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Rear Suspension Bushing Replacement
 
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Pelican Technical Article:

Rear Suspension Bushing Replacement

Tom Morr

Time:

2 hours2 hrs

Tab:

$10-$28 per bushing

Talent:

***

Tools:

Ratchet, sockets, combination wrenches; bushing R&R tool if available, possibly an M12 triple-square bit, bench vise or arbor press

Applicable Models:

Mercedes-Benz SLK230 (1998-04)

Parts Required:

Replacement bushings, grease

Hot Tip:

Freeze the new bushings

Performance Gain:

Clunk-free handling

Complementary Modification:

Replace shocks

Rubber bushings eventually wear out: ozone, oil and road grime degrade the rubber. Once the rubber cracks, the bushing's metal sleeve deflects beyond its designed range of motion. Vibrations from suspension movement are no longer absorbed. Metal-on-metal clunking sounds can result.

Although failing bushings can often be heard and felt, visual inspection verifies their demise. They can even be replaced on-vehicle in some instances using the professional (i.e., not inexpensive) bushing removal/replacement tool.

Most SLK owners will likely remove the suspension arms that have the faulty bushing(s). (Please see the dedicated how-to for arm-removal details.) Then the old bushings can either be pressed or cut out and their replacements pressed in.

Replicating the professional bushing tool is one approach to removal/replacement. Most of the R170 SLK's rear bushings' outer shells have approximately a 1.5-inch/38mm diameter. The theory is to push the bushing with something slightly smaller into something larger. Sockets or metal pipe are two pushing/receiving possibilities.

Temperamental bushings sometimes need to be cut out. Shops often use an acetylene torch. An at-home butane or propane torch will usually melt the rubber, but the metal sleeves will still need to be forcibly removed. Try soaking the area in penetrating lubricant and using the push/press method before you resort to using a saw.

Worn bushings are often obvious.
Figure 1

Worn bushings are often obvious. This rear knuckle control arm bushing has deflected beyond spec.

Viewed straight on, the worn bushing's inner steel sleeve is no longer concentric with the outer shell once its rubber cracks.
Figure 2

Viewed straight on, the worn bushing's inner steel sleeve is no longer concentric with the outer shell once its rubber cracks.

If the purpose-specific remove-and-replace tool is available, the bad bushing (arrow) can sometimes be swapped out on the vehicle.
Figure 3

If the purpose-specific remove-and-replace tool is available, the bad bushing (arrow) can sometimes be swapped out on the vehicle.

The pro removal/replacement tool has sleeves that are slightly larger and smaller than the bearing's outside diameter.
Figure 4

The pro removal/replacement tool has sleeves that are slightly larger and smaller than the bearing's outside diameter.

Even if the pro tool isn't available, one approach is to replicate it in the garage, squeezing the bad bushing (yellow arrow) out of the suspension arm.
Figure 5

Even if the pro tool isn't available, one approach is to replicate it in the garage, squeezing the bad bushing (yellow arrow) out of the suspension arm. As the nut is tightened on the R&R tool, the sleeve that's slightly smaller than the bushing (blue arrow) pushes the bushing out of the arm, into the larger sleeve (purple arrow).

The new bushing (yellow arrow) is centered in the suspension arm using a sleeve that abuts the outer shell but is larger than the arm's hole (blue arrow).
Figure 6

The new bushing (yellow arrow) is centered in the suspension arm using a sleeve that abuts the outer shell but is larger than the arm's hole (blue arrow). The female sleeve has similar dimensions as the "pusher" end but is contoured to grab non-smooth surfaces (purple arrow).

The key to success: freezing the new bushings (yellow arrows) overnight.
Figure 7

The key to success: freezing the new bushings (yellow arrows) overnight.

Once the old bushing is out, clean the mounting surface, smoothing with emery paper if available.
Figure 8

Once the old bushing is out, clean the mounting surface, smoothing with emery paper if available. Then apply grease to the area (arrow).

Also apply grease to the new bushing (arrow).
Figure 9

Also apply grease to the new bushing (arrow). Then press it in until it's centered in the arm/knuckle.

An arbor press is the preferred garage tool.
Figure 10

An arbor press is the preferred garage tool. However, bushings can usually be pressed in and out in a bench vise if the proper-diameter sockets, sleeves or pipe are available.

The occasional bad bushing that won't budge can be cut out.
Figure 11

The occasional bad bushing that won't budge can be cut out. Secure the suspension arm or knuckle in a vise. Use a reciprocating saw with bi-metal blade to slice through the inner sleeve and rubber. Score the bushing's outer shell with the saw or a rotary cutting tool, taking care not to gouge the suspension arm. Then tap out the bushing with a chisel or a socket that has a slightly smaller OD than the bushing.

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Comments and Suggestions:
carlos92 Comments: Can you guys please post a tech article of the front lower control arm bushing replacement. Please and thank you!
May 8, 2015
  Followup from the Pelican Staff: We don't currently have that tech article. If we get a chance to perform the procedure, we will be sure to document it.

I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 

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