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Discussion Starter #1
I have a 2010 SLK 350 with the Sports Pkg. Frankly, I'm not thrilled with the suspension, because the ride is similar to a hay wagon!

I'm thinking about going back to the standard or non-sport pkg setup. Looking at a MB online parts website it doesn't look too difficult to do:

https://www.mbonlineparts.com/auto-parts/2010/mercedes-benz/slk350/base-trim/3-5l-v6-gas-engine

The front struts & springs along with the rear shocks & springs need to be replaced. I was considering using all MB OEM parts except for the front struts, R&R them for Bilsteins. So B6 or B8?

I have a long email conversation with Bilstein Tech Support who told me the B6 is the correct replacement. I questioned this, because in previous inquires, I was told B8. To resolve my confusion, I was able to nail down the difference between the B6 & B8 from the horse's mouth.

I would happily post the entire conversation here except it's privileged. Hence, I'll give you the essence of it:

"According to our interchange the B6 is the direct replacement for your vehicle. In further investigation our B6 and B8 products for you Mercedes have the same valving profile/ride characteristic just the B8 has a slightly shorter travel stroke. The housings of the shocks are dimensionally the same between the two. Only difference is the travel. For your vehicle the B8 would be a more appropriate shock if you were using an aftermarket lowering spring."

That makes sense, since a lowering spring would be shorter and stiffer and wouldn't need as long a stroke as the normal/standard spring.

Finally, I'd like a favor from a member who might have a late model R171 350 without the Sports Pkg. A 2010 would be nice, but something earlier might do. I want to find the MB part#s for the front and rear springs. On the front spring, there is a color code painted on the spring. The same for the rear spring, but it might be difficult to see.

BTW, for those of you who might want to lower your cars, I'll have the complete Sports Pkg suspension components available.0:)
 

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Registered 2005 SLK350
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I have a 2010 SLK 350 with the Sports Pkg. Frankly, I'm not thrilled with the suspension, because the ride is similar to a hay wagon!

I'm thinking about going back to the standard or non-sport pkg setup. Looking at a MB online parts website it doesn't look too difficult to do:

https://www.mbonlineparts.com/auto-parts/2010/mercedes-benz/slk350/base-trim/3-5l-v6-gas-engine

The front struts & springs along with the rear shocks & springs need to be replaced. I was considering using all MB OEM parts except for the front struts, R&R them for Bilsteins. So B6 or B8?

I have a long email conversation with Bilstein Tech Support who told me the B6 is the correct replacement. I questioned this, because in previous inquires, I was told B8. To resolve my confusion, I was able to nail down the difference between the B6 & B8 from the horse's mouth.

I would happily post the entire conversation here except it's privileged. Hence, I'll give you the essence of it:

"According to our interchange the B6 is the direct replacement for your vehicle. In further investigation our B6 and B8 products for you Mercedes have the same valving profile/ride characteristic just the B8 has a slightly shorter travel stroke. The housings of the shocks are dimensionally the same between the two. Only difference is the travel. For your vehicle the B8 would be a more appropriate shock if you were using an aftermarket lowering spring."

That makes sense, since a lowering spring would be shorter and stiffer and wouldn't need as long a stroke as the normal/standard spring.

Finally, I'd like a favor from a member who might have a late model R171 350 without the Sports Pkg. A 2010 would be nice, but something earlier might do. I want to find the MB part#s for the front and rear springs. On the front spring, there is a color code painted on the spring. The same for the rear spring, but it might be difficult to see.

BTW, for those of you who might want to lower your cars, I'll have the complete Sports Pkg suspension components available.0:)
The color coding on the springs are indicative of the options on the specific cat taht the spring is mounted on. You would have to use the options for your car to know what spring MB provides for your car. In addtion to springs and dampers, the front and rear anti sway bars are also different between the sport and non-sport suspension. Note: I thought there was not a call for differnet rear springs between the sport and non-sport suspensions.
 

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Discussion Starter #3
The color coding on the springs are indicative of the options on the specific cat taht the spring is mounted on. You would have to use the options for your car to know what spring MB provides for your car. In addtion to springs and dampers, the front and rear anti sway bars are also different between the sport and non-sport suspension. Note: I thought there was not a call for differnet rear springs between the sport and non-sport suspensions.
There are two part #s for the rear spring depending if it is sport or non-sport.

