - notice the upper drag link arm location in reference to the top of the king pin - see how much lower it is than your setup. My guess is that you may have some conflicts with your shock setup - so a few changes might "spill over" as a result of changing the top drag link arm.

As noted by others, don't get too frustrated with this stuff and give up. These are the things we all go through and we are all continuously learning along the way!

 

Don't do this unless you have four bar suspension.

Run a string line from the steering arm pivot [front drag link] back to the pivot point for the bones.
Then crouch down and see if the pitman arm pivot intersect that line.

With bones the axle and the drag link should rotate on the same arc.
You'll never totally eliminate mechanical bump steer unless the drag ling is the same length as the bones, but you can get a very tolerable compromise [this is nearly always the case with modern Rack &Pinion steering]

 

Marts on the money with the steering arm. This pic is of my 32 with F100 box. The design of the arm brings the
drag link down and closer to the kingpin and will also give you easier steering effort. You cannot alter the position of the pitman arm as the 56 arms only go on one way. Centre the steering box as suggested and use the drag link to keep the the box in the ' tight spot ' and the wheels straight ahead. I run 6.5degrees of caster.

 

If you refit the steering arm so it sticks up you will introduce 2 problems.
1, The bump steer will be even worse than it is now.
2, The car will steer backwards. You will turn left and the car will go right.

No 1 is undesirable
No 2 is a job stopper.

Take that idea straight off the drawing board.

Don't get frustrated, but you will have to actually make a change to fix it.

Here's what I'd do.

Set the toe in to 3/32".
Remove front brake drum from drivers side.
Fit new steering arm as sold by speedway, Macs etc. Fit it so the drag link bolts in from underneath.

Make sure the steering box is centralised (in the sweet spot). Set the wheels straight, adjust the length of the drag link so it just slips into place.

Assuming it bolts together ok, go and test drive it.

Pat yourself on the back for making a fundamental improvement to your ride by actually doing something for yourself.

Mart.

 

I never cease to be amazed at some of the stuff that gets posted on here...... If the wheel base is off side to side than something moved! The steering arm is just fine where it is and there will be no bumpsteer, (which is a totally different line of bullshit), and moving it down and in on this frontend will just result in the car being very difficult to steer and won't do shit to stop the bump steer.

In reality if you throw a steering damper on it the problem will be solved. I know this is not a "purist" attitude but is not a hack either. All VW bugs through the modern design have one because the originals were notorious for this which the VW factory never was able to solve. SoCal puts these on every car they build according to their website and I'll bet every one of out there has had a car that had this condition. The only reason I didn't mention this upfront is I wanted you to check to make sure there wasn't something catastrophic going on.

When the chassis was set up I did it on my frame table which drops to the floor so I can throw a finished car on it. Everything was within tolerance and there was no bumpsteer through the entire suspension travel. My table is within .002 and I'm not near that good.

We're makin' this way too hard here. Mart and FJ are correct in saying that the 1/4" isn't going to make this happen. It will make the car run a bit "crabby" and wear your rear tires only. We all like to think of ourselves as perfectionists but a lot of good running rods are off that much or more. Lots of good info here and a bunch of uninformed stuff as well, which is pretty normal. Put the damper on and it will be fine as long as yu checked to make sure everything is OK otherwise.

 

Koz...Not that it matters, but I never made a comment on the 1/4, which I assume you mean the W/B.

I bailed on the thread because "I just can't see good enough" over the net. I did say that if we were there in person, it could be a whole lot easier to look at angles and whatnot. I have been fooled so many times on hamb for years, with pictures taken from certain angles and different lenses, and I tend to see things that just are not there.

I do not have a simple one step answer. I'm not there in person.

I guess I'm an idiot because I wouldn't mind trying to sort it out myself, just for the heck of it....
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Koz; Not trying to start a p-contest at all, just adding damper info on bugs. I was a "factory trained" VW mechanic first going to the VoA school in march 1970, Orangeburg NY. Also got my front end ASE certification in those years with VW. >>Here is a snipit from a VW "yearly changes" website, showing first year of damper in 1960.
1960 (1 Jan 60 to 31 Dec 60)
Chassis 2,801,614 - 3,192,506
Engine 3,424,454 - 3,912,903

Recessed steering wheel for safety.
Steering damper.
Steering box is worm-and-peg instead of worm and roller.
Generator increased from 160 to 180 watts (26.5 to 30 amps).
Outside door handles now push button (was pull type).
Padded sun visor.
Seat back re-contoured.
Wolfsburg crest on front hood has less colour.
Last year for semaphores in Europe, Canada, Australia.

>Honestly, I did not know the box roller was changed to peg at the same time (food for thought)

My only daily driver from 2002 to 2007 was a 57 Bug, and it never had wobble. It had used tires and I only had a bubble balancer, if I even bothered...I don't recall.

Enough of dampers... the thread seems to have many people interested in why a known stable build was fine for a very long time, never got hit, and went to a DW car so quickly. That could be why so many here are trying to help figure it out.

I don't see any bashing of your build, but maybe I would if it was my build?

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I run a VW steering damper on mine

 

Koz: I usually stay out of online pissing contests - but you've raised the "bullshit" card and basically told us all that everything was designed in a perfect manner and we're all pissing up a rope. So did what you suggest solve the problem . . . or does the guy need more help to get through it? If this setup needs or needed a steering damper from the get-go, then why isn't there one on it? What the heck changed to now require one? We're all trying to figure out "why" in addition to "how" to fix it . . . we'll take all the help you and others can give to the subject.

