pitman arm

pitman arm
O

oldguy

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Ishpeming, MI
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1978 CJ-5 304.
OK guys, I know this topic has probably been beat to death BUT I'd really like some help. I have a 78 CJ5 with the turning radius of a mack truck. I need to know the dimensions of a "stock" pitman arm from a 78 "or so" CJ. The PPPPPPPO put some kind of drop (about 4") arm on it but it looks short hole to hole. With the new setup I have that amount of drop isn't necessary. About an inch would work or two would be great but I need it longer "hole to hole" than it is now. SO long story short -- whats the dimensions of a stock CJ or Waggy arm, will a Wrangler work, how about a Scout II????? Any of you out there with the same problem or maybe just wanted to tighten up the radius -- what did you do??:confused::confused:
 
I don't understand how changing the Pittman arm is going to change the turn radius. It may change the number of times you need to turn the wheel , lock to lock, but not the final angle of the wheel.:wtf:
 
IOPort51 said:
I don't understand how changing the Pittman arm is going to change the turn radius. It may change the number of times you need to turn the wheel , lock to lock, but not the final angle of the wheel.:wtf:
Click to expand...

It's all geometry. shorter line at the same radius as a longer line yields a shorter distance between points. Try it with a compass, 2 fixed points (say, 45 degrees), and varying settings on the compass
Dropped pitman arms will shorten turn radius because they are shorter eye to eye then a stock pitman. It doesnt sound like much until you transfer that geometry out to the tires. I've seen up to an inch and a half difference which is a lot of turn radius lost when translated to the actual physical turn.
 
IOPort51 said:
I don't understand how changing the Pittman arm is going to change the turn radius. It may change the number of times you need to turn the wheel , lock to lock, but not the final angle of the wheel.:wtf:
Click to expand...

Actually it does change it..since I don't have the link anymore due to a Sudden Death in my computer family, I'll call it F'in Magic. But it does change it.
I learned that a couple years ago, when I read that when making a drop pitman arm, most companies just bend a stock length pitman arm to make a drop pitman arm. The overall length thus gets shortened a bit due to the radii of the double bends.
This makes the pitman arm react differently when turning the tires. Something to do with the leverage of the arm or something.
Anyways, I put a 1" longer (overall length, not drop height) drop pitman arm on my Jeep to replace the one the PO had installed. Before, my Cj has the turning radius of a mack truck. After, I could turn the CJ around in a much tighter area. NO other changes were made right then.
Like I said, F'in Magic!
It turns even better now that I installed a PSC Variable ratio power steering box on the truck. It handles much better now in every way.

:chug:
 
The first pic is a graphical representation of a steering system looking down (only the right wheel is depicted). The wheel is 30", the pitman arm pivot (the gear box) is 7" from the center of the wheel (just for display purposes), the tie rod is 38.312" long, the pitman arm is 5" in length and 20 degrees from center, the tie rod attaches to the knuckle 13" from the center and the wheel is straight at 90 degrees.

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This pic shows the same measurements except the pitman arm has been moved 10 degrees (30 degrees total) so the wheels have now pivoted on the knuckle turning the wheels to 93.4143 degrees.

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Now the measurements are the same EXCEPT the pitman arm length is now 6". Notice the wheels have turned to a greater angle of 95.7262 degrees? The longer arm moved the wheels more.

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Geometry at work... :chug:
 

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:(Hmm maybe I got it backwards...I don't remember if I put a longer or shorter arm on now...Thanks, CJ! :mad: :D
 
I dunno....something is amiss there.
I've witnessed way more times then naught where going to a dropped pitman arm widened turning radius because of the decrease in actual arm length.

Geometry supports it....Think of a large V vs a small V. with the same radii, measure the distance between the top points on each and compare. That's where the turning radius is lost.
 
mylittlecj5 said:
:(Hmm maybe I got it backwards...I don't remember if I put a longer or shorter arm on now...Thanks, CJ! :mad: :D
Click to expand...

CJim7 said:
I dunno....something is amiss there.
I've witnessed way more times then naught where going to a dropped pitman arm widened turning radius because of the decrease in actual arm length.

Geometry supports it....Think of a large V vs a small V. with the same radii, measure the distance between the top points on each and compare. That's where the turning radius is lost.
Click to expand...
Opps - Sorry about that - I edited my post and pictures, the angle was dimensioned to the wrong side of the wheel and axle showing the inverse angle. I corrected it.
 
The one variable is the angle of the linkage (tierod). The purpose of a dropped pitman is to alleviate the angle of the steering linkage to the knuckle. If the angle is to great, steering radius is hampered. This is the case where a dropped pitman can return the shorter turn radius by leveling out the linkage.

But most cases I've seen have shown a decrease using the dropped pitman. The simple solution is to relocate the steering linkage to the top of the steering arm on the knuckle and return to a stock pitman arm.

Edit: case in point, Im running 4½ of suspension lift, stock pitman with the TRE relocated to the top of the steering arm and have almost perfectly horizontal linkage from the pitman to the knuckle.
 
