DIY W126 Guide Rod, lower control arm bushing and Eccentric Pin Replacement

[whunter]

This is the perfect time to replace the lower control arm bushing and Eccentric Pin.

Loosen the front wheel bolts.
Raise and support the front end.
Remove the front tire.
Remove the spring, special spring compressor required.

picture of spring compressors******************

Remove the lower shock absorber bolts.
Separate the lower ball joint from the lower control arm.
Mark the position, and remove the Eccentric Pin from the lower control arm.

picture of eccentric pin*****************************

Separate the lower control arm from the body.
Remove the lower spring seat plate from the lower control arm.
Remove the Guide rod to control arm mount bolt.
Remove the lower control arm from the car.
MARK the union threads of the guide rod mount, so you will know where to stop screwing on the new guide rod.

picture guide rod mount.JPG**********************

Loosen the clamp on #14 in the picture, and hold the guide rod mount with a wrench, while using a large pipe wrench to unscrew the old guide rod.

picture 1985_300sd_suspension6846684.gif*********************

Lubricate the guide rod mount threads with grease, gently thread the new guide rod on by hand, as far as possible, then hold the guide rod mount with a wrench, while using a large pipe wrench to screw the new guide rod on, tighten the clamp on #14 in the picture.

picture guide rod.jpg**************************

Remove the Guide rod bushings from the lower control arm, and clean the mounting area.

picture guide rod bushing.JPG***************************

Remove both of the inner control arm bushing caps.

picture lower control arm bushing.JPG************************

Drive out the old inner control arm bushing.
Install the new inner control arm bushing.
Install the new inner control arm bushing caps, (a heavy thread or light fishing line works well to hold them in place for body installation).
Insert the guide rod into the lower control arm.
Use a floor jack to press the inner lower control arm into the body.
Use a large tapered punch to align the Eccentric Pin body holes with the lower control arm.
Install the new Eccentric Pin into the lower control arm, align it to the mark and tighten.
Install the Guide rod mount bushings.
Install the Guide rod to control arm mount bolt. (use LoctiteŽ thread adhesive)
Install the lower spring seat plate to the lower control arm. (use LoctiteŽ thread adhesive)
Install the spring, but do not release it yet.
Install the ball joint, and tighten. (use LoctiteŽ thread adhesive)
Install the lower shock absorber bolts. (use LoctiteŽ thread adhesive)
Release the spring compressor, and remove the tool.
Install front tire, and snug (best possible) wheel bolts.
Lower the car.
Torque all wheel bolts.

FYI:
Here is the related W126 procedure DIY link.
Suspension Bearing Bracket guide rod mount replacement
on the 1985 300SD
http://www.peachparts.com/Wikka/W126GuideRodMount
DIY Bearing Bracket guide rod mount replacement for Mercedes Benz 300SD.
DIY Bearing Bracket guide rod mount replacement for Mercedes Benz 300SD.

[whunter]

two more pictures for the DIY

Picture three shows bushing install orientation.

[1985 300SD Sady]

Great write-up thanks!

I may have to do this sometime.

[420SEL Jake]

I smacked my wheel up against a curb and bent the control rod. I extended the control rod to compensate and it drove like new, yet the bend was sever. Upon replacing the control Rod I didn't have spring compressors so I had to cut the top of the bolt off that holds the control Rod to the control arm and put a new bolt in where the nut was on top and the bolt came through the bottom, basically reversed. I did not use lock tight am I in big trouble.
By the way if you have to do this jod, do rent the compressors and change everthing you can, I had to use my car jack to push everything forward.

[Brian Carlton]

Originally Posted by whunter

Install the new inner control arm bushing.
Install the new inner control arm bushing caps, (a heavy thread or light fishing line works well to hold them in place for body installation).

I'm in the middle of this process as we speak. It appears that the end caps are pressed onto the inner LCA bushing after it's installed in the arm. Those caps will not install without a press. Therefore, I don't grasp why a fishing line is necessary to hold them in position prior to installation into the body?

[whunter]

Originally Posted by Brian Carlton

I'm in the middle of this process as we speak. It appears that the end caps are pressed onto the inner LCA bushing after it's installed in the arm. Those caps will not install without a press. Therefore, I don't grasp why a fishing line is necessary to hold them in position prior to installation into the body?

