Baffled F100 Pitman arm dia smaller than sector shaft!

It was a long day and I wasn't expecting this!

I'm fitting an F100 steering box to a Model-A. It's all shortened up and reflanged and sits in there nice and tight.
The sector shaft is 1 1/4" diameter. I'd purchased a '57-'60 Pitman arm for the tierod end hole at the end instead of a ball but the sector shaft hole in the Pitman arm is too small. About 1 1/8". There's no way it'll stretch over. Both look right though with the 10 or so splines at the bottom and the pinch bolt up top.

What's wrong? What kind of Pitman arm have I got? I though 50s F100 boxes were mix and match compatible.

Cheers

Ed

 

Econoline is similar but smaller. Are there any numbers/letters forged on the thing?

 

My first thought was are you sure you have an F100 box and not an F1?

 

57-60 f100 boxes are different. You aren't seeing things. When most refer to "F100" for steering, they mean 53-56.

 

That's odd, something is mismatched. I am running a couple of 54-56 boxes with 57 arms on them and they fit like a glove.

Don

 

Factory Ford pitman arms should have the part number on them, something like BAAA-3590(-and maybe a suffix letter). 3590 is the Ford generic number for pitman arms, prefix gives year started/modified, suffix indicates later version or separate version.

 

If you have the right parts they should look like these. Is the gap at the top of your pitman arm opened up like this one ?





Don

 

yup

 

The gap in the arm is open. Is a 57-60 sector shaft a smaller diameter than 53-56?
Or is my pitman arm maybe not F100 at all?


Twitter @edsrodshop

 

53-56 pitman arms have the ball end, 57-60 look the same but with a tierod hole.

If you need a 57-60 arm, pm me!

 

That seems to be the case, that what you think is a 57 type arm is something else. The picture I posted is of a 56 box with a 57 arm to get the tie rod end, and it fits right on.

Once you get the correct arm you will be fine.

Don

 

x2 on econoline arm. i bought one many years ago for my '55 f-100 box. it looked perfect but the hole was a little too small.

 

About 7/8 life size...

 

If the 57-60 box has the same shaft size whereas the arms are interchangeable, then he has a later pitman arm. My 57 had a 63 box in it. I sourced a 57-60 box and swapped them out. To my surprise, the 63 arm would not fit, just like you describe. You must have a later pitman arm.


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