Drop the 300SD rear end
 

This is a job which started to remove and reboot axles from a oil leak and replace emergency frozen brake cables. What it turned into is an semi R&R of the rear end. So her goes!
Car got backed into garage and put on four jack stands. Then the differential got drained. Notice the leaking axles around the differential. Got to be fixed.

This is gonna be fun!

Next was to remove the wheels and prep for pulling the axles. Research indicates that people have had difficulty re-installing the axles. I found a thread in which a member used a few 8 mm bolts with washer to pull the axle back into the carrier. Took a pic of the bolt as it came out of the hub. I was told that the emergency brake was never used. That information appeared to be correct. Another pic of the leaky axle.

Removed the differential mount from the cross-member and differential and marked axles as to sides. The teeth in the differential look good and there is the C-clip. Not sure if this needed to be done, but each C-clip got bag and tagged as to the side it came from.

After removing the axles from the car, I took them out into the light for inspection. Investigation shows the the sealing band broke on the passenger axle. Packed up axles to be shipped and covered differential with towels to keep out dirt.

Since the e-brake system was original, I going to replace the shoes. Also to get to the e-brake cable they need to be removed anyway. Next attention turned to tackling the sub frame bushing bolt. In my case I was in luck for they where not frozen. Research un-covered a pic from WHunter which shows the best way to remove the sub-frame bolt. The hydraulic jack keeps the 24 mm socket in-line with the bolt head. Pulling on the breaker bar with the slight tension applied by the jack keeps the pull all in line and parallel to the bolt.

Next was to cut the brake cable which was frozen. Used an air dye grinder to do this job. Next was the shocks. The passenger side came out without an issue, but on the driver side, the last bolt broke off at the head while removing the shock. I don't expect that to be a show-stopper in dropping the rear end. I might have to jack the car up a little more to get clearance.

Oh dear that centre hand brake mechanism looks like it could do with a bit of sand blasting

http://www.peachparts.com/shopforum/...scn3020_r1.jpg

Is the return spring dead?

Stretch, I wondered about that also ! That's what salt does to car's coming from the north in this country. The spring still has tension. I've removed it so as to get the free range of the other cable off and to check movement of the front cable. The front cable moved quite easily when pulled with plyers. I plan on replacing the spring as well as the brake cable clips.

Answer
 

The park brake cable spring is fine, as long as reflex tension is good.

I suggest cleaning the parts small enough to fit in one of these, prime and paint after.
Abrasive Blast Cabinet

.

Ya might want to get an ultrasonic cleaner for the brake parts... Or, I can bundle up a set of them from one of my cars when your axles are ready...

Oh... Each axle stub will have a set of spacers on them where they go into the diff... Be sure to keep them on the side they came off of...

From the comments then I'm seeking some guidance from the collective wisdom on the forum. Going by Stretches comment on the brake cable mechanism being in the condition it's in, then it needs to be removed from the car and R&R'd. When removing the cable hooks, I didn't study how to remove it from the car but I seem to remember fittings covered with grease and corrosion and what looked like a folded over cotter pin. From the attached pic, what trick is there to removing the assembly ?

There isn't really a trick; but it is often a bit stubborn.

Now that you've got the cables going to the tailing arms cut (or alternatively neatly unhooked from the mechanism!) and you've got the return spring unhooked there's another hook on the lever / cross piece (piece 6) that comes out of the chassis mount on the RHS of the picture you posted.

http://www.peachparts.com/shopforum/...e-assembly.jpg

Then you just shove the cross piece towards the front of the car. Then you can unhook the front cable (if this hasn't already decided to self detach)

Yeah, out won't be any problem... Getting everything back in with it all working becomes a chasing your tail kind of thing, but it's fairly obvious what needs to be loose and what needs to be tight when you are reassembling.

Heed this!!!

Made some progress tonight. Sub Frame dropped out of car and moved out from under car. It took some manipulation and prying differential away from driveshaft, but it finally broke free. Inspection of sub frame shows rust towards outer wing on each side and on both top and bottom. Media blasting will probably get rid of the rust, then prime and Rino-liner.

Are you going to replace the trailing arm bushings?

Currently I don't know. I looked at two which I can see at the moment and the rubber didn't seem to look old and cracked. Stretch I've read the threads from you and whiskey Dan on replacing these and the procedure does not seem to be difficult. How do you tell if they are bad ? What is the indicator ?

I have new trailing arm bushings for a 123. I assume they're the same bushings for the trailing arms are the same between a 123 and a 126. The subframe is different between the two frame types.

I'm pretty sure the W126 trailing arm bushings are the same as the W123 ones. These should be 126 352 01 65

The only different variants I have heard about are special off centre ones that used to be sold by fastlane so you could adjust the camber (I don't think the Pelican sells these though) - and besides that's not a problem for you is it?


It is difficult to check the integrity of the trailing arm bushings. Try clamping the subframe and then try pushing the trailing arms at the hubs in towards the differential and in the opposite direction. If you can get someone to do this whilst you look at the bushings cracks or gaps might be easier to see. If you (as human) can feel any great movement at the hub whilst doing this check I imagine they are shot and should be replaced - just imagine what it would be like on two wheels Starsky and Hutch stylee...