RE: Install the new inner control arm bushing caps, (a heavy thread or light fishing line works well to hold them in place for body installation).

A press is nice, but not critical. Note: Some of the aftermarket repair kits will fail to remain pressed together.
The caps can be held in position with a heavy thread or light fishing line, while jacking the arm into the body bracket.
The body bracket applies enough compression for initial seat, and the eccentric bolt completes the compression seating.

With a spring compressor, this is a relatively easy DIY. Note: Unless there is extreme corrosion seizing the eccentric in place.

[Brian Carlton]

Originally Posted by whunter

A press is nice, but not critical. Note: Some of the aftermarket repair kits will fail to remain pressed together.
The caps can be held in position with a heavy thread or light fishing line, while jacking the arm into the body bracket.
The body bracket applies enough compression for initial seat, and the eccentric bolt completes the compression seating.

With a spring compressor, this is a relatively easy DIY. Note: Unless there is extreme corrosion seizing the eccentric in place.

The OE caps will absolutely not install without a press. They don't even begin to start down over the end of the bushing. Interesting how the aftermarket kits are different..........

Yep, without that spring in place, the removal and reinstallation of the arm is a 15 minute job. It's the pressing of the bushing and caps that concern me.

Speaking of presses.........have you ever installed the two rubber bearing bracket bushings (the two that live in the bracket next to the guide mount?) They don't look like a pleasure to R & R either.........but, I'm committed to doing it.

[thefreestate]

I too am having the same problems. The end caps on the LCA were a pain to install. Used a shop press which worked but the end caps seem to be the wrong length/size. They dont fit quit as nice as the old one's. This is a Lemforder part-not aftermarket. The bearing bracket bushings have me stumped. Tried a shop press but they are still approximately 1/2" high. Any advice would be appreciated.

Wayne

[Brian Carlton]

Originally Posted by thefreestate

I too am having the same problems. The end caps on the LCA were a pain to install. Used a shop press which worked but the end caps seem to be the wrong length/size. They dont fit quit as nice as the old one's. This is a Lemforder part-not aftermarket. The bearing bracket bushings have me stumped. Tried a shop press but they are still approximately 1/2" high. Any advice would be appreciated.

Wayne

I'm going to try the bearing bracket bushings tomorrow in the shop with a manual arbor press. The manual calls for rubber sliding paste........and lots of it. I'm going to use vaseline.

[SD Blue]

Having done the Lower Control Arm bushings and the Carrier bushings, here are a couple of hints that should make it easier.

For the LCA bushings, I used 7/16" all-thread, nuts, washers and some 3/4 dr. sockets to press things together. For lube, believe it or not, KY as the FSM mentions a water-soluble lubricant. I'm not sure how much difference it makes but there is mention of aligning the bushing flats with the LCA.

The carrier bushings required the same "tools". I tried the cold chisel and sledge hammer trick and believe me it was a lesson in frustration. With the amount of rubber you're working against, it just bounces back! And I agree with the lots of lube as it will take a lot to overcome the 4"+ of rubber friction. I've used the all-thread for several bushing jobs and it makes a nice, easily-controlled press.

[whunter]

Originally Posted by SD Blue

Having done the Lower Control Arm bushings and the Carrier bushings, here are a couple of hints that should make it easier.

For the LCA bushings, I used 7/16" all-thread, nuts, washers and some 3/4 dr. sockets to press things together. For lube, believe it or not, KY as the FSM mentions a water-soluble lubricant. I'm not sure how much difference it makes but there is mention of aligning the bushing flats with the LCA.

The carrier bushings required the same "tools". I tried the cold chisel and sledge hammer trick and believe me it was a lesson in frustration. With the amount of rubber you're working against, it just bounces back! And I agree with the lots of lube as it will take a lot to overcome the 4"+ of rubber friction. I've used the all-thread for several bushing jobs and it makes a nice, easily-controlled press.

KY is a great lube for rubber bushings..

[whunter]

Danger:
In theory, anyone with a floor jack, jack stands + car = a very crude light field press.

STOP,Bad idea...
Using the jack to press the part in, by lifting against the car is not a safe procedure.

