Steering shimmy question

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Model T Ford Forum: Forum 2012: Steering shimmy question
Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Friday, November 09, 2012 - 01:00 pm:

My friend George is installing a damper in his 1923 coupe to fix shimmying of the front wheels. While this will likely fix the problem, I think the real source of the problem is the steering column twisting. When you turn the steering wheel, the column turns in the opposite direction. It is not loose but seems to be twisting, adding some springiness to the system.

In my 1915 touring car, the steering column is absolutely solid without any tendency to twist. I have never had any shimmying.

What keeps the steering column from twisting? It is the inner tube that is moving, not the outer tube that the lever quadrants attach to.

Neil


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Friday, November 09, 2012 - 01:16 pm:

Hmm, if flexing steering column is a contributor I should be able to remove the shimmy damper, since I intalled modren '37 Ford steering gear. It's been over ten years, and I haven't tried that. Out of sight, out of mind, I guess.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky, Lytle TX on Friday, November 09, 2012 - 03:22 pm:

It could be that the gears or lower support are binding. Tightness in the steering box or lower support will cause an opposing force on the column. Both should be checked out and corrected. It could cause metal fatigue on the steering shaft and/or pinion. Not a pretty sight when something in the steering breaks.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stephen D Heatherly on Friday, November 09, 2012 - 04:11 pm:

The damper will not fix the problem just cover it up. If you turn the wheel does just the gear case move or does the whole column move? If the gear case moves inside the column the column tube is cracked around the rivits.

Stephen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Friday, November 09, 2012 - 04:20 pm:

The damper reduces strain on the downstream (upstream?) parts.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jack Daron - Brownsburg IN on Friday, November 09, 2012 - 05:09 pm:

Neil,your friend needs to do himself and his co-riders a big favor and remove that column and rebuild it. If it twists,it indicates the main shaft isn't moving as easily as it should. This will result in metal fatique at the top of the column and very bad things happen quickly thereafter.. I suspect excessive play in the upper gear shafts.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Friday, November 09, 2012 - 05:20 pm:

Thanks all for comments.

Yes, rebuilt is in order. I told him it is unsafe.

Yes, damper will not fix root cause.

The rest of the steering is free. The inner tube is flexing in torsion. The gear housing is not loose on the tube.

What holds the inner tube from twisting in torsion? Is there something loose at the top of the steering column? He will find out when he rebuilds it, just wondering about the design and what could have failed.

There are other issues with the steering on this car, but by far, the flexing of the inner tube is the biggest thing.

Neil


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky, Lytle TX on Friday, November 09, 2012 - 07:30 pm:

He needs to find out where the binding is occurring. It could be tight king pins, rusted steering bracket, or tight gears in the steering gear case. Could even be the wrong steering bracket bending the steering shaft. (This could be a real disaster.) With everything free with correct clearances and the front wheels off the ground, he should be able to turn the steering wheel with no more than two fingers on the spider. One if he has big hands. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Friday, November 09, 2012 - 07:34 pm:

I think it is a good time, given this thread, to mention that it is a very poor idea to turn the steering wheel when the car is not moving. This is true for all of the early cars, not just Model T Fords, but it is even more true for the Model T because of the nature of the steering mechanism. The stress that is put on all of the components when the Steering wheel is turned while the car is not in motion is significant and that stress is even more significant on pavement as opposed to the dirt and gravel that the Model T was driven on back in the day.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Friday, November 09, 2012 - 07:50 pm:

Because the kingpin of the T is aligned with the inboard edge of the tire, it is should not be as bad as cars like the A with the kingpin aligned with the center of the tire.

OTOH, T steering gear and mounting is marginal.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Friday, November 09, 2012 - 08:31 pm:

Just to make things clear, there is no binding.

Question remains, what could have failed that will cause the inner tube to flex? It flexes with just a small amount of turning effort at the steering wheel.

Neil


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jack Daron - Brownsburg IN on Friday, November 09, 2012 - 08:35 pm:

Neil,they all flex just a little. If the case has been hit or dropped and is not round,it will bind the tripple gears badly.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Friday, November 09, 2012 - 09:10 pm:

Case is not bent, no binding of triple gears. No binding anywhere else.

Yes, I know that they all flex a little, but this is excessive.

I guess George will find out what failed when he takes it apart. My thoughts are that there is a crack in the tube or an attachment point has failed.

