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Old 01-04-2017, 05:58 PM   #1
Houdini
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Default Re-thinking shortened pitman arm

My car had a lot of play in the steering when I got it, plus it steers hard (which from all that I've read here is not unusual). I have a regular size pitman arm.

Last year, I redid the front end, new king pins, new steering arm balls, etc. That took a lot of the play out, but it still steers hard. I also adjusted my two tooth steering box, to take out more play to where I felt it was acceptable. But there is still some play in the steering box.

some club members suggested I put in a shorten pitman arm to make steering easier. I've resisted as I theorized that although it would make steering easier, it would also increase the "effective" play.

I've thought about that more and perhaps I was wrong. Let me explain about my "play theory" and see what some of you think.

First, play could originate from the steering box or the linkages and front end components. My original reaction to not putting in a shorter pitman arm was centered around play other than the steering box. Why?

Well, the pitman arm's rotation is translated into linear movement of the drag link and so, the shorter pitman arm, means when you turn the steering wheel, say a quarter of a turn, you actually move the front wheels less, with the shortened arm, because the drag link moves less on the shorter radius of the shorter pitman arm. So it makes steering easier, because of the increased mechanical advantage. My concern was that if there is play in the front end components, then the slop in the steering as you encounter grooves and crowns in the road, will mean you have to turn your steering wheel further to correct or check for that, thus making it feel like you have even more play than before.

But at this point, I feel I took out all that play in the linkages and my play is isolated to the steering box itself. So after more thinking on the subject, I am theorizing that a shorter pitman arm might actually make the play less noticeable, because the correction I'm making with play is in the steering box. I'd still have to rotate the steering wheel the same amount to "bump" against the "sides" of the play before my movements in the steering wheel correct the wheels on the ground, but that same steering wheel movement means the play effects less movement of the wheels on the ground, thus controlling steering more precisely.

So assuming there is any validity to this, do you think a shorten arm will make steering more precise or feel like I have better control, as well as the obvious of making steering a bit easier.

I know some of you will simply say I should rebuild the steering box etc, and I was thinking of doing that, but this might be a fix for now that is more affordable and makes driving more fun until I can do the box.

In any event, I'm sure your opinions on my "theory" will be interesting to read. Hopefully, we can keep this discussion on the shortened pitman arm theory and your experience with it.
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Old 01-04-2017, 06:04 PM   #2
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Default Re: Re-thinking shortened pitman arm

Some times we can over think and over analyze. I think you are in that situation right now. Do you really think that you have garnered more knowledge than the automotive engineers. If so keep your hard steering. If not admit they are smarter than yo are. Wayne .
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Old 01-04-2017, 06:10 PM   #3
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Default Re: Re-thinking shortened pitman arm

I just put a shortened steering arm on a car that had the front end and the steering
box rebuilt. The shortened arm did give just a little more play, but its just an inch.
With the rebuilt front end you aren't wandering all over the road and you don't notice
the play in the steering.
It really made a difference in the steering effort a pleasure to drive.
Your going to hear all kinds of different opinions on this.
How much play is in the steering wheel now?
Try it, you can always go back if you don't like it.
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Old 01-04-2017, 06:13 PM   #4
Tom Wesenberg
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Default Re: Re-thinking shortened pitman arm

If the freeplay is in the steering box, then the shorter pitman arm won't have any effect on the play, but if the freeplay is forward of the pitman arm, then a shorter arm will add to the freeplay felt at the steering wheel.
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Old 01-04-2017, 06:32 PM   #5
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Default Re: Re-thinking shortened pitman arm

I put a shorter pitman arm on my coupe because I have a shoulder injury and cannot move the steering wheel easily. The car is much easier to steer, but I do notice a shorter steering radius. I know about the adjustable drag link, but the difference is not so much that I worry about it.
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Old 01-04-2017, 06:34 PM   #6
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Default Re: Re-thinking shortened pitman arm

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Have you ck'd tire pressure?? toe in?? If you've rebuilt what you say and it still steers "hard" you missed something. JMO
Paul in CT
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Old 01-04-2017, 06:51 PM   #7
Tom Wesenberg
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Default Re: Re-thinking shortened pitman arm

I agree with Paul.
Get the original steering all correct first, then see if you still feel the need for the shorter arm. My friend rebuild his steering about 10 years ago and it made a world of difference in driving pleasure.
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Old 01-04-2017, 07:05 PM   #8
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Default Re: Re-thinking shortened pitman arm

I suspect people have grown so used to having power assisted steering that they find it difficult to go back to the way it was before.
Don't take this the wrong way but your "heavy" steering might not be abnormal, maybe it's your expectations. Just sayin.
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Old 01-04-2017, 07:06 PM   #9
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Default Re: Re-thinking shortened pitman arm

