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DIY - Replacing rear SLS struts with normal Bilsten Shocks. (Bypassing SLS)

43K views 52 replies 21 participants last post by  Aerosurfer 
#1 · (Edited)
Hey comrades..

Here is my story of how I bypassed the Self Leveling Suspension and installed "normal" Bilsten rear shocks on my S320.

A few months back I uploaded a pic of my car to this forum, and one member pointed out to me that the back of my car is "sagging" very low.

Upon further inspection, I too had to agree something was not right with the rear suspension. It was even sagging more one side than the other! lol

After many months of learning about the W140 on this forum and other resources, I thought it could be the "Spheres" or "accumulators" as they are also known.

One thing that also bothered me about my S320 is that the ride at the back was very rough, and you would feel every bump. To make things even worse, there would be a loud "Clunk" when going over even small bumps. I guess ignored this for a long time by just putting the music louder lol..

But enough was enough..

So I bought two used "Spheres" at my local breakers for $100. I printed out the DIY guide on V12Uberalles about replacing these spheres.

I read through it multiple times untill I understood how the SLS hydraulic system works completely. It made me feel confident that I could do this job by myself... lol, oh how wrong was I..

It was almost impossible for me to loosen any bolts on the accumulators, even though I sprayed some "Q10" to loosen them up. I did call a mechanic to do the repair, but the prices that he quoted me were unsatisfactory. Not to mention, there were no guarantees that the system would work after replacing only the "spheres."

Im glad that all of that happened, because I remembered that the white S320 LWB which was brought into the breakers about 3 weeks ago had normal rear shocks, which were in great condition.

So my best move, (which I dont regret at all) I took the spheres back to the breakers and swapped them out for the "normal" Bilsten rear shocks from the S320 LWB in the yard. All I had to do was add an extra $30, and both shocks were mine :) That means I got 2 Great condition Bilsten shocks for only $130!!

Saturday came, and I decided I was going to tackle this job. I have replaced rear shocks on my ex-BMW 3-series, so it did not seem so daunting at all.



You will need:

1 x Jack
1 x average car jack (from a toyota or chev)
1 x Car stand (2 Ton +)
2 x Bilsten shocks (or what ever brand you prefer)
2 x 19" spanners + sockets and rachet
1 x 17" spanner
1 x allan key (forgot the size)
2 x 13" (spanner size) bolts
2 x small coins
1 x roll of plumbing tape





Step 1:

Jack up the car, secure it on the stand right below the jack point. (A piece of wood to buffer between the car and stand is a good idea)
Remove the wheel.

Step 2:

Loosen the nut and bolt that hold the shock / strut at the bottom. (2 x 19" spanner / sockets)

Step 3:

Open the trunk, remove the carpet on the sides, untill you can see the bolt that holds the top of the shock / strut to the body.
loosen, and remove the nut completely. (A good idea is to lay inside the trunk while you removing the nut, more comfortable that way)
The shock / strut should drop out of the top. If not, a light tap with a hammer should do the trick lol..

Step 4:

Loosen and remove the nut and bolt that hold the shock / strut at the bottom. The shock / strut should be completely free now.

Step 5:

Using a 19" and an 17" spanner, loosen the hose connection at the point where the hydraulic cable on the strut connects to the next hose. (HAVE A CONTAINER
TO CATCH THE HYDRAULIC FLUID, BE CAREFUL THIS IS A VERY MESSY STEP) Disconnect the hose completely and let it drain into the container.

Step 6:

This is the step where I had to get a little creative. How to block the hydraulic line, and bypass the SLS system completely.
At this step others may do it differently, but this is how I did mine.
I cut of the head of the hydraulic line from the strut. I then screwed in a thick bolt (13" spanner size) into the piece of rubber hose
that is on the head. Some plumbing tape also was used.
Then I took a 1c coin. Held it with a pair of pliers and filed it down untill it could fit into the hole of the head. ( I had to dig into
my coin collection because they dont make these anymore lol, but I have quite a few of these)

I then connected this head back onto the hydraulic line, and tightend the bolts as far as they would go.

Hydraulic line now completely sealed off. No leaks.

Step 7:

Install the replacement shock, (slide behind the brake line) and connect it loosely at the top.
Use the average car jack to lift the hub so that the holes align at the bottom of the shock. (you can NOT use a Mercedes jack for this step)
Insert the bolt and nut at the bottom of the shock and tighten it as best as you can.
Then go to the truck and tighten that nut as best as you can. (You might need an allen key here to hold the bolt from turning)

Once everything is tight, ONLY then you may lower and remove the average car jack from the hub.

Check that all bolts are tight as they can be.

Step 8:

Fit the wheel back on, and remove the car from the stand.

Step 9: Start the car, run the engine for a minute or two, then while reving it up to 1500RPM, turn the steering gently left and right multiple times. This should excersize the hydraulic system.

Turn the engine off, and check both the Hydraulic tank, and the power steering resivor. Top up with recommended hydraulic fluid if needed.

Now repeat all the same steps on the other side, and then CONGRATULATIONS! No more SLS headaches lol!




Side note:

Thank God that I decided not to repair my SLS, and rather install these normal shocks. When I removed the struts from my car,
The liquid was milky (indicating the spheres have definitely gone bad) and BOTH struts were damaged and would have needed to have been
replaced anyway! So on top of the money I spent for the spheres, I would still have had to buy BOTH hydraulic struts! I dont even want to know how much that would have cost me if I went that road. And even if I did replace those parts, there still would be no guarantee that the rear suspension would be back to normal, maybe another part of the system has also failed and would also need
more cash to been thrown at lol..

(Not that I will miss the SLS on the car, My S500 has also got SLS so I can enjoy when I drive that car. My S320 does not need it)

So now I am completely happy with ride quality of my S320 :) :) :) All it cost me was $130 and one Saturday morning to eradicate this problem.

I saved alot of money on this repair, especially since I did it myself. And you can too!
 

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#2 ·
More pics..
 

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#3 ·
See how these struts are badly damaged..

The left strut had the head completely broken off, while the right one was also broken with the rod at the top coming loose from its place. Making the hydraulic strut un-usable..

No more SLS problems on my S320, it drives like its gliding on the road now!:thumbsup::bowdown:
 

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#4 ·
Bilsten shocks removed from the white S320 LWB..

There are slightly dirty in this picture, but there were cleaned there before I took them. They looked almost NEW when I got them.

I tested them by bouncing the car before they were removed from the donor vehicle.. Not too stiff, and not too wavey.. Felt brand new if you ask me.

$130 for BOTH of them, and one Saturday morning got my S320 floating like butterfly lol
 

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#5 ·
oh my god, this is the best thread on benzworld for me of all times:bowdown::bowdown::bowdown::bowdown:. i have a 95 s500 that the strut is creaking and i wanted to replace them with regular struts. however i cant find the strut that is used for my car. my car has sls, but the sachs part number was 140 320 89 13 the dealership couldnt find the number???. can you please post the part number of your sls strut because mine looks just like that and i want to save the $800 it would cost to buy a new strut.
 
#6 ·
Part number on both struts is 140 320 87 13 (on the body)

And 140 320 09 44 (on the head)

Hope that helps comrade!

Don't forget to make sure the "spheres" are working fine..
 
#7 ·
I just realized that I did not replace the springs to normal non-SLS springs.

I understand the SLS springs are softer and don't support the full weight of the car..

The car rides beautifully, and its a pain to change the springs..

My question is, what would happen if I leave the SLS springs and use the normal Bilsten shocks? Will it damage the shocks or something like that?

I will enquire how much the springs will cost tomorow.

(Damn means I will have remove the shocks again lol, twice the work lol.. Should have replaced them at the same time I was doing the shocks.)
 
#8 ·
if you leave the springs they will get compressed and worn out so they will get wobbly. it may damage your shocks after a while but the only thing you may notice is that your car will start to sag in the back. new stronger springs aren't that expensive. i would just go back and get the springs off that old s320.
 
#9 ·
Thanks, Don. That's most useful.

I ran out of time repairing the ADS on my 600SEC so I've left it in the local garage's hands to sort it out. Both my struts were ok but the spheres were knackered, pipes all rusted to hell and pipe ends so firmly corroded into the damping valves that I had to buy a lot of parts off ebay and from the local Benz dealer. I'm hoping it all fits together because I do really like the ADS since it makes such a big car handle so much better.... but fallback position is to do what you've just described so thanks for the advice.

I had the top bolt break off the strut on my W210 E320CDI just like the second picture in your 2:25 post above ... but when I saw the replacement price I just welded a 10mm x 30mm bolt on the top and it was fine :)
 
#10 ·
Very nice MafiaDon! I am sure this will become very useful for many users here.

About your springs, if you want the correct performance then you should swap them out. It won't cause your car to explode or anything, but the springs will get fatigued faster (probably same as putting tons of weight in the trunk in a w140 with normal springs). So yes, I won't be surprised if they wear out the shocks faster.
 
#11 ·
+ 1 on that Sinned..

Nice Thread MafiaDon,this surely will save a lot of Money to some users here .:thumbsup:
 
#12 ·
I don't know how much that coin is going to deform and seal against the fitting, but it may end up making a good seal. I think a better method is described by snik and The Andrew in snik's SLS-to-normal-shock conversion thread.

http://www.benzworld.org/forums/w140-s-class/1313833-has-anyone-here-converted-hydraulic-rear-8.html

Cut the SLS feed and return lines and plumb the feed directly to the return, so the fluid flows without getting pressurized, and just take the valve, accumulators, and tubing out and throw them away. (Actually, ebay the valve. It's worth something.) The levelling valve is responsible for creating pressure in the system. Removing the valve puts less stress on the pump which you now no longer need. You can make the loop anywhere along the run of the lines. Snik described doing it just behind the left front wheel. The Andrew said he looped the two toward the rear. Snik mentioned using actual hydraulic fittings to connect the hard lines, but it's not clear that he did. He didn't post pictures that he said he would. The Andrew said he just used 1/4 in. rubber fuel hose with 2 clamps on each end.

Brett
 
#13 ·
Thanks for all the kind words comrades!

Yes you guys were right, the springs had to be swapped out also.

I went back to the breakers and got the springs from the same S320 LWB that my Bilsten shocks came from. Perfect :)

Had to pay $95 for the both of them, but it was worth it.

Spent pretty much most of the day installing the new springs. It was my first time replacing suspension springs on a car lol..

Had to buy a set of spring compressors for $20, and with some crafty use of a jack, those compressors and some tactics, we successfully installed the normal non-SLS springs! :)

Noticed the diference from the second the car was put back on the ground. The ride height is much higher at the back, and matches the front perfectly!

I will post some pics of the job and the before / after pics..

So now my S320 riding on proper Bilsten shocks, with solid non-SLS springs. It feels AMAZING! Like a limousine lol..

Brett:

I agree, I will read up more about "looping" the hydraulic pipes. I will definitely do a more solid job on bypassing the hydraulic system completely. For now the system is blocked off nicely..

The spheres need to go into the trash, but leveling valve I will put in storage since my S500 has SLS and might need it in future for that car. The pipes were all in great condition also, no rust at all..

But the bottom line to this repair is, when changin to normal Non-SLS shocks, you have to also change to Non-SLS springs. (The springs very tough to install, but not impossible)

Well worth all the trouble.. And so far I have done everything for less than $250 :)
 
#14 ·
Sorry to revive and old thread.
I'm thinking of replacing my sls suspension with regular suspension. My steering pump is making noise, and I read the it also feeds the suspension.
So in an effort to raise the car a bit, I was going to get new h&r or eibach springs.
But are the front shocks, are they apart of the sls system or is it just the rears?
I see the steering pump is considerably less as well.
I figure less moving parts, less headaches in the future.
Any input is appreciated.
 
#15 ·
The SLS is the rear only. You won't have to do anything to the front. The pump is not one pump feeding both the steering and suspension. It is two separate pumps built into one housing. There are separate hydraulic systems with their specific fluid and reservoirs for the steering and the suspension.

Brett
 
#16 ·
Just a little update since this thread was bumped up..

SO far my repair of the suspension has been great! I Have no problems with my rear suspension or ride heaight. Everything is working perfectly and I have no regrets removing the hydraulic suspension and replacing it with normal Bilsten Shocks and springs :)

Especially if you plan to keep the cart for a long time, This is not a bad method to eliminate the string of headaches and problems that come with the SLS system.

At least I can focus on all the other problems lol, suspension is perfect :D
 
#19 ·
I think it would be worthwhile, if you need to replace the steering pump, to just get the simple power steering pump if you are getting rid of the SLS. You will probably need the bracket to mount the steering pump. There may also be different reservoirs and hoses, so it may be more expensive than you think to change the pump. Salvage parts can save some money.

Brett
 
#18 ·
Nope.. Just left the original pump and have had no problems ever since..

Interesting enough, it used to have a leak somewhere, but after this fix the power steering fluid is remaining the same level so the leak must have also healed? Lol, either way it was the best couple dollars and couple hours I ever spent :) the car now floats on the road like the ship that it is lol..
 
#20 ·
the steering pump is making some noise when it's cold. but goes away when it warms up. my mechanic calls it "morning sickness" and thinks the steering fluid needs to be flushed and replace with new fluid. but I'm worried that there's a bearing that's noisy as well. He has yet to hear the issue in person and likely won't for a month or two. but I'm looking down the road thinking worst case scenario.
 
#22 · (Edited)
No. SLS is completely mechanical. The car doesn't "know" it's there.

You may be thinking about cars with SLS and ADS. ADS adds solenoid valves at each strut. If the valves are not plugged in, for example, if you remove them from the car, this triggers an ADS fault, and the ADS system defaults into firm mode. No limp home mode involved. In the rear the valves are separate from the struts, however, so you could remove the struts and leave the valves in place and plugged in. They just won't be doing anything. Up front, the valves are integral with the struts, so it's not so easy to remove the strut and keep the valve on the car to keep the ADS computer happy. If you end up removing all the ADS struts anyway, (I think) the only annoyance will be the constantly lit ADS lamp, which can be cured by removing the bulb from the cluster.

Brett
 
#27 ·
I did this on my 500 about 1.5 years ago. Never missed the SLS since.

Car absolutely glides.

I looped the supply/return hydraulic lines with fuel line and 4 hose clamps.

Replaced the springs with ones from EDDIE off a 300SE, and new Bilstein shocks.

Done!
 
#30 ·
Goodluck and all the best!

Indeed it is not impossible, and does not have to be expensive at all if you can do it yourself :D
 
#33 ·
Hey comrades..

Here is my story of how I bypassed the Self Leveling Suspension and installed "normal" Bilsten rear shocks on my S320.

A few months back I uploaded a pic of my car to this forum, and one member pointed out to me that the back of my car is "sagging" very low.

Upon further inspection, I too had to agree something was not right with the rear suspension. It was even sagging more one side than the other! lol

After many months of learning about the W140 on this forum and other resources, I thought it could be the "Spheres" or "accumulators" as they are also known.

One thing that also bothered me about my S320 is that the ride at the back was very rough, and you would feel every bump. To make things even worse, there would be a loud "Clunk" when going over even small bumps. I guess ignored this for a long time by just putting the music louder lol..

But enough was enough..

So I bought two used "Spheres" at my local breakers for $100. I printed out the DIY guide on V12Uberalles about replacing these spheres.

I read through it multiple times untill I understood how the SLS hydraulic system works completely. It made me feel confident that I could do this job by myself... lol, oh how wrong was I..

It was almost impossible for me to loosen any bolts on the accumulators, even though I sprayed some "Q10" to loosen them up. I did call a mechanic to do the repair, but the prices that he quoted me were unsatisfactory. Not to mention, there were no guarantees that the system would work after replacing only the "spheres."

Im glad that all of that happened, because I remembered that the white S320 LWB which was brought into the breakers about 3 weeks ago had normal rear shocks, which were in great condition.

So my best move, (which I dont regret at all) I took the spheres back to the breakers and swapped them out for the "normal" Bilsten rear shocks from the S320 LWB in the yard. All I had to do was add an extra $30, and both shocks were mine :) That means I got 2 Great condition Bilsten shocks for only $130!!

Saturday came, and I decided I was going to tackle this job. I have replaced rear shocks on my ex-BMW 3-series, so it did not seem so daunting at all.



You will need:

1 x Jack
1 x average car jack (from a toyota or chev)
1 x Car stand (2 Ton +)
2 x Bilsten shocks (or what ever brand you prefer)
2 x 19" spanners + sockets and rachet
1 x 17" spanner
1 x allan key (forgot the size)
2 x 13" (spanner size) bolts
2 x small coins
1 x roll of plumbing tape





Step 1:

Jack up the car, secure it on the stand right below the jack point. (A piece of wood to buffer between the car and stand is a good idea)
Remove the wheel.

Step 2:

Loosen the nut and bolt that hold the shock / strut at the bottom. (2 x 19" spanner / sockets)

Step 3:

Open the trunk, remove the carpet on the sides, untill you can see the bolt that holds the top of the shock / strut to the body.
loosen, and remove the nut completely. (A good idea is to lay inside the trunk while you removing the nut, more comfortable that way)
The shock / strut should drop out of the top. If not, a light tap with a hammer should do the trick lol..

Step 4:

Loosen and remove the nut and bolt that hold the shock / strut at the bottom. The shock / strut should be completely free now.

Step 5:

Using a 19" and an 17" spanner, loosen the hose connection at the point where the hydraulic cable on the strut connects to the next hose. (HAVE A CONTAINER
TO CATCH THE HYDRAULIC FLUID, BE CAREFUL THIS IS A VERY MESSY STEP) Disconnect the hose completely and let it drain into the container.

Step 6:

This is the step where I had to get a little creative. How to block the hydraulic line, and bypass the SLS system completely.
At this step others may do it differently, but this is how I did mine.
I cut of the head of the hydraulic line from the strut. I then screwed in a thick bolt (13" spanner size) into the piece of rubber hose
that is on the head. Some plumbing tape also was used.
Then I took a 1c coin. Held it with a pair of pliers and filed it down untill it could fit into the hole of the head. ( I had to dig into
my coin collection because they dont make these anymore lol, but I have quite a few of these)

I then connected this head back onto the hydraulic line, and tightend the bolts as far as they would go.

Hydraulic line now completely sealed off. No leaks.

Step 7:

Install the replacement shock, (slide behind the brake line) and connect it loosely at the top.
Use the average car jack to lift the hub so that the holes align at the bottom of the shock. (you can NOT use a Mercedes jack for this step)
Insert the bolt and nut at the bottom of the shock and tighten it as best as you can.
Then go to the truck and tighten that nut as best as you can. (You might need an allen key here to hold the bolt from turning)

Once everything is tight, ONLY then you may lower and remove the average car jack from the hub.

Check that all bolts are tight as they can be.

Step 8:

Fit the wheel back on, and remove the car from the stand.

Step 9: Start the car, run the engine for a minute or two, then while reving it up to 1500RPM, turn the steering gently left and right multiple times. This should excersize the hydraulic system.

Turn the engine off, and check both the Hydraulic tank, and the power steering resivor. Top up with recommended hydraulic fluid if needed.

Now repeat all the same steps on the other side, and then CONGRATULATIONS! No more SLS headaches lol!




Side note:

Thank God that I decided not to repair my SLS, and rather install these normal shocks. When I removed the struts from my car,
The liquid was milky (indicating the spheres have definitely gone bad) and BOTH struts were damaged and would have needed to have been
replaced anyway! So on top of the money I spent for the spheres, I would still have had to buy BOTH hydraulic struts! I dont even want to know how much that would have cost me if I went that road. And even if I did replace those parts, there still would be no guarantee that the rear suspension would be back to normal, maybe another part of the system has also failed and would also need
more cash to been thrown at lol..

(Not that I will miss the SLS on the car, My S500 has also got SLS so I can enjoy when I drive that car. My S320 does not need it)

So now I am completely happy with ride quality of my S320 :) :) :) All it cost me was $130 and one Saturday morning to eradicate this problem.

I saved alot of money on this repair, especially since I did it myself. And you can too!
do you know the part number for the Bilsteins? Someone has done the replacement before I got the car and the rear is very floaty. I need to replace the shocks.
 
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