I'm well aware of the point system and how options impact it. Here's some info on it:

Suspension conversion mission accomplished - strut installation details. - Mercedes-Benz Forum

With a little study, you'll see that it is possible to determine the correct springs for the American non-sport pkg.

The sway bars won't have much to do with how the car rides.
 

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Discussion Starter #4
Some additional information!

For those of you thinking about replacing the struts, the B6 will replace the following MB OEM part#s:

171.320.10.30
171.320.03.30
171.320.01.30
171.320.12.30

Also the B6 shock is the correct replacement to go along with these struts. >:D
 

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Registered 05 SLK55 & 06 Kleemann 55K S8
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And Bilstein is switching to a new plant right now and it is late opening up so you can't find the B8 rear shocks. I did fine one place in the US that had them, Autozone of all places.
 

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Discussion Starter #6
Just to be complete!

The B6 strut will replace the following MB OEM part#s:

171.320.10.30
171.320.03.30
171.320.01.30
171.320.12.30

The B6 shock will replace the following MB OEM part#s:

171.326.10.00
171.326.08.00
171.326.01.00
171.326.11.00
171.326.02.00

This covers all '05->'11 SLK 350s, SLK280s '06->'08, & SLK300s '09->'11.

Regarding the B8 strut & B8 shock, it can be used on any of the above SLKs with a lowering spring. However, just how low do you want to go? On the Sport Pkg, you'll be scarping the pavement!:surprise:
 

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Discussion Starter #7
SLK Sport Pkg to SLK Comfort!

The color coding on the springs are indicative of the options on the specific cat taht the spring is mounted on. You would have to use the options for your car to know what spring MB provides for your car. In addtion to springs and dampers, the front and rear anti sway bars are also different between the sport and non-sport suspension. Note: I thought there was not a call for differnet rear springs between the sport and non-sport suspensions.
I said there were two different part#s for the rear springs. What I meant to say is there are two different part numbers for the rear shocks. The sport & non-sport both use the same spring! This answers the question is the sport pkg lower in the rear than the standard suspension? The answer is NO. The B6 shock will cover both part#s:

171.326.10.00 - sport suspension
171.326.11.00 - non-sport

Further research and using the link detailing the point system reveals which spring to use:

171.321.10.04 - sport suspension, one yellow & two blue paint markings which I have.
171.321.09.04 - non-sport, one white & two blue.

So to change my Sport Pkg to the standard or comfort suspension all I have to do is change the front springs and R&R the front struts for the B6. I really don't have to do anything to the rear. I might change to the B6 shocks later?:grin:
 

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Discussion Starter #8
The Parts Have Been Ordered!

I ordered the B6 struts today, 35.113430, from Summit Racing at $216.99 each with free shipping. I also ordered two front springs, 171.321.09.04 from RMeuropean made by Suplex $34.14 each.

I don't know if I'll do this job or farm it out. If I do it, it'll be my winter project!:smile:
 

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Discussion Starter #9
Now comes the hard part, replacing the struts!

Searchin the net, this was the closest instructional video for replacing the struts:


The major differences are the SLK strut is held at the top with three nuts and the top hat. The top hat centers and holds the top of the spring on the strut.

It's always a good idea to take some pictures of the strut before disassembly for something to refer to if you get stuck. Pay close attention to how the spring hooks into the bottom of the stut and the top hat.

There is a special tool called the Schwaben Strut Nut Tool which is necessary to tighten down the nut that compresses the top hat and hold the strut-spring assembly together. You'll need the 21mm version for the B6 strut.

Torque specifications:

Top 3 nuts -35NM
Bottom two bolts - 110 NM
Bolt at top of wheel carrier - 200 NM
Torsion bar link rod - 100 NM

Probably some blue thread locker should be used on the bottom two bolts. Another recommendation is to use new self locking nuts. Honestly, I'll reuse the old nuts and just "lean" on wrench handle when tightening the bolts. >:D
 

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Registered 2007 SLK350
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I would not attempt to replace the front springs, unless you have a "good" spring compressor.


