Loose Pitman Arm
 

I have a reballed Pitman arm that I bought from a vendor at a swap meet (remember those?) several years ago. When I began to install it I found that it is too loose even after cranking down hard on the clamp bolt. On one of the sector shaft flats I can insert a 0.008 inch feeler guage!

What is the best fix for this problem: shims, heat treatment followed by clamping the arm in a vice, or ...?

Re: Loose Pitman Arm
 

Usual solution is to mess with the bolt element rather than the arm. For example, are there threads left on the bolt or is the nut all the way down to the shoulder (thus preventing you from tightening all the way)? If the bolt has room left to go, another tactic is to remove a bit of metal from the pinch point on the arm (where the bolt goes through) which would allow you to tighten it further.

Re: Loose Pitman Arm
 

Is there still a gap where the bolt goes through? If so you should be able to tighten it up. I used a 3’ breaker bar to snug mine up. Those original bolts can take it.

Re: Loose Pitman Arm
 

A bit of anti-seize on the bolt would reduce the amount of torque needed, in case you don't have a three-foot breaker bar handy. :)

(This applies only to the case where the pinch points have *not* fully come together.)

Re: Loose Pitman Arm
 

My solution to this problem is:
>Widen the gap in the arm that the lock bolt squeezes;
>Shim the gaps that may exist between the arm and sector using steel sheet, not aluminum and not brass.

Re: Loose Pitman Arm
 

Hang tight and do not modify the Steering Gear (Pitman) Arm just yet. There were some reproduction Sector Shafts that did not have the correct ¹⁵⁄₁₆" size shaft. You need to measure your shaft to see if it measures 0.9375". The problem may not be your arm.

Re: Loose Pitman Arm
 

Just as a hypothetical, suppose he measures and the problem is the sector shaft. Is he likely to want to disassemble the steering column to replace it? Even if the arm isn't the part at fault, it's by far the easiest part to adjust.

Re: Loose Pitman Arm
 

Is it the safest way? :eek:

The square portion of the Steering Gear (Pitman) Arm was originally broached to be a direct fit onto the Sector Shaft with likely less than 0.004" of total clearance. I would need to verify on the print to confirm though. In essence, that equates to less than a thousandth on each of the 4 sides.

Take a look at my PDF illustration below. The corners of the Sector Shaft are relieved so there is not any binding stress in that area, and because the shape of the Steering Gear arm extruded area matches the shank of the Sector shaft, when the pinch bolt is tightened, it applies an equal mount of clamping force on all four sides. I have illustrated this with the red arrows to show the contact points.

Now if the shank of the Sector is less than the correct size, -and if just the pinch bolt area is relieved to allow it to clamp further, all it does is allow the Sector to be clamped in the two areas opposite of the pinch bolt, and by a very small margin at the top nearest the pinch bolt. With this small amount of contact surface, this area has the ability to wear quickly. Wear is what allows the Steering Gear Arm to become loose on the Sector shaft and cause 'shimmy' for the steering system. I trust this now makes sense why grinding the Steering Gear Arm is not the most prudent way to do this.

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Re: Loose Pitman Arm
 

Thanks to all that responded to my query! The sector shaft shank is fully up to the Ford dimension of 0.9375 inches and there is plenty of gap for the pinch so I am just looking at a sector arm that was broached a bit to far, with an I.D. of 0.951 inches. I will try really cranking down on the sector bolt with an extension ( how much torque can that 7/16 bolt take?) Failing that, I will proceed to making a shim from some 0.010 steel sheet that I have kept for those "just in case" situations.

Re: Loose Pitman Arm
 

A drop of oil on the bolt will make sure all that torque goes toward closing the gap instead of thread friction.

Re: Loose Pitman Arm
 

If the existing bolt fails, try a "Supertanium" bolt and nut.

Re: Loose Pitman Arm
 

Make sure your not running out of threads on the bolt before the arm squeezes down on the shaft

Re: Loose Pitman Arm
 

Well that is good news.

If you are still concerned, maybe put a small amount of Prussian Blue on each side of the shank, re-install the arm and then tighten the pinch bolt to see exactly what areas have pressure being applied.