39039

My Mercedes S550 (W221) ball joint boot was broken. That's located at the front lower rear control arm. It is necessary to replace the entire control arm according to the requirements of Mercedes-Benz, (If don't replace the boot may lead to wear the ball joint with a long time). So they only sell the entire control arm. , the cost should be $300 for the genuine control arm, plus $100 for alignment, the number of costs should be $400 excluding labor. I found the damaged boot timely, so I decided to look for an alternative boot and replace it. The boot costs only $12 from Amazon. Ball Joint Boot Link
Here is the video

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DaleB

Hey, thanks for that!! Just this weekend I was under the car and noticed that my driver side boot is torn and needs to be replaced. Very timely topic for me, I appreciate it.

39039

You are welcome ��
And if you like my video, subscribe my channel, Thank you.

OldManBabyBody

Anyone done the uppers joints? Looking for what boots to use there.

P.S., used your tutorial today to success. Thanks and great job. (might want to note that your car is a 4matic, had the parts guy at Mercedes running in circles with the part numbers for my non 4matic).

BenzNinja

iTrader: (4)

Arrie

An old thread but did not want to start another one.

Just replaced the front right lower control arm, the rearward one with the Airmatic strut mounting. I was able to change it out without going under the car and removing the bottom covers. The plastic cover flex enough for wrenching it thru the wheel well. This made the job much easier than setting the car up high enough to remove the bottom covers.

Part cost $147 + tax from FCP Euro and the job quite easy.

Just remember to measure the distance between center of the wheel to the top of fender when car is at normal height before the job. You need to set this distance before you tighten the bolt at the inside end of the arm under the car.

EURO-JIM-121

Since I got my W221, been looking at some of these posts. and have a couple questions:
How did you do this job without getting grease on your pants, shirt? HA

Next, more technical: This would be fine if only the boot was torn, but generally speaking, I've found worn ball joints before seeing torn boot. Grease wont stop a joiny from clunking.

39039

1, Sometimes I used to get grease and oil on my shirt, I just won't show it

2, If the ball joint is already worn, you have to replace the entire control arm to solve the clunking.

EURO-JIM-121

HA, I wouldn't wear a shirt with a hole in it if I was going show in a video.
I'm the owner of a new-to-me 2008 S550 and love it. Your videos are very classy. Thanks in advance and I'll be looking at them all.

.

Bayrat

Love your posts. Most efficient mechanic I’ve ever seen! Thanks for sharing all your knowledge!

gfmerc

Recall from MB USA if not done already

slainla

Thanks so much to OP for the instructions. Just did this today while changing the air struts on the base W221 S550.

I measured the ball joint which came in around: 19.5 x 36.5 x 30 in mm for ball joint stud opening diameter, ball joint base diameter (where the clip locks into), and length of stud from the base to the start of the threads. From there, I found a boot that is slightly smaller on the opening diameter since it can stretch. The height can be as low as 20mm since the boot is depressed most of the time. As for the base, I just needed something that’s around the size. It can be slightly larger since the clip will hold it into place.

Based on the above, my parts list is slightly different:

1. CRC Sta-Plex Red Grease – I got this from Harbor Freight but any red grease should work. I was going to get Red n Tacky btu I was closer to harbor Freight and they had a 30% off coupon.
2. Universal ball joint boot– I got one from Amazon that’s listed as 16.5 x 37 x 29 but the actual specs are slightly smaller. This actually helped.
3. M14 x 1.5 nylon lock nut (class 8 or better) – I got a 4 pack from Amazon since I couldn’t find smaller quantities. The OEM nut is about $7 from my local dealer so the 4 pack for about $9 is a better deal.

And here are my steps:

1. Disconnected air line from the air strut
2. Used breaker bar to loosen the nut on the lower ball joint.
3. Loosened the nut until it covers the end of the stud
4. Used a small jack to slightly jack up the lower control arm
5. Used the ball joint separator tool and jammed it into the ball joint boot area.
6. I had to take off the nut on the ball joint stud as the tool wouldn't fit with it on
7. Start wrenching on the separator tool and be careful since there's no nut to protect the threads on the stud.
8. Once it popped out, I removed the ball joint from the steering knuckle and released the jack.
9. Removed the old boot and clips with a flathead screw driver
10. Wiped off all old grease
11. Pumped new red grease onto the the ball joint and moved it around. Rotated and pumped more.
12. Pumped some grease in the boot
13. Pre-installed clip on the smaller end of the boot
14. Slide the boot up into the ball joint
15. I used a zip tie in between the clip and the boot and pulled the zip tie which makes the clip a bit larger and spun the boot as it went into the recessed portion, essentially locking it in.
16. I reversed the process and put in the new lock nut
17. If you notice the nut won’t screw on properly, check the threads. I noticed I dented a small portion of the stud, probably from when it popped out while using the separator tool. I borrowed a thread repair kit from Autozone and used one of the files to sharpen the flattened threads a bit.
18. I jacked up the lower control arm to simulate the car being on a wheel. I then torqued the lock nut to 50nm and turned it an additional 60 degrees