Chasing front end 'clunks'
 

Chasing front end clunks in ’78 280CE w123 60k miles

Searched ‘clunks’……read most of the threads

Is there a link to a definitive article on front end troubleshooting?

Haynes & Chilton not much help

My 'clunk' comes on corners……........but not on a second or third etc. turn in the same direction……....'clunk' with the next turn in the other direction

Recent wheel bearing repack & adjust to spec with dial gauge when replacing rotors

Seems to have excessive movement when rocking wheel when holding at 12 & 6 o’clock and also pulling on upper section of the steering knuckle

This suggests to me to problem is the inner bushing on the upper control arm or the upper ball joint

My questions ……..........is my thinking correct
..........…….................how can I distinguish problems with the inner bush of the upper control arm & the upper ball joint

No 'clunks' with braking or going over bumps

Doesn’t appear to be any excessive play in steering

I have a gauge and magnetic stand so can measure excessive play if someone could give me the maximum allowable with regard to the lower ball joint & upper control arm

Thanks in advance for any help………………… judging by some of the long threads on ‘clunks’ I’m sure a concise troubleshooting guide would be of help to many of our forum members

David

I don't know your car well but as general advice - you need to raise the front tires off the ground (jack stand time) and push, pull, yank everything down there. I chased some noises for some time before advice was given to me to check again with the front end up. Tie Rods should only have a slight movement rotational and never a up/down movement.
Here was my 126 problem
[IMG]http://www.**************.com/alerts/126joint2.jpg[/IMG]

My intermittent hollow clunk with the turning of the steering wheel and sometimes going into a driveway was a worn drag link.

Under the car, you could grab it and easily rock it forward and backwards. With the new link, I couldn't move it.

Although both rubber seals were still good, one end of the link was shot.

If it is just a drag link, replacement is easy and no need to realign.

glenmore
1991 300CE

Thanks for the replies

Keen to know if my symptom of my 'clunk' coming on corners……........but not on a second or third etc. turn in the same direction……....'clunk' with the next turn in the other direction....points to any particular suspension component

This is my suspension setup

#4 is the bush I am suspecting

TX76513 is # 20 the part in your picture?

Don't mean to hijack the thread, but such a nice picture.
How to check/change #20? In the catalog of performace products, it is called "Track Rod Mount". Thanks.

Any Techs out there able to help?

I've done it with the spring installed, but I recommend taking the springs out to relieve the tension that is placed on that bushing. It is a bear to get everything back together with the spring installed.

If you are going to go so far as to take your spring down, be sure to replace everything you can. Especially the subframe bushings that the track rod mount is retained in. The removal of #20 is very straight forward once you are under there. Be sure to carefully measure your track rod length as I have found that the length of the mount threads can vary. I would recommend measuring from the front of the track rod to the front of the mount.

Thanks for the reply Q

Do you remember the symptoms you were having that led you to replace the bush

I'm usually game to try almost any repair. but I have a fear of working with springs........especially after reading a recent spring compressor thread

link to near disaster with spring compressor thread

I thought I could probably use a small floor jack under the lower arm with the chassis on stands to unload the suspension

I'm still keen to get some info on diagnosis...Steve...Arthur......anyone??

My w124 also had the same clunk problem when turning the steering wheel to the right and returning it to the center at a stop. To fix it I went to the auto repair shop at 10 am in the morning today. The mechanic raised the car and found out that the front tires also had a loose left to right movement which was not good.

Then the mechanic pulled out the #1, #2, and #3 part from the picture above. All of them are steering components and all of them had a small tire rod mounts on both ends (see the picture). The mounts were loose and had been easy to twist and turn.

He then disassembled the mounts on both ends of those parts by pushing the bolts in from the back where they have a cover using a hydraulic compressor. There is a plastic that keeps a ball like looking tip of the bolt in it that was deteriorated. He then replaced the plastic pieces inside the mounts, put some WD40 inside and sealed them using the hidraulic compressor to squeeze the back cover to the plastic and then used the hummer to bend the sides to mount the back cover .