Eat ya wheaties and retest
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Old 01-04-2017, 07:15 PM   #10
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Default Re: Re-thinking shortened pitman arm

i assume when you put new kingpins in you put new bushings AND REAMED THEM correct? and new thrust bearings? are they actually taking the load of the car and NOT the lower eye of the spindle?

i also assume you greased all the balls and properly tightened them to spec correct?

you didnt get your steering box too tight did ya? its supposed to be tighter in the "center" than on the ends so if you adjusted it at full lock it may bind hard in the middle.
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Old 01-04-2017, 08:36 PM   #11
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Default Re: Re-thinking shortened pitman arm

Ford made the Model A
Firestone made the tires
Armstrong made the steering.
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Old 01-04-2017, 08:49 PM   #12
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Default Re: Re-thinking shortened pitman arm

Thanks for all the replies. The answers to some are yes, I checked tire pressure, with new tires too, and yes the bearings and the king pins, and bushing are new and inline reamed etc. And when I say steering is hard, like some said, its probably normal since we're all use to power steering and I have forgotten what manaul steering is like all these years. The steering isn't hard at all when moving down the highway, just when turning and going slow in the drive way. toe in is correct too. The steering box is old, I think original and don't know if it ever was rebuilt, but I doubt it. I haven't over-trightened the box. My main question was if handling might be better with a shortened pitman arm considering the play is in the box and down down stream. I realize the movement or slack in the wheel will stay the same, but I suspect even though the same steering wheel movement will make smaller corrections it may not really improve the feel of control on the road.

I've also thought about getting an F100 box from Randy Gross, but thought maybe the shorter arm might be somewhat of an improvement for the short term. As was mentioned, its not an expensive option to at least try.
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Old 01-04-2017, 10:00 PM   #13
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Default Re: Re-thinking shortened pitman arm

Yes, you should feel better in control with the shorter arm due to better leverage ratio. If the car gets pulled by heavily worn tire ruts in the road, you should feel less of a tendency for the steering wheel to be pulled to one side.
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Old 01-04-2017, 10:48 PM   #14
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Default Re: Re-thinking shortened pitman arm

http://www.macsautoparts.com/store/m...cs/#7toothgear

A bit off topic, but according to Macs specs the steering ratios are different between a 7 and 2 tooth. Is this correct?
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Old 01-04-2017, 11:29 PM   #15
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Default Re: Re-thinking shortened pitman arm

I had a 7 tooth, rebuilt by "professional A mechanic, highly recommended." Still wandered and was hard to steer. I have driven trucks and tractors the better part of 70 years and I know hard steering. I put in a 56 box conversion AND a short pitman arm. Note it is not a "shortened," but short. It steers like power steering and does not wander even tho" it's been years since I rebuilt the front end. I would never go back, but I know of some that have because they like the challenge of driving the stiff steering. I don't, but it's your car.
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Old 01-04-2017, 11:46 PM   #16
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Default Re: Re-thinking shortened pitman arm

I temporarily installed a short pitman arm and felt it took way to much turning radius off so I switched back to the regular arm.
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Old 01-05-2017, 12:44 AM   #17
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Default Re: Re-thinking shortened pitman arm

OK. I'm on a roll here.

From the V8 forum on ratios and things
https://www.fordbarn.com/forum/showpo...0&postcount=11

".... be aware that for earlier 1933, the ratio is/was (as was 1932) 13:1, which is difficult to steer. For later 1933, the ratio was changed to 15:1, which is MUCH better."".... A big benefit can be gained in reducing steering effort by installing a needle bearing and race in the upper column to replace the (high-friction) bushing that Ford used there. This makes for a huge improvement in effort and smoothness of steering.

The F-1/F-100 steerings have about an 18:1 ratio, which provides for much easier steering, but which also SLOWS THE STEERING WAY DOWN so have to steer more, and road feel at high speeds is reduced. Lengthening the steering (Pitman) arm can speed it back up"


I have a 1929 RHD two tooth that has been converted to use the 1932 sector and pitman arm. I wondered why this was done, but it could be to use the new 15:1 gears.
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Old 01-05-2017, 12:56 AM   #18
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Default Re: Re-thinking shortened pitman arm

Last winter I rebuilt and/or replaced all the steering components in our 1928 Tudor except for the draglink and king pins which were in very good shape. At the same time I fitted a short pitman arm and a steering damper. It took several months for the stiffness to settle out, now it steers as easily as my MGB. Just not as precisely which is not surprising considering the archaic steering geometry on the Tudor.
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Old 01-05-2017, 07:08 AM   #19
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Default Re: Re-thinking shortened pitman arm

I think I remember reading that if the front spring is sagging a lot, it will throw off the castor and make for hard steering. Is there any truth with this?
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Old 01-05-2017, 07:28 AM   #20
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Default Re: Re-thinking shortened pitman arm

I shortened my pitman arm and converted a 1954 F11 steering box and it steers like power steering and I do not see any difference in steering radius. I think Ford went to a shorter arm shortly after the model A.
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