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Power Steering Rack Replacement
 
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Pelican Technical Article:

Power Steering Rack Replacement

Nick Czerula

Time:

4 hours4 hrs

Tab:

$300

Talent:

*****

Tools:

Set of sockets (13, 15, 16, 19mm) wrench set, hammer

Applicable Models:

BMW Z4 Convertible (2003-06)
BMW Z4 Coupe (2006)

Parts Required:

Power steering rack, power steering fluid, tie rod ends

Hot Tip:

Drain power steering fluid before beginning

Performance Gain:

Repair steering rack leaks

Complementary Modification:

Install new tie rod ends

The power steering rack connects the steering shaft to the drive wheels. It has hydraulic assist, using fluid supplied from the power steering pump to decrease steering effort. Over time the power steering rack bushings can wear, causing a clunking noise in the steering. Or the most common issue, the rack seals fail, causing power steering fluid leaks.

Known as power-assisted rack-and-pinion steering, rotating the steering wheel spins a small pinion gear, thus sliding a toothed rack left or right. The ends of the rack attach to tie-rods which steer the front wheels. A hydraulic pump, powered by the engine accessory belt, forces steering fluid into hoses leading to pistons in the steering rack. A hydraulic valve in the steering rack varies the hydraulic fluid pressure in the two cylinders, dependent on how fast or forcefully the pinion gear is rotated. This multiplies the driver's force in steering the wheels.

When purchasing a rack, you will likely have the option of buying it with new tie rod ends attached. I prefer to go this route. It makes fighting with the old tie rod ends a non-issue and freshens up all of the steering components. Once complete, you will have to have the vehicle aligned. You can eye ball the tie rod ends and get it close, but I would not suggest driving it further than the few miles needed to have it aligned.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Raise and support front of vehicle on jack stands. See our tech article on jacking up your vehicle.

Remove front wheels.

Remove the power steering fluid from the reservoir using a suction pump.

This photo shows the power steering rack (purple arrow) and the tie rod end (red arrow).
Figure 1

This photo shows the power steering rack (purple arrow) and the tie rod end (red arrow). The good news is the rack is easy to access on BMW Z4 models.

Working at the left side tie rod end, remove the 16mm mounting nut (red arrows).
Figure 2

Working at the left side tie rod end, remove the 16mm mounting nut (red arrows). If needed, once you remove the tie rod from the steering knuckle, remove the tie rod end boot, then remove the tie rod end from the rack. You will not have to do this unless your new steering rack lacks tie rod ends. See our tech article on tie rod end replacing.

Using a hammer, tap area of steering knuckle where tie rod end connects to break the connection.
Figure 3

Using a hammer, tap area of steering knuckle where tie rod end connects to break the connection.

The tie rod end will drop out once free (red arrow).
Figure 4

The tie rod end will drop out once free (red arrow). Repeat the previous steps for the right side of the vehicle, disconnecting that tie rod as well.

Now it is time to remove the steering shaft from the power steering rack.
Figure 5

Now it is time to remove the steering shaft from the power steering rack. Working above the left side subframe, near the corner of the oil pan and the engine mount (purple arrows), remove the E10 External Torx pinch bolt (red arrows). Once it is removed, secure the steering wheel so it does not move. If the steering wheel rotates with the steering rack removed, the clock spring may be damaged.

Then, remove the steering shaft coupler from the steering rack by sliding up and off.
Figure 6

Then, remove the steering shaft coupler from the steering rack by sliding up and off. If it will not come off but slides a little, lever it off using a prybar (red arrows). Be gentle, don't damage it.

Later, when reinstalling the steering shaft, be sure to align the split in the shaft coupler (purple arrow) with the plastic tab (red arrow) on the rack.
Figure 7

Later, when reinstalling the steering shaft, be sure to align the split in the shaft coupler (purple arrow) with the plastic tab (red arrow) on the rack. This will properly align the two.

Next, you have to remove the power steering line connections to the rack.
Figure 8

Next, you have to remove the power steering line connections to the rack. Using an 18mm (red arrow) and 22mm (purple arrow) socket, remove the banjo bolts. Be sure the sealing washers come off with bolts and are not misplaced. These washers should be replaced when the new rack is installed.

Working at the rack, remove the 10mm hose loop mount (red arrow) fastener.
Figure 9

Working at the rack, remove the 10mm hose loop mount (red arrow) fastener.

Lift the hose loop up (red arrow) and place it out of the way.
Figure 10

Lift the hose loop up (red arrow) and place it out of the way.

The rack should be ready to unbolt and remove out at this point.
Figure 11

The rack should be ready to unbolt and remove out at this point. Remove the two 16mm mounting bolts (red arrows). You will have to counterhold the nuts at the top of the rack when removing these bolts.

For the right side fastener, you can fit an open end wrench (purple arrow) through the opening at the top while removing the bolt (red arrow).
Figure 12

For the right side fastener, you can fit an open end wrench (purple arrow) through the opening at the top while removing the bolt (red arrow). The left side is a little tighter, you will have to go in at a similar angle from the left side, through the area of the line connections to the rack.

Once the rack is unbolted, slide it out of the subframe to remove (red arrow).
Figure 13

Once the rack is unbolted, slide it out of the subframe to remove (red arrow). Be sure the steering coupler and shaft are not attached as you slide it out. Guide it out, checking for snagged power steering lines. Once the old rack is removed, compare the new part to confirm it is a match. Then install new rack into subframe and install fasteners finger tight. Attach steering coupler, then tighten rack to subframe mounting bolts. Then tighten steering coupler bolt. Attach and tighten power steering lines to the rack. Then attach tie rod ends to the steering knuckle. Reassemble remaining items and have vehicle professionally aligned. You will have to fill and bleed the power steering system. See our tech article on power steering pump replacing for bleeding information.

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Page last updated: Sat 12/3/2016 03:03:14 AM