All of that took 2 hours and I ended up paying $15 in total. The mechaninic guaranteed they will last at least 50000 kms.

If you come to Uzbekistan I will help you fix your problem for $15 :)

A test drive showed no more clunks, tire vibrations at any speeds under 140 kmh.

Hurshi

David:
You don't need to remove the spring to replace that #4. The spring only bears on it through the spindle. When I did my lower ball joints, I used a hydraulic jack under the lower control arm. I put it in place, jacked it up slightly, removed the nut for the upper ball joint, lowered it a little and with a couple of taps the spindle is released. #4 is now easily and safely accessed. Bear in mind the wheel and what not were all removed prior. A link to my post on the matter is below.

My Ball Joint Thread

Thanks for the reply Hurshi..............in Australia two hours labour would cost over $100(US$70) +parts........next time I'm driving through Uzbekistan I'll drop in....bit of a drive from Oz though!

I have no significant play in my steering and my links feel tight.......so that is why I'm looking at the suspension

bjcsc.........read your thread........lower ball joint sounds like a pain to get apart.........the upper ball joint sounds like it comes apart quite easily in comparison

I'm keen to be sure with my diagnosis before pulling things apart.........the lower ball joint seems to be a more common problem and the test for that seems to be up down movement with a jack/stand under the lower control arm...? Right

A front end diagnostic run down would still be much appreciated

Steve Brotherton.........any possibility of a brief diagnostic routine ?

It is hard to give a completely accurate diagnostic on a suspension noise from here:). I have just today finished a suspension rebuild on a 1989 300SE. I replaced all the suspension components that the rubber boots were torn up on. That did include item 20. I would recommend as a minimum item 20 and the lower ball joints. Again, perform a thorough visual inspection of the boots. If there is any doubt then replace them. Look real good at all the bushings and replaced what is dried up/cracked and busted up looking. I wish I had photographed the way I change them without compressing the spring. I use a "come a long" fastened to another cars tow hitch (I have it parked in front of the car I am working on) and pull the lower control arm forward with the come along. Works like a charm. I totally remove the fasteners holding the back plate and use the track rod adjustment to help drive the track rod mount out. Use it to help pull the new one in too. Works like a charm:).

Sorry, I can't say for certain this will work on your model. Send us a pic of it and we will advise as able.

Sorry for the delayed response. I replaced mine because everything that was rubber under my car was pretty much garbage when I took ownership. I'm slowly working my way through the rest of it. What I have left are upper control arm ball joint and bushings, front subframe bushings and rear trailing arm bushings.

I've replaced:
rear subframe mounts
differential mount
engine mounts
engine shocks
transmission mount
idler arm bushings
steering shock
lower ball joints (shop did this one)
track rod mounts
tie rods
center link
shifter linkage bushings
rebuilt front calipers
front wheel bearings
brake hoses

I had to laugh at myself one day. I took my car to an MB shop to have some tires mounted. I had the rear seat out to see if I could have the busted seam restitched. I also had all of the panels in the trunck removed from a car audio bug I had up my butt one day that never got followed through on.

The mechanic asked me if I was restoring the car. I said no, but in retrospect, I guess I am. ha ha

Wrong. If the boots are torn (or completely missing as in my case - they had totally deteriorated) they should be replaced. Eventually, they will groan and you can simply bounce the car up and down to hear it, but it will groan around corners, over speed bumps, etc. If your boots aren't in perfect shape, it would be crazy not to replace them while you're in there. It really wasn't that hard to do, I just had to wrestle with removing my old ones. I think it is reasonable to associate clunks with bushings as they allow play when they fail.

bjcsc.............everything looks visually ok........boots, rubbers etc...........but I have detected play when rocking the tire holding it at 12 & 6 o'clock..........I feel my bearings are ok....recently repacked & adjusted with a gauge, so am thinking ball joints or inner bush of upper control arm

