Mercedes-Benz Forum banner
1 - 15 of 15 Posts

·
Registered
1990 560SEC, 2001 SL500
Joined
·
41 Posts
Discussion Starter · #1 ·
Has anyone replaced the 560SEC self-leveling rear hydraulic shocks, accumulators, pump, and lines with conventional shock absorbers as I believe W126's without self-leveling rear suspension have? My 1990 has just over 100,000 miles, and the ride is rougher than I'd expect, with loud thumps from the rear end over every bump and pothole. I don't know what the problem is, but I'd rather not spend over $1,000 to replace the self-leveling shocks and accumulators, compared to about $80 each for conventional Bilstein rear shocks.

Autohauz AZ tells me the non-self-leveling shocks will not fit cars with the self-leveling suspension. If it's a matter of making new mounting brackets for conventional shocks, I can handle that. I'd very much appreciate hearing from anyone who has converted 560SEC rear self-leveling suspension to conventional shock absorbers, what was involved, and when finished, did you notice any negative difference with conventional shocks on the back? Thank you very much in advance. John in Baltimore, MD
 

·
Premium Member
1989 560SEC AMG Euro / 2018 C43 4Matic Sedan / 2006 CLS500 AMG
Joined
·
2,350 Posts
It can be done but the $1000 figure is fanciful as chances are at 100,000 miles you'd only be into it for accumulators which are inexpensive and easy to DIY replace.

When the SLS is working properly the ride is *FAR* superior to anything conventional shocks/springs will produce.
 

·
Registered
'91 560SEC, '91 300SE (sold), '98 Yota, '02 S-10 Hauler
Joined
·
9,496 Posts
281lxm just did his I think, I know he stripped a parts car that had all that on it, he could tell ya what you'd need and how to do it
 
  • Like
Reactions: 281lxm

·
Premium Member
1991 560 SEC 1994 E500 2014 E350 Cab
Joined
·
7,027 Posts
Has anyone replaced the 560SEC self-leveling rear hydraulic shocks, accumulators, pump, and lines with conventional shock absorbers as I believe W126's without self-leveling rear suspension have? My 1990 has just over 100,000 miles, and the ride is rougher than I'd expect, with loud thumps from the rear end over every bump and pothole. I don't know what the problem is, but I'd rather not spend over $1,000 to replace the self-leveling shocks and accumulators, compared to about $80 each for conventional Bilstein rear shocks.

Autohauz AZ tells me the non-self-leveling shocks will not fit cars with the self-leveling suspension. If it's a matter of making new mounting brackets for conventional shocks, I can handle that. I'd very much appreciate hearing from anyone who has converted 560SEC rear self-leveling suspension to conventional shock absorbers, what was involved, and when finished, did you notice any negative difference with conventional shocks on the back? Thank you very much in advance. John in Baltimore, MD
JOHN -- you can replace the bushings on either side of the strut where it bolts onto the frame behind the seats. If you do not get bouncey, and your shocks are not leaking, then that is your issue. They are two different size donuts of rubber. Originals become too soft like marshmellows and prolapse so to speak under pressure. Less than $30 bucks plus the shipping from parts.com and you are golden. Just did it a few weeks ago myself.
 

·
Registered
Smoke Silver '87 560SEC, Black Pearl '87 560SEL
Joined
·
4,651 Posts
I have replaced the SLS suspension in one of my 560SECs with a "standard" (non-SLS) setup. First, the folks above are right, the SLS suspension is a great thing. I had to replace the rear springs with proper non-SLS springs, remove the SLS pump off the engine and get the blanking plate, remove the hydraulic fluid reservoir, remove the SLS control valve from the rear sway bar, and then remove as much tubing as you feel like doing. I pulled the SLS off my other SEC as it has an LS6 engine in there, which doesn't have any way to power the pump.

Second, you have some common and simple to fix problems. A very hard ride is one or both of the accumulators blown. The banging sound is what happens after the rear suspension goes solid from the bad accumulators and the rubber doughnuts on top of the rear hydraulic struts (the shock absorber looking things) get pushed around too much and die. There is a great deal on ebay right now, $179 for two (2) accumulators!! That part number is correct for the 560SEC.

Buy some rubber bumpers for the top of the rear hydraulic struts now since those can't be replaced until the pressure is bled off. Replacing the accumulators depressurizes the SLS system.

Search for this on ebay: Mercedes W123 300TD Set of 2 Accumulators Rear Corteco OEM 1233200215
 
  • Like
Reactions: helgen

·
Registered
1990 560SEC, 2001 SL500
Joined
·
41 Posts
Discussion Starter · #8 ·
Thanks to all for your replies and good advice. The previous owner told me he replaced the accumulators within the last year, so I'm assuming that is not the cause of the thumping in the rear suspension over bumps. It sounds like my next step is to depressurize the system ands replace the rubber bushings on the tops of the hydraulic struts. Can you depressurize the system by opening what looks like a bleeder valve on top of the valve body connected to the sway bar, or should I depressurize the system by cracking the connections on the lines going to the hydraulic shocks? Also, I read somewhere the system is self-bleeding, butg if not what is the best way to depressurize the system when complete? Again, thank you all very much. John
 

·
Premium Member
87 Euro500HVSEC. 88 Euro 560HVSEC. 89 Euro 560HVSEL
Joined
·
4,499 Posts
When you remove your rear seats and plastic covers to expose the tops of the rams you will see the locking nut/tension nut/metal plate washer that sits on top of the upper rubber.
The metal plate is designed so it can only go down so far and it hits its stop position (this is to prevent you squashing the new rubber down too far on instal.
What happens is the old rubbers flatten out over time and eventually allow the top of the rams to literally bang up and down making that thumping noise.

To do a simple test to see if this is the problem-
Undo the locking nut/remove the 2nd nut and the large washer.
Place a piece of rubber washer aprox 5mm thick (cut a shape from any dense rubber you can find lying around or buy some rubber spacers.) on top of the old rubber bush
Screw it all back down so its is nice and firm.
Go for a drive and see if the thumping has gone away
My guess is it will.
You can drive like this no problem at all until you eventually sort out replacing the rubber bushes by dropping the rams out - yes you can bleed the system off to release the pressure)
 

·
Registered
1990 560SEC, 2001 SL500
Joined
·
41 Posts
Discussion Starter · #10 ·
SLS rear shocks on 1990 560SEC

Thank you for your response and good advice regarding the rear shocks on my 1990 560SEC. I just bought this car a month ago, and its CarFax says "rear shock absorber(s) replaced" on May 10, 2001 at 64,414 miles . The previous owner said he replaced both accumulators within the past 12 months.

This afternoon I removed the passenger-side rear hydraulic strut after cracking the tube fitting from the accumulator slightly to depressurize. When I took out the thick rubber spacers/washers at the top both the upper and lower spacers appeared in good shape without being squashed. As such it doesn't look to me they are allowing the shock to bang up and down in the upper chassis mount and cause the thumping noise.

Also the balljoint at the bottom of the shock was fairly tight with no play, which someone on this forum said was causing thumping and banging in his car. The only problem I saw was the bellows over the bottom of the shock was torn in two in several places, but the ram was shiny and not rusty or pitted.

On the bench I worked the shock up and down and each time it spewed out oil through the hose connection. The car now has 100,400 miles, and if the shocks were replaced at 64,414 miles, that indicates only 36,000 miles on them, although over 13 years. Other than the torn bellows, it does not appear to me this hydraulic strut needs replacing. From my description, does it sound to anyone that it does need replacing? Thank you again. John Doak in Baltiomre, MD
 

·
Premium Member
1991 560 SEC 1994 E500 2014 E350 Cab
Joined
·
7,027 Posts
you cannot replace the ball joint on the newer ones. The broken boot should be repaired but if it isn't leaking, its not broken. The bushings may look ok, but I can assure you that they are not shouldering the load as you may think. Your banging over bumps is the metal moving up and down on those donuts, resonating thru the frame. Mine looked good too, perhaps the other side has more visible reason to change but if you do, your knocking will be softer, almost non existant. You cannot replicate the force of the load and the compression of those donuts on the rear of the frame by the bench. The SLS is a simple valve and pump system. The springs shoulder the load and the struts raise and lower the car based on weight. You may want to review how high the car is and potentially lower the starting point to be more neutral. If you car's struts are supporting the car rather than the springs, you may find the problem. If your springs are tired at age 25, they should be. But I still would replace the bushings on the upper strut to frame first. Just my 2centavos!
 

·
Premium Member
87 Euro500HVSEC. 88 Euro 560HVSEC. 89 Euro 560HVSEL
Joined
·
4,499 Posts
Yes i agree with Louis - repair the splits in the dust covers with a good quality silicon as used on windscreens or sikaflex, so no dust gets inside as this is the cause of the ball joint wearing and failing in most cases.
Discard the donuts for new ones seeming you have one strut out already.
My little trick i mentioned earlier is a test before doing anything to determine if the donuts are causing the thumping under load and it works a treat. Most times this is cause of the thumping.
The lower donut takes a hell of a weight if the SLS is not set to neutral as the SLS is there to assist the spring and not bear the weight of the car.
If the lower ball joint is shot (you would feel play/slack from wear) you need to replace the whole strut
Cheers
 

·
Registered
1987 560SEL Astral Silver/Silver blue leather,Michelins,SONY
Joined
·
820 Posts
Got tired of farting around when first got my Beast. Junked it all in the rear...new everything....struts, donuts, accumulators. Nice ride. But I still feel those damn expansion strips in some roads and I guess it is just something we live with. Otherwise it gets soft and squishy riding.....like a big Caddy or Lincoln.
Don't dump the SLS......repair it and it will probably last as long as you have the car.
 

·
Registered
2016 E400 coupe, 2018 GLE350, 2007 CL600, 2019 C43 coupe
Joined
·
132 Posts
Had my resevoirs replaced a couple of weeks ago. The resevoirs were $200 and I had the work done in Yorkville, Il. at Star European Imports. It's like a brand new car. I think replacing all of the suspension components to get rid of the resevoirs is much more expensive. Removing the springs is a giant pain in the ass. My car has 140K miles on it.
 

·
Banned
Joined
·
2,987 Posts
I've had every piece of my suspension replaced and had it adjusted multiple times and the ride in the rear can still be rough over bumps. It's not consistent though; sometimes it glides, and sometimes it bangs. I thought I noticed the it rode better with a full tank of gas, but that could have been my imagination.
 
1 - 15 of 15 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top