[aam]

The members hit almost all the spots.

One more thing to CK is the rubber bumper stop, it is located on top of the strut.

In the rear, some link troubles, the shock rubber donuts/bushings, one of them brakes....
But you don't have a lot of miles.

Regards,
aam.

 

[WarrenC]

The first thing I would replace if the clunking heard at low speed, is the sway bar bushings...

They are an hour to replace, and cost about 9 dollars...

the are probably due for replacement anyway...

Advice, spray the 10mm nuts that holds the bar to the lower control arm with some penetration fluid about an hour before you take it off, so you dont break it...

I can attest to the fact that these can cause some horrendous sounds from the front suspension. I had some bad ones on a pickup that two different shops could not diagnose correctly.
One condemned the ball joints, and the other admitted they didn't know what the problem was.
I finally found it myself, replaced the bushings for $10 and drove away into the sunset. Or something like that....

 

[silver50]

A great many thanks for all the helpful pointers. Wasn't sure whether to post because I know it's a bit like asking "how long is a piece of string" without seeing the car. But been very helpful. If I get anywhere this weekend i'll post back.

 

[Zachmac]

Not sure I saw it mentioned but what about the top bushings on the strut towers?

These dry out and rot allowing the strut to move and clunk. If left unattended you can eventually damage the shock tower itself leading to very large problems. An easy and cheap fix if that's the case. You can look at them on a rack by letting the front hang down (a lift on the frame versus tires) and look up above the strut at the bushing bottoms (if you have strut boots that are intact you have to pull them down to see the bushings but most are shot). Replaements are about $60 each and simple to replace.

 

[silver50]

The only thing i've done so far was a good bounce test. I must admit i'm thinking the front shocks are if anything a bit soft, although it'd be good to bounce a car with new dampers...! I think i'll price some up. The rear of the car feels ok to me, better than the front did but I guess the rear shocks are not really worked as hard. When I first bounced the front end I may have heard the knock, but it stopped.

I assume there is a rubberised cover on the 22mm strut top bolt mentioned above?

I've got someone else in mind for a second look at my car. Think that is probably wiser than me trying to prod about underneath. Up on a ramp seems sensible.

 

[silver50]

Meant to say thanks for the reminder about strut top mounts. Ive read about them here. If perishing is thier downfall mine are probably ok. But worth checking. Definately worth checking..I know what can happen if they go out on you!

 

[aam]

The only thing i've done so far was a good bounce test. I must admit i'm thinking the front shocks are if anything a bit soft, although it'd be good to bounce a car with new dampers...! I think i'll price some up. The rear of the car feels ok to me, better than the front did but I guess the rear shocks are not really worked as hard. When I first bounced the front end I may have heard the knock, but it stopped.

I assume there is a rubberised cover on the 22mm strut top bolt mentioned above?

I've got someone else in mind for a second look at my car. Think that is probably wiser than me trying to prod about underneath. Up on a ramp seems sensible.

If you think that the struts/front shocks are soft, then that is it.
I replaced mine about a year a go.

If I push down on the car.
I am 200 pounds.
(Wife's love and Greek food. ) Haha.

Car is not moving.

Remember that they are gas charged to about seventy pounds cold.
So when you push you have resistance from the strut, and the spring.

Regards,
aam.

 

[silver50]

Yes I think changing them can't be a bad idea. I've emailed my friendly MB parts man for a price. Think they're pretty expensive but I suppose needs must. I once replaced a pair of BMW EDC shocks on a 750iL after being told they were shot on a couple of occasions. Noticed no difference whatsoever in the way the car drove afterwards. My wallet is still recovering from that episode. I now would prefer to see puddles of oil from my shocks before replacing!!

 

[Keepontrucking]

Recently had the same problem. Was told that the idler arm bushing was worn and loose. Replaced by an INDY and quess what, no klunk. Also the vibration in the front wheels at 75 mph is gone. Problem was hard to diagnose without a lift.

 

[silver50]

Thanks for reply. As I said the garage I took my car to did have quite a thorough look on a lift/ramp. However not being an MB specialist they may have been a little less familiar with the steering (box) system.

I'm definately going to get a second opinion on it before blindly changing anything. This week a guy at our dealer parts dept I know said front shocks are not at all often ordered over the years (from info on computer system) so i'd want to be 100% sure they were the likey culprits before splashing out on a pair.

 

[MrShades]

I had those sounds on my car. I replaced the worn shock absorbers and it was okay after that.

Any here replaced the lower ball joints?
I heard that those is so difficult to change yourself.

 

[Skiffcap]

Please reexamine 'sw23185's' post. Also search 'thonk'. I sprayed the crossbraces with WD-40 and fixed the 'thonk, clunk, knock' that was coming from the passenger side footwell.

 

[MrShades]

If it is the ti rod ends, subframe bushings i suppose that if you take a tire iron and go to work on the undercarriage of your car you will soon see whats wrong.

I suggest not to do that if you have are not used to work on cars

 

[moil]

Hello.

I think that I have the same clunk/thong problem as yours at low speed.