Seems best option is to replace both while I am there..........your struggles with the lower ball joint causes me some concern

May opt to pay for a Tech to do it, but that is usually the last option for me

David,
On MBs it is the lower ball joint that is loaded. You need to unload the joint by jacking one side up and placing a jack stand at the outermost point of the lower control arm. Remove the tire and stick a long pry bar between#6 and #9 the lower control arm and lower ball joint. If you get more than a couple of millimeters, the joint is fairly worn. You can prang around on #4 the bushings for the upper control arm and see if you get any movement there.
I think your clunk may be coming from a broken engine mount. I've seen it before. The weight of the engine shifts once in one direction until you turn in the opposite direction which makes it shift again.

Good luck,
Peter

Thanks for the advice Peter..............interesting thought re engine mounts.....I'll check them out, do some prying as you suggested and report back

David Speed,

have you checked yor springs they may be broken. I had it on both sides.

Does your vehicle has a torsion style front end anti-sway bar? If so, check for worn bushings ( or just plain dry) at the points where the bar is fastened to the frame. The bar flexs in one direction when turning left, then the oposite way when turning right. Thus, usually only one of the bushings will "pop" at a time, giving the alternate turning effect thunk. I once replaced my rubber bushings with high performance "poly" bushings. The poly bushings snaped and poped and the noise was amplified through the frame. I went back to rubber. ttt

Replacing #20 (Guide Rod Bushing)
 

Here's a thread on the subject, which discusses various options for moving the control arm forward http://www.peachparts.com/shopforum/tech-help/66169-w126-guide-rod-bushing.html

Thanks guys.............I feel I'm narrowing down my 'clunk'

I'm becoming obsessed to the stage that it is ruining what is really quite a smooth ride

I'm now convinced the 'clunk' also comes with braking while turning and the first brake after change of direction (back to forward) ........but it is a bit variable.....AHHH!

My latest thought is the guide / track rod bushing......#20........seems changes in the longitudinal forces strain this bushing

I read your thread donbryce.........will have to work out a way to unload this bushing to check it.......I have a come-along / hand winch so will try pulling the LCA forward at the weekend........mine is a w123, but I suppose similar except for the subframe

I guess I'll end up replacing everything that doesn't require removal of the spring........so would have to leave the lower ball joint to a Suspension Tech

David:
Just so you're clear, the spring does not have to be removed when replacing the lower ball joint...

bjcsc.......thanks..........had another look at it and of course you are right.......seems with the spring in place and using a jack under the LCA, the only things I can't replace are the inner bushes of the LCA and the guide / track rod bushing where it connects to the LCA

Still a bit concerned about removing the lower ball joint.......but hey, I've got to give it a go !!

David,

Removing the spindle and hammering out the lower joint is a piece of cake. Installin the new joint is another story. You or your machine shop need a special tool to install. Your machinist may be able to do it without the tool, but he may never do work for you again. Good luck.

Peter

Thanks Peter..........if it's the lower ball joints she's going to the shop after your advice and reading all the threads of the struggles to pop the joint out of the LCA

I spent half a day pushing, pulling & prying .......everything feels pretty tight...............used a 5ft piece of wood as a lever under the hub with a jack under the LCA and couldn't get any significant movement in the lower ball joints.......boots look good

Set up a come-along to pull the LCA forward.......track /guide rod felt tight with no detectable movement (pic below......followed your description engatwork........is this something like the pic you 'wish you had taken'?........if it is feel free to use it)

I'm now thinking the torsion bar mountings.........got a 'groan' backing out of a park after a 50mile drive........could feel it through the pedals / fire wall.........tecqboy may be right on the money..........his description of how my 'change of direction clunks' could be realated to the torsion bar seems logical

Seems the only way to check the torsion bar mounts is to remove them.........is a check/replace possible without removing brake booster :confused: