Sub Frame - Trailing Arm Bushings - PeachParts Mercedes-Benz Forum

R Leo · #1 09-08-2003, 04:02 PM

Thing One and I will be pulling the rear of his TD apart for replacement of the subframe and trailing arm bushings.

After looking through the FSMs and the Forum threads, I think it might be easier to make these repairs by removing the entire subframe.

Unfortunately, no place I've looked for this info concurrs with my hypothesis.

Any suggestions?

psfred · #2 09-08-2003, 07:54 PM

You only need to drop the appropriate side down to get the bolt for the bushing out. You will need to pull the axle out of the wheel carrier if you need to take the control arm off to get the bushings in and out. You should be able to make appropriate pullers out of pipe, washers, and spare bolts. Copious amounts of PB Blaster or equivalent a couple days before are in order if you think the sleeve in the center of the bushing is stuck on the bolt -- even the subframe mounts have been known to seize.

I'd not take it off unless you had to, too much more work. You will REQUIRE an internal spring compressor to get the control arm loose, be VERY carefull as the spring is compressed quite a bit in place, and will be very dangerous loose.

Handling will improve dramatically!

Peter

dmorrison · #3 09-09-2003, 12:33 PM

To remove the entire subframe you have to remove the differential. The subframe goes above the diff and the diff is attached to it. So the removal of the subframe would require removal of:
differential
drive shaft
wheels
brake lines disconnected
coils springs
trailing arms, or leave them attached, its getting heavy
shocks or autoleveling strut
disconnect sway bar
parking brake cables, remove

Its alot.
I will attach a picture of the rear from above that is in a manual I have. Notice that the subframe goes from one side to the other. To remove it you have to remove everything that is below it. thats a lot of stuff.
The subframe is attached at the 2 subframe mounts. It is also attached to the top of the differential. The diff is then attached to the mount which is attached to the car floor

Second item
Removing subframe mounts without removing coil springs. Yes it can be done. Jack the car up and place it on jack stands. disconnect the subframe with a jack under the subframe. When you release the subframe bolt the coil spring will push down on the subframe mount point. It does this by pushing on the trailing arm which is connected by the trailing arm bushings to the subframe. So the jack will now be holding the submount assembly. How much force will be on the subframe assembly I do not know. The coil spring is pushing on the trailing arm which pivots on the rear of the subframe, SO now the coil force is tranfered to the subframe, I do not know how much force . but it looks like a lot.

If you need to replace the subframe mounts, How are the trailing arm bushings. The reason people need the coil spring compressor for rear end work, Is that if your rear subrame is worn out then the trailing arm bushings may need replacing also. that requires the coils springs to be removed.

Dave

R Leo · #4 09-09-2003, 01:16 PM

We know without a doubt this car needs trailing (swing) arm bushings on the port side. We're not sure about the starboard side but will replace them too.

I'm not sure about the condition of the sub frame bushings either but, I've ordered a set and plan to replace them anyway.

dmorrison,
After looking at your series of posts on the rebuild of your TD rear end, it had me thinking that, considering the amount of things we're doing back there, removing the entire subframe and working on the trailing arm bushings out in the open might actually be easier.

Either way, I'm benefitting from your experience and posts. Thanks!

leathermang · #5 09-09-2003, 04:07 PM

Randy,,,, your paper copies of the 123 chassis manual show a huge measured steel plate used to realign everything in the rear end before putting it back on the car..... are you going to make one of those ? Won't be any longer job than that trailer you made...

R Leo · #6 09-09-2003, 06:18 PM

Quote:

Originally posted by leathermang
the 123 chassis manual shows a huge measured steel plate used to realign everything in the rear end before putting it back on the car.....

Greg,
I think that plate is for getting everything all hunky-dory if those parts have been damaged in a collision.

R Leo · #7 09-15-2003, 09:32 AM

FWIW...in reference to removing the subframe to to R&R the trailing arm bushings...

I've reviewed the FSMs section on replacing trailing arm bushings on the 123 chassis and discovered that the first step in the instructions states: Remove the rear subframe assembly.

dmorrison · #8 09-15-2003, 10:20 AM

Yes it does. And if I had a floor lift, A large garage, And the frame holder, and another lift just for the frame assembly, I would have done it that way. But lacking a few of those things, I could not do it that way.
As my post explained, I did one side with the trailing arm installed and the second with it out. The second was easier to work on. It took a little more time to get it out. But the rebuild job after that was mush easier. I clamped it to my work bench and went to work on it. With the rotor attached it weighed about 30#. Very easy to manuever by myself. I did have the car rasied fairly high. I have 12 ton jacks from HF just for this reason. A lift would be so nice, ah I digress. So consider removing just the trailing arm, then do all your subframe work. The subframe will now be easy to work on. everything will be out of your way.

Dave

R Leo · #9 09-15-2003, 10:53 AM

Quote:

Originally posted by dmorrison
...consider removing just the trailing arm, then do all your subframe work. The subframe will now be easy to work on. everything will be out of your way.

Dave

Dave,
Thanks for the pointers...I'll give this a process a shot w/o removing the subframe. On thing, I can't remember from your prior posts, did you leave the half-axles in the differential or did you have to pull them when removing the trailing arms?

R Leo · #10 09-16-2003, 09:31 AM

Springs came out last night (that Sir Tool spring compressor is a really 'gee whiz' thing!)... but, we could only get one of the trailing arm pivot bolts out. There is simply not enough room under the car to get the leverage necessary to break loose these bolts.

We gave up for the evening at 11:00pm.

Tonight, we'll give one more shot at getting those bolts loose with the subframe in the car. If that doesn't work, out it comes! At least then we can get the big breaker bar on thoose bolts.

dmorrison · #11 09-16-2003, 10:14 AM

Had the same problem. I used some penitrating oil and a 500 Ftlb impact wrench with an extension and a universal swivel. It came out after waiting for the penitrating oil to do its job.

Dave

R Leo · #12 09-16-2003, 11:39 AM

Quote:

Originally posted by dmorrison
Had the same problem. I used some penitrating oil and a 500 Ftlb impact wrench with an extension and a universal swivel. It came out after waiting for the penitrating oil to do its job.

Dave

I'm a tad light in the impact drive/air compressor department. My compressor is really made for running a nailer and doesn't have the oomph to go at it very long with my impact.

R Leo · #13 09-17-2003, 11:19 AM

It's going back together.

Trailing arm bushings and subframe reinstalled last night. Yes, you can do this without taking the subframe completely out of the car. Sorry if I was an unbeliever. BTW-That Harbor Fright bushing tool really does the trick on pushing those bushings out and, back in.

This evening, we'll install the springs, shocks and e-brakes plus the new rotors and pads that came with this car.

Ya know, with an early enough start, it might just roll tonight.

R Leo · #14 09-18-2003, 12:09 PM

The Pale Horse rides again...

My, what a difference bushings make.

samiam4 · #15 05-12-2005, 11:11 PM

Congrads...

Glad we were able to convince you to give it a try in the car...
Bushing installer/remover sets are sweet ..

Always encouraging to hear it went well!

Michael