Trailing arms rear axle refurbish I

[mbzse]

A step by step on how to replace the rubber parts in the trailing arms, where these attach to the rear axle.
The job needs to be performed off the car, trailing arms detached. The tricky part when disassembling and
re-assembling is to compress the two rubber cones, while removing the old and then mounting the new C-shaped
snap ring. One has to apply quite some force. I have a self-made tool for this purpose, see pic "Trailing arm_1".

The old snap ring is most likely corroded in its groove. Apply rust penetrant, and use a good mini chisel to
break C-clip free. See pic "Trailing arm_3" (arrow)

Clean, touch up paint and mount new parts. The parts are available as a kit from M-B, No is 110 350 1475
Compress with tool (or in vise) and mount C-shaped snap ring into position (pic "Trailing arm_5"), release
and make sure ring sits squarely in its groove.

/Hans in Sweden

[mbzse]

Four additional images

"Trailing arm_5" shows snap ring going in.
"Trailing arm_6" shows end result. Note, the brown visible in the picture is copper paste (to enable the next
disassembly to go more smoothly)
Of course, exchange the donut shaped rubber ring in the front part of the assembly as well (left in pic)
You need a M14x1,5 Nylock nut there, one each side (aquire these beforehand!)
Last image "Rear axle trailing arm attached" shows it in place (Note: pic borrowed, off Bob Possel I believe)
Also, a drawing showing the parts involved

/Hans in Stockholm

[jameshoward]

You can also do it using a workbench vice and a few bolts to compress the rubber and get the circlip on.

Photos attached.

Takes a bit of practice, but the results are the same.

JH

[George Des]

Old post I know, but someone here had made the tool to locate the rubber donut on the forward part of the trailing arm. They had also posted a picture of the tool and it looked like a tapered steel furniture leg that screws onto the cone. I have replaced donuts in the past and locating the trailing arms is a royal PITA without a locating tool.
It may have been Joe Alexander that made the tool.
George

[Pedrocamp]

Sorry I can't answer your question about the tool but I have not had too much difficulty installing the arm and aligning the joints. I just jack the axle until I get the joints aligned and bolt up. I have had some issue though with keeping the two cones centered in the arm once I get the car on the road. I have installed my second set and had them shift again. The cones get squeezed out the inside. The first set I installed with a light silicone lube all over, these squeezed out within a few miles. The second set I installed with clean, dry OD and arm bore, I only lubed the washers and tube, this in hopes to allow these parts to rotate without shifting the cones... no luck. Should the cones be glued? Are the aftermarket cones, I believe Febi or Meyle, inferior? I am convinced I need to get my next set from the Classic Center nonetheless. Thanks.

Edit: I checked the receipt for the cones I purchased and they were Mercedes parts, must be an install issue. Glue?

[mbzse]

The cones get squeezed out the inside. The first set I installed with a light silicone lube all over, these squeezed out within a few miles.../... Should the cones be glued?

Nope, no glue required. You are on the right track by identifying that lube like silicone or chassis grease etc. must absolutely not be used!
Metal parts should be dry metal or painted surface. Rubber parts installed just as they come from the supplier. If you absolutely feel you must have something there to ease the assembly, use talcum or even soap (which will evaporate with time)
/Hans in Sweden

.

[mbzse]

...someone here had made the tool to locate the rubber donut on the forward part of the trailing arm. They had also posted a picture of the tool and it looked like a tapered steel furniture leg that screws onto the cone. I have replaced donuts in the past and locating the trailing arms is a royal PITA without a locating tool.

Below is an illustration from the M-B Blue Book (workshop manual) showing the mounting cone tool (No 64). Having one certainly makes the task easier. You can turn one yourself, or have it made, in perhaps Delrin or aluminium. The base should preferably have a M14x1,5 thread so you can secure it to the fitting on the cars´ chassis. The hole visible in the tool is there to insert a dowel to unscrew it, once the rubber donut is fully seated.
Note: A general tip for assembling the radius arm is that the rear axle should be close to  horisontal (not scissored). Also, the whole axle may need to be nudged rearwards; install tool should fit into the middle of the donut hole (as best possible).
JoeA also suggests securing the rubber donut in position in the radius arm with some wire, the wire is cut and then pulled out as a last step.
.

[jameshoward]

George,

You really don't need a special tool. A length if piping that has a similar diameter to the donut helps, but what helps most is the help of a strong friend to manoeuvre a jack holding the rear axle. It's about leverage in my experience. I've had to do this task a few times of late and it's a knack thing rather than a science thing.

Persevere.

JH

[George Des]

Sure there are several ways to do this without the cone tool. I just recall the last time I did this job, it was tough keeping the arm aligned as thejack compressed the spring. The whole idea of working with compressed springs is sometimes a little unnerving especially working under the car with limited access to a quick getaway!

[Pedrocamp]

I removed the spring with one of those threaded rod compressors, disconnected the shock, removed the arm and replaced the bushings. I installed and bolted up the arm then installed the compressed spring with the arm suspended by the shock (as the droop limiter). Sounds dangerous compressing the spring with a jack while trying to install the arm.

[ja17]

Very nice write-up and pictures Hans.   Yes I have made a special cone tool which screws onto the mounting of the chassis.  Not required, but makes the job go fast and easy every time !  I will try to post a picture later. Install the rubber mounts in the front of the trailing arms before raising them into place. I use some plastic wire ties to hold the rubber mounts in place, in the front end of the trailing arm, during installation. Simply cut the ties  and pull them out when the arm is in place and the attachment is made.