PeachParts Mercedes-Benz Forum - How To: Upper Ball Joint Replacement, step by step with pictures. W123

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and, 79Mercy, I'm still interested in how you got those aluminum rims looking so good. Could be a how-to post with pics you could guide us through.:)

Those a 14x6.5" bundts, they are from a S-class.

I sanded them down, painted with primer, then i painted the rims with heavy duty Rustoleum "Aluminum" spray paint(about 3 coats), and topped them off with 3 coats of clear. They look ok, some imperfections up close. I don't think i have pictures of the process, so no "how-to" to make.

I have sanded the rims down with a wire brush drill attachment, then painted mine with aluminum "flake" paint from Autozone. It's considered to be rim paint, yet mine don't look as good as yours. I'm wondering if the clear coat makes the real difference. Also, I'm wondering if after the sanding, one could simply apply clear coat to the raw aluminum to achieve maximum results.

Although I am primarily concerned with the engineering involved with these cars, I am admittedly a fan of the overall design and want to find ways to improve and restore appearance.

Perhaps this is best something explored in another thread? Or perhaps is it already covered if I search well enough. I have searched in the tires and rims section of this website and have found no definitive guide on rims restoration.

Disclaimer: I live in Memphis, so please no posts by anyone bashing Autozone. I support Autozone, and are not employed by them. I am only a Memphian who supports Autozone (as they are integral to the local economy) and has found them to be diverse and knowledgeable. I'm in this forum for MB's and advice.:D

Quote:

Originally Posted by littlerobot (Post 2507705)

My upper ball joints are terrible. They need replacing. Here's how I did the passenger side. It took about an hour.

http://www.mousefoundry.com/mercedes...l_joint102.jpg

Remove the air filter housing under the hood.

http://www.mousefoundry.com/mercedes...l_joint137.jpg

This gives us access to the bolt holding the ball joint arm to the frame of the car. Don't loosen it yet, just remember where it is.

http://www.mousefoundry.com/mercedes...l_joint131.jpg

http://www.mousefoundry.com/mercedes...l_joint158.jpg

Now we jack up the car using a hydraulic jack. I placed the jack directly under the jack-up ports behind the wheel. There is a piece of wood between the jack and car. I've placed wheel chocks behind both rear wheels. Now, remove the tire.

http://www.mousefoundry.com/mercedes...l_joint121.jpg

:EDIT:
Danger:
Place a jack stand under the lower control arm by the ball joint, and lower the car into contact.
The shock absorber can break, dropping the lower control arm = possible injury or death.

Here's where the top of the steering knuckle connects to the upper ball joint. Mine is crusty, with bad rubber on the bushings and on the ball joint itself. Grab your breaker bar or socket and loosen the bolt connecting the ball joint to the steering knuckle arm.

http://www.mousefoundry.com/mercedes...l_joint144.jpg

Now we have the car jacked up, but the weight of the suspension system is pulling downward. This will help us in a moment. After you've removed the bolt you want to use a cool tool.

http://www.mousefoundry.com/mercedes...l_joint123.jpg

This is a "joint popper". It's an invaluable tool for suspension work. I purchased this one from Harbor Freight for 15 bucks or so.

http://www.mousefoundry.com/mercedes...l_joint122.jpg

Place our cool tool on the joint like so. This is where the weight of the steering knuckle pulling downward helps us. Turn the tool until the joint pops apart. It came apart very easily for me.

http://www.mousefoundry.com/mercedes...l_joint114.jpg

Pop. The joint separates and is no longer connected to the upper knuckle arm.

http://www.mousefoundry.com/mercedes...l_joint112.jpg

Now remove this bolt. There is a rubber bushing under it. Pull that off too.

http://www.mousefoundry.com/mercedes...l_joint103.jpg

Now we move to the top of the car.

http://www.mousefoundry.com/mercedes...l_joint137.jpg

The bolt runs horizontally through this part of the car. The nut is facing us. The bolt itself is facing the battery. It's a little tough, but you should be able to get a crescent wrench or open ended wrench on it, then place a breaker bar on the nut itself.

http://www.mousefoundry.com/mercedes...l_joint138.jpg

Break the nut loose and remove it from the bolt. Here's where it gets a little tough, because the high-side of the air conditioning runs between the battery and where we need to pull the bolt out. I tapped the bolt from the other side with a screwdriver, pushing it out toward the battery, and tried to hold the high-side R134 line out of the way. I managed to get it out, but here's where we change a little something.

http://www.mousefoundry.com/mercedes...l_joint129.jpg

Because the bolt and nut faces this way, it's difficult to get out. But....

http://www.mousefoundry.com/mercedes...l_joint107.jpg

When we put it back in we are going to put it this way, technically its backward, but its going to be WAY easier to put back in this way, and WAY easier to take back out if we ever have to work on this ball joint again. It's a win-win situation. Don't worry, it won't affect performance or safety.

http://www.mousefoundry.com/mercedes...l_joint141.jpg

Pull the old ball joint out.

http://www.mousefoundry.com/mercedes..._joint141a.jpg

Also remove this rubber grommet and replace it with a new one.

http://www.mousefoundry.com/mercedes...l_joint105.jpg

Get your new ball joint and push it into place.

http://www.mousefoundry.com/mercedes...l_joint107.jpg

Move to the top of the car. Put the bolt back through the frame like this and tighten it up.

http://www.mousefoundry.com/mercedes...l_joint120.jpg

Tighten this bolt with our new rubber grommets.

http://www.mousefoundry.com/mercedes...l_joint142.jpg

Notice that the distance between the bolt and the knuckle arm is like an inch or so. What we need to do is "lift" the knuckle arm. Here's an easy way to do it.