What can go wrong:
* Car falls on you (loose a limb or die).
* Work piece or jack shift (injury).
* Dropping the car (oops) vehicle/equipment damage.
* The irregular working shape can Bend the sub-frame or punch through the body, due to application point pressure.

[thefreestate]

Originally Posted by SD Blue

Having done the Lower Control Arm bushings and the Carrier bushings, here are a couple of hints that should make it easier.

For the LCA bushings, I used 7/16" all-thread, nuts, washers and some 3/4 dr. sockets to press things together. For lube, believe it or not, KY as the FSM mentions a water-soluble lubricant. I'm not sure how much difference it makes but there is mention of aligning the bushing flats with the LCA.

The carrier bushings required the same "tools". I tried the cold chisel and sledge hammer trick and believe me it was a lesson in frustration. With the amount of rubber you're working against, it just bounces back! And I agree with the lots of lube as it will take a lot to overcome the 4"+ of rubber friction. I've used the all-thread for several bushing jobs and it makes a nice, easily-controlled press.

I used 1/2" bolts, washers, nuts, sliding lubricant, etc..to pull the bushing into the bearing carrier. They will not completely seat. I ended up crushing the metal cap on one of the bushings...the lubricant is pushed out by the bearing...the indy I use told me he has never replaced the bushings in the carrier bearing, only the brake support. The service manual makes it look ez.

[SD Blue]

Originally Posted by thefreestate

I used 1/2" bolts, washers, nuts, sliding lubricant, etc..to pull the bushing into the bearing carrier. They will not completely seat. I ended up crushing the metal cap on one of the bushings...the lubricant is pushed out by the bearing...the indy I use told me he has never replaced the bushings in the carrier bearing, only the brake support. The service manual makes it look ez.

I believe this is where the 3/4" dr. sockets make the difference as they apply pressure along the outer edge. If you are just using the metal cap and washers, all of the pressure is in the middle and the rubber is just flexing and distending at a certain point.

[Brian Carlton]

Originally Posted by thefreestate

I too am having the same problems. The end caps on the LCA were a pain to install. Used a shop press which worked but the end caps seem to be the wrong length/size. They dont fit quit as nice as the old one's. This is a Lemforder part-not aftermarket. The bearing bracket bushings have me stumped. Tried a shop press but they are still approximately 1/2" high. Any advice would be appreciated.

Wayne

I did the LCA bushing, the bearing bracket bushings, and the guide rod bushing today on one side of the vehicle.

My comments on the bearing bracket bushings:

1) To remove requires cutting the rubber flange off the lower part of the bushing to allow a supporting tube to sit beneath the carrier. When a tube of the proper size is found, the bushings press out without any difficulty.

2) The bores of the carrier are not clean and require a good hour with acetone and 80 grit emery cloth to polish them up. It's definitely necessary to get a good finish prior to the installation attempt.

3) The smaller bushing was coated in vaseline (didn't have the rubber slide compound).

4) Pressing the smaller bushing down (bracket is bottom side up in the press) resulted in it stopping about 1/2" from the seat. Keeping relatively high pressure on the press (center is down almost 1") and smacking the periphery with a rubber mallet moved it the remaining distance. It's surprising how soft they are in the axial direction between the core and the housing.

5) The larger bushing presented no difficulty after being coated in vaseline. It pressed right to the stop.


The LCA bushing presented more problems. Removing it was a complete PITA because the cap would not release from the bushing. Following the manual whereby a countersink into the end of the bushing to expose the end of the center radial bearing was necessary to free the cap. Once the first cap was removed, the second cap didn't present anywhere near the difficulty. With both caps removed, the rubber bushing easily presses out.

Installing the bushing was not difficult. However, the OE caps have an interference fit with the end of the bushing and it's nearly impossible to press them on squarely. They start on one side and it was necessary to finish them with a hammer on a surface plate. Clearly, this assembly is different than any of the aftermarket components that require fishing line to hold the caps in place. The aftermarket design, with clearance in the caps is clearly inferior to the OE design.

I also did the guide rod bushing at the same time.........no issues in tapping it out and installing the new OE replacement.

The four components took the better part of four hours including all of the sanding work to polish the housings.

One point of note..........the LCA bushing must have been replaced at one time in its past........the condition of the old bushing was excellent and I will pass on replacing the same component on the right side.