Trailing Arm Swap: I'm very intimidated - PeachParts Mercedes-Benz Forum

indybenz · #1 06-26-2012, 09:36 PM

So I've done a good bit of research on this forum and elsewhere on swapping out the trailing arms on an 83 300D. Mine are definitely rusted through. Pics later, but just trust me on this one.

But I get a bit nauseated at the thought of disassembling everything to do this and then not being able to get it back together again ala Humpty Dumpty.

Nevertheless, it has to be done and I can't afford to pay someone to do the work. I have a good bit of experience with disassembling/reassembling suspension parts [pretty much everything you could think of, but all on a stick axle setup] from my days tracking/closed circuit road-racing a Mustang and wrenching on various cars.

I am trying to come up with a list of stuff to have on hand 'just in case'. I may not have all the terminology perfect, but hopefully you'll get the gist of it. Here goes:

1. subframe bushings
2. new trailing arm bushings [ones in replacement arms look fine but could get buggered up during install] and homemade removal tool
3. parking brake 'tool'
4. parking brake shoe/s
5. new rotors/pads [already purchased]
6. wrenches, tools, etc. [have HD air compressor and accessories]
7. jack/stands [no lift currently avail,,,or necessary?]
8. PB Blaster
9. what else?

My biggest hurdle is basically where to begin and what to disassemble in what order. Like I said I've looked around but not yet found a concise step by step primer on how to do this...and perhaps that's because there isn't one and I need to make one!!!

Thanks in advance for your help with this $700 car that I've spent $3,000+ on already

smiffy6four · #2 06-26-2012, 10:09 PM

The most important tool you will need is a spring compressor to SAFELY remove the rear coil springs. Removing Suspension Springs on 123 and 126 Chassis Mercedes by Kent Bergsma - YouTube

vstech · #3 06-26-2012, 11:21 PM

Quote:

Originally Posted by smiffy6four

The most important tool you will need is a spring compressor to SAFELY remove the rear coil springs. Removing Suspension Springs on 123 and 126 Chassis Mercedes by Kent Bergsma - YouTube

nahh... I have the tools, and they are not needed in the rear.
zero pressure on the REAR springs when the subframe is lowered.

I would SECURELY block the front wheels... I MEAN CHAIN THEM TO A TREE SOLID! (I used TWO 2" ratchet straps attached to the front LCA's and another vehicle securely blocked off in front of it)
then raise the rear as high as you can, and get proper 6 ton or larger jack stands on the frame rails in front of the subframe and set it down.

this way you can get safely under the car to disconnect everything needed to get it all out of there.

are you changing the diff mount and subframe bushings as well?

it's all pretty simple once you get in there.

are you getting used TA's with hubs already on them? axles? (how are the boots?) flex discs? Shocks? the MAW list gets spendy quick...

vstech · #4 06-26-2012, 11:24 PM

keep in mind, that if the TA's are rusted through, the unibody could be as well! so be sure the jack stand surface is SOLID before trusting yourself under the car!
I had two sets in different places to be certain the car was secure, and my car was RUST FREE!!!! it does not hurt to place tires and such under the car for added protection of YOU!!!!!!

vstech · #5 06-26-2012, 11:26 PM

BEFORE YOU TAKE THE FLOOR JACK OUT FROM UNDER THE CAR AFTER YOU HAVE THE STANDS IN PLACE...

JUMP UP AND DOWN AND PUSH ON BOTH SIDES OF THE CAR AS HARD AS YOU CAN to be certain the car is secure... you will be doing a lot of wrenching under the car. you don't want ANYTHING unsafe while you are under there. best to find out when the jack is in place to catch the car!!!

charmalu · #6 06-26-2012, 11:29 PM

I have done this job, not as intimidating as it seems. reading and thinking about it is harder than doing the job.

Here is a good thread Army started and is around 5 pages. this should be a good one to walk you through it.
Rear subframe removal and bushing replacement

Charlie

Stretch · #7 06-27-2012, 03:02 AM

Quote:

Originally Posted by charmalu

I have done this job, not as intimidating as it seems. reading and thinking about it is harder than doing the job.

Here is a good thread Army started and is around 5 pages. this should be a good one to walk you through it.
Rear subframe removal and bushing replacement

Charlie

I can't remember if I added this information at the end of that thread so I'll say it here just in case...

If you are able to jack the rear end up high enough you can roll the whole subframe + differential + trailing arms + axles intact out from under the car. I have never done this with an engine and transmission in place but there are others who have!

If you can do it this way you save a lot of crawling about in the dirt - unless of course you're going to be doing this on a gucci 2 post lift.

indybenz · #8 06-27-2012, 08:59 AM

Quote:

Originally Posted by vstech

zero pressure on the REAR springs when the subframe is lowered.

Yeah I'm not afeared of that part of it, although I definitely appreciate the force they can unleash.

Quote:

Originally Posted by vstech

I would SECURELY block the front wheels... I MEAN CHAIN THEM TO A TREE SOLID! (I used TWO 2" ratchet straps attached to the front LCA's and another vehicle securely blocked off in front of it)
then raise the rear as high as you can, and get proper 6 ton or larger jack stands on the frame rails in front of the subframe and set it down.

I have access to a Bobcat and a John Deere skid loader so those will help with securing, possibly lifting lol...probably not though. I'm pretty careful with not wanting to die crushed under a car and all that.

Quote:

Originally Posted by vstech

are you changing the diff mount and subframe bushings as well?

Should I plan on that? I am into 'deep spend' already with this. I purchased TAs from ngarover on this forum and they have hubs and one side has parking brake/pads and a cut cable [do these cars only have the parking brake assembly on one side?]. I've also heard it recommended to 'go ahead and replace flex discs, centering cone, and vibration damper on drive shaft'. Realistically, I just don't want to have a catastrophic failure of the TAs and am not going for comfort but rather safety. Comfort will come later.

Quote:

Originally Posted by vstech

axles? (how are the boots?) flex discs? Shocks? the MAW list gets spendy quick...

Didn't plan on axles. Car has 172k so not sure that it's time for that. Don't know! Boots are just ok. Not compromised yet but definitely dry and a tad cracked. Wasn't planning on shocks/springs just yet. I have not had a chance to even see if the attachment point at the top of the shock is compromised by rust. If that's the case, then I have a whole other situation on my hands.

This car does seem to have some substantial rust lurking beneath the undercoating. At some point I'll have to decide to ditch the body and transfer the good stuff from this car to a better body, but that's down the road.

This car *was* supposed to be 'inexpensive' but as usual with me, one thing leads to another and many ducats later, here I am!!!

indybenz · #9 06-27-2012, 09:05 AM

Quote:

Originally Posted by Army

unless of course you're going to be doing this on a gucci 2 post lift.

That's hilarious! (can't find roll on the floor laughing emoticon, but would have inserted it here).

To quote Dr. Steve Brule, "That would be cool."

Stretch · #10 06-27-2012, 01:15 PM

Quote:

Originally Posted by indybenz

...

Should I plan on that? I am into 'deep spend' already with this. I purchased TAs from ngarover on this forum and they have hubs and one side has parking brake/pads and a cut cable [do these cars only have the parking brake assembly on one side?]. I've also heard it recommended to 'go ahead and replace flex discs, centering cone, and vibration damper on drive shaft'. Realistically, I just don't want to have a catastrophic failure of the TAs and am not going for comfort but rather safety. Comfort will come later.

...

If I were you I'd find the cash for the subframe mounts and new trailing arm mounts as well as the differential mount - do it all once and feel the benefit.

Sure the more frequently you do the job the better you get at it but seriously how often do you want to remove the subframe?

If you need to skimp on any of the mounts mentioned above I'd leave the diff mount off the list because whilst it reportedly makes the biggest difference (what I've read here) it is the easiest to change. You could "quite easily" change that one later with the rest of the stuff in place.

charmalu · #11 06-27-2012, 02:23 PM

Just changing the Sub Frame Bushings, come as a kit for around $65. Trailing Arm Bushings around $7 ea X 4 = $28 and a Diff mount for around $55. so around $150 + -. that is the basdic bottom line stuff to replace.

There will be other things that will be determined as you go along to replace increasing the cost some.

You can always go back in and replace the shocks as needed, Flex Disc`s, center support/carrier bearing, centering bushing on DL etc....

Read through the link I posted above in post#6. that should lay it out pretty well on how to do it.

Charlie

indybenz · #12 06-28-2012, 11:31 AM

Quote:

Originally Posted by Army

If I were you I'd find the cash for the subframe mounts and new trailing arm mounts as well as the differential mount - do it all once and feel the benefit.

Trailing arm mounts? I'm assuming you meant bushings. Do I need the 'eccentric' ones or does it matter?

indybenz · #13 06-28-2012, 11:36 AM

Quote:

Originally Posted by charmalu

Just changing the Sub Frame Bushings, come as a kit for around $65. Trailing Arm Bushings around $7 ea X 4 = $28 and a Diff mount for around $55. so around $150 + -. that is the basdic bottom line stuff to replace.

There will be other things that will be determined as you go along to replace increasing the cost some.

You can always go back in and replace the shocks as needed, Flex Disc`s, center support/carrier bearing, centering bushing on DL etc....

Read through the link I posted above in post#6. that should lay it out pretty well on how to do it.

Charlie

Good stuff thanks Charlie. Where can I pick up a subframe bushing kit? PP says they're out.

charmalu · #14 06-28-2012, 01:27 PM

You did call Phill? HMMM....usually he can source about everything.

Charlie

Stretch · #15 06-28-2012, 04:06 PM

Quote:

Originally Posted by indybenz

Trailing arm mounts? I'm assuming you meant bushings. Do I need the 'eccentric' ones or does it matter?

Sorry I did mean trailing arm bushings.

In normal circumstances you need to buy the normal bushings.

If, however, there is problem or you are lowering(?) or want some non standard set up then you'll need the eccentric bushings. I haven't actually come across a thread showing the eccentric bushings fitted to a W123 yet...