It's like driving a brick here - PeachParts Mercedes-Benz Forum

Ara T. · #1 12-09-2005, 05:31 AM

My 1985 W123 300Dturbo (204K miles) lately has been riding really rough. A year ago I replaced the shocks with bilstein HD's, and back then I found the car to ride firmly but not uncomfortably so... it just felt really stable. SInce then I have replaced the front sway bar bushings in an effort to tighten up the handling, and it worked. I doubt my ride quality is affected by that though.

The suspension seems to be original... bushings and such dont look like they've been replaced. I don't have much money (college student) so a full suspension rebuild is out of the question, but are there a few simple bushings change-outs I can do to help ride quality? Rear suspension mount maybe? That feels almost plasticy, i believe its supposed to be rubber

I hear of people talking of subframe mounts but I have no idea what that is, whats a frame mount doing on a unibody constructed car? Or is the subframe mount kit on fastlane the same thing that HAyne's refers to as the rear suspension mount? It looks similar.

Despite the originality of the suspension there are no clunks or anything when I am driving on rough roads or going over speedbumps...also very minimal play in the steering, though it is kinda vague off center... pretty much why i havent really touched the suspension. But i figure all the bushings are shot after 20 years. Also I am rather intimidated by it, all the sledgehamemrs and prybars involved, i wouldn't really know where to start.

I started to realize how bad my car rides after we test drove a 2006 Miata MX5. We went over some train tracks to test how it would take them and it took them extremely smoothly, with my 300D it would feel like you're driving over some rocks.

Oh, and tires are new michelins with about 8K miles on them...wheels are upgraded 22"... just kidding. Stock 14" wheels, tire pressures are set at 28 front 32 rear just like the manual says to.

t walgamuth · #2 12-09-2005, 07:31 AM

do not drive any new cars.

serously it looks as if you have done all the obvious things. i guess if the bushings were so bad that ther is a lot of slop in the suspension it would bang around a lot. but i think yousaid it feels tight, so i dont know what to suggest. shocks would have been first thing, but you have done that.

tom w

#3 12-27-2005, 07:12 PM

Ara,

You might get some better responses if you tried to list exact symptoms. I've been chasing suspension trouble on my 190e 16v for a couple of months; have put new HD's up front, replaced 4 links in the rear suspension (am pretty sure your 300E has similar, 5 link setup) and will be replacing the subframe mount bushings (4 of 'em if i'm understanding it correctly) and rear shocks soon.
The front HDs obviously helped the 'bouncy', and I expect the back set will do the same. On the other hand, the old rear links will cause a the rear of the car to raise at different rates under hard acceleration and breaking; the effect is kinda like a almost-flat rear tire. I haven't done the sub-frame bushings yet, but I'm trying to get rid of a left-n-right motion that happens around 40+mph, particularly in the wind. Another thing that I attribute to the bushings is a back-n-forth vibration in the drivetrain when i drop the clutch and pull into traffic. I'm not sure you'd have this feeling with an automatic though.

The drivetrain problems were also much, much better after engine mounts were replaced. I also replaced the front strut mounts (you can see these in the engine bay, they hold the top of front shocks/struts in place. They had small tears in them, so I replaced them, but they didn't improve the handling/ride quality. I'd also take a gander at the rear sway bar bushings-they will need to be replaced if the front ones did. Oh yeah...I'm looking at the front A-arm bushings (not sure if this is MB's name), word is they help high-speed stability and low-speed shock absorbition.

These cars seem to have alot of rubber (compared to others i've worked on anyhow), and i think the majority of it is just plain shot after 20 years-don't give up on the new car feel!

cheers,
dan

EDIT: Whoops! I misread your w123 as a w124; i'm not sure your 123 has a rear suspension that is similar to my w201! Much of the other advice should hold though.

whunter · #4 12-27-2005, 08:12 PM

Take a look at these threads:

Rear sub frame Bushings W126 1985 300SD DIY
http://www.peachparts.com/shopforum/diesel-discussion/112850-rear-sub-frame-bushings-w126-1985-300sd-diy.html#post796976

Anyone ever broke a rear subframe bushing bolt?
http://www.peachparts.com/shopforum/diesel-discussion/73580-anyone-ever-broke-rear-subframe-bushing-bolt.html#post461406

W126 subframe mount clarification needed
http://www.peachparts.com/shopforum/tech-help/60587-w126-subframe-mount-clarification-needed.html#post370569

W126 Ride quality
http://www.peachparts.com/shopforum/tech-help/84033-w126-ride-quality.html#post543139

#5 12-28-2005, 03:29 AM

BTW your bilstein HD shocks are probably partially to blame for this problem.

My 300SD with 293k will blow over speedbumps at any speed other than 15 and won't even wink an eye.

One night I was going around and around in circles in the highschool parking lot after hours and mistakenly just flat out ran over a parking spot stop (those curbl looking things in front on the space with slightly beveled tops).

I was like...what was that?

Basically the only way I knew I ran over it was becuase I HEARD it...didn't even feel it. No damage to the stock 14inch wheels, tires, or anything....well anything other than the doughnuts were doing

I would say your firm ride is just your bilstein HD's settling in and making your ride a bit firm. How is your ride height? Can you snap a side photo of your car?

BTW it was one of these: About 4 inches tall if I remember correctly.

pawoSD · #6 12-28-2005, 03:37 AM

My car's shocks are dead, I know this all too well because I can drive over most anything like a speed bump (or the stops like are shown above) and all it does is go "bounce bounce" and I am over.