The ones that come in pairs, and clamp to the side of the springs just will not work on these springs.


I used a hydraulic compressor, exactly the same one as the video, and you need to compress so the coils touch each other (far fewer coils in SLK strut than the video strut) before the tension comes off the top nut.



I recomend removing the strut yourself, and send the strut to a good garage for the spring replacement. Will help your nerves!



Takes about 1 hour per side to remove the struts (takes longer to jack up the car and safely support!)


When i did mine, I dismantled the steering bearings (in the top hat), cleaned thouroughly, and re-assembled with HP grease. Well worth doing at the same time.
 

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Discussion Starter #11
I've done this job on other cars, and you are right about compressing the springs something I'm not looking forward to. The typical pair of threaded rods with hooks on either end are a real PITA to use.

I may send the whole job out to a shop if I can get a reasonable price or just have them put the new springs on the new struts. Another idea was to buy a couple of new/used top hats, so I could leave the old strut-spring assembly together. It then would be easier to sell as a unit. Also a great deal for someone who wants to lower his car.
 

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Discussion Starter #12
To make the job easier!

I decided to leave the Sport Pkg unit (strut, spring, & top hat) assembled. Since I have bought the B6 struts and new springs, all I needed to complete it and have a two complete struts ready to install is the top hats, MB part# 171.320.00.73:

https://www.rmeuropean.com/Products/1713200073-MFG36.aspx

Notice I got the springs and top hats from this outfit. These parts are getting old, chronologically, and are cheap!

I'll sell the Sports Pkg assembly for a reasonable price. Anyone who wants to lower their car a 0.5" in the front will find this the cheapest and easiest way to do it.:smile:
 

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Super Moderator CA 2012 SLK55 AMG w/P30
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Discussion Starter #14
Ya gotta pay the piper!

So how much did all this stuff cost?

2 B6 struts - $463.28
2 Suplex springs - 68.28
2 Top hats - 169.30
Thread locker & Tap 21.90
Labor to assemble strut - 105
Alignment - 98

Total - $925.76 which includes all Ohio taxes:crying:

There is plenty of detail in this thread to give any DIYer the how for this project. Pay special attention to the link in the Mercedes-Benz forum plus the video.

The ride height can be judged by examining the gap between the top of the tire and the fender. Currently, in the rear, almost three fingers will fit and in the front, two. When I finish the job, I'll post before and after pictures.
 

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Discussion Starter #15
I want you to know the true cost of this modification, so I have an additional expense to add, $25.10 for 10 new MB self-locking nuts! The total so far now adds up to $950.86.

Six of the nut were a mere $1 each. These fastened the top of the strut to the body. Two were $4 each which I believe connected the sway bar link. The big surprise were two priced at $4.70 each! These bolted the tab in the middle of the strut to something I don't recall the name of. Looking at them, they are a work of art. I hate to even use them!

I'm still waiting on the B6s. I ordered them on 7/14 and might show up 8/7!
 

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Discussion Starter #16
Woo Hoo Woo!

The B6 struts I ordered in August from TireRack finally arrived on the boat or submarine from Germany!

I have already had the springs and top hats assembled on them by a local shop for $105. Next week I'll stuff them in. For all the time trouble and expense, my car should sit 0.5" higher in the front, and with the extra spring travel, it should ride a bit better.

I did install the B6 shocks in the rear in August. It was a tough job, since the shocks need to be compressed to slip them in. I used a pair of long-handled pliers and a lot of cursing to pry them in. A tip, compress the shocks several times by hand before you install them.

I've attached a file of the front with the Sport Pkg suspension. I'll later post a picture of the newly installed struts.

BTW, the old struts & shocks are for sale. They are in perfect condition with very low miles.
 

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What about the B4?

"According to our interchange the B6 is the direct replacement for your vehicle. In further investigation our B6 and B8 products for you Mercedes have the same valving profile/ride characteristic just the B8 has a slightly shorter travel stroke. The housings of the shocks are dimensionally the same between the two. Only difference is the travel. For your vehicle the B8 would be a more appropriate shock if you were using an aftermarket lowering spring."

0:)

Did you look into the B4 as well? If so, what did you find? Did the rep comment on it at all?
 
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