Is there any way to restore the ride quality in the 126 to the way it used to be when new? Or better? My car rides just fine for its age but I’d like to make it better. I've heard of subframe kit advertized on some MB parts stores that supposed to improve the ride significantly. The dealer told me there isn’t such thing as a sub-frame kit for the 126 and that the only ride improvement that I can make is by replacing the shocks and/or the springs. Which bushings influence ride quality other than those associated with the shock absorbers?

Cheers

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Riadh
'89 560SL Rauchsilber
And what is good, Phaedrus, and what is not good -- Need we ask anyone to tell us these things?

The subframe mounts play a big part in determining the temperament of the rear suspension. It's called a kit in the aftermarket because it comes as a set of left and right bushings and a diff mount. The parts are available separately from the dealer.

I think springs only address the height of the car. The condition of the spring pads probably contribute more to ride quality than the condition of the springs.

Put it this way - I haven't heard anyone say, "I put new springs and the ride is so much better." Unless a spring was broken or it was part of a swap to/from a sport tuned suspension.

Sixto
95 S420
87 300SDL

With both of the wheels off the ground, is there any play in either of them? I wouldn't doubt that your tie-rod ends are original. If so, they are probably worn. The wheels should be stiff when you push and pull on them. You could also have bad idler bushings, you wouldn't be the only one. How old are the tires? They may need to be balanced. The car could need an alignment. There are a lot of things that could make the car ride better. It is all a matter of how much you want to spend.
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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There also are front subframes on 126 cars (one on each side) and they do affect ride. They seem to harden over the years and they do very similar to running the tires with too much air pressure - they make the pavement feel rougher - they make the markers in the road surface seem harsher.

When dissolved by a power steering leak the ones on the left side will cause movement in the front end and decrease caster sometimes causing a pulling condition under braking.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Try a picture:

Attached Thumbnails

 

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Are the shocks origanal? If they are replace them with bilstiens (sp?) Also bushings get tired with age, so do tie rods etc. It really depends on how much you are willing to spend. With the diesels it is commen to do a front end rebuild around 250k or so. Your car with so many less miles should still be pretty tight.

The pic shows one of the bushing has been eaten away (W126 car). The other one is soft and bouncy.

Appreciate pointers/method/tool to replace the bushing.

Attached Thumbnails

 

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Shane83SD

Gentlemen,

Thank you for your valuable insights. There is a wealth of information in your posts and it will take a novice like me a while to digest. But digest I will. The tires are brand new and well balanced. Alignment work was performed recently. The shocks appear to be original and there is no record of them being replaced by the PO. However, they seem to be in good working order. But I realize there is bound to be some ride improvement with a new set. Yes Steve, going over lane reflectors and rough pavement does feel a bit harsh compared to how I remember a new 126 felt. It appears that the subframe work is a bit beyond my capabilities at this time. I feel comfortable performing fluid replacements, brake pad work, electronic diagnosis and relatively minor replacements such as injectors, EHA valve, etc. Thanks again for your help. I believe any prospective MB mechanic should be required to join this forum for at least a year after reading “Zen and the Art of Motorcycle Maintenance” before he/she is allowed to learn on the job.

Cheers

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Riadh
'89 560SL Rauchsilber
And what is good, Phaedrus, and what is not good -- Need we ask anyone to tell us these things?

Steve, are these subframe mount bushings hard to replace? Can I do it in my garage? Do I need a press? Should I take them out and visit my friendly dealer or machine shop?

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Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.

I just did this job on the driver's side of the 1984 300SD. Had the parts just in time for the really warm weekend two weeks ago. I have the parts for the passenger side too but decided not to deal with it this past weekend.

The reason I did this job was because the dust boots on the guide rod mount are ripped, and the mount was making some noise on slow rough roads.

The main tool you need to make this job work at home is a shop press. Got mine from Harbor Freight at a little over $100. It has paid for itself several times over.

Both of those bearing bracket mounts (some call them subframe mounts) need to be pressed out and the new ones pressed in. The guide rod mount also has to be pressed out and the new one pressed in. The parts are available here on FastLane. The guide rod mount kit includes nice new bolts.

You also need spray silicone to lubricate the new mounts before installation.

There is a cover over the back of the guide rod mount. Get the allen-wrench drive bolts loose first. Then remove the locking screw in the clamp on the screw-joint between the guide rod mount and the guide rod itself. Then take out the three bolts that hold an under-engine strut to the bearing bracket. Then drop the two big bolts that hold the bearing bracket to the frame. Now all you have to do is tediously screw the guide rod mount out of the guide rod. Assembly is the reverse. No need for any pulling or pushing of the control arm.

