w123 trailing arm bushing: remove rear end or not?

[patbob]

I need to do the trailing arm bushings on my '83 300D, so I've been reading threads here and elsewhere trying to understand what all is involved. Some people seem to be able to do it without removing the whole rear end like the FSM says, but those threads are for cars other than the w123 sedan (mostly the w126 & w123 wagon). Others remove the rear end.

A question to all those of you who've done this job on a w123 sedan.. can this job be done without removing the whole rear end? Just do the drop-and-tilt of the subframe to get access to the bushing bolts? And more importantly, do I need to compress the springs, or is it safe to do the job without compressing them first?

I just don't want to get under there and start unbolting things thinking I'll be OK without first compressing the springs, only to find out the hard way I'm not. Compressing the spring isn't a problem if necessary, but I don't enjoy the idea of being under the car a few feet away from a loaded spring compressor if it wasn't necessary in the first place.

Thanks.

[Diesel911]

Try looking for the info here:
http://www.pauldrayton.com/uploadfiles/merc/Service/W123/Index/617Tindex.html

For specifics here:
http://www.pauldrayton.com/uploadfiles/merc/Service/W123/w123CD2/Program/Chassis/35-110.pdf

[Diesel911]

When I changed the passanger side trailing arm (the complete arm). I used a spring compressor to compress the spring. Also the exhaust system runs on that side and interfered a little with my room.
I dose look like you might be able to swing the ends where the rubber bushings are down and have enough room to change them. (there is a metal tab that also interferes with the arm going down). This could break the plastic sway bar links so I would remove those. If you need to disconnect the axle at the wheel hub that should not be a problem as only one through bolt holds it in the hub.
The nuts/blots on the Trailing Arm Bushings were really tight on mine.

[patbob]

Originally Posted by Diesel911

Try looking for the info here:
http://www.pauldrayton.com/uploadfiles/merc/Service/W123/Index/617Tindex.html

For specifics here:
http://www.pauldrayton.com/uploadfiles/merc/Service/W123/w123CD2/Program/Chassis/35-110.pdf

Yeah, it's that first step I'm trying to avoid

As for your other post.. thanks. From what you say, it sounds like its doable. I'll give it a whirl as soon as the parts come in.

[Diesel911]

Originally Posted by patbob

Yeah, it's that first step I'm trying to avoid

As for your other post.. thanks. From what you say, it sounds like its doable. I'll give it a whirl as soon as the parts come in.

I bought a front suspension parts set and will be doing the fron end of mine in a week or 2. Some of the menbers said that KY jelley works as a lube on the rubber busings others say dish soap and water; in my case for he lower control arm bushings.

[patbob]

I used soap and water when I did my LCA bushings.. and a vise to coerce them to seat all the way in

BTW, on the trailing arm bushings, did you do the eccentrics or the standard ones?

[patbob]

Just a quick followup now that I'm done.

I managed to do the job without removing the entire rear end, but doing it that way is a significant departure from the FSM and what others have done.

Yes, the spring must be compressed and removed. There's only three attachment points for the trailing arm -- the shock (which doubles as one of the arm stops) and the two bushing attachments -- and both bushings have to be disconnected simultaneously to do the job. Even if you don't remove the trailing arm from the half axels, you end up with it attached only by the spring. No matter how you figure it, that much force with only one attachment point is extremely dangerous.

I'll do a complete writeup soon, but briefly, I removed the spring, propped the arm up on some blocks to prevent from hyperextending or hyperbending the half axel joints, then removed the bushing bolts and swung the arm around for access to the bushings. A threaded rod, a pile of washers, some nuts (left over from an earlier subframe bushing R&R) and a 2" PVS fitting made quick work of the bushing R&R. Then reassemble. Once I figured out what to do, the second side took a (whole) day start to finish.