Steering over centering

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration
Model T Ford Forum: Forum 2013: Steering over centering
Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Rimmer on Thursday, August 22, 2013 - 05:22 pm:

Hello all, can someone give me some advice please?
I'm working on a 1913 Tourer that has an issue with the steering going over centre at full lock. This caused the owner to have an accident last year and I don't want it to happen again!

What actually limits the travel of the steering on early cars? On late cars there is a longer pin in the "steering box" at the top of the column which runs in a groove. The brass gear housing on this car doesn't have a groove.

I have heard that the engine pan/shield acts as a stop but this seems unlikely as it is only thin sheet steel.

Were shorter pitman arms used on earlier cars? This would reduce the throw but I have only seen one size offered as a replacement part.

Any advice gratefully received.
Richard


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Brancaccio - Calgary Alberta on Thursday, August 22, 2013 - 05:29 pm:

See this link

http://www.mtfca.com/discus/messages/257047/300409.html


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Rimmer on Thursday, August 22, 2013 - 05:37 pm:

Thanks Chris!
As suspected, there does seem to be a shorter pitman arm. I'll check the other items tomorrow but I don't think they are the issue. The pitman arm is vertical with the steering centered, it's just that there is too much lock. May struggle with finding a shorter pitman over here in the UK.
Richard


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kerry van Ekeren (Australia) on Thursday, August 22, 2013 - 06:07 pm:

For the front wheel to turn over centre on full lock on any T means you have a worn spot on the spindle arm and, or the part it hits on the front axle, that's the stopping point from lock to lock.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Darel J. Leipold on Thursday, August 22, 2013 - 06:13 pm:

Pre 1917 Ford Ts are well known for going over lock. For the 1915-16 many just install a 1918-1919 column which will not go over lock. That is what I did on a 1916 roadster. I swichted to a 1917 column.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Thursday, August 22, 2013 - 07:49 pm:

They won't go over lock if the parts are matched properly. I believed what you did, Darel, until I started measuring things to see if they were a matched set.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Richard Bennett on Thursday, August 22, 2013 - 10:08 pm:

Richard, the drag links for 1913 are relatively easy to identify from the others. The ends are separate forgings like the 1912 items, but they are bronze welded and pinned on rather than threaded like the earlier ones. This should get you on the right length.

Hope this helps,

Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Friday, August 23, 2013 - 06:23 am:

The shorter pitman arm shown in my thread last year is for 1909 - 11 with one piece spindles and tie rod above the wishbone.

The correct link for 1913 was originally 30-11/16. Be sure you don't have later spindle arm components that drop the tie rod down lower. Be sure you don't have a later tie rod with a replaceable ball - that will make it impossible to fix over center steering problems.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Rimmer on Sunday, August 25, 2013 - 06:19 am:

Well, i spent some more time on the car on Friday and I'm still a little puzzled. All the components seem correct, longer pitman arm, drag link is pinned type with non removeable ball.

The only thing that seems to limit the lock is when the stub axle hits the axle beam? There are small indents where this has been happening but could this be enough to allow the over center issue?

The Pitman arm is vertical with the wheels straight. The tracking is set with 1/4" toe in.

The only way I can seem to stop the over centering is to fit stops on the steering arms that touch the axle beam before too much lock can be applied but I don't really want to leave teh car like this as it is just covering up a problem somewhere!

Very confused.

Richard


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kerry van Ekeren (Australia) on Sunday, August 25, 2013 - 06:34 am:

Those small indents mightn't look like much but for every 1/16" or so wear, that will give you an extra 1/2"+ of travel on the drag link.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Rimmer on Sunday, August 25, 2013 - 07:25 am:

Hi Kerry, that was the only thing I could see that could be causing the problem. You could be right that there is just too much wear at that point!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Sunday, August 25, 2013 - 07:40 am:

Can you go to a safe place, like an empty parking lot, and duplicate it? If so, you could get some pictures of exactly what is causing it. I suspect movement of the suspension system plays a role. What you could never get it to do in your shop sitting still, can happen when the car I leaning to the outside of a turn with some weight in the car while simultaneously hitting a bump.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Sunday, August 25, 2013 - 06:02 pm:

Remember. It isn't the pitman arm straight up and down with the wheels straight ahead that determines whether the steering will flip over or not. If everything is as it should be, it would be.
Hand pull the steering all the way right, and check to see how high the pitman arm goes. Then pull the steering all the way left, and see how high the pitman arm goes. If the frame is bent, or sagged, or the spring/motor mount is off center, the two directions may not be matched.
Now. Remember that every time the spring gives, or the shackles move for any reason, that center point changes. IF either direction is close to flipping over with the steering all the way over (sitting still), a little motion on the shackles could be enough to let it go the rest of the way.
Theoretically, a proper, good, well maintained, model T should not have this problem. However reality intrudes. The simple fix may be to mount a small, simple, bracket onto the engine or frame or both to block the pitman arm from flipping up and/or over. I have never done this. Never needed to. But safety is important. Make sure everything else is working as it should first. Then consider a couple little brackets.
Drive carefully, and enjoy, W2


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Monday, August 26, 2013 - 01:44 pm:

I think the LH side engine pan can add safety, if it stops the LH frame member (with the steering bracket) from any flexing sideways relative to the engine. A few screws distributes the force, the thin steel pan will be strong enough to reduce any flexing there significantly.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Rimmer on Monday, August 26, 2013 - 03:16 pm:

Without stops fitted the pitman arm can be "encouraged" to over centre whilst the car is stationary. It takes a little more effort than turning the wheel to "normal" steering lock positions but if the driver was on the road and moving I suspect it would't take much and that is what worries me.
As the axle beam is the only form of "stop" to limit the lock available, I'm suspecting that the indentations that have been worn into it may be the cause after all??
Thankyou all for your input.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Rimmer on Tuesday, August 27, 2013 - 06:25 pm:

I have tried to take some pictures of the various steering components to see if I am missing smething obvious here. The shot of the pitman arm shows it turned to full lock left but it can be "encouraged" to over center without too much effort!
I have noticed that there is a little chassis rail flex and also the column itself can flex but these are both standard so I can't see how that can be stopped.

















Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem on Wednesday, August 28, 2013 - 02:51 pm:

Richard,

You state, "...drag link is pinned type with non removable ball."

What you're describing is not the drag link, it's the tie rod. The drag link goes between the pitman arm and the tie rod. They were made in several different lengths over the years and if you put the wrong length drag link in, it will cause over centering. The worst case would be a 26/27 link, they were the longest and will cause over center on right turns. Does your over center happen on right & left turns, or just in one direction only?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jem Bowkett on Wednesday, August 28, 2013 - 04:08 pm:

My 09 has the one piece spindles with a notch in the back of each end of the axle so the spindle can really swing to an extreme angle. I have fitted a short pitman arm to give better steering ratio (1.75 turns instead of 1.25 lock to lock)and it will now over-centre on extreme left lock. But I mean extreme, you won't swing the wheel that far round at anything but parking speed (SLOW parking speed, that is). And you can wrench it back. But I intend to fit some form of stop because you just don't need that amount of extreme lock. I believe Neil Tuckett has devised a steering stop.

What was the nature of the accident? And what angle will the spindle go to, relative to the axle beam?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Richard Bennett on Wednesday, August 28, 2013 - 06:58 pm:

Jerry, in the first photo you can see the shoulder on the drag link end, indicating that the drag link is the correct one with the separate forged ends.

But that doesn't help Richard.

Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Rimmer on Thursday, August 29, 2013 - 02:53 pm:

Once again, thanks for the replies. The car had the over centre issue before which is what caused the accident! The steering will over centre in either direction. Having studied things again with a friend we believe there is a problem with either the stub axle or the axle beam as the only thing that appears to limit the travel is the stub axle hitting the beam. At present the steering can go over centre before the stub axles hit the beam. Does that sound reasonable to anyone?
I'm wondering if either there were differences in stub axle castings as the beam appears to be the same as others.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Rimmer on Thursday, August 29, 2013 - 02:54 pm:

Forgot to mention, we also fitted an engine pan shield on the steering column side of the engine but that made no difference.


Posting is currently disabled in this topic. Contact your discussion moderator for more information.
Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration