Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help




Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 03-21-2005, 05:04 PM
Registered User
 
Join Date: Jan 2002
Location: Washington, DC
Posts: 512
Ups & Downs Of Self Leveling Suspension?

What is the purpose of the self leveling suspension? What does it really do and why does Mercedes use it in some models but not others?

Besides E class wagons (123, 124, 210, and 211), Mercedes has used it in some versions of the W201, W124, W126, W140, R107, and R129. I get the concept of compensating for a heavy load in a wagon or even a big sedan, but what was the idea of using it in the W201, W124, R107, and R129? Besides compensating for a heavy load, what else does it do? If it has such great benefits in some models, why not use it in all models?

Just curious. Thanks.
__________________
Michael

1988 300 SL (5 Speed)
1994 E320 Wagon
1997 C230
Reply With Quote
  #2  
Old 03-21-2005, 07:13 PM
Registered User
 
Join Date: Aug 2001
Location: Evansville, Indiana
Posts: 8,150
Well, it keeps the car level all the time.

The W108/109 chassis had a mechanical system that is usually long gone by now -- and replaced by a simple spring. The W109 had air suspension, too, not steel springs.

The hydraulic rear suspension also rides MUCH nicer than springs and shocks, but is also mor expensive. Usually optional on most models, although not in the US. European taxis almost always have it, keeps the rear from squatting so badly when really loaded up.

The W116/W126 6.9 and other various luxury models had full hydraultic, and many top line sedans have rear SLS (and it's optional on all).

I really like the SLS in the TE, and I think it handles BETTER than the steel spring suspension in the 300D.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
Reply With Quote
  #3  
Old 03-21-2005, 09:42 PM
A. Rosich's Avatar
Registered User
 
Join Date: Nov 1999
Location: San Jose, Costa Rica
Posts: 883
As stated above, basically the SLS helps the rear of the car to be levelled in case is heavily loaded.

But that's really about it. I have owned three T's (one 123 and two 124s) and have driven several sedans of the same line. Almost never in any situation I could tell the difference in ride or handling with and without SLS.

The only time you can feel a difference, is when the SLS system fails and then your rear axle becomes a cement grave and the slighest hole will make it bounce up to the sky. Then, be prepared to mortage your house to pay for repairs. That is about the only difference with this set up and the regular springs.

I admit it, when the Ts were heavily loaded, the ride was smooth and competent. Although, this happened about twice a year. So, were is the advantage???

Thankfully, my S 500 L is Euro spec and does NOT have the SLS.
__________________
A. Rosich
CL 500, 1998
S 500 L, 1998
E 320 T, 1995 [Sadly sold ]
Reply With Quote
  #4  
Old 03-21-2005, 11:43 PM
sfloriII's Avatar
Still pedaling...
 
Join Date: Aug 2003
Location: Northern VA
Posts: 1,614
I think it also helps keep our 190-D 16 valves level when screeming around corners!
__________________

Current:
2014 VW Tiguan SEL 4Motion 43,000 miles.

2016 Hyundai Santa Fe Sport (wife's).

Past:
2006 Jetta TDI 135,970 miles. Sold Nov. '13.
1995 E-320 Special Edition. 220,200 miles. Sold Sept. '07.
1987 190-E 16 valve. 153,000 miles. Sold Feb. '06.
1980 300-D 225,000 miles. Donated to the National Kidney Foundation.
1980 240-D manual, 297,500 miles. Totaled by inattentive driver.
Reply With Quote
  #5  
Old 03-21-2005, 11:45 PM
Registered User
 
Join Date: Jan 2002
Location: Washington, DC
Posts: 512
Thanks. I get that but still feel like I must be missing something. What you all are saying is, for a heavy load, it's nice to have but some sort of engineering overkill? What does this thing really do? There must by more to it. Why would the Cosworth W201 or 500E have it? I really feel like I'm missing something... What about day to day? How fast does it react to changing loads and is it a kind of active suspension? Say I was driving the wagon without a load at 125 mph and was turning, would the SLS compensate in real time according to the load for each side? Is it slower than that? Does it always do both sides equally? On another note, is the real purpose of this thing to sacrifice itself for more expensive rear suspension parts of vehicles that are expected to receive heavy hauling or racing service? Correct me if Iím wrong, but to refresh the system (which will be needed once about every 100,000 miles), is relatively cheap, about $200 for parts (accumulators), $50 for fluid, and a couple of hours of labor. If it prolongs the life of other, expensive rear suspension bits, would it not save cost over time? When I drive the wagon, I feel like SLS has some intangible value that I canít quite put my finger on. Day to day, what does it really do for me?
__________________
Michael

1988 300 SL (5 Speed)
1994 E320 Wagon
1997 C230
Reply With Quote
  #6  
Old 03-21-2005, 11:48 PM
TheV12pwr's Avatar
Registered User
 
Join Date: Dec 2004
Posts: 220
The best thing is that you can switch from soft to hard ride...with a push of a button
And you can manualy adjust the suspension hight!
There is no comparison!
Refering to 129
__________________
DRIVE IT LIKE YOU STOLE IT!

Last edited by TheV12pwr; 03-22-2005 at 12:42 AM.
Reply With Quote
  #7  
Old 03-21-2005, 11:59 PM
sfloriII's Avatar
Still pedaling...
 
Join Date: Aug 2003
Location: Northern VA
Posts: 1,614
To give you a more serious answer, I'd have to be honest and tell you that I've never really felt the suspension compensate for anything. For that matter, there's a loud banging sound in the left-rear side of the car whenever the suspension comes back out after compressing over a bump. Very loud, irritating, and it hasn't been figured out by my mechanic who happens to specialize in these cars. Go figure.

That may be one reason why so many 16 valve owners replace the rear self-leveling suspension with more conventional ones after they begin to have problems.
__________________

Current:
2014 VW Tiguan SEL 4Motion 43,000 miles.

2016 Hyundai Santa Fe Sport (wife's).

Past:
2006 Jetta TDI 135,970 miles. Sold Nov. '13.
1995 E-320 Special Edition. 220,200 miles. Sold Sept. '07.
1987 190-E 16 valve. 153,000 miles. Sold Feb. '06.
1980 300-D 225,000 miles. Donated to the National Kidney Foundation.
1980 240-D manual, 297,500 miles. Totaled by inattentive driver.
Reply With Quote
  #8  
Old 03-22-2005, 12:36 AM
TheV12pwr's Avatar
Registered User
 
Join Date: Dec 2004
Posts: 220
"loud banging sound in the left-rear side of the car "

You better think of taking your car to another 'mechanic'
When diaphragm sphere burst loses the nitrogen and there is no 'back up' pressure to support the load on the shock!
There is banging just because there is no pressure...simple as that
__________________
DRIVE IT LIKE YOU STOLE IT!
Reply With Quote
  #9  
Old 03-22-2005, 03:16 AM
Senior Canadian Member
 
Join Date: Jul 2000
Location: British Columbia, Canada
Posts: 827
1) SLS is used to maintian a level ride irrespective of the load placed in the rear of the car.

2) This was a feature in only a few models because it was considered a "higher end" component, so vehicles like the W140, R129, W124 500E and W201 16v were equipped with it. Additionally, it was added to the T-class because - in theory - these vehicles would be carrying greater loads than the 'regular' sedans.

3) Sport models such as the EvoI and EvoII as well as the R129 had a variation of the SLS which involved hydro-struts at both ends of the car. This resulted in improved dive & squat resistance along with the ability to adjust ride height from the driver's seat. This would be an obvious advantage on the race track and since the EvoI and II were homologation specials, they came equipped with this system.

4) the SLS is not really designed to counteract body roll. the system employs a valve which is connected to the rear swaybar. when the valve opens & closes it allows pressurized hydraulic fluid into/out of the rear struts. the valve is actuated by the rotational displacement of the rear swaybar. That having been said, if there is enough torque applied ot the rear swaybar, it is possible for it to deflect enough to actuate the valve. I have experienced this in the 500Es during hard cornering. you can feel the rear end resist the body roll.

5) The SLS is NOT cheap. Each strut retails for approx $400 CDN. This is why most 16v owners replace the system with conventional shocks & springs when their SLS fails. Another reason many owners replace the system with conventional shoclks is because there is only a certain amount of "drop" that you can achieve by adjusting the SLS in a 2.3-16. remember, these cars had early versions of the SLS. they did not have the full SLS system with ride height control ready for production until around 1988/1989.

6) the loud banging could also be a result of worn rear suspension bushings. The bushings in the 5-link suspension take a LOT of abuse and are subject ot high loads. as the wheel travels vertically, the bushings have to allow it (the wheel) to move in an arc, while at the same time preventing it from mving in an arc. this is why the suspension bushings wear out so frequently. if the bushings are worn, there is nothing holding the mounting bolt to the suspention strut. the bolt is just floating in the eye of the strut with approx 1/2" of play on all sides of it. you may also want to check the swaybar links as well as the struts. noises like a bang or a clunk in the rear suspension have also been traced to worn swaybar link bushings and collapsed bumpstops in the struts.

7) as for why it was not available in all models, i suspect one word would be an adequate explanation: cost. cost to produce, cost to sell (increased retail price), and cost to support the system at the parts desk (greater volume of parts to carry).
__________________
'94 W124.036 249/040 leder; 8.25x17 EvoIIs
'93 W124.036 199/040 leder; 8.25x17 EvoIIs, up in flames...LITERALLY!
'93 W124.036 481/040 leder; euro delivery; 8.25x17 EvoIIs
'88 R107.048 441/409 leder; Euro lights
'87 W201.034 199/040 leder; Euro lights; EvoII brakes; 8x16 EvoIs - soon: 500E rear brakes
'70 R113.044 050/526; factory alloys; Euro lights
Reply With Quote
  #10  
Old 03-22-2005, 04:21 AM
Registered User
 
Join Date: Aug 2001
Posts: 530
Stefano,
Replace the upper shock bushings 2 each side, and you get rid of your problem. Mine did the same thing, replaced the bushings and it`s great now. When the accumulators go bad these get hammered, especialy the lower one. On the top there is a lower and upper bushing replace both.

John
__________________
President Minuteman Section MBCA
www.mbca.org/minuteman
Reply With Quote
  #11  
Old 03-22-2005, 07:49 AM
sfloriII's Avatar
Still pedaling...
 
Join Date: Aug 2003
Location: Northern VA
Posts: 1,614
Thanks, John & others.

John: did the loud banging noise on yours occur when the shock was being compressed or extended? In other words, if I go over a speed bump, I hear the noise as the wheel comes back down to meet the pavement as it extends.
__________________

Current:
2014 VW Tiguan SEL 4Motion 43,000 miles.

2016 Hyundai Santa Fe Sport (wife's).

Past:
2006 Jetta TDI 135,970 miles. Sold Nov. '13.
1995 E-320 Special Edition. 220,200 miles. Sold Sept. '07.
1987 190-E 16 valve. 153,000 miles. Sold Feb. '06.
1980 300-D 225,000 miles. Donated to the National Kidney Foundation.
1980 240-D manual, 297,500 miles. Totaled by inattentive driver.
Reply With Quote
  #12  
Old 03-22-2005, 11:13 AM
A. Rosich's Avatar
Registered User
 
Join Date: Nov 1999
Location: San Jose, Costa Rica
Posts: 883
Quote:
Originally Posted by TheV12pwr
The best thing is that you can switch from soft to hard ride...with a push of a button
And you can manualy adjust the suspension hight!
There is no comparison!
Refering to 129

The system you are referring to is COMPLETELY DIFFERENT from the SLS fitted to the T series and some sedans as either standard (in some markets for high end models) or as an option (for almost ALL models in most markets).

The SLS just levels the rear axle, period. No buttoms to adjust ride characteristics or anything. No advantages over the regular setup in terms of handling and ride (unless, as said many times before, the car is fully loaded).
__________________
A. Rosich
CL 500, 1998
S 500 L, 1998
E 320 T, 1995 [Sadly sold ]
Reply With Quote
  #13  
Old 03-23-2005, 04:25 AM
Registered User
 
Join Date: Aug 2001
Posts: 530
It happened everytime I hit a bump. Sounds like the same thing to me

John
__________________
President Minuteman Section MBCA
www.mbca.org/minuteman
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
self leveling suspension 1982 300TD Goldie Diesel Discussion 5 01-14-2004 08:27 AM
Replacing Self Leveling Suspension with Shocks and Springs g5sp Tech Help 2 07-07-2003 10:45 PM
Self Leveling Suspension MB4Life Mercedes-Benz SL Discussion Forum 2 01-20-2002 10:14 AM
self leveling suspension question Wael El-Dasher Mercedes-Benz Performance Paddock 8 03-19-2000 11:28 AM
E55T self leveling suspension. wwong88 Featured Cars 2 03-07-2000 01:01 AM



All times are GMT -4. The time now is 05:46 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page