http://www.mousefoundry.com/mercedes...l_joint109.jpg

Slide a safety jack under the axle. Make it as close to the brake rotor as you safely can. Extend the top of the safety jack until it is touch the suspension arm.

http://www.mousefoundry.com/mercedes...l_joint108.jpg

This is what we are looking at. The red hydraulic jack on the left will (slowly and carefully!) lower the body of the car, while the safety jack holds the knuckle in place. As the car lowers, so does the bolt on the upper ball joint, with the safety jack holding the knuckle in place, the two will meet.

http://www.mousefoundry.com/mercedes...l_joint118.jpg

Line the hole up with the bolt. When they are aligned, slowly, slowly, slowly lower the hydraulic jack, causing the ball joint bolt to go through the hole.

http://www.mousefoundry.com/mercedes...l_joint134.jpg

Success. Place the nut on the bolt and tighten it. Double check that all your nuts and bolts are tightened. The new parts I purchased came with the nylon-lined bolts that stay tight. No need to use Loctite or anything. When you are done, jack the car back up using the hydraulic jack, remove the safety jack, and put the tire back on. Lower the vehicle. Then put the air filter housing back on, go in the house, and grab a beer.

You rule.

Disclaimer: I am not a licensed mechanic. I am a DIY guy. Follow all safety guidelines and wear eye protection. Use the proper equipment and tools, and be careful. Failure to follow safety precautions can lead to injury, or even death. Always use safety jacks when raising the car up on hydraulic jacks. The brake pads of your car may contain dust particles that are hazardous to your health. When in doubt, wear breathing protection, such as a respirator. The use of nitrile gloves is highly recommended, as some fluids, such as motor oil, can be damaging to the skin.

Please note my edit.
If you could tweak the text, this would be a great DIY for the WIKKI.

General FYI for other members: Yes, I did it this way until I had the lower shock mount rip away from the cylinder, the spring smashed it's way across the shop.
I have also witnessed the top of a shock absorber rip out of a stripped nut several times.

I just did the lower ball joints, upper control arms, and sway bar bushings on one of our W126's the other day. Not really that bad of a job. I did put a jack stand under the lower arm while working, and also chained the springs together with heavy duty chains between them. No playing around! :eek:

I'll be doing the steering and UCA's on my brother's 300D soon, and then on my car. We've been overhauling suspensions and steering on the fleet lately. :D

My W124 drives absolutely perfect but my 300SD drives pretty bad....the suspension is well-beaten with 300k on it.

I've had hydraulic jacks lower faster and further than intended and would lift the knuckle arm using a jack. I also would have had the car solid on jack stands before the wheel came off.

great overall info guys thanks!!

Caliper and Rotor issues discussed earlier.

Caliper pics:

http://www.mousefoundry.com/mercedes/caliper100.jpg

http://www.mousefoundry.com/mercedes/caliper101.jpg

http://www.mousefoundry.com/mercedes/caliper102.jpg

http://www.mousefoundry.com/mercedes/caliper103.jpg

Something is wrong with my caliper or rotor. I think piston of the caliper may be stuck and thus not pressing the pad against the rotor.

Great job, pictures are really good. But you called the upper control arm a upper ball joint.

Just an fyi but the ball joint bolt is cut out for an allen key if your not going to replace it. Maybe just working on the lower ball joint?
Also good to know that you can use an allen key and a wrench to get it off if you need to.

Also, if you don't want to destroy the ball joint bolt using that popper you can put the bolt back on to protect it.

All in all a good writeup but I do agree with the jackstand under the LCA. Much safer that way.

Thanks

Quote:

Originally Posted by littlerobot (Post 2508478)

Probably a sticking caliper. If it were me I'd replace: calipers, rotors, pads, hoses, fluid. :D

Quote:

Originally Posted by dannym (Post 2508521)

the upper control arm IS the upper ball joint.
you cannot change just the ball joint, so the control arm/upper ball joint are ambidextrous/interchangeable terms

Quote:

Originally Posted by vstech (Post 2508672)

the upper control arm IS the upper ball joint.
you cannot change just the ball joint, so the control arm/upper ball joint are ambidextrous/interchangeable terms

Correct, though confusing to some people.

Quote:

Originally Posted by vstech (Post 2508672)

the upper control arm IS the upper ball joint.
you cannot change just the ball joint, so the control arm/upper ball joint are ambidextrous/interchangeable terms

I wouldn't say "ambidextrous" since there is a Left UCA and a Right UCA and they're not interchangeable. Synonomous, maybe, or "one big 'ol part all stuck together".

As a guy who was shipped two left UCAs and discovered it mid-repair, I learned to check the parts were right.

For the DIY, I'd add torque numbers as well: 80 NM for the nut on the shock tower, 40 for the nut on the ball joint, 65 for bolt to the torsion bar.

Nice write-up. X2 on the jack or stand under the lower control arm before freeing the ball joint.

As an alternative to the special tool to separate the ball joint, you can use a pickle fork. I've also seen it done by putting tension on the joint and hitting/tapping it on both sides with hammers.

I just did mine today and threw in a few twists to the original ones posted here. I thought I'd share them. I put the car on jackstands and lifted the lower control arms with the floor jack instead of the other way around. This way I could control the LCA from dropping when I released the upper ball joint. Also I thought it would be better to go up on the LCA with the jack rather than lowering the car to re compress the spindle back onto the upper ball joint. It gave me more control. My spindles did not drop as far as the the original posters did. I had to muscle the LCA down a bit to separate them. A pickle fork on a air hammer separated the ball joint from the spindle in nothing flat. I waited until the car was back on the ground before tightening the upper control arm bolts. That way the bushings are not over stressed. Thank you for the original post. The whole job took an hour.