Modification Modification
Car: Mercedes-Benz | CLK | W209 | Avantgarde | Coupe
Engine: CDi | 0 | Inline 5 | (170 BHP) | Turbocharged | Diesel

CLK upgrade to Sport specification

I love the W209, it has such classic lines. I purchased a 2003 270 CDi Avantgarde with 2 owners, 27k and FMBSH. It was in great condition but I wasn't happy with the overall look; it didn't really fit in with my age group (mid 20's) so I commenced a project to give the car a more sporting appearance and raise the equipment level

This article documents the many changes I made to the standard car.


CLK upgrade to Sport specification CLK upgrade to Sport specification CLK upgrade to Sport specification CLK upgrade to Sport specification CLK upgrade to Sport specification


CLK upgrade to Sport specification CLK upgrade to Sport specification CLK upgrade to Sport specification CLK upgrade to Sport specification CLK upgrade to Sport specification CLK upgrade to Sport specification CLK upgrade to Sport specification CLK upgrade to Sport specification

Interior features

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The project started with the simple addition of AMG mats (far right) from a Sport model, which are available in Black or Grey.

I also fitted a set of AMG pedals (right) which push on in place of the existing black rubber covers.

© Mark Stewart, Friday 28th November 2008

C/CLK Sport/AMG Brake Retrofit


The majority of non-V8 W209 CLK's and W203 C Class cars come with 288mm or 300mm front discs and cast iron single piston sliding calipers (right), which in my opinion are marginal for the weight of these vehicles, especially the larger diesel and 6 cylinder petrol models. A simple upgrade is to move to the W203/W209 Sport Package brakes, or even AMG versions.

Upgrade options

This article concerns the front brakes as the CLK comes with at least 290mm rear discs which provide adequate balance for even the 350mm front package. C Class often has 278mm which is an adequate match for the 330mm front upgrade.

Front: 2 piston, 330mm | Rear: 2 piston, 290mm

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2 opposed piston calipers constructed of Aluminium. These are typically grey with 'Mercedes-Benz' lettering on the outside face between two large external Torx bolt heads. Discs are 330mm and perforated.

This package is fitted to Sport Package vehicles. 17" wheels required.

Front: 4 piston, 345mm | Rear: 2 piston, 300mm

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4 opposed piston calipers constructed of Aluminium. Silver in colour with black '/////AMG' lettering (CLK55), or plain grey. Four external type Torx bolt heads on front face. Discs are 345mm and perforated.

These are fitted to 2002-2004 CLK55 and large capacity models (350, 320 CDi). 17" wheels required.

Front: 4 piston, 350mm | Rear: 2 Piston, 300mm

w209sportbrakes w209sportbrakes

4 opposed piston calipers constructed of Aluminium. Grey in colour, outside face has two external Torx bolt heads with a raised ridge running beween them. Discs are 350mm and perforated. Identify these by their shape, which suggests 2 pistons per side.

Thiese are fitted to late, large-capacity CLK models. 18" wheels required.

Front: 6 piston, 360mm | Rear: 4 piston


Late CLK55 AMG calipers moved up to 6 pistons front and 4 pistons rear and are again of 'Monobloc' Aluminium construction. The cost of these is way in excess of the two options mentioned above, and retrofitting of these generally requires a change of mater cylinder to support the additional fluid volume in the calipers. Discs are composite 360mm (front) and require 18" wheels.

Braking Bias

Mercedes fit a different brake balance valve A 005 430 99 01 to Sport Package vehicles. The valve allows slightly more brake pressure to the rear in order to provide better braking feel, but is entirely optional when retrofitting 330mm or 345mm front brakes with 290mm rears (or 330mm front and 278mm rear).

Please always use common sense when choosing brake upgrades and keep front/rear disc sizes proportional.

Retrofit Sport Package or 4 piston AMG brakes


My CLK is the 270CDi model and therefore I did not need not out-and-out braking performance, just a useful increase in power. With this in mind I chose to fit the Sport package brakes, but note the procedure for fitting any of the other options would be identical.

I used eBay to find a set of brakes (right); the calipers came from the US and the discs in the UK.

Mercedes are often keen to recommend early disc replacements and due to this second-hand sets with good life remaining do appear on eBay, I paid £30 including delivery for my discs and a further £30 to have them resurfaced. The resurface or 'skim' left 1.5mm thicnkness remaining before the wear limit which equates to approximately 15k miles of braking life.


I chose to paint the calipers Silver and add AMG decals (left). This is of course a matter of taste; I was adding the whole sport package at the same time.

Fitting is easy! Remove the wheels, 2 * 18mm bolts holding the caliper, the fluid hose, a T30 Torx screw holding the disc, and the disc itself. Reverse to fit using the new parts. Time required is approximately 1 hour for both sides, plus time to bleed once finished.

© Mark Stewart, Sunday 28th September 2008

Replace Standard CLK Bumper Covers with AMG versions


This article details how to fit AMG Bumper Covers to the W209 CLK, which I did to replace the standard 'non-sport' bumpers right

The 'Cover' is the actual moulded part of the bumper which this is typically sold separately to the structural reinforcing piece that sits behind and mounts the cover to the car.


Remove existing Bumper

CLK AMG Bumper Cover Fitment

The front bumper is held in at 3 main areas; behind the front grille, behind the lower air dam, and at the front of each wheel arch.

To start with, the front under trays and splash guards must be released from the lower edge of the bumper. Look underneath the car and remove all of the plastic retainers right using a trim removal tool or set of Pincer Pliers


Next put the steering on full lock (either direction) and remove the front lower section of the wheelhouse splash guard on both sides (look in front of the wheels for 2 x 10mm bolts).

With the splash guards removed look inside the opening on both sides up to the lip of the bumper to find a 13mm bolt, remove this, then use a flat blade screwdriver to pry the locking plate outwards from the wing/bumper, freeing the sides of the bumper from the car.

Open the bonnet/hood and remove the grille as described here, then look either side of the grille opening next to the headlamps for a black 10mm bolt, remove this bolt on each side and the top edge of the bumper should become loose.

The final 2 bolts are behind the central grille of the bumper, on my car I removed the grille by squeezing it inwards to remove the locking tangs from the bumper. Whilst removing the grille pull out the external temp sensor from the back of it and place carefully back on the car. Now 2*10mm bolts should be visible either side of the opening; remove these and the bumper can be withdrawn enough to allow access to the fog lamp connectors. Once they are free the bumper can be moved away from the car (above Left).

Mounting the AMG Cover


The black plastic reinforcement frame must be salvaged from your existing bumper to mount the AMG bumper. To do this, first remove the 2 impact-absorbing foam pads and then use a grinder to grind down the plastic welded tabs around the circumference of the frame. When all are removed the frame will pull away from the old bumper cover together with the fog lampsright.

The old fog lamps can not be re-used; I sold these on eBay along with the bumper covers.


The old bumper cover cannot be dispensed with yet. Compare the bracket which holds the headlamp washer flap (left); the facelift version was subtlety different to mine and meant the existing flap could not be fitted on the AMG bumper.

My solution was to mount the old brackets on to the AMG bumper, rather than purchase a set of the correct flaps.

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As it happened the brackets on my bumper were far more sturdy than on the AMG bumper anyway.

Please see the images to the right for a comparison between my pre-facelift non-AMG cover (far right) and the Facelift AMG cover (right).


I removed the AMG bracket by using a 115mm Angle grinder with thin metal cutting disc to carefully grind away most of the bracket and adhesive (Left).

I used the same technique on my old cover, but only in the areas which had been plastic welded and so leaving the majority of the cover in tact to re-use.

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Next, I wiped the pre-facelift bracket and the AMG bumper with panel wipe and used a liberal coating of Sikaflex 221 adhesive sealant to bond the pre-facelift bracket to the rear of the AMG bumper cover (Far Right), using the installed flap as a mounting guide (Right).


The facelift AMG Fog Lights mount directly to the bumper cover, and I'll state again the standard bumper fog lights cannot be used for any type of the AMG bumper.

I obtained the mounting screws, clips and wiring connectors and 10" of wire from Mercedes; the facelift wiring connectors are different. Now on to mounting the bumper reinforcement


Facelft vs Pre-Facelift bumper mounting


The Facelift cars employ a slightly different method of mounting the sides of the bumper; the Facelift bumper cover has a lip which attaches to the wheel arch splash guards, and this lip isn't present on the pre-Facelift cover and is instead integral with the reinforcement.