Pressing the old parts out of the bearing bracket is a piece of cake. Getting the new parts in takes some care, patience and liberal silicon lubrication. The hardest part to press back in is the guide rod mount because you need a piece of pipe just the right size to hold the bearing bracket (on the mount's bolt side) to press against.

No more guide rod mount noise. And when going over pavement joints, the driver's side is much quieter and transmits less shock to the body. Looking forward to warm weather to do the passenger side too.

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

Ken wrote "No need for any pulling or pushing of the control arm"

Read the related info in the Archive. Most indicates using some form of pushing/pulling of the lower control arm. I'm wondering why? Would you post what you did such that pulling/pushing of the control arm is not needed (W126 chasis). Did you take out any other suspension components? Is the suspension loaded, i.e., car on ramp? Thanks!

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Shane83SD

The car was jacked up using a bottle jack under the lower ball joint bolt. This kept the suspension in nearly normal compression. Then I used the standard MB jack in the frame to serve as a safety. Then I put an old wheel under the frame as another safety.

With the suspension normally loaded like this, all you have to do is drop the bearing bracket and unscrew the guide rod mount bolt. When assembling, thread the guide rod mount bolt further up into the guide rod than it was originally - so that the bearing bracket easily goes up into position. After the bearing bracket is tight, then position the guide rod bolt properly (showing the same number of threads as when you started).

Close enough to start. Some would say after this job a good alignment is warranted.

Now the W123 is a different story. No bearing bracket. There you have to apply some significant force to clear the guide rod mount bolt.

Shall I start a bearing bracket rebuild service?

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

Hey Ken, maybe I could come over?

After I get my car back together again, waterpump work at the moment.

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Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.

First--- Find a new dealer.

The 126 has rear subframe bushings, trailing arm bushings and maybe a hydraulic leveling suspension.

The rubber in the car may have deteriated and need replacing.
In the rear you have either sub frame bushings, trailing arm bushings, differential mount rubber, and sway bar connections and rubber swaybar mounts. OR you have the subframe bushings, trailing arm bushings, sway bar mount rubber and connectors and a hydraulic shock leveling system. You will have to determine which your car has.

If you have just a rubber/shock absorber system look here. This is the rebuild on the 300TD I have. I did the front and rear. Both can effect the ride. Mercedes used basically the same setup in the 123 and 126 for suspension design, the only big difference was the track mount setup in the front suspension.

300TD suspension rebuild progress

rear rebuild

300TD REAR suspension rebuild

Go here to see a diagram of your rear suspension

http://www.************************/BitMapPage.aspx?bitmapid=149&bitmapname=Rear+Suspension

Item #5 sub frame bushings
Item #4 trailing arm bushings
item # 2 sway bar connectors
Item # 1 shocks

Go here to see the hydraulic leveling system, You will have the same rubber system but your shocks are hydraulic not gas filled stand alone units. The hydraulic system has actuators ( shocks), control valve, 2 accumulators, an engine pump and resevoir, and lines to the rear system.

http://www.************************/BitMapPage.aspx?bitmapid=151&bitmapname=Rear+Hydraulic+Suspension

Its not a diagram but lists the parts.

Item #1 accumulators, act like shock absorbers
item #4 hydropnuematic shock replaces a shock absorber, but usually don't fail and are expensive.

Here is your front suspension

http://www.************************/BitMapPage.aspx?bitmapid=150&bitmapname=Front+Suspension+%26+Steering

The items that can effect your ride are #'s
1,4,5,7,13,16

The other items are probably not effecting ride as much as they would effect steering

So yes you do have subframe mounts.

Dave

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1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

After reading and rereading all the responses provided by the forum gurus, I've decided to take the plunge and do the subframe bushings myself. The dealer quoted me $2,800 P&L to replace 4 shocks, F&R subframe bushings, F&R sway bar bushings and 4 spring pads. I’ve just received the rear subframe bushing kit. Paid $87. I’ll also order the rear sway bar bushings and links for $40. I feel comfortable replacing the rear subframe bushings at this time, thanks to all the input provided. Dave, you made the whole process sound straight forward, thank you.

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Riadh
'89 560SL Rauchsilber
And what is good, Phaedrus, and what is not good -- Need we ask anyone to tell us these things?