shortened pitman arm

[rusted]

What is the advantage of a shortened pitman arm? How short should it be?

[Randy in ca]

This has been discussed quite a few times before. Do an advanced search for (pitman arm) and a bunch of threads will come up. Here's one that had quite a bit of discussion:

https://fordbarn.com/forum/showthread...ghlight=pitman

[V4F]

buy one , dont make one . vintage ford has them on sale !! they shorten them by 1 1/2" ....... not safe welded ............. steve

[ford1]

shortened pit man arms make for quicker steering, but also makes for harder steering because of lost leverage to the steering arms, and as was said, never weld one, its like a death wish if you do, to you or some one else

[steve s]

Originally Posted by ford1

shortened pit man arms make for quicker steering, but also makes for harder steering because of lost leverage to the steering arms, ...

This is totally opposite to my experience.

[ford1]

Sponsored Links (Register now to hide all advertisements)

Steve, i dont really understand why it works differnt for you, a pitman arm is like a lever, the longer it is the more leverage you get to move something, even the steering on a car, but if what you have works for you then more power to your set up, send a pic or post something about your set up that makes it work so weel, im interested

[Steam Engine Pete]

A shortened pitman arm has the same affect as using a smaller diameter gear to drive another gear. A smaller gear would cause more torque multiplication and reduced output speed.

A shortened pitman arm will slow down the steering and increase torque which would make the steering turn easier but also slower. The benefit is reduced steering effort.

Pete

[CarlG]

Has anyone used a shortened Pittman arm with an F100 Steering box?

[jerry shook]

I dont know just how they work. I just know when i put one on my coupe it steers quicker and easier then before. When i put one on my 31 town sedan with the f-100 box even though it steered very easy then, now it steers even better. Like power steering. I have a f-100 box ordered from mell gross to put on my 31-s/w.it already has a shorten pittman arm.

[hardtimes]

Originally Posted by jerry shook

I dont know just how they work. I just know when i put one on my coupe it steers quicker and easier then before. When i put one on my 31 town sedan with the f-100 box even though it steered very easy then, now it steers even better. Like power steering. I have a f-100 box ordered from mell gross to put on my 31-s/w.it already has a shorten pittman arm.

I'll second jerry's remarks, as my own experience also same setup !
I'm using this setup on a '30 roadster, which is comparatively light weight.

[Keith True]

The shortened arm makes a difference.Much easier after.I've installed maybe a dozen or so.The man I worked for in the early 70's used to install them that was already made.He said it was a Ford truck pitman,but I've never seen a part number for one.He did them in the 40's,50's,etc,so it probably was an aftermarket part.A long lever works easy one way,if the other end is pushed it can be harder.If you reach down to the table with your arm and try to push a 5 pound bag of sugar,it will push hard.If you fold your arm,and push it with your elbow,it is much easier.Same idea as the shorter pitman arm.I've heard people insist the steering radius is reduced with the short arm.If the spindles hit the stops with the long arm,and they also hit the stops with the short arm,how can the radius be reduced? As one guy put it to me,I dunno,but it just is.He was an armchair expert,everything he read he accepted as gospel,but he refused to believe his own eyes.I've only done shortened arms on 2 tooth boxes,none on the 7.I did have a guy tell me his spindles had hit the stops with the long arm,but no longer with the short.He had a 7 tooth box.He said it was no big deal to him,he never turned the wheels to full lock anyway.He said that if he turned the wheels to full warp it was just too hard to bring them back the first couple of inches.Any broken welded parts I have seen have been the fault of the welder,not from the fact that something was welded.I buy the redone ones for customers,the only reason being it takes me a while to do it,and it is cheaper to buy the part than to pay me for 2 hours to clean,cut,grind,fit,tack,check,weld,grind,check again and paint.If you ever ran the highways between southern Maine and N.J.in the 50's,60's,and early 70's you met a lot of B model Macks with shortened and welded pitman arms.One outfit alone that I know of did over 100 of them. The pitman arm though is NOT the place to learn how to use your $299.Harbor Freight welder.

[sukhoi]

A pitman arm can be welded and be totaly safe. The question is "who does the welding and what aren there qualifications ?'

If either question is not answered satisfactorily, buying one new may be the answer.