If you are upgrading facelift car to a facelift AMG cover, or a pre-facelift car to a pre-facelift AMG cover then no action is required.

If you are upgrading a pre-facelift car to facelift AMG such as I, then cut away the lip on the inside of the bumper Right.


There is no shortcut to modifying the existing reinforcement, careful trimming, trial fitment and more trimming is required to produce a quality fit. I started by laying the reinforcement in place around the headlight and grille recesses (the top profile of the AMG bumper is identical for all models as the front lights and wings of the CLK never changed) and began trimming and cutting until a good fit was attained.


I found that the central impact-absorbing foam required modification to suit the front profile of the AMG cover

I used an angle grinder to cut the foam and trial fit in the bumper cover until I was happy (Left).


The final stage was to wipe all mating surfaces with panel wipe in order to remove traces of grease and other pollutants. I applied a liberal coat of Sikaflex to all mating surfaces and mounting tabs, then secured the reinforcement to the cover using a mix of welding clamps, G clamps and duck tape.

The bumper should be left overnight in order to give the Sikaflex time to sure.


When the Silaflex has cured the clamps and/or tape can be removed, leaving the finished article (Left). My bumper didn't come with grilles or fog lamps so I obtained these from Mercedes, the cost for these is approximately £400. I also trimmed my existing number plate mount to fit the AMG bumper.

The bumper is now ready for immediate fitment or paint.



As always with painting, the preparation is key to a good finish. It was evident after I'd finished preparation that the bumper had been sprayed several times before, especially around the parking sensor holes (Right), so I needed to ensure there was a good barrier between old paint and new.

I recommend using the best paint available and DuPont is used my Mercedes themselves. I used a two-pack DuPont primer in a light shade of grey (right), a version chosen to suit their Cromax® water based paint in 744 'Brilliant Silver'.


This was to be the first time I'd sprayed with a water based paint, and in fact only the second time I'd sprayed at all. I used a DeVilbiss GTi gun intended for two-pack paint but didn't have a problem achieving a perfect finish with the waster-based base coat.

I found that water-based lays on 'wetter' than two-pack basecoat (no quick-dissolving solvent) so the amount of paint to 'lay on' must be judged carefully to prevent runs.


I used DuPont ChromaClearx® two-pack for the clear coat, which is a one shot clear I mixed with 10% Thinners. I achieved a finish that could be likened to a sheet of glass!

I would urge anyone thinking of spraying their own parts to get stuck in and have a go, it is incredibly rewarding.


Remove existing Bumper


To remove the standard rear bumper (right), jack up the rear of the car so that the wheels 'droop' enough to give good access to the back of the rear wheel arches. The bumper is secured here by a 13mm bolt through the lip of bumper, inside the wheel arch.

Next, inside the boot area there are a further 2 bolts along each side edge of the bumper, and these are accessed by 'peeling back' the boot carpet around the rear light area. Finally, there is a securing nut below each rear light.

Mounting the AMG Cover


Mounting the rear AMG bumper cover is very easy compared with the front, as the reinforcing piece (right) requires minimal modification.

The reinforcement is removed from the old bumper by using an angle grinder to carefully grind away the plastic welded tabs around its circumference.

If you have parking sensors fitted ensure these are in place before the reinforcement is fitted to the AMG bumper. To fix the reinforcement simply coat the fixing tab locations with Sikaflex 221 or equivalent, and lay the reinforcement piece in place. Use clamps or duck tape to hold down if necessary.


One final task is to install the metal mounting strips that run along the top edge of the bumper at the sides (the side mounting bolts attach here). Check your AMG cover; you may be lucky and find them already attached, if not, drill out the rivets in your old bumper and transfer the strips across.



I found that the black infil section was bonded to the bumper cover, therefore I masked this off rather than attempt to remove it.

As with the front, I sprayed with the chrome trims removed and used DuPont Cromax® water-based base coat and finished with DuPont two-pack Lacquer. The final finish was better than my original bumpers.

