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Rear Knuckle Wheel Carrier Removal
 
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Pelican Technical Article:

Rear Knuckle Wheel Carrier Removal

Tom Morr

Time:

3 hours3 hrs

Tab:

$0

Talent:

***

Tools:

Ratchet socket set, combination wrenches, 30mm socket, M12 triple-square bit, hex Allen wrenches/bits, breaker bar

Applicable Models:

Mercedes-Benz R170 (1998-04)

Parts Required:

None (unless knuckle is broken)

Hot Tip:

If available, use a spring compressor

Performance Gain:

Removal allows other components to be serviced replaced: axle shaft, wheel bearing, suspension arms and bushings

Complementary Modification:

Check rear suspension bushings, replace as necessary

Rear knuckles normally don't fail, unless they're subjected to blunt-force trauma. However, many rear-end service operations required removing the rear knuckle, also known as the wheel carrier.

The average Mercedes-Benz owner might not have a couple of the tools required to remove the R170 SLK's rear knuckles. These include a 30mm socket for removing the axle shaft's collar nut and an M12 triple-square (12-point) bit for the bolts that connect the suspension arms to the knuckle.

If you have access to a spring compressor, consider using it. Normally, the knuckle and suspension arms work with the shock absorber to contain the coil spring's considerable energy. With the knuckle removed, the entire spring-containment load falls on the shock absorber. Using a floor jack or a jack stand under the suspension's spring control arm is an alternate insurance policy.

The bulk of the job involves removing all the components outboard of the knuckle. These include the caliper and rotor, emergency-brake drum assembly, wheel speed sensor, and axle shaft nut. (Please refer to our articles on those components for details). Removing the hub/spindle can be the most difficult part of the job. Unless the wheel bearing is being replaced, time can be saved by leaving the hub and backing plate attached to the knuckle.

Once the knuckle is free, various other wear parts are accessible. These include the wheel bearing and the suspension bushings. Details on replacing those components are covered in other articles.

Knuckle re-installation reverses the disassembly steps with one exception: the camber strut is installed first. To restore rear wheel alignment, jack up the suspension until the axle shaft is horizontal prior to final-torqueing the arms' fasteners. And if the knuckles are damaged, Pelican Parts offers factory-new replacements: 202-350-94-08-MBZ left, 202-350-95-08 right. At time of publication, each knuckle retailed for $820.25.

Begin by jacking up the car and securing it on jack stands.
Figure 1

Begin by jacking up the car and securing it on jack stands. A 30mm socket is necessary for removing the 12-point collar nut that secures the axle shaft to the wheel hub.

Remove the parking brake shoes.
Figure 2

Remove the parking brake shoes.

Use metric hex/Allen wrenches/bits to remove the cap screws that hold the wheel speed sensor (red arrow) and e-brake cable support bracket (yellow arrow) to the knuckle.
Figure 3

Use metric hex/Allen wrenches/bits to remove the cap screws that hold the wheel speed sensor (red arrow) and e-brake cable support bracket (yellow arrow) to the knuckle.

If the wheel bearing isn't being replaced, the hub and backing plate can remain attached to the knuckle.
Figure 4

If the wheel bearing isn't being replaced, the hub and backing plate can remain attached to the knuckle. (We removed them for the wheel bearing replacement article.) The various suspension arms' bolts take an M12 triple-square (12-point) bit (red arrow). First off -- and first on during reassembly -- is the camber strut (yellow arrow). It connects to the knuckle's 12:00 boss. Its nut takes an 18mm wrench. 

Next remove the torque strut (arrow), which bolts to the left knuckle's 11:00-ish boss.
Figure 5

Next remove the torque strut (arrow), which bolts to the left knuckle's 11:00-ish boss. It also takes an M12 triple-square bit on the head and an 18mm wrench on the nut.

The same bit and wrench are used for the thrust arm (arrow).
Figure 6

The same bit and wrench are used for the thrust arm (arrow). This arm bolts to the left knuckle's 7:00-ish boss.

Use a 17mm wrench to unbolt the tie-rod (arrow) from the knuckle.
Figure 7

Use a 17mm wrench to unbolt the tie-rod (arrow) from the knuckle.

The knuckle can now be pivoted outward and downward.
Figure 8

The knuckle can now be pivoted outward and downward. This allows the axle shaft's splines (arrow) to be slid out of the wheel bearing (and wheel hub if it is still attached).

The final bolt connects the knuckle to the spring control arm (red arrow).
Figure 9

The final bolt connects the knuckle to the spring control arm (red arrow). The head is 22mm; the nut is 21mm. For peace of mind, we installed the Mercedes-specific internal spring compressor (yellow arrow) so that the shock wouldn't have to control the spring's downward pressure by itself. Then we pulled the bolt and removed the knuckle.

Bearings and bushings can be replaced once the knuckle is loose or completely removed.
Figure 10

Bearings and bushings can be replaced once the knuckle is loose or completely removed.

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