The guy is just trying to get his problem solved and folks are trying to help him diagnose the problem and hopefully resolve it. None of us likes to hear about a guy that is afraid to drive his car because it scares the crap out of him.

 

We are getting progress here, after 3 pages we finally got some reasonable photos.
Now I hope the OP runs a string line along the steering to put the bump steer theory to rest [ it should be like examples 1 or 2 in my previous post]
I'd hate to see the OP do something stupid like bend the steering arm down and actually engineer mechanical bump steer into it.



Something has moved ...... After 1500 miles the front spring has probably settled down a bit.

When the arch is flatter the distance between the spring eyes is increased and the front shackles are too vertical and cannot control lateral movement of the axle.
The car is stable on corners and high speed , but not when going over a railroad crossing whch could be an example of "shackle wobble" [especially if the crossing is at a slight angle]
When one side of the suspension compresses [and the spring "arcs" outwards] the shackle will be closer vertical. The shackles on both sides try to reach a point of equilibrium by shifting the axle sideways starting oscillations from side to side [split bones don't help]
If a steering damper was mounted to the frame/tie-rod it would make the wobble worse [the tie-rod stays still while the axle moves sideways] If the damper was mounted to the axle/tie-rod it would be better.

Even if the front end [caster/scrub/ toe and wheel size] is exactly as Ford intended, there are 2 modifications that don't help the situation.
1: Split-bones , they parallelogram themselves with any sideways shift of the axle.
2: Reverse Eye springs.
When spring eyes are reversed the eyes are now on the outside of the arch so the distance between them is longer [altering shackle angle]
Reverse eye springs should be shortened

The best fix is a long panhard bar [and leave the spring /shackle angle as already fitted]
The OP could easily make a clamp-on type using U bolts to test the theory

 

Point is well taken. Stuff like this is the very reason I no longer post on the HAMB although I do buy a ton of parts on the forums. Some of the stuff posted makes perfect sense and some doesn't make sense at all. My shop is a mega budget place and most of the cars that come here are built on nickels and dimes. The high dollar shops probably would not have put one on either. Most cars never end up having any benefit from them and it's a couple of bucks that can go somewhere else. I've know the front end geometry was right on and I made the point as in about 40 years and many, many cars it has proved to work. Everything is set up as to generally accepted "boilerplate" design guidelines. There is nothing odd or original here. That was my point. I was hoping that will help. I have never since the early 1960's when I started playing with these things, found any real studies or even articles on what actually causes this. When I was at Dana Corporation I had access to some of the best Ford and GM engineers on chassis design and never got a straight answer as to what causes this as I was sorting out my roadster at the time, ( it turned out to be bent spindle that time), I found it by shit luck after going through everything several times. If anyone has an article on this I would love to read it.

Back to Joes car. If he puts the damper on I'm confident he'll be happy to drive again. Without seeing the car, I probably think that it might benefit from having the steering box rebuilt but it was well within "hot rod" typical tolerance and I would doubt that it loosened up that much in 1500 miles but you never know. Total speculation! That box was donated to the project out of my '27 that I was building and it was one of the nicer ones I've come across and I centered it and set the play when I put it in. I'm only mentioning this and posting of this thread because I'm the only one who has first hand experience and know what is on the car and how it was put together. If I had my druthers, hindsight being 50/50 I would have put a Vega box in and cross steered it which in my experience never has this problem. The decision to side steer it was a combination of access around some of the stuff under the Dodge that is different than a Ford, obviously cost, as the stuff to side steer it was free, and in true hot rod fashion, what looked cool.

I'm asking F&J, as he is a certified front end tech, if he has ever come across a shop bulletin or other reading on this condition. (Not being a wise ass, I am actually asking). I know this was a common condition on old Fords but have never seen a Ford shop bulletin on solving it although they may be out there.

Like to hear if anybody has any literature on this. In the mean time, back to lurking.

 

Lol, EX certified as I let it expire. Anyways, no, I have never seen anything specific on DW in a manual or at school.

But it's definitely not just Ford as in "common". There were many add-on inventions in the 20s-early 30s for older cars, that had something like spring steel things dragging against the tie rod as the rod moved.. The device bolted to the beam, and the ones I saw were non-Ford parallel leaf/I beam.

I also agree on your cross steer conclusion, but I have no proof.

Back to the mysteries; why is Ford so much greater on caster, I never got an answer on hamb or anywhere. Why did Ford go to cross steer on a beam axle, some brands did not.

Back 45 years ago with me struggling with my own DW nightmare with zero skills, I tightened up those drag link screw ends to take the movement out of the spring loaded ends. Huge mistake, as it went into DW much more often, and much more violent. Why?

After you just confirmed the box was definitely set and centered, I'm off of the box being the "new" culprit.

This came on too sudden, with no prior evidence of a problem...I still wonder if there is something that got loose? Example of non-suspects: a drag link angle would not change enough to cause this? even if the spring settled a tiny bit? I doubt it.

can it be stopped with a damper or a P-bar? I think it could, but would you have him do that if he/we did not know the king pin was falling out. Poor example, but we don't know what went wrong yet

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