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Installing a Pitman Arm Correctly

4x4 repairs how-to

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#1 Moses Ludel

Moses Ludel

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Posted 28 October 2013 - 09:02 PM

The steering gear and linkage are vital safety concerns—yet the pitman arm on a 4WD Jeep or other light 4x4 truck can easily be installed incorrectly. With the popularity of oversized tires and suspension lift kits, many pitman arms get replaced long before there is a parts wear issue. A dropped pitman arm is often part of a suspension lift kit, and the pitman arm on a new or relatively new vehicle may get replaced with a dropped arm.

 

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Here are some procedures that I use when installing a pitman arm:

 

     1) Never turn the arm against either of the steering gear's extreme left or right turn positions. Force against the gear in these positions can damage the steering gear internal parts—the gear is not intended to absorb this kind of force at either end of the worm or ball nut's travel.  I like to keep the steering gear and pitman arm close to the center or straight-ahead steering position during pitman arm removal and installation.

 

     2) When removing the pitman arm nut on a typical steering gear, there is a lot of force required.  It is easier on parts to use an air impact gun and socket to remove the nut, as there is less tendency for the pitman to rotate...If you have the steering gear removed from the vehicle, consider holding the arm in a large bench vise (with the gear assembly free) while loosening or tightening the nut.

 

     3) Once the nut is removed, use the correct pitman arm puller tool to prevent damage to the steering shaft and other parts. Make sure the tool fits properly between the backside of the arm and the neck of the steering gear housing, with enough clearance to prevent damaging the housing/casting!

 

     4) There is considerable force with the pitman arm secured on tapered splines, so use extreme caution with the puller tool. Once the initial tension relieves, the arm will come off readily.

 

     5) Clean up the sector shaft splines as needed. It is critical that the new pitman arm fits properly, an interference fit that demands clean mating surfaces. If installing a powder coated aftermarket pitman arm, I always use a suitable drill motor-powered wire brush to remove the powder coating from the tapered seat and splines of the new pitman arm. (I remove paint here, too.) Don't damage or dull the spline teeth in the process!

 

Warning: If you mate a powder-coated part at the splines, you will get a false torque reading. There is a high likelihood that the pitman arm will loosen at the splines as steering force wears through the powder coating.  If you have a powder-coated arm already installed, and if the arm has been in service, re-check the nut torque with the pitman arm in the straight ahead steering position.

 

     6) Always use the required torque wrench and socket to bring the sector/pitman nut to proper torque.  Again, make sure the arm is near the straight ahead steering position to prevent damaging the steering gear. The torque required is high, especially on a recirculating ball-and-nut power gear, much more than on a light-duty vintage Jeep cam-and-lever gear! Do not second-guess the torque setting. Use a factory or professional shop manual to determine the correct torque for the pitman/sector nut on your steering gear.

 

     7) When reattaching steering tie-rods, make sure they are clean and free of debris. If the outer end of the new pitman arm has a tapered seat with powder coating or paint, I use a drill motor-powered wire brush to remove the powder coating and take the tapered seat to bare metal.

 

     8) Attach a clean tie-rod ball stud to the pitman arm tapered seat, using the correct type nut (typically castellated or flanged self-locking) that comes with the tie-rod end. Flanged, self-locking nuts are often one-time use only. Consult the factory workshop manual for recommendations on replacing fasteners or use of thread locking liquid. Always use OEM grade hardware and fasteners.

 

     9) Align steering joints, adjusting sleeves and tie-rod ends so that the ball studs are on center with the steering linkage aligned. Make sure none of the joints bind or run out of travel over the full range of steering turn positions and angles. Make sure that parts do not interfere with each other.

 

     10) I always recheck the torque on the pitman and tie-rod fasteners after a short time in service. This is a safety precaution that may catch a part requiring a slight re-torque. 

 

Again, this is all about safety. Use of oversized tires places an even bigger load on these parts...

 

Moses


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#2 biggman100

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Posted 10 December 2013 - 12:29 PM

Moses, i know this one has been on here awhile, but after what happened to a friend on his ford the other day, i have one other bit of advice to add to this. When you take the old pitman arm off, mark it in relation to the steering box, and make sure the new one goes on the exact same spot as the old one. I know this may seem like common sense, but the other day, my neighbor did the one on his 1995 F-150, and somehow the wheels got turned while the old pitman arm was off, and instead of realizing that, he just lined up the pitman arm so it would go back on the steering box, and into the hole in the center shaft, which in turn caused the steering wheel to be way out of position, and caused his air bag to go off while he was driving. Another bit of advice, make sure the steering wheel is locked in the center position, and take the keys out of the ignition so the steering wheel cant turn.


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#3 Moses Ludel

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Posted 10 December 2013 - 03:59 PM

Very good comment, Biggman100.  Most pitman arms and sector shafts are indexed with a "tooth flat" or similar method, but some, especially older steering gears, do not always have that provision.  Sometimes, there are multiple notches, and the pitman might fit the sector splines in more than one position. 

 

Critical is that the steering gear is on its precise center position when the front wheels and tires point straight ahead.  Some of this is accomplished with steering linkage adjustment, especially on IFS vehicles with an idler arm and steering center link. 

 

Regarding your suggestion that the steering gear get locked in position with the steering column lock, I have a concern here.  If the installer torques the pitman nut with full force against the column lock, damage to the lock mechanism can occur.  The safest bet is to index the pitman in the straight forward position and mark the steering sector shaft with a yellow "parts marking" pen, which you can get from NAPA and other sources. 

 

If the gear gets off center during work performed, you can gently turn the gear from left to right extremes (do not put pressure on the gear at the steering extremes, or the gear can become damaged) and carefully count the turns.  Divide the lock-to-lock turns by 2, then turn the steering wheel and sector shaft back to center by rotating the steering wheel from either extreme to center (one-half the total lock-to-lock turns).  This should be very close to your original position if the front wheels point straight ahead.

 

Never "center" the steering by repositioning the steering wheel on the steering shaft—unless the steering wheel is already off-center with the steering gear from earlier, improper work performed on the vehicle.  Always use the steering gear's actual midpoint or center position as a guide and reference point for front wheel and steering wheel alignment.

 

Always center the steering wheel by first placing the steering gear in its center/straight ahead position.  Then place the steering wheel onto the steering shaft, aligned for straight ahead...There may be an index point for the steering wheel-to-steering shaft.  Some systems have a notch or other means for placing the steering wheel on the shaft correctly.  With the steering wheel on the steering shaft correctly, look at the steering linkage to determine whether slight steering wheel centering, with the front wheels aligned and pointed straight ahead, can be accomplished with the steering linkage adjuster sleeves.

 

In my original post, point #6 emphasized that the pitman arm needs to be near the center position of the steering gear when torqueing the nut into place.  When I'm rebuilding a steering gear, I hold the pitman arm in a soft jawed vise (with the gear suspended) and torque the nut.  All force goes into the pitman arm and not against the steering gear internal components.

 

If the steering gear is on the vehicle, I set the wheels straight ahead with the pitman and nut in place but not torqued completely.  Making sure the front wheels stay forward with the vehicle's weight on them, I torque the pitman nut to specification without the arm moving the steering gear to either extreme.  Like the steering column lock, the gear can become damaged by forcing its internal ball nut to either extreme.

 

When you have a very accurate air wrench/gun and know its torque settings, it is often easier to use the air gun to tighten the pitman nut, then verify torque with your torque wrench as I describe.

 

Moses





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