Neil


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dale Peterson on Friday, November 09, 2012 - 09:31 pm:

The steering column may have a problem and need to be fixed, but is most likely not what is causing the shimmy. In order to correct a shimmy problem you must address the entire steering and suspension systems. This needs to start with reasonably strait and sound wheels, good and properly adjusted bearings, good spindle bolts and bushings, both ends of the wishbone tight and fit, proper alignment, etc, etc. I am shocked at what some of our members are driving on tours at cruising and faster speeds. If you have a shimmy problem or your front end is not in tip top shape, you should not be using your car for other than static show or SLOW parades. JMHO


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Friday, November 09, 2012 - 11:14 pm:

Neil:

You keep mentioning the "inner tube". The T does NOT have any inner tube. There is the outer housing column and a gear case at the top end of that. The triple gears are mounted to a spider that is part of the inner steering shaft which then goes directly down to the pitman arm. There is no inner "Tube" that the steering shaft rides inside of. Maybe it is just semantics but I am confused with what you are describing. If the pitman arm is solid to the shaft and the upper spider is solid to the other end of that shaft then the flexing you are talking about is either a loose pitman arm at the bottom end or loose fit of the triple gears/case/center gear. On early brass era cars the outer brass gear case was riveted and soldered together out of 2 pieces of brass to make up the whole gear case and those rivets and solder are known areas to break and cause the upper end to flex but that sort of gear case would not normally be on a 23 T. I don't think the shaft is flexing since it is a solid piece of bar stock of substantial size. The play has to be at the top or bottom end of that shaft. The steering column just holds the shaft in position. there is no steering gear case at the pitman arm end like in modern cars. Now if the bottom bracket is not fastened solidly to the frame then the play could be down there. Hope this helps.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Saturday, November 10, 2012 - 08:14 am:

John,

You may have hit on the problem. Although George things this is a 23, it might be an earlier car, or have earlier parts. I know there is something broken, and it might be the riveting and soldering you refer to. On this car there is an outer part that has the quadrants attached to it. There is an inner part, that is round and cylindrical, that the triple gear case is attached to. The inner part, which, being cylindrical, I call an inner tube, is moving independently of the outer part.

The rest of the steering system is in good shape. There is some play in some of the parts, that should be fixed, but the play is not excessive. The root cause is definitely at the top of the steering column.

I am gone for a couple months, otherwise I would take photos.

Neil


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Semprez-Templeton, CA on Saturday, November 10, 2012 - 11:23 am:

I think what we have here is failure to communicate!

Shimmy in the Ford front end is almost always caused by geometry problems, or broken/ loose parts. It sounds to me that the symptoms are the result of a front end that is way out of spec. and being telegraphed to the steering column.

When I first got my T, someone had installed the front perches on the wrong side causing the caster to to be way off. After rebuilding the front end I could drive my Ford without holding the steering wheel at all and she tracked straight ahead with no shimmy.

Try driving your Ford in reverse at high speed... Two men and a boy can't keep the column from flexing!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Saturday, November 10, 2012 - 01:19 pm:

Shimmy is pretty unusual - I have not been able to make any of my T's shimmy. Like John says there must be something dramatic wrong to cause the problem in the first place. Instead uf hanginf an ugly shock absorber below the car and making the car harder to steer, why not just figure out what the real problem is?


Top of pagePrevious messageNext messageBottom of page Link to this message  By ex trooper on Saturday, November 10, 2012 - 02:21 pm:

First of all is this what yours looks like?
Second, the radius rod (front wishbone) mount on the oil pan is worn out. troop

[IMG]http://i50.tinypic.com/73jc7m.jpg[/IMG]


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kerry van Ekeren (Australia) on Saturday, November 10, 2012 - 04:09 pm:

Unusual or not, google the topic of T wheel shimmy or wobble and a lot of info on how to fix comes up, my T did it 3 times on a 3 day run last week, the only thing I did different for the trip was run an extra 5 psi in the tyres.
So now have gone through the front end, what I found is,
a bent king pin,
loose rivets that hold the steering box to the tube,
tighten the ball cap on the pitman arm,
wheels had a 1/4" toe out instead of toe-in.
Maybe it needed all of these things combined or just one of the faults, all I can do now is hope I've fixed it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Saturday, November 10, 2012 - 06:14 pm:

If the housing that has a gear around its inside perimeter is moving separately from that part of the brass casting that has the levers passing through it then you either have an early case with broken solder/rivet joint or your have a case that is broken since well before 1923 Ford began to cast that entire gear case and upper steering column end casting out of one solid piece. That is the only way that upper outer gear case at the top could move as you describe.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Saturday, November 10, 2012 - 09:00 pm:

John,

I think you have hit it on the head.

All,

There may be a host of other problems that initiates the shimmy, but the looseness in the top of the steering column amplifies things and allows the shimmy to go out of control, IMO. I intend to help George straighten out his front end problems and solve the issue so that the dampener is not needed. I am out of town for a couple months, so it will have to wait.

Neil


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