My money is on the sub-frame cross braces. A couple of years back I cured a suspension-related 'clunk' in my 2001 R129 by having the dealership mechanics loosen and then re-torque the subframe cross-braces. The noise happened predictably at low speeds over small bumps and was easy to reproduce, so they couldn't claim the ever-popular "No Fault Found".

So I'm going to re-torque these two subframe cross-braces on my 1992 R129 500SL.

These two front cross-braces have MB. ref 1295240247 (position 29 on MB's EPC picture).

Looking in MB's R129 DVD, I was only able to find the torque for the two similar rear subframe cross-braces (1295240447 pos 35 and 1295240347 pos 32). The specified torque is 120 Nm.

I assume that the two other torque values specified by MB's DVD for the R129 subframe deal with the X shaped cross member in front of the radiator, and the bridge below the transmission tunnel. For these, the specified torque is only 25 Nm.

The screws 0019902512 (8 total) are the same for the two front braces and the two rear braces. So, I'm tempted to re-torque the two front cross-braces at 120 Nm.

But if someone here could confirm that this value is right, it will help me sleep better at night.

Thanks !

 

[silver50]

Sorry can't help with the cross brace question but as I am reminded about my thread via email this morning I can report that in the main my clunk was cured with new outer and inner front sway/anti-roll bar bushes.

Took three different diagnosis on it, and being shown the play in them (think it was really the inner two- not the two nearer the wheels) I was sceptical this was going to cure the problem BUT it definitely cured what was plaguing me.

I still have a trace of a clonking but have new shock absorbers waiting to be fitted (still not gotten round to it...). If they don't help I imagine slight bottom ball joint wear. Also have a set of springs to fit. As I said above when my old R129 was stripped down to fit the springs/shocks bad ball joint wear was discovered, even although no clunks

Moral is, make sure you get those roll bar bushes checked/replaced before buying shocks/ball joints etc! ...And maybe checking/torqueing those cross braces!

 

[moil]

Thanks for your help :bowdown:

I have disassembled the two braces mentioned in my previous post, cleaned everything, and re-torqued the 4 bolts at 120 Nm (same torque value as the one specified for the two rear braces) while the car was resting on its wheels,
and guess what ? the clunk / thong noise is gone :thumbsup: (I've done quite a few tests with the same configuration load/bumps/speed, just to be sure).

Some extra details if they can help others :
- the car is an 1992 500SL with about 150 000 miles
- I guess that the shocks and most of the hard parts are original, except for one steering link, shocks top mounts are cracked but the nuts seems to be OK, and I think the steering damper has to be replaced because I have from time to time strange feelings in the steering wheel while cornering on an uneven surface
- I guess that all the "easy access" bushes have been changed before 120 000 miles because they look good (perhaps the only thing that looks good under that car !)
- there was no strange noise coming from the front of the car, before I slightly overloaded the two rear seats (in Europe we can use that car as a four seater, but the two rear seats are intended for two childs, when you put two mothers in these seats, problems may arise )
- the next day the the clunk / thong noise started, and developed in only one day
- the noise happened quite predictably over small bumps at low speeds and was very easy to reproduce (see SW23185 previous post)
- the noise was coming exactly from the front center of the car (in fact where the subframe braces join)
- by twisting by hand one of the braces I was able to make that thing "clung" from time to time
- I know that I will have to do some extra work on the front (shocks, upper mounts, steering damper, ...) at that time I will change the 4 self locking bolts or secure them with some blue threadlocker

Thanks for your help :bowdown:

 

[silver50]

Hope you can get on to starting to replace some items, but if you're top strut mounts look cracked, I think this should be done as soon as possible just incase the horror story unfolded which is the strut punching through the bodywork!

 

[moil]

Hope you can get on to starting to replace some items, but if you're top strut mounts look cracked, I think this should be done as soon as possible just incase the horror story unfolded which is the strut punching through the bodywork!

Yes, thanks for your warning. These parts (shocks, top strut mounts, steering damper) have already been ordered. I hope to receive them soon and to work on it ASAP.

This small clunk / thong noise problem has made me aware just how bad the state of these parts is. While replacing these items, I will thoroughly check the other parts of the front end (ball joint, wishbone, steering linkage, wheel bearing play, alignment ...).

 

[silver50]

I'd imagine a lot of stuff will be fine, like W124's that go on an on. And on!

I see you have a 1995 E220. I regret selling my estate/wagon 1995 E220

I meant to say this morning in my post that I had a steering shock absorber fitted at the same time as the roll bar bushes. Not maybe a night and day change, but noticeable nicer feel to steering

 

[moil]

I'd imagine a lot of stuff will be fine, like W124's that go on an on. And on!

I see you have a 1995 E220. I regret selling my estate/wagon 1995 E220

I guess that the R129 "standard" suspension get more stress that its W124 counterpart and their architecture seems to be the same.

The R129 is heavier, and some drivers like to ear the sound of their engine , even on curvy roads. I confess, I'm one of them.

I love my W124 E220 estate/wagon, and when compared with the R129, it is really trouble free at 180 000, apart from this damn engine harness thing but usage is not comparable.