Pitman arm install

I'm working on installing my new pitman arm on my 69 Dart. I'm using 73 Duster steering linkage and my car's original power steering box. Per things I've read, because the 69 power steering box shaft is smaller than the 73-up shaft, I had to get a 73-up manual steering pitman arm to fit both the 69 box shaft and the 73 center link which I did (Mevotech brand). My service manual says the torque spec is 120 ft. lbs. on the nut. So. I have it torqued to that but the nut doesn't look to me like it is on far enough. It is basically flush with the end of the shaft. I looked on my 70 Dart to compare and the shaft on it sticks out beyond the nut about 1/4". Your thoughts please.

If you achieved proper torque that is a good sign and it is probably fine.

BUT

1. Make sure the arm isn't binding against the box. It should not rub when you turn the wheel. There should be a gap between the arm and steering box/seal.
2. I would also suggest you remove the nut and make sure that the nut/washer isn't binding on the splines before it clamps the arm into the splines. After removing the nut you will not be able to simply remove the arm. It should take a puller and a little force.

If the arm isn't binding and the nut is applying all that force to the shaft/arm spline mating you are good.

Here is a pic of it. The gap between the arm and the box is 5/8". I don't know if this would have anything to do with it or not but the 69 service manual calls for 120 ft. lbs. torque and the 73 manual calls for 175 (or 170) I believe. I went with the 120 because the box is a 69 unit.

It almost looks like you missed spline key slot.

No, it's lined up on the splines correctly. I was able to push it on by hand some before I started using the torque wrench.

That is a bigger gap than I am used to seeing on a mopar but it could be the new pitman arm is narrower inside than the old.

Do you have the old one to compare it to?
If so you could remove and compare the parts inside diameter with a caliper.

If the splines are correct and engaged. The nut is tight and all the threads of the nut are used.
You should be fine.

I agree though, it looks wierd.

Maybe take nut off and tap the arm on a little with a brass hammer? Does it look like it’s in alignment/free movement with the center link?

Yes, it all moves like it should. I had it all centered when I started tightening the nut but the pitman arm turned to full lock (as shown in the pic) while I was tightening it.

Is the bottom of the pitman arm flush with the splined shaft ? How's the angle of the centerlink , does it seem parallel under the pan ?

A little moly lube on the splines couldn't hurt anything either.

i like to use anti-seize.

With the quality of todays parts I might suggest removing the arm and checking /verifying the spline engagement AND taper with Prussian blue or Dykem keep us posted

Looks pretty much right to me. If the splines came through, the nut would tighten to the splines and not the bottom of the arm. All the ones I have worked on the nut was pretty much flush with the end of the threads when installed.

this is a good idea, siting the "quality" [or lack thereof] of parts today.

Update. I took the pitman arm off today. I measured the overall length of the steering box shaft (2 1/8"), the length of the splined part of the shaft (1 1/8"), the length of the threaded part (1") and the width of the pitman arm body (7/8"). I also measured the length of the threads that were exposed (5/8") after I took the nut and washer off but before I pulled the arm back off. After calculating everything, I'm coming up with only 1/2" of spline engagement when the arm was installed and torqued to spec. These are the calculations I used:

2 1/8" (overall length of shaft) - 5/8" (exposed threads with arm in place) - 7/8" (width of arm body) = 5/8" (unused splines at top of shaft)

then

1 1/8" (length of splined part of shaft) - 5/8" (unused splines at top of shaft) = 1/2" (of splines covered by arm when in place)


Should be more than 1/2" engagement, shouldn't it?

I wouldn't trust just a 1/2". Can you see why the arm won't go further on?

I don't see anything unusual. The splines on both the box and the arm look fine to me. I torqued it to the 1969 factory spec of 120 ft. lbs. because I'm using the original 69 steering box. But, being it is a 73-up style arm, I wonder if I should use the 73 spec. which I think is 170 lbs.? Just don't want to cause any damage to the steering box.

Here is a non-OEM setup, Borgeson specifically, but for what it's worth it shows the level at which the nut finished with a fair bit of room between the pitman arm and the box housing itself - which in this install is covered with a dust shield.

FYI - HERE is my thread on the pitman arm nut torque for that Borgeson install, for what it's worth.

How did the original arm fit? Was it the same way?

The original arm fit fine but it was the 69 style arm, not the 73-later type I bought to match the 73-later steering linkage I am using.

Curiosity question; why did you go to the 1973-later type rather than stay with the stock 1969? I have a 1969 GTS and am wondering what the advantage is of the later setup.

Must be a design mis-match somewhere between the two.

He changed the centerlink to the 73/up unit because I think he was having an issue with the pitman arm being close to header tubes and the centerlink hitting the pan ... the stud points down instead of up so you have to use the 73 up idler also .

Here is the thread ...

centerlink issue

Thanks, that makes it much clearer.

Yes, that was the reason.

I called Mevotech today and they won't do anything about it. All the woman would say is she agreed there is a problem with the arm but she doesn't know what. I said, there is only one thing it can be, obviously the i.d. of the splines is undersized but she made no offer of rectifying the situation. So, I'm going to have to eat the $40 I paid for it and get another arm.

did you measure the distance from each end of the steering link to the floor, presuming the floor and the car are level? Steering linkage is suppose to be a moving parallelogram
this is the real test to see if it is on far enough

Before assy on the car did you dress burrs off the mating surfaces?

Did you lubricate the splines?

Who did you buy it from ?

I'm surprised you got that attitude , When I called their customer service line , granted a year and a half ago , the guy I talked to was very helpful.

"did you measure the distance from each end of the steering link to the floor, presuming the floor and the car are level? Steering linkage is suppose to be a moving parallelogram
this is the real test to see if it is on far enough

Before assy on the car did you dress burrs off the mating surfaces?

Did you lubricate the splines?

Yes, yes and yes.


"Who did you buy it from ?"

I bought it on Amazon. The vendor name was USAutopartsCar.

Have you tried the prussian blue of machinist' dye suggested earlier? the taper of the splines may be the issue.
if you still have the old one, measure the thickness, and ID of the splines at the large and small ends and compare it to the new one. A local machinst may be able to hel you with the dimensions if needed

Might also just try a different brand from a local parts store. take your old one with you for comparison or look for an NOS one

kinda what I was thinking but I was wondering if the taper of the shaft is different between the years and not the arm itself? Trying another arm should answer that.

going to guess it's way past returning it ?

Yes, the return period from Amazon closed in mid January.

I'd do the Prussian blue check and then start some careful filing on the contact area of the pitman arm splines. With that taper, a little bit will gain you a lot.

Still think this is way over thinking this.

1/2 inch of spline engagement, seems about right to me. The splines can't come through and the total thickness is what 3/4?

I was just wondering this as I was reading. So, How thick is the pitman arm?