...I'm sympathetic to the attitude "change 'em whilst the subframe is out" - however I'm also sympathetic to the evidence that "new parts aren't necessarily better than the ones already fitted to the car" => As always this is going to have to be based on your gut feeling of what you find

Don't all W126s have SLS? If so, does your car 'raise' after starting? If so, I would say your bushings need to be replaced. Bergsma states that if there is movement in the SLS after starting, replace the bushings, diff mount, etc., until it no longer raises.

Also might help if you had a rear-side view of your car before you began this repair, as in is there rear-sag?

As for me, I have a newer diff mount installed, and yet when the car starts it raises a good 1.5-2", and needs to come up more. I Want to do this repair, but I live in a Townhouse just now, and have limited tools... :-(

No.
Very rare to find an SD with SLS... I'm not saying it's impossible they are out there... But I've never seen one.

I agree with Stretch. It is difficult to determine the condition of the subframe bushings without removing them. If you find one that is marginal, it is pretty easy to change them all. Fairly inexpensive as well.

Finding worn subframe bushings on mine, I think contributed to rear wheel bearing wear as well.

Once you change them, you will be amazed at the difference!

Gentlemen, I agree with your assessment of the trailing arm bushings. If you've gone down to this level, replace bushings makes sense and that's what will be done. This is turning into a true R&R. SOOOOO next is to seperate the trailing arms from the sub frame, clean parts, have media (soda blast) sub frame, trailing arms, prime and POR15 / Rino liner parts. Next is to install new bushings and then re-install.

Got some work done tonight. Goal was to get the sub frame and trailing arm assembly on a work surface table so as to save my aging bad back. First we tried lifting the assembly minus differential, but according to my helper (12 yr old son) he said it was to heavy. Since my wife was at work and my other son was out with his girlfriend I needed another plan. :rolleyes: So, going to plan "B" I decided to use leverage.
I strapped a rope around the sub frame assembly and lifted up and leverage onto a rolling table. Worked nice....... and I didn't get a herniated disc. :D

Once assembly is on the table was to, we rolled it to the other side of the garage. Since their about 5 engines, a bunch of wood working equipment and various other junk, room is a little tight. :(

In the picture of the coil pertch, one of the bolts threads is left from removing the shocks. Apparently this is par for the course for suspension components. I'll either drill it out or maybe weld some threaded rod and heat the nut with Acetylene.

I found the reason why the emergency brakes wouldn't work. Investigation showed why !:D

In the pic of the differential, can someone tell me what this electrical connector on the differential is and what is it for ?

I would use a combination of heat and a drill.

http://www.peachparts.com/shopforum/...scn3058_r1.jpg

Once you have removed the trailing arm from the subframe you will be able to attack both sides with ease - (assuming the other side is snapped flush) heating the snapped off bolt and then drill from the snapped side might push the bolt out of the hole (so if the shock was still in place it would be like trying the crew the bolt all the way through)

http://www.peachparts.com/shopforum/...scn3060_r1.jpg

That's your ABS sensor - ideally you should pull the sensor out of the differential before removing everything from the chassis! These sensors, however, can be a bit tight to remove and sensor damage may result.

What does the inside of you differential look like? Is it quite clean? If not removal of the sensor to check for muck might be worthwhile. Now is the time to get things cleaned out and ship shape.

Note for later on after you've changed your trailing arm bushings =>

http://www.peachparts.com/shopforum/...ent-35-110.jpg

Make sure you align the trailing arms in such a position that the axles would be horizontal BEFORE you tighten the tralining arm bolts. To check this I find it is easiest to look though the wheel hub (no axle fitted!) and line that up by eye with the output shaft hole / flange on the differential.

http://www.peachparts.com/shopforum/diesel-discussion/276507-rear-subframe-removal-bushing-replacement-8.html

Thanks Stretch, now I understand and it makes sense ! From your pic, everything needs to be in parallel with the input shaft of the differential. Then the differential input shaft needs to be parallel with the rest of the drive train ! Currently the trailing arms are still assemble to the sub frame. Studying the trailing arms show a weld line which is directly inline with a reference bump mark on the mounting flange on the sub frame. I assume this could be used as a beginning reference mark. Through the use of a dowl rod which could be inserted through one hub, and going out the other hub, you could check for level. The final check would be with the differential attached. I'll include a pic of this reference bump mark later today.

Got a little further on this project. I've separated the trailing arms from the subframe and removed the sub frame bushings and the trailing arm bushing. Wasn't that hard but had to build a tool. Research indicates that the Whiskeydan tool is the ticket for the trailing arm job and a slight tool modification for removal of the sub frame bushings. I added one item which isn't in the original Whiskeydan write-up. That is a small block of 1/4 aluminum with a 5/8 inch hole in the middle. I was concerned with pul/forcingl equal compression through the entire bushing so as to not cause problems and extra work. Worked great ;)

The w123 and the W126 (First gen) have the same rear suspension.
The W126 just has a wider Sub Frame and axles.

