Group,

I posted this question yesterday but that post has dissappeared unless I'm dreaming......wonder where it went?

Anyone know steps to replace the rubber bushings that connect the rear trailing arms? There are four points where the arms tie in and at each point, there are two bushings (one on each side).

It looks like I will need to lower the subframe to get at two of the pivot points. I'm just not certain how to proceed with that. Someone advised that springs would have to be compressed as with work on front suspension but I hope there is a way to do it without that complication.

Thanks,

Nic
'85 300CD

I did this job on my 84 300SD back in December....

And having recently done this job, I don't see a way you can SAFELY replace the trailing arm bushings without removing the springs and the trailing arms from the car.

You CAN use the spring compressor that AutoZone rents to compress the springs. I wouldn't use it on front springs (they are mounted in an arc) but it works fine on the rears.

One the trailing arm is out of the car, I created a special tool to press the old bushings out and press the new ones in. Go to a hardware store and get a 2' or 3' section of 1/2" or 5/8" (I think I used 5/8") threaded rod (take one of the new bushings to the store to make sure you get a rod that will fit in the bushing's hole). Also get several large washers and several nuts to fit the rod. You can then (by putting the nuts in the washers in the right place) get the bushings to screw/pop out and and get the new ones in. It's complicated for me to write down, but think about it for a few minutes and I'm sure you can figure out what I am talking about.

I used a similar approach to press in/out my subframe bushings.
Total cost of the tool is less than US$5. It will probably take you an hour to do one side and then 20 minutes to do the other.

Chris Blanchard
1984 300SD 151k

Thank you Chris,

I'll follow your advice and compress springs.....but I'm not clear on how to remove the arms. After compressing spring and releasing bottom of shock, will I have to drop the subframe by undoing the subframe bushing connections and then the four bolts above the differential? I don't see how to get at the outside trailing arm bolts otherwise.

I used a "c" clamp to press in bushings on front suspension after applying sly-glide. That worked fine. Your home made tool idea is creative and I'll go that route if I can't get the clamps to work.

Nic

Oh yeah, you will have to unbolt the differential mount and support the diff as you lower it down. The diff will lower by about 8"-10" and that will give you the clearance you need for the trailing arm bolts. There is not a lot of room to work on those outer bolts, but it is do-able.

I think I might have also unbolted the subframe at the subframe bushings for additional access.

When I did all of this, I was _replacing_ the trailing arms (due to mucho rust/corrosion where the shocks bolt on) and had the entire rear end of the car dismantled.

Sorry if my recollection is hazy, but I will be happy to answer any questions you have until you the job done. Good luck!


Chris

I thought you could get to the outer bolt on a W123 without dropping the subframe, but I could be wrong. I know you have to for the W126 -- huge pain in the ass without a lift.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Oooops. I forgot we were talking about a 300CD. I've never seen the arrangement of the rear suspension on one of those. I'd imagine it's very similar to the W123 300D, which is almost _identical_ to a W126.

In fact, the (used) trailing arms that I got were from a W123 and they fit the W126 perfectly, save for the parking brake cables which were the wrong length.

The job is a royal pain, but now I am secure in the knowledge that when it comes time to pull and replace the axle shafts, I will be ready and able to do it quickly.


Chris Blanchard

Peter,

I can feel that outside bolt but just can't see how to access it without a bit more clearance. Thanks to couple of pointers by Chris and another fellow from Tech Forum I am ready to attempt this repair. Will take it slowly.

For some reason I am unable to visualize how the subframe works re: the car's suspension. The whole thing doesn't appear to be connected properly to the chassis......but of course I know that it is. Maybe as I go through this process the light will dawn.


Nic

Nic:

The subframe is attached by two large bolts up front, under the rear seat, and by some bolts above the diff, I think. The diff is bolted directly to the frame. The semitrailing arms pivot on the bushings. Very simple, very elegant. The springs seat on the body and the trailing arm.

You MUST remove the spring, using an internal compressor. If you try to just lower the control arm it can fly out, and will probably damage something. It must be compressed to fit in the fully extended position.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Nic,
You can get the control arm bolts out by removing the large sub frame bolts and prying down on the subframe to get clearance to withdraw the bolts that the arm pivots on. As Fred says, do remove the spring first.

Bob D

__________________
Bob D.
Parrish, FL
1 SDL, 1 D, 1 TD, 1 Mog

Thanks everyone for the advice. I would have never been able to undertake some of the repairs that I have done without help from people on this forum. I do this stuff myself partly to save money but more to learn about this car I like so much. I really appreciate the help.

I will:

1) compress the spring correctly using right tool;
2) remove front subframe bolts and place support under it;
3) remove bolts above differential while supporting it and lower several inches;
4) pry or lower the front of the subframe so that I can get to the outside bushings;
5) lower the trailing arms and remove the old bushings (the hard way), will wait to see if shocks must be undone to allow arm to fall far enough;
6) apply syl glide to new bushings and press in with "c" clamp;
7) reverse the whole affair.

thanks again,

Nic

You probably will have difficulty pressing in the new subframe bushing with just a C clamp. I used a tool that I made that was very similar to the tool for the trailing arm bushings: a length of threaded rod, some nuts, and a few appropriately sized washers.

Chris Blanchard

Nic:

You will have to remove the shock to compress the spring as the only way to compress it is with an internal spring compressor -- you can't reach enough of the coils from outside.

Don't overtighten the top nuts on the shock going back in -- the thread should just stick out of the locking nut (there are two).

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

With the subframe bolts out you can pry down enough (easily) to get the clearance to extract the trailing arm bolts without touching the diff mounts. unless your replacing it too.

Bob D.

__________________
Bob D.
Parrish, FL
1 SDL, 1 D, 1 TD, 1 Mog

Update on this job for any who are contemplating it.

1) its a difficult repair without a lift. I have limited skills but have redone the front suspension (for example) and this job was much harder.

2) the subframe does lower enough to get at the trailing arm bolts (that contain the bushings) but those bolts are very hard to access even then and getting the old bushings out is very difficult. I ended up creating a tool using threaded rod, large washers, and short section of exhaust pipe. Even so, it was awful. I had to remove main drive shaft, rear flex disc, and lower muffler to get at the things!

3) new bushings went in ok using syl-glide lubricant and large C clamp.

4) total time for me......probably 5 hard hours. I've never been so greasy.

5) did compress the spring just a little to remove pressure on trailing arm before removing bolts and it was a shame to have to spend $100 to rent a tool to do that. Had to remove shocks first.

This ones a major mess. Glad its done and on a 15 year replacement cycle.

Nic