front end suspension parts advice - PeachParts Mercedes-Benz Forum

chetwesley · #1 10-09-2008, 01:10 AM

Hi guys, I have been looking through past posts on this topic, but I am running into some difficulty understanding partially because of a lack of pictures, and partially from not knowing for sure what the different parts are called.

You know that no new to you mercedes could be without front end issues, and I am discovering that my 240D is no exception.

In short, I have a clunk from the driver side front that comes around at times when there is a significant shift in weight on the car - when I start up a hill, slow down on a hill, accelerate quickly, go for a turn, go over a bump, etc. It is most noticeable on very bumpy roads.

I am thinking it is the upper ball joint, because the boot seems to have separated from the shaft.

I don't think it is the guide rod mount, because I had a bad one of those on my old 300SD and although it would rattle around on bumpy roads too, the difference there was that you could always hear it whenever you hit the breaks and release them fast (from the guide rod pushing into the mount and releasing out). This doesn't do that.

I attached pictures of the upper and lower ball joints (I think that is what my pictures are of). I don't see any tears in the lower one, but let me know if you see anything suspect there. Sorry the picture isn't the best, but I think it is clear enough to see what is there.

Any ideas of what else would be causing the clunking, or does this sound like classic upper ball joint?

sixto · #2 10-09-2008, 01:21 AM

With the wheel in the air, push and pull on the wheel at the 12 o'clock position. Is there any slop? How's the steering? A worn upper balljoint will throw off camber which should make the car pull to one side. Depending on how long that's been the case, you should see uneven wear on that tire.

The balljoint is part of the upper control arm so the whole deal has to be replaced. I think it can be done without compressing the spring. Might as well get a new swaybar end bushing.

Sixto
87 300D

Diesel911 · #3 10-09-2008, 01:23 AM

Some people say the clunking sound can come from worn Rear Swaybar Links. If you can make the clunking sound show up at slow speeds; have someone stand beside your car to listen as you drive by and see if they can tell you which end off the car the sound is comming from.

Other than that worn front upper and/or lower ball joints as well as a worn Swaybar support can all cause that thunking noise.
You might search for some threads to find out how to test the ball joints for play.

chetwesley · #4 10-09-2008, 01:41 AM

The sound is definitely coming from the front, I can feel it in my foot.

The tire on the driver side is very worn on the inside (pretty much bald), and the car pulls to the right.

Whether or not the upper CAB could be replaced without compressing the spring or not was one of the things I had a hard time figuring out from the past postings I was looking at. I seemed to find conflicting info.

If it can, is there any other special tools that are needed? If it involves compressing the spring or pressing in a ball joint, I would rather leave it to a professional. I haven't quite worked up the confidence for that yet.

chetwesley · #5 10-09-2008, 03:13 AM

My problem was that I was searching for ball joint but I should have been searching for upper control arm.

I found this:
http://dieselgiant.com/mercedes_upper_control_arm_repla.htm

I have a question about the tutorial. It all makes sense until the last picture and bit of text. Is that just a mistake? It seems it is repeating something that was done earlier, but maybe I am missing or not understanding something.

Also, I'd still be interested in any other possible ideas about the cause of the clunking.

Scott98 · #6 10-09-2008, 08:13 AM

You need to get a pry bar and star tugging on some stuff under there and figure out what is loose. You can guess all day long at this stuff. You can have someone hold the steering wheel while you try to rock the wheels side to side with the tires in the air to eliminate your tie rods. Are the lower control arm bushings or upper control arm / sway bar bushings completely dry rotted and possible falling out? Don't forget to inspect those carefully too.

Scott

toomany MBZ · #7 10-09-2008, 11:21 AM

Quote:

Originally Posted by chetwesley

I have a question about the tutorial. It all makes sense until the last picture and bit of text. Is that just a mistake? It seems it is repeating something that was done earlier, but maybe I am missing or not understanding something.

That last shot is just another pic, and an overview of the procedure.
I found to line up the sway bar, use a long bolt with correct threads, and screw it in, that brought everything together for me, it even stayed that way after I removed that to install the proper bolt and washers.

rrgrassi · #8 10-09-2008, 11:28 AM

Worn out UCA bushings can also cause the clunking. Do all the checking as advised.

chetwesley · #9 10-09-2008, 02:06 PM

Thanks guys, I will check it out tonight hopefully... then to figure out what's up with the brake lights not working... always something

bbail2x2 · #10 10-09-2008, 05:59 PM

Quote:

Originally Posted by chetwesley

Whether or not the upper CAB could be replaced without compressing the spring or not was one of the things I had a hard time figuring out from the past postings I was looking at. I seemed to find conflicting info.

I just changed out my UCA on the 87 300SDL without compressing the spring. just remove the wheel and support the hub while R&R. LCA is a different story.

tenmaz · #11 10-09-2008, 06:13 PM

check the condition of the sway bar end which is behind the bushings. This has a history of rusting away.

Diesel911 · #12 10-10-2008, 02:09 AM

Quote:

Originally Posted by tenmaz

check the condition of the sway bar end which is behind the bushings. This has a history of rusting away.

This is a pic of my Sway Bar end (the part that goes through the Upper Congrol Arm). You can see by looking at the tip there is metal missing. But at least there is alot left and mine is still there.
Some Members have had the whole tip rust complpletely off. There is a repair if that happens.

chetwesley · #13 10-10-2008, 02:36 AM

Thanks everyone for your additional advice. I thankfully don't think I have problems with rust on these parts as this car has spent all of its life in cali and texas, and rather than rust the parts are coated in dusty dirt.

So I jacked up the car from under the front driver side jack point and tried moving the wheel pushing and pulling at 12:00, 6:00, 3:00, 9:00, and the various front end parts by hand. I could not get anything to budge by pushing, pulling shaking, etc. Everything seemed tight. I took some more pictures though, let me know what you think. The UCA bushing in back looks pretty bad and rotted out to me, in fact the control arm even looks crooked in there, and I am suspecting that might be where the clunking is coming from. I think it might take more force than I am able to apply by hand to get it to shift though. I don't have a pry bar, unfortunately.

I also noticed the tires were even worse than I thought. There is steel braiding poking through the rubber on the inside!

I haven't taken the car on the freeway yet, thankfully.

Take a look at the pictures and let me know what you think.

chetwesley · #14 10-10-2008, 02:38 AM

More pics. What are the parts in the first one and the last two pics called, by the way?

wbain5280 · #15 10-10-2008, 10:16 AM

The outer ones are the tie rods and the center one is the drag link. Steering parts.

You are going to have to overhaul and replace all the ball joints and bushings in the front end. The rubber is bad, cracked, and that lets water and dirt inside the joint causing wear. The grease also gets out. The best way to preserve the rubber is by using silicone spray.