How to – Repair faulty/failing ABC Strut top rubber mounts

On 215’s and 220’s the top of the abc strut comes loose from the top of the rubber mounting, as can be seen in this picture:

This is with the car jacked up so the wheel is off the ground. You can see that the strut has seperated from the top mount and is hanging down, from the top of the strut mount.

From the engine bay, you should be able to see this gap at the top of the strut:

P1020389-001

If this gap closes up when the car is jacked up them the rubber top mount has failed. It creates this kind of play in the system:

As you can imagine, this gives about 15 mm play in the shock mounting which isnt great for bigger potholes or undulations in the road that allow the strut to drop and then move back up again with the wheel as opposed to actually doing some damping.

The ideal solution here would be to re-bond the top of the strut with the bottom of the top mount, but I dont think there will be anything reliable here, so instead we are going to add a bush to the top of the strut mount, underneath where the strut travel sensor connector is.

To do this you will need:

  • 10mm rubber sheet (mine was 10cm squared and was plenty.)
  • 35mm Pin spanner (an adjustable one is not strong enough, it must be fixed)
  • A whole saw.

I got all the bits I needed on ebay for less than £25.

Firstly, remove the connector for the strut travel sensor. You must be carefull with this as if you damage it, you will need a new strut! Squeze the outside connectors with some pliers, and pry up gently, it will click and lift straight out:

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Once you have this off, use the pin spanner in the wholes on the top mount, they are quite shallow, so if you have an ill fitting pin spanner, you may need to drill them through to get better grip. Luckily on mine I was able to remove them without drilling the holes.

This must be done with the car on the ground, as you want the weight of the car pressing on the struts. You also must ensure that only the top mount bush rotates and not the strut itself! If the strut rotates you will damage the hydralic line and fitting.

Once off, you will have this:

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Grab a 35 mm hole saw (I think this is what I used, but do measure) and cut a disc shaped piece out of the sheet of rubber:

150122-IMAG0782

 

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I used a cardboard box as the base for cutting, which allowed the rubber sheet to curve slightly, giving my disc these odd diagonal edges, but this isnt a problem.

Drill out the center of your disc using a 20mm hole saw, it has to be bigger than the whole in the original bush, as there is a small lip on the strut itself, It must sit below this:

150122-IMAG0786 150122-IMAG0787

 

Now go back to the car and insert the bush over the top of the strut and then screw the original top bush/stop back on, you want to sandwitch the bush between the car mount and the top bush/stop. You must ensure you get the top strut back on enough so that the level sensor can clip back on. Mine ended up a tad squished, In the future I would use a bit of silicon spray on them whilst fitting to prevent this.

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7 thoughts on “How to – Repair faulty/failing ABC Strut top rubber mounts

  1. Pingback: DIY: How to faulty/failing ABC Strut top rubber mounts - MBClub UK - Bringing together Mercedes Enthusiasts

  2. Pingback: DIY: How to change ABC Accumulators - Page 2 - MBClub UK - Bringing together Mercedes Enthusiasts

  3. Pingback: Odd ABC problem - MBWorld.org Forums

  4. Many thanks for the detailed posts you have made public. Following your instructions, I was able to do a full ABC system flush – something I will be doing frequently (Yes a dirty system leads to early breakdown). I added to the ABC suspension and power-steering system, Xado’s hydraulic additive. So far so good.
    I bought a 2003 Cl500 because of its design lines, engine and because I absolutely LOVE mechanical engineering (and the unbelievably low second hand price). I do all my mechanical and electrical repair on my cars, and with this car I’m getting good at hydraulic suspension diagnostics/repair work. LOL.
    Never driven or sat in a CL before, so I don’t really know how the car should ride. I believe you have a CL an SL and you’re also a fan of ABC- lucky you.
    I live in Oxford UK and would appreciate a possible invitation to your place to chat on cars bikes engines, grease and oil. Sorry I don’t do Tea only Coffee (black with sugar). LOL
    Many thanks (on behalf of all your site visitors) for all your postings.
    Kind Regards Simon

  5. Was the rubber you purchased for the strut repair Neoprene? Do you remember the sturdiness of it (soft or hard)? How is the repair holding up? I want to do this job and don’t want to purchase the wrong thing.

  6. Pingback: cl500 2000 w215 front strut mounts - MBClub UK - Bringing together Mercedes Enthusiasts

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