I recently purchased an 83 240D. Only problem with it is that the rear passenger side swingarm is dangerously rusted.
Can anyone link me to any guides on getting this replaced or contribute some information regarding this. Is there a manual that covers this well? Are there any special tools needed for the job?
I've never undertaken such a project and will need all the help I can get.

Heres a picture





A smaller problem I'm having is that the trunk refuses to lock. The whole vacuum system needs to be diagnosed as the door locks aren't working properly and a few other things probably too. Is the trunk lock problem just a vacuum issue?


Also, is it possible to install a keyless entry system on these cars? Im not familiar with all the vacuum shenanigans and not sure if its possible.

To replace that trailing arm, you will need to drop the subframe. In brief, dropping the subframe entails supporting the car sufficiently high off the ground, pulling the wheels, disconnecting the driveshaft from the differential, removing the aft part of the exhaust system, removing the springs(proper spring compressor required), pulling the axles (some brake caliper removal reqd), disconnecting the brake lines and sway bars, supporting the subframe, then removing the subframe bushing bolts and lowering the subframe to the ground and moving it to where you can unbolt the trailing arms from the subframe.

When you find a replacement trailing arm, you'll need to install new trailing arm bushings in it. The parts houses provide regular and eccentric bushings. You need the regular ones; eccentric bushings are for a level of alignment that cannot be performed outside the factory or phenomonally-equipped service shop.

Search in here on subframe, trailing arm bushings, subframe bushings and, in particular, posts by dmorrison who knows a lot about the backend of these cars.

Good luck, that's a big job.

__________________
Never a dull moment at Berry Hill Farm.

PS, a locking system is the least of your worries right now...that trailing arm is an accident looking for a place to happen.

__________________
Never a dull moment at Berry Hill Farm.

I replaced the rusted left rear trailing arm on my '82 240D.
If you're only doing one side, it's possible to leave the driveshaft connected and using two jacks, lower the rear crossmember just enough on the side you're replacing, for the outer trailing arm bushing bolt to clear the body.

(Note: Reconsider attempting this yourself if you have any doubts as to the reliability of your jacks, or your ability to place them securely under the parts that need supporting.)

Jack up and place the rear of the car on jackstands. Remove the brake caliper and disc and disconnect the parkng brake cable for the trailing arm you're removing. Remove the upper backseat for axcess to the upper shock mount. Leave the crossmember attached at the side of the car opposite from the bad trailing arm. Place a jack under the bad trailing arm, then unbolt and remove the shock, undo the stabilizer link from the trailing arm, and remove the bolt and washer holding the axleshaft to the wheel hub. Make sure the outer axleshaft joint isn't rusted in place and will now slide out of the hub.
Lower the bad trailing arm till it contacts the stop bracket on the crossmember. Move the jack under the differential and unbolt it's mount from the body (4 bolts). Place another jack under the end of the crossmember to be lowered and unbolt that end from the body (3 bolts- 2 short, 1 long). Lower the differential and crossmember jacks just enough for the outer trailing arm bushing bolt to clear the body. The one end of the crossmember only needs to come down about 3 or 4 inches. In my case, once the differential and crossmember was lowered enough for the outer trailing arm bolt to clear the body, all tension was off the coil spring, so a spring compressor wasn't neccessary.
Also, I was lucky my trailing arm bushing bolts weren't rusted or seized.

It's tricky manuvering the arm, spring and axleshaft apart and then back togther, but IMHO much less hassle than detaching the driveshaft and removing/reinstalling the entire crossmember assembly.
The bushings and hub-bearing in the salvage-yard trailing arm I used checked out OK, so I installed it as is. It's up to you if you want to renew those items in your replacement trailing arm before you install it. Good luck.

Happy Motoring, Mark

__________________
DrDKW