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Pelican Technical Article:

Replacing the Pitman Arm

Mike Holloway

Time:

2 hours2 hrs

Tab:

$25 to $200

Talent:

**

Tools:

10mm, 24mm socket wrench, floor jack, jack stands, wheel chocks, safety glasses, lug wrench, torque wrench

Applicable Models:

Mercedes-Benz R107 (1972-80)

Parts Required:

Pitman Arm

Hot Tip:

Use plenty of penetrating oil

Performance Gain:

Better handing, less vibration, smoother ride, and increased tire life

Complementary Modification:

Replace idler arm bushings, replace shock absorbers, realign tires

As you turn your steering wheel, a steering column shaft rotates in the steering column. At the other end of the steering column is the power steering gearbox. This power steering gearbox changes the rotating motion of the steering column shaft into a side-to-side movement of the Pitman Arm. The Pitman Arm is connected to a center link. This center link connects the left side of the tie rod ends to the right side tie rod ends. This maintains the alignment of the left and right side wheels during turning maneuvers. The center link has ball joints on the end of it to flex with steering inputs. Over time the ball sockets can wear out. This allows the inner and outer tie rod ends to move around and allows small deviations in front wheel alignment. This can cause handling problems, steering wheel vibrations and uneven tire wear. In this tech article I will go over the steps to remove the center link.

Pitman Arms connect to the steering gear on a recirculating-ball steering system and transmit the force from there to the center (drag) link. They connect by way of the ball joints and also support the center (drag) link. The Pitman Arm does not have many parts. It is a sturdy part of the steering system. Some common problems include rusting and a compromise of the plain bearing that connects the center link can wear out. When the ball joint wears out, steering can become loose and will continually deteriorate until it needs to be replaced. You will want to replace both Pitman arms.

Lift and support your vehicle. See our tech article on lifting and supporting your vehicle. While you are under your vehicle have an assistant turn the steering wheel back and forth 45° with the ignition key on but the engine not running. Watch the center line link and inner tie rod end and see if you can see the idler arm move around in the frame mount. If the bushings are worn, you will notice the play between them. If you grab on to the tie rod and the tie rod, move them back and forth to feel if there is play. If they seem loose the bushings may be compromised. In this tech article I will go over the steps to replace your idler arm bushings.

Remember your car may have been serviced before and had parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts I give may be different from what you have so be prepared with different size sockets and wrenches.

Before you do any work on your car it is important that you wear safety glasses and work gloves. If you have to jack up your car, make sure to use jack stands and chock your wheels as well as applying the parking brake. Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. Never work on your vehicle if you feel the task is beyond your ability. Always disconnect the battery before working on your car.


Lift and support the front axle of the vehicle.
Figure 1

Lift and support the front axle of the vehicle. Place a jack stand under the lower control arm. You have to remove the tires to perform this job, which makes access much easier since you may not have the use of an automotive lift. See our tech article on jacking and supporting your vehicle and removing the front tires. 

I placed a jack stand under the chassis as well.
Figure 2

I placed a jack stand under the chassis as well. The procedure to replace the Pitman Arms is the same for both the left and right sides. These pictures are of the passenger side of the vehicle. It is recommended you replace both sides at the same time to keep your handling neutral. Placing a jack stand under the chassis provides additional safety.

This is the Pitman Arm.
Figure 3

This is the Pitman Arm.

Using a 24mm socket, loosen and remove the top bolt on the idler arm.
Figure 4

Using a 24mm socket, loosen and remove the top bolt on the idler arm.

Using a 23mm, loosen and remove the bottom bolt loosening the idler arm.
Figure 5

Using a 23mm, loosen and remove the bottom bolt loosening the idler arm. The bushing can now be replaced.

Using a 10mm socket, loosen and remove the Pitman arm from the exhaust manifold.
Figure 6

Using a 10mm socket, loosen and remove the Pitman arm from the exhaust manifold.

If you decide to realign your wheels, the following are the specifications:

Camber (degrees): 0 degree +10' -20'
Caster (degree): 3 degree 40'; +/_ 20'
Toe-in (in): 0.04 - 0.12

Replacement is the reverse of removal. 




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Page last updated: Fri 12/9/2016 03:05:18 AM