CJ said:
Yep, a flip kit is cheap and really helps your geometry.

Rock Equipment Tie Rod Flip Kit

Old Dogs flipped tie rod and drag link is spot on...

img_1049_700x525.jpg
Click to expand...
Yep, that's how mine looks...plus it gets the tierod and steering higher up and out of the way of the rocks I routinely run over :D
 
I had the same problem with a drop arm ie. lost some turning rad.
after I fliped the rods and returned to a stock arm, all was good again.
 
Thanks all for the interest. I got the measurements I needed. I found a 81 CJ7 up here with a 4" drop pitman arm from Skyjacker and it's 6 1/4" center to center (steering box attachment point to drag link attachment point). I also found a 79 with a stock system thats 6 9/16" center to center. The one on my CJ is 5" center to center which reduces the end to end distance therefore reducing the turning radius, so -- the PPO, or whoever put it on shouldn't have because as pointed out by several thats where I lost my turning radius. It's possible that the arm is for another vehicle since everything else on the CJ was mix and matched when I got it and a Saginaw box is the most common in use. So back to the question, or sort of -- has anyone out there changed their pitman arm to tighted, or reduce their turning radius and if so what pitman arm did you use?? Part numner?? Skyjacker?? Wagoneer?? Astro van??

Again thanks much for all the input Oldguy (dave)
 
Old Dog said:
I had the same problem with a drop arm ie. lost some turning rad.
after I fliped the rods and returned to a stock arm, all was good again.
Click to expand...

CJim7 and Old Dog, thanks for the input and suggestions. I "NEED" one of those flip kits. Where do I find one. That along with a stock pitman arm and I'm golden. Thanks much again.
 
Now wait a minute.

My turning radius is Limited by the tires hitting the springs.

Changing the length of the pitman arm will only change the turning radius if your are using all the rotation from the steering box.

Are your stops on the knuckle hitting?

My ball joint to TRE is 7" on my Dana 44 . My pitman distance is (flat arm) is 6". My new dropped arm is 5". The tires still hit the springs before the. Box runs out of travel.

The arm needs to be centered to the center of the steering box. Stock arms are keyed to the box with a missing spline. The length of the drag link length will center the box and arm. Many aftermarket arms are not keyed.

I used a Camaro PS box where the box was not centered with the stock CJ drag link. The solution was to rotate the dropped arm to the center of the box travel.

For starters, measure the side to side travel of the arm by rotating the steering wheel lock to lock. The measure the knuckle TRE travel lock to lock. When the wheels are pointing straight forward, the travel needs to be equal left and right.

As long as the lengths are similar, the only thing a dropped arm improves is the vertical alinement of the drag link TREs.

Manufactures of dropped arms do not bend their arms. They are cast or forged.
 
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Wait a minute guys. I don't think changing the length of the pitman arm changes the turning radius. I think it only changes the quickness and sensitivity of the steering. Let's say you install a very long pitman arm. Now when you turn the steering wheel a little, the end of the pitman arm moves a lot. Your tires now turn quite a bit to the side. It won't be long before the stops on the knuckle would hit. THAT's what determines the turning radius - the stops on the knuckle not the length of the pitman arm. 73CJ was hinting at that in his post. Now if you go to the other extreme and get a very short pitman arm I guess it is possible to turn the steering wheel all the way and still not move the steering knuckle against the stop.
See if the wheel stops turning before hitting the stops on the knuckle. If so then yes you don't have all the turning radius that the factory intended.
 
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When I had my drop arm thats what happened, it's would not go all the way to the stops. With the stock arm (longer) it went to the stops.
 
Thanks Old Dog I'll be getting one.

For the record my frame is 1" narrower than a stock frame which gives more clearance for tires when turning and I'm using a set of 1 1/4 inch spacers which gives even more clearance for the tires. I have a steering box out of a 75 Z28 which gives me a ratio of about 2.1 turns lock to lock rather than the Jeeps normal of about 4.75 turns lock to lock ""BUT"" changing the steering box does not change the turning radius and calling Cardone who remanufactures them will verify this (It's like 2:73 gears vs 4:88 gears, less turns of the wheel to go the same turn of the shaft). When turning the wheel lock to lock with the 4" drop pitman arm that came on the Jeep (5" center to center) I don't come close to the stops. I borrowed the 4" drop arm that's 6 1/4" center to center and when turning lock to lock it DOES hit the stops. I also tried the stock 6 9/16" pitman arm and when turning lock to lock I hit the stops. I want to make this Jeep's turning radius as sharp as possible since it'll spend most of it's life in the woods.

I started this thread to get the dimensions of a stock pitman arm so I could compare them to the one on my Jeep (which I don't know where it came from) and to find out if any of you had done anything to your Jeep that makes the turning radius smaller. Even though I've worked on cars and 4x4's for forty years I'm smart enough to know that I can always learn from others, especially from people who a passion for something, in this case Jeeps. I apologize to all that this thread seems to have gotten out of control.
 
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