It bottoms out quite often too, resulting in a BOOM sound through the car when the upper control arm comes down and hits its stop....or vice versa, when the suspension goes up....a tad scary sometimes!

Especially when its....BOOM...CHINKLE (all the coins in my change bin jumping up then landing again)

I miiight install all new shocks this summer, as well as new rear springs and maybe some bushings. What I do will depend on my greenback flow.....if I work a lot I will be able to do lots of SD improvements.

First of first however is getting the body fixed up on my right rear door and the fender behind it, where it was hit 2 years ago by a drunkard.

My car has so much $$ into it I will be able to compete with Hatterasguy sometime in the future...

I have my tire pressure up around 38psi rear and 36psi front....I found this makes bumps even harder, but results in better handling and a smoother feeling on the freeway.....

t walgamuth · #7 12-29-2005, 11:28 PM

put new shocks on there... even if you have to go with cheapy sears steadyriders. it is unsafe the way it is! the cheapys will last a year or two and when they go you can go for the bilsteins. you could easily have a wreck because of them when they are as gone as you describe.

tom w

Brian Carlton · #8 12-29-2005, 11:33 PM

Quote:

Originally Posted by Ara T.

I started to realize how bad my car rides after we test drove a 2006 Miata MX5. We went over some train tracks to test how it would take them and it took them extremely smoothly, with my 300D it would feel like you're driving over some rocks.

Repeat of Tom W. statement:

"Note to self: Do not drive any new cars"

I sympathize. Both the SD and the SDL appear to ride "too stiff" and definitely find every irregularity in the pavement. They are horrible when compared to a new vehicle. My brother, who drives a new C class loaner home every night, commented on the harsh ride when he rode in the SD.

The suspensions on the older vehicles simply cannot compare to the new vehicles. They must have some cool progressive rate springs that are soft as hell for the first inch and then firm up dramatically. I dream of getting a custom made set for the SDL that are similar.

BTW, the W123 rides even stiffer than any of these...........one of the reasons that I had to sell it.

My advice: Drive another W123 and see if it's similar to your own. Make sure you take it on the same roads.

PagodaLover · #9 12-29-2005, 11:43 PM

John Olson progressive springs for Benz.

You are not likely to be disappointed.
http://www.sl113.org/forums/topic.asp?TOPIC_ID=4584

#10 12-29-2005, 11:43 PM

I guess it is a matter of preference but personally I think riding on a bubble in new cars is uncomfortable. My SD feeds back real nice and I don't like the way new cars feel in corners.

Nobody has ever said my SD is too stiff. If they think its stiff I would just hit a speed bump at speed.

I think my w123 does ride too stiff (but I like the way it feels). I can admit that it is stiff.

But the w126 body? Hmm...maybe compared to new cars...but is it sacraficing handling?

Brian Carlton · #11 12-30-2005, 12:04 AM

Quote:

Originally Posted by Brandon314159

But the w126 body? Hmm...maybe compared to new cars...but is it sacraficing handling?

I call it too stiff because it can travel down a concrete expressway that appears smooth to the eye and it will be banging along constantly on the pavement cracks. That's too stiff.

If the springs are progressive, it certainly can ride smoother yet handle very well. I'll bet the C class can do circles around the SD.

Brian Carlton · #12 12-30-2005, 12:10 AM

Quote:

Originally Posted by PagodaLover

John Olson progressive springs for Benz.

You are not likely to be disappointed.
http://www.sl113.org/forums/topic.asp?TOPIC_ID=4584

Can you provide any additional info?? Contact info?? W126 availability??

PagodaLover · #13 12-30-2005, 12:18 AM

Google and go to his website with the SL stuff. He makes custom springs for different models. Probably 123 too, but I've never done that application. He says any MBZ through 1989.

http://www.slmarket.com/springs.htm

Hope that helps.

#14 12-30-2005, 12:25 AM

Again, I think that much of the 'stiffness' is related to the rubber being shot. I don't think anybody here can boast a 100% restored suspension system (i won't even ask who is still riding with the original horse hair in the seat pads!), so lets not blame the design of the car. Rather, its aged rubber, blown shocks and possibly fatigued springs (i've heard different stories about this) that are causing a poor ride.

I'm just not sure that its the design of the cars and not the age of the components that deserve the blame for many ills of older benz's. Perhaps the truth will come out as these 20 year old cars start to have complete restorations?

cheers,
dan r
rubber nazi

Brian Carlton · #15 12-30-2005, 12:45 AM

Quote:

Originally Posted by Dan Rotigel

Again, I think that much of the 'stiffness' is related to the rubber being shot. I don't think anybody here can boast a 100% restored suspension system (i won't even ask who is still riding with the original horse hair in the seat pads!), so lets not blame the design of the car. Rather, its aged rubber, blown shocks and possibly fatigued springs (i've heard different stories about this) that are causing a poor ride.

Well, I can tell you that the SDL ('86) has new front shocks, new upper arms and bushings, new rear spring pads, new rear springs, new subframe bushings, new differential mount.

All new? No. It still could probably use LCA bushings. The rear trailing arm bushings appeared to be in good shape.

It still finds every bump in the road on concrete.

And, just so you don't start blaming the seat spring........it's a brand new seat spring frame and all new additional foam padding in the driver's seat.

These vehicles ride harshly........no matter what the condition of the rubber.