I did this job a few years ago on my 85 300D. Looking back, this really isn`t all that difficult of a job.

Be sure to have the Differential mount facing the correct way. I bolted mine the wrong way
and for the life of me couldn`t figure out why the holes didn`t line up with the 4 13mm bolts. Turned it around, and all was good.

The 123 and 126 bolt on 180 deg of each other.

I used this product for the lubricant to get the Sub Frame Bushings in.



http://ecx.images-amazon.com/images/I/41QT4n1qWhL.jpg

KY might be good for some things, :rolleyes: but this isn`t one of them.

If you can`t get the bolt out of the Trailing Arm, just source another set with lower miles. (yours looks pretty rusty)
The 123 and 126 use the same Arms.
When I did mine, I found a 85 300CD with much lower miles, used it`s arms and Diff.

When you put it back under the car. if you have 3 Floor jacks, place one under the Differential,
and one under each Trailing Arm. Then just raise it up into position.

I read Whisky Dan`s thread too, and made a few adjustments along the way.

I think I added to it or in another thread on my R&R job.


Charlie

Oooo vicar!

Oh wow - there's the space heater

http://www.peachparts.com/shopforum/...scn3088_r1.jpg

Now that's the way to do winter mechanics

I've replaced all of the bushings on the front and rear suspension on mine. The press "tool" was some all-thread, nuts, washers, and a cheap Harbor Freight 3/4" drive socket set. I didn't have to deal with rust, which may/may not influence the difficulty, but haven't ran across a large bushing it couldn't handle.

I agree with Charlie, silicone lube is a necessity if you want those bushings to install correctly. However, I have used KY when the FSM calls for a water-soluble lubricant. I've looked in parts stores and haven't found anything they carry that meets that requirement. It's not needed very often (front LCA bushings come to mind) but it works. Sil-glyde, Dow Corning 4 and silicone dielectric grease not only ease the installation but is good to keep corrosion out of those suspension joints.

I thought all garages had space heaters in them?:D

that one looks identical to mine.

I've also toyed with the idea of building a portable radiant plate to slide under cars I'm working on ...

If only I had space for a space heater!

Radiant plate? Isn't that something you keep your curry warm on?

nahh...

a radiant plate is a 2" thick plate of urethane, or concrete with small tubing run through it connected to a pump and run to a heater, like a small water heater... then you fire up the system, and the plate heats up to like 100F, and the vehicle above the plate stays toasty, and working under the car becomes pleasant.:D

My plan was to use 3/8" tubing, and a set of air tank fittings, for portability. then fill the tank and tubing with antifreeze...
fairly simple to build and use.

Yes, that's one heater in the garage. The other is a furnace hanging from the ceiling. Both the 1 ton hoist and the ceiling furnace where inherited with the house when we moved in.

Ahhh an HVAC engineer's term for under floor heating - now I see!

...and I bet they were your reasons for getting the place!

OK guys, I need the collective wisdom of more experienced users than me. The new sub frame bushings arrived today and I compared them to the originals. My goal with this car is to re-establish the factory ride and replacing all rubber will hopefully accomplish that objective. Removing the old one and installing new ones is academic to me but what does a worn out sub frame bushing look like ?
I took a few pics of the new sub frame bushing next to the old. Although the aluminum collar is separated from the rubber, the original one is not dished as much as the new one. What else it there to look for ?

Ok folks as the saga continues. My parts came in, being new springs, sub frame bushings, trailing arms bushings and both the sub frame and the trailing arms came back from the sandblasters. For a car from up North where there is allot of salt used, I was surprised on how good these parts looked.

Painting is the climate I live in can be a problem. Primer needs at least 60 degrees to dry. The kerosine heater came into play for outside temps where in the 20's today. The paint dries in 30 minutes to the touch, so I had to maintain at least that to get things done.
I used self-leveling etching primer which contains zinc. Next, and according to directions on the can, I sanded the primer to 320 grit and then applied an epoxy primer. This is the state in the below pics. Since I cannot hang this up, I have to do one side at a time. This will dry and finally it will get Rhino lined them. The Rhino liner can be applied in temps from 32 to 90 degrees F, but colder temps equal longer drying time. I have to wait it out and see how fast it dries over the next few days, ie once applied.

Nice
 

It looks good. :)

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I hope you aren't getting paint or rhino liner in the bushing pockets!

I guess that's a NO NO and something I need to sand out easily. When taking it apart I couldn't tell for the bushing pockets where black from either the original bushing wear or sub frame paint. Let me know ?

Greg

Answer
 

They are factory painted.

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Ran into a difficulty and looking for advice! Installing the sub frame bushings went fine for the first one, but problems with the second.
The bushing goes in and stops approx 1/4 of an inch from bottoming out and becoming fully seated. What could be causing this ? Only idea I have is I painted the bushing cavity with to much paint which would restrict movement. :eek: Any other ideas ?

Greg