Pitman Arm (Power Steering)

[M882]

About 5 months ago I purchased a M882 with 17,400 miles on it. Its got its share of dings but very little rust. Was owned by a volunteer fire department in central Indiana. Recently I had the manual steering gear go out. Rather than replacing it, I am trying to convert it to power steering. I have the new p/s gearbox, but I cannot find a pitman arm to fit. I haven't had any luck with the junkyards in my area yet. Anyone know if a Ford arm would work? Or maybe where I could find a new one, haven't had any luck there either.

Thanks

 

[N1265]

I am wondering why the pit man arm from the manual box does not fit the power streering box ?

These P/S boxes were used for many years and should be pleantifull in the junk yards...

 

[M882]

pitman arm

Thanks for the comment. That is what I thought, but the shaft that the pitman arm connects to is slightly larger on the p/s gearbox. It is my understanding that the gearbox was only used from 72-77. I was wondering if any other manufacturer used a pitman arm that might work.

 

[N1265]

The P/S box on my truck came from a 1979 RamCharger, ( I Pulled it off myself at a local junk yard)

if I remember right, Dodge used these Saginaw boxes
( reverse rotation ) up to 1990. I really don't know if the same box was used for other companies, Maybe the old Jeep J-10s

Here is a picture, Hopefully you have the same box...

 

[Avn-Tech]

M882,

A machine shop should be able to enlarge hole and respline it to fit. Or find a pitman arm that fits the spline and make the other end fit the truck.

Laterrrr
Avn-Tech

 

[M882]

Thanks to both of you for the info....my steering box appears to be the same.

 

[Bob H]

While I am not familiar with ramchargers.
75 thru 77 4x4 trucks have the reverse rotation, different setup than the 78 I have or 79 I had.
The PS pitman arms are not available new (that I know of)
Junk yards look to be your best bet.

 

[M882]

Thanks Bob, you're right about not selling any new ones. It seems as though you can get a new pitman arm for any other vehicle from the era, though. The only other trucks that I have found that used the same style gearbox were a few International models from the late 60's to the mid 70's. I thought maybe they had a similar pitman set-up but I could not find the part that International used either. I'll keep checking the junkyards.

 

[nattieleather]

Hate to bring an old thread up, but I was wondering if anyone with the reverse rotation PS gear box could take some messurements of the pitman arm. Length, width, drop distance, hole sizes and spline count that would be very helpful. I am trying to locate a replacement one or maybe even a universal one and if I have that information it will help. If I do find one then I will post the results so anyone wanting to make the change in the future will be able to look it up.

Thanks,
Joe

 

[gringeltaube]

M880 Pitman arm, mod. to fit PS-Box

Attached are some pics + dimensions from the original one, as it comes on the manual box -maybe this helps as well?

The splined hole size shown in the drawing would be for the larger power steering pitman shaft.
Whatever you find out there needs to have the 4 coarse splines correctly indexed (= 20º CCW); besides being about the same C-C length and drop, to maintain correct st. geometry.

It would be very difficult to impossible to find one in my area so one needs to be creative: re-use the stock arm and just modify the hole accordingly...
BTW, getting that arm to fit on a PS box is easier than one would think. It requires no machining at all, just simple tools and an old shaft out of a worn- out PS-gear.
Detail pics showing correct fit and arm ready to mount. (Sorry, no soldier B available, to take pics during the process...)

G.

 

[nattieleather]

Gringeltaube...thanks for the info. I will see what I can find with this information and if I do find anything I'll let everyone know.

 

[Bob H]

I believe the only difference is the spline size.
1st pic 76 PS
2nd 77manual (sorry about poor pic)

 

[gringeltaube]

I believe the only difference is the spline size.
.........

I agree.
Attached another pic, for comparison....

G.

 

[MrFusion]

I realize this is a really old thread but what exactly did you do to fit the MS pitman arm on the PS box? Did you take the old PS shaft and just pound it into the pitman arm then pound it back out or did you file the splines on the pitman arm with a triangle file just a little bit? Thanks.

 

[gringeltaube]

... take the old PS shaft and just pound it into the pitman arm then pound it back out...

Almost that easy; think of what a blacksmith does - or would do in this case...

Besides a 10-pound hammer and an anvil with a 30mm hole in its top face (or any suitable heavy piece of steel to support our workpiece), we need two tools: First one is a piece of 1-1/8" round steel, turned down on the lathe to conical shape. Same taper as the original shaft and the smaller end barely protruding when stuck into the original MS arm.
Second tool is the already mentioned, splined shaft out of an old PS box.

Then comes the forge (or a good torch instead), to apply heat to the splined end of the arm, until it turned cherry-red. Quickly insert tool #1 and give it a few good blows with the hammer. Then knock it back out, heat up again, and eventually repeat process until the splined end of the second shaft (tool #2) barely fit. Now continue in the same way until the splines went in, almost all the way through. Stop at 2mm from being flush with the backside of the arm. (2nd pic, post #10)

The pitman arm is just forged steel. Once red-hot (and soft) it can be reshaped as desired without really compromising its mechanical properties. Still, I'm only telling what I do...but not really recommending this!

As always: OFF-ROAD USE, ONLY!


G.

 

[MrFusion]

Thank you for the info sir! The application I need it for is an on road truck. If I can find a machine shop locally I might see what they would charge me. I'll use your method as a last resort though. I have most of the tools necessary to do the job. And it might be the perfect excuse for me to build a forge! I've been toying with that for awhile.