I need some basic education on rubber bushed joints in suspension systems. I have a ’84 300CD and the inner lower control arm joint is worn. This is evidenced by the rubber bushing not being square in between the mounting plates on the unibody. My question is, on this joint, which two parts move against each other when the control arm moves up and down? Which parts need lubrication? The tube sleeve is so thin walled that it is hard to believe that it can stand movement. But it seems that it must be involved with the motion of the joint unless the rubber bushing rotates in the control arm.

Please help me to understand how this joint works and what needs lubrication and what does not. That would really help me to understand rubber bushed joints in general!

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1984 300CD (sold)
1973 220DPK 4 spd (died)
1978 350SL 4 spd gray market
2003 SLK32 AMG
1988 300CE (sold)
1997 E420 (Totaled)
1998 E320 Wagon

It is not easy to visualize this but the front lower control arm bushings are pinched by the eccentric bolt+washer (which effects and is also part of the adjustment) and it traps the lower control arm bushing between those metal flanges that are welded to the chassis.


The lower control arm bushing is pressed into the lower control arm (there is a specific position it has to go in when you install it) so tight that it also remains stationary to a point.


So the lower control arm does not pivot on any metal. It pivots on the elasticity of the thick rubber lower control arm bushing. That is also one of the reasons you when you torque the eccentric bolt you ant the arm in a neutral position; the same position that the arm would be in if the car was sitting normally on all 4 wheels.

http://www.peachparts.com/shopforum/diesel-discussion/272206-lca-bushing-failure.html See post number 8 for a pic and description.

Also read up on what spring compressor to use.

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84 300D, 82 Volvo 244Gl Diesel

Thanks for all that great information Diesel911, it makes better sense to me now. Should the bolt, sleeve and tube in the bushing be assembled with anti-seize applied then?

I am going to buy the two plate and center screw type spring compressor which seems to be the safest type for this car.

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1984 300CD (sold)
1973 220DPK 4 spd (died)
1978 350SL 4 spd gray market
2003 SLK32 AMG
1988 300CE (sold)
1997 E420 (Totaled)
1998 E320 Wagon

How did the car drive before you noticed the LCA failure? I've started loving driving the SD since the rubber joints and ball joints have been renewed. It drives like a Mercedes.

You can buy a spring compressor for ~$140. Parts to renew the suspension are ~$500 for both sides. This included everything except tie rods which are easy to change and were good on my cars. I also did the brakes but don't remember what if any brake parts were included in the $500.

The LCA bushings are cut out then pressed in. You need to press on the rim and have center supported so that you aren't only pressing on the rim. Threaded rod and large washers worked on the SDs. Fine thread is better than coarse. You are basically using brute strength to get the bushings installed. I was lazy and let the indy use his special expensive Mercedes-only ball joint press to install the lower balljoints. The only other tool needed that wasn't already in the box was the spring compressor.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.