[steve s]

Originally Posted by ford1

shortened pit man arms make for quicker steering, but also makes for harder steering because of lost leverage to the steering arms, and as was said, never weld one, its like a death wish if you do, to you or some one else

Originally Posted by steve s

This is totally opposite to my experience.

Originally Posted by ford1

Steve, i dont really understand why it works differnt for you, a pitman arm is like a lever, the longer it is the more leverage you get to move something, even the steering on a car, but if what you have works for you then more power to your set up, send a pic or post something about your set up that makes it work so weel, im interested

Originally Posted by Steam Engine Pete

A shortened pitman arm has the same affect as using a smaller diameter gear to drive another gear. A smaller gear would cause more torque multiplication and reduced output speed.

A shortened pitman arm will slow down the steering and increase torque which would make the steering turn easier but also slower. The benefit is reduced steering effort.

Pete

I'm struggling to stay out of physics teacher mode (it all has to do with conservation of energy), but here goes.

Saying that "a pitman arm is like a lever, the longer it is the more leverage you get to move something," is kind of ambiguous; "more leverage" can be good or bad, depending on which end of the lever you're on.

Think of trying to lift a fat man who is sitting out on the end of a teeter-totter. If the lever on your end is made longer, your job is easier; if the lever on his end is longer than yours, your job is harder. Who "has" more leverage?

In terms of the physics (I buckled), it takes the same amount of energy, or work, to lift fatso a given height in the air, no matter how long either levers are (or, even if there are no levers). However, you have options as to how much force you must apply over what distance to do that work. If you're a featherweight, you have little choice; you need him sitting on a short lever and you pushing down on a long lever. This means you have to exert your force (i.e., weight) over a larger distance to get fatso to move a smaller distance. Quibbling about who "has more leverage" could go either way and so does not really help, IMO.

Think of the ball at the end of the Pitman arm. Like lifting the fat man, it takes the same amount of work, and the ball on the end of the arm (and the drag link, etc.) has to move the same distance, to turn the front wheels a given amount, no matter the length of the Pitman arm. If the arm is shorter, it will take more turns of the steering wheel to move the ball a given horizontal distance; the longer arm will swing the ball a larger distance for the same number of steering wheel turns. The total effort (or work, or energy, if you prefer) to turn the front wheels will be the same, but it will seem easier with the shorter arm because less force is required, ALTHOUGH over a longer distance! I believe that most people would describe this as "slower" steering: a given rotation of the steering wheel turns the car wheels less. Conversely, the longer original Pitman arm would give faster steering (assuming you've got the strength to make it happen).

I hope this is clear.

While I'm rolling here, the shorter arm is only partly like power steering. True, it reduces the force needed to turn the steering wheel, but with REAL power steering the steering response would not be decreased--it's often faster than non-power steering.

Steve

[Steam Engine Pete]

Steve,
I see I am quoted in the previous post. We are both saying the same thing the way I understand it. Just wondering if you feel my post was incorrect or if it was quoted just for reference.

Thanks,
Pete

[jerry shook]

I dont know about physics, conservation of energy,leverage or force needed to turn. I just know my cars steer great. Try one you will like it.

[Steam Engine Pete]

Jerry,
Mine is worn out and needs to be replaced. I am sure I will go with the shortened one when I do.

Pete

[steve s]

Originally Posted by Steam Engine Pete

Steve,
I see I am quoted in the previous post. We are both saying the same thing the way I understand it. Just wondering if you feel my post was incorrect or if it was quoted just for reference.

Thanks,
Pete

Pete,

Sorry to create confusion--we are indeed saying the same thing. I was just trying to pull the relevant contributions together.

Steve

[Steam Engine Pete]

Steve,
Thanks for replying. I appreciate it.

Thanks,
Pete

[columbiA]

On both my A,s,I shortened the arm by 1.1/2",needle sector & thrust brgs & teflon seats & its the next thing to PS once your moving.Ive shortened a few p-arms over the years,but with new short arms available I would just buy one if needed.

[Marco Tahtaras]

While such changes are not needed with good original steering, unfortunately that is probably one in five hundred cars at best. Folks need to overcome that as best they can and proper restoration is not easy.

It's not the easiest thing to visualize, but a shortened Pitman arm is essentially a gear reduction. It's really no different than shifting down from third gear to second to climb a hill. The engine turns more revolutions to get you there but requires less effort. Similarly, a shortened pitman arm makes it easier to turn the steering but requires more turns of the steering wheel to do so.