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  #1  
Old 12-01-2012, 08:37 PM
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300SDL Advice Needed: Driver's Side Upper Control Arm / Sway Bar Connection Broken

I recently had to slam the brakes on my '87 300SDL to avoid an accident. My wheels locked up and as I was skidding to a stop, I heard a thud (the sound was very similar to the transmission shifting hard as a result of low vacuum). I made it home and realized that the ball joint broke off that connects my sway bar and upper control arm.

I read a post where someone else broke a piece off their rusted sway bar and mentioned it was a $1000 fix with an indy mechanic due to the nature of the repair. I could be wrong in my visual diagnosis, but it doesn't appear that the sway bar itself is broken. If possible, I'd really like to repair this on my own and save the money.

I see that there is a threaded connection. Does anyone know how I can fix this? I've attached a few photos for reference. Thank you for any suggestions or advice!

300SDL Advice Needed: Driver's Side Upper Control Arm / Sway Bar Connection Broken-1.jpg

300SDL Advice Needed: Driver's Side Upper Control Arm / Sway Bar Connection Broken-2.jpg

300SDL Advice Needed: Driver's Side Upper Control Arm / Sway Bar Connection Broken-3.jpg

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  #2  
Old 12-01-2012, 08:52 PM
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126 Torsion bar end repair

Here is the $100-200 answer to your problem

http://www.peachparts.com/shopforum/mercedes-benz-tools-reference-library/178104-qp1000-torsion-bar-saver-w123-w126-s-class.html
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  #3  
Old 12-01-2012, 08:59 PM
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it looks like the bolt just fell out.
you need a new bolt and washer set, along with new bushings for the swaybar connection.
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"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
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Old 12-01-2012, 09:03 PM
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nope. I see in your pic, that the end is indeed broken. you will need the repair end to avoid pulling the entire false firewall from the car to change the entire swaybar.
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #5  
Old 12-01-2012, 09:25 PM
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Thank you for your reply. Are you referring to a specific replacement part ('repair end') that I would need to buy to fix this myself, or do you mean that I need to take it somewhere to get the entire swaybar replaced?

I added a few more pics for extra detail. The last image is from the opposite side of the car (passenger's side, still intact and functional).

300SDL Advice Needed: Driver's Side Upper Control Arm / Sway Bar Connection Broken-4.jpg 300SDL Advice Needed: Driver's Side Upper Control Arm / Sway Bar Connection Broken-5.jpg 300SDL Advice Needed: Driver's Side Upper Control Arm / Sway Bar Connection Broken-6.jpg 300SDL Advice Needed: Driver's Side Upper Control Arm / Sway Bar Connection Broken-10.jpg

Last edited by chasw3; 12-01-2012 at 09:43 PM.
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  #6  
Old 12-01-2012, 10:16 PM
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Quote:
Originally Posted by vstech View Post
nope. I see in your pic, that the end is indeed broken. you will need the repair end to avoid pulling the entire false firewall from the car to change the entire swaybar.
It appears that your original diagnosis was correct. The bolt and bushing and washer on the forward side has disengaged and allowed the bar to come loose. The threads appear to be fully intact and not damaged in any way. There appears to be some significant corrosion on the forward face, but this does not appear to be a fracture of the bar.

If the bar is fractured, there is an available kit to weld a new tip to the bar. Replacing the entire bar (10 hours work) isn't cost effective for a vehicle of this age.
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  #7  
Old 12-02-2012, 12:20 AM
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Quote:
Originally Posted by Brian Carlton View Post
It appears that your original diagnosis was correct. The bolt and bushing and washer on the forward side has disengaged and allowed the bar to come loose. The threads appear to be fully intact and not damaged in any way. There appears to be some significant corrosion on the forward face, but this does not appear to be a fracture of the bar.

If the bar is fractured, there is an available kit to weld a new tip to the bar. Replacing the entire bar (10 hours work) isn't cost effective for a vehicle of this age.
nah, look at the pic, there is no where near enough threaded end to clear even the inner part of the UCA... it's broken. the threaded end should stick out of the inner bushing, and have plenty of meat to reach the outer bushing.

OP, click on the link in the 2nd post, and then click on the link in whunter's thread, and look at the part that needs to be welded onto the end of your sway bar. the instructions for what needs to be done are also in that link... the end of your bar needs to be cut smooth, and the new end needs to be welded onto it.
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #8  
Old 12-02-2012, 08:33 AM
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It would help if you took off the rubber bushing before taking pictures.
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  #9  
Old 12-02-2012, 10:08 AM
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Originally Posted by vstech View Post
nah, look at the pic, there is no where near enough threaded end to clear even the inner part of the UCA... it's broken. the threaded end should stick out of the inner bushing, and have plenty of meat to reach the outer bushing.
Yes, I see it now........surprisingly clean at that break, however. The bar must have been two inches longer.
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  #10  
Old 12-02-2012, 10:19 AM
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This link explains, in detail, what is necessary.

http://www.peachparts.com/shopforum/mercedes-benz-tools-reference-library/178104-qp1000-torsion-bar-saver-w123-w126-s-class.html

You'll need to bring the vehicle to a certified welder to be able to do a proper job on the heat treated swaybar.

You'll also need to prep the swaybar by cutting it to a reasonably accurate length.
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  #11  
Old 12-02-2012, 12:47 PM
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John, Brian, and mespe, I removed the rubber bushing and took a few more photos.

Question 1: If I follow Pete Burton's DIY, could I trim the metal at the red line in the 2nd picture below and then drill/tap a thread following the yellow arrow to a certain distance in order to accommodate a new bolt and rubber bushings? If this would work, I could eliminate the need to spend ~$230 in parts & labor and drive the vehicle to a certified welder. If not, then I'll need to cut behind the remaining disc and prep. everything for welding.

300SDL Advice Needed: Driver's Side Upper Control Arm / Sway Bar Connection Broken-7.jpg 300SDL Advice Needed: Driver's Side Upper Control Arm / Sway Bar Connection Broken-8.jpg 300SDL Advice Needed: Driver's Side Upper Control Arm / Sway Bar Connection Broken-9.jpg

Question 2: Whatever repair path I take, do I need to make sure the distance from the sway bar to the control arm connection is exactly the same as it was before it broke, or would a wheel alignment correct for any offset? If the distance needs to be the same, do you add spacers to lengthen the connection?

Here's Pete Burton's DIY that I was looking at per your suggestion. On page 4, it looks like whunter tapped a new thread into the existing breakpoint without cutting anything at all:
Swaybar repair pictoral, 300SD

Thank you for any further suggestions.
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  #12  
Old 12-02-2012, 01:12 PM
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Been there, done this. Both sides even though one side was all that broke.

You will have to cut off the end, nice and square, and weld on the new ends. If you just ran a bolt there is a high probability, no matter the strength, that is will bend or break off. There is just not enough metal.

Replacing the ends is pretty simple. You MUST cut the end to the proper length. You may have a couple millimeters of play, but it really needs to be spot on. With that said, when welding you could make minor adjustments. The sway bar and uppers are not adjustable via alignment.

As for a certified welder... if you really want to. Mine have been holding up fine since I bought the car. The sway bar end these weld onto is not really flexed in any way. That action happens more in the long run between arms at at the bends. The concern is welding tensioned steel. but I have no issues simple having an experienced friend make the welds. Just make sure you clean, prime and paint the ends after welding.
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Old 12-02-2012, 01:17 PM
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Quote:
Originally Posted by LandYaghtLover View Post
The sway bar and uppers are not adjustable via alignment.
If necessary, the outer UCA bushings could be shimmed to a more forward position.
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  #14  
Old 12-02-2012, 05:41 PM
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Unless there is a special kit for your Year and Model to use the W123 Kit the OD of you Sway Bar has to be the same.

One or 2 of our Members had drilled the end out for Studs and used something to Sleeve the Stud to the OD of the Original projection. Instead of a Bolt going thought the Control Arm the Stud goes through and you uses a Self Locking Nut or you can double Nut it.

Sway Bar issues, front and rear.
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Last edited by Diesel911; 12-02-2012 at 05:53 PM.
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  #15  
Old 12-02-2012, 09:27 PM
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Quote:
Originally Posted by chasw3 View Post
John, Brian, and mespe, I removed the rubber bushing and took a few more photos.

Question 1: If I follow Pete Burton's DIY, could I trim the metal at the red line in the 2nd picture below and then drill/tap a thread following the yellow arrow to a certain distance in order to accommodate a new bolt and rubber bushings? If this would work, I could eliminate the need to spend ~$230 in parts & labor and drive the vehicle to a certified welder. If not, then I'll need to cut behind the remaining disc and prep. everything for welding.

Attachment 107678 Attachment 107679 Attachment 107680

Question 2: Whatever repair path I take, do I need to make sure the distance from the sway bar to the control arm connection is exactly the same as it was before it broke, or would a wheel alignment correct for any offset? If the distance needs to be the same, do you add spacers to lengthen the connection?

Here's Pete Burton's DIY that I was looking at per your suggestion. On page 4, it looks like whunter tapped a new thread into the existing breakpoint without cutting anything at all:
Swaybar repair pictoral, 300SD

Thank you for any further suggestions.

The repair as done by Pete is mechanically sound. He simply replaced the lost section of swaybar with a longer grade 8 cap screw. At first glance, the cap screw is not quite as stong as the original swaybar because it's of a smaller diameter, but the much stronger grade 8 rating on the screw probably doubles the psi rating as compared to the bar. The only difficult task in this approach is attempting to drill a hole, by hand exactly parallel to the axis of the bar. If you can do it............go for it.


The distance is irrelevant within reason. The use of large spacer washers on the aft side of the control arm will prevent the tendency to drive the control arm rearward when you tighten the new cap screw. You want the swaybar to just fit the upper arm...........not force the upper arm either forward or rearward when you tighten the cap screw.

If you go this route, be absolutely certain you find a grade 8 cap screw (available from McMaster-Carr). You'll need to be reasonably certain of the length...........you must use at least .750" of thread inside the bar (10 threads) and you certainly do not want the screw to bottom out inside the bar before it's fully tightened. If you drill and tap for 1" depth (very difficult by hand)............you're only working with .25" of length as play.............

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