© Mark Stewart, Wednesday 15th October 2008

CLK Lowering springs

I recommend choosing a quality brand for all suspension components, cheaper brands are often poorly developed and in my experience the spring rates are too high for comfortable road use. Quality manufacturers will invest money in R&D to get the best comfort/performance balance for the road, and will often list different part numbers to suit the weight of particular engines and specifications.

I chose Koni part number 1020-6078 for my CLK, which is a spring pack offering an all-round 35mm drop.


Strut removal


The front suspension on the C/CLK is extremely easy to remove. With the wheel removed and car jacked up, the strut is removed as follows:


The strut is now free to be withdrawn. The photo left shows my front strut and standard spring next to the uncompressed lowering spring. Now, typically with a lowering spring the uninstalled height is somewhere close the standard springs installed height thus making installation a cinch. The CLK is different and is the first car I've worked on that uses a very high spring length/damper piston length ratio.

This configuration serves to put the installed spring under very high compression, even with a shortened spring. I do not yet understand the effect of this compared with a more traditional lower spring length/damper length ratio; I assume the static compression is paired with a softer spring rate to change suspension dynamics in order to lessen NVH and/or provide a more comfortable ride. If anyone reading this article can provide more info, please leave a comment as I'd be interested to learn more.

Spring removal

As mentioned in the previous section, the C/CLK front springs are installed under an incredible amount of compression and care should be taken when removing them, in fact, I recommended taking the uninstalled strut/spring to a garage and have them install the new springs. 'Claw' type DIY spring compressors should not be used with the front suspension, a professional tool must be used.

In the end, I decided to stick with the standard front springs as they were firm and low enough for a daily driver.



CLK Lowering springs

A special tool is required to remove the front strut spring cup securing nut, which itself must be removed to allow the spring to uncompress on the strut before it can be withdrawn.

The special tool (right – internet photo) is available direct from Mercedes-Benz, the part number is: 203-589-00-07-00 Strut Retainer Tool. The price is around £25 at the time of writing.



Rear spring replacement is relatively simple and the springs themselves are under what I'd term a 'standard' amount of compression, because of this the uncompressed spring length gives a much better indication of lowering distance.

The photo to the right shows a Koni spring next to my standard Avantgarde spring; a height difference of approximately 35mm can be observed, which is the stated lowering measurement.


With the rear of the car on axle stands, remove the plastic guard on the bottom suspension arm, then remove the strut securing nut and bolt completely and loosen the outside arm mounting nut, leaving the bolt in place so that the arm can pivot around it.

Now place a jack underneath the arm and raise it so it touches the bottom of the arm.


Next, ensure that the jack is secure and remove the inside lower arm mount nut & bolt, and lower the jack, which will bring down the arm and uncompress the spring as it goes. (No need to remove the entire arm as I did - right)

The old spring can now be removed entirely and the new one put back in it's place, also the damper if required; the top mount bolt is inside the boot. It is recommended that new nuts and washers are used on the lower arm inside bolts.

The refit procedure is the exact opposite of removal, this time using the jack to raise the arm and compress the spring.

© Mark Stewart, Saturday 18th October 2008

CLK 63 AMG Wheels


As I was adding a facelift AMG package to my CLK, the original 16" Alloy wheels (right) were no longer relevant, nor suitable to cover the Sport brakes.

I settled on a set of replica CLK 63 alloy wheels, in 18", with the following spec:

w209clk63wheels w209clk63wheels w209clk63wheels w209clk63wheels

If available, I would recommend ET40 at the rear or go down to an 8.5" wheel in order to provide a little extra tyre overhang for rim protection. Neither of these options were available to me at the time of ordering.

I didn't like the gunmetal inserts on the wheels, although these look fine on the 63, my car is no 63 and I think they were a little too ostentatious for me. I thought the wheels looked nice and would be more subtle with a silver infill, so I looked to create this look myself.

I set about the laborious task of masking off the machined polished faces and using wet and dry paper to rub down the gunmetal painted areas. These areas were then etched primed (in case the paint had been worn down to bare metal) and sprayed with Wurth "German Wheel Silver" aerosol can. I finished by removing the masking tape and rubbing down the entire wheel with 1500 grade wet and dry, then finishing with DuPont lacquer from a professional gun.


CLK 63 AMG Wheels CLK 63 AMG Wheels CLK 63 AMG Wheels
© Mark Stewart, Saturday 1st November 2008
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