Looks like it.

 

The diff is indeed mounted to the subframe. The subframe is held in by two mounts forward and the differential aft.

If I were going to drop the entire subframe, I'd disconnect the driveshaft at the rear flex disc and remove the exhaust before I got into the rest of the job. I, personally, would also use spring compressors, both because I already have one and because those things scare me. Note that the shocks provide the main downstop for the trailing arms, so you'll want to jack the trailing arm a bit before removing the shock. The stops on the subframe are there for backup. The manual says to lower the trailing arms slowly onto the subframe stop, lest you damage your CV axle joints; that's good advice.

There's lots of little things you'll need to disconnect to actually remove the subframe assembly, like brake lines (main and parking) and the sway bar links. Take it slow, think it through, and be safe.

 

You can take the whole thing out assembled but if you are unfamiliar with the job, removing the diff first might be the smarter move just to deal with the weight.

 

I did use spring compressors just because I had them and it does help. It also depends if you work with a bridge or on jack stands.

Check here to find the workshop manual. Chapter 35-010

One advice, do not under estimate the weight!! The complete subframe weighs a ton! A transmission jack is a must have to get it back in place.

Yes, the diff comes out with the whole subframe.

Good luck!

 

Ok. It is out.

The whole lot is out.
Spring comoressor was totally in the way. It would need the Mercedes type with 2 plates and bolt in the middle of the spring.


Anyway, procedure was:
0) Remove/undo prop shaft, brake hoses, hand brake cables, wheels etc.
1)Car on stands. Jack under brake disc/arm.
2) Undo shock absorber top and bottom and remove it.
3) Lower jack slowly. Arm will bottom out on a stop.
4) Repeat for other side.
5) Jack under diff and undo diff rear mount 4 bolts.
6) 2nd jack under subframe next to left front mount.
7) Undo mount bolts.
8) Lower both jacks slowly until spring is free and remove it.
9) Lift diff jack again and move second or 3rd jack to right side subframe.
10) Repeat from 6) and get spring out.

Lower the whole thing slowly and evenly with the jacks and that is it!

Regards
Bern5

 

Ok. It is out.

The whole lot is out.
Spring comoressor was totally in the way. It would need the Mercedes type with 2 plates and bolt in the middle of the spring.


Anyway, procedure was:
0) Remove/undo prop shaft, brake hoses, hand brake cables, wheels etc.
1)Car on stands. Jack under brake disc/arm.
2) Undo shock absorber top and bottom and remove it.
3) Lower jack slowly. Arm will bottom out on a stop.
4) Repeat for other side.
5) Jack under diff and undo diff rear mount 4 bolts.
6) 2nd jack under subframe next to left front mount.
7) Undo mount bolts.
8) Lower both jacks slowly until spring is free and remove it.
9) Lift diff jack again and move second or 3rd jack to right side subframe.
10) Repeat from 6) and get spring out.

Lower the whole thing slowly and evenly with the jacks and that is it!

Regards
Bern5

Great! Thanks for sharing.

 

Yes, you would need to use the disc-type compressor. That's what I have.

Glad to hear you got it out. Hope getting it back together goes as well.

 

Okay. This is my second dead thread resurrection in a week. I pulled my crossmember out on the 1981 380SL to rebuild it and fix some body rust. The crossmember came out easy. I took it out as one unit with control arms, diff and half shafts all in place. I took in all apart. Bead blasted, galvanized and painted the subframe and installed all new parts. I just spent the past 4 hours trying to put it back in as one unit, the way it came out. I am having trouble. Either one of the sides are hanging up, or the front of the crossmember is not clearing the driveshaft (propshaft). Or the Diff cover is hitting the spare tire compartment. I know I'm missing something. Just cant figure out what it is. The driveshaft is pushed in all the way and the flex disk is off.

 

When I put mine back in, I used the front mounting bolts to locate it, then raised it to put the diff bolts in place. You do have to jockey it around to get it up in place. I couldn't originally get mine bolted up. I finally left it with the front bolts started and the assembly approximately in place, and came back to it a couple of days later - and when I jacked the diff up, everything magically lined up. I bolted the diff down right then and there so it wouldn't screw me up again.

 

Thanks for the fast response Jay. So I gather your crossmember was partially assembled? was your propshaft in?

 

My subframe was completely assembled. The driveshaft was in place, but partially collapsed, so I could mate it up with the differential after mounting the subframe.

 

Thanks

 

Still no luck. I easily have 8 hours in to this trying to put the rear subframe back on. I've got to be missing something. The driveshaft is as collapsed as possible. The driveshaft is new and I verified the part numbers as well as compared it in length to the old one. At first I thought it stuck out the back too far. But measured it as if it were to be bolted and it doesn't seem to long. I googled R107 undercarriage and saw several examples where the driveshaft extends beyond the front of the rear subframe. Should I have to remove the parking brake parts? That could give me a little more room. I'll keep trying. After over 30 years of working on my own cars, this is definitely in the top 10 of bafflers.

 

Not sure what the problem is. Is the drive shaft too long and not allowing the subframe to move forward enough to mount. Have you disconnected the center bearing ?

 

I removed my prop shaft first before removing the rear suspension, it made removal and replacement of the subframe/suspension much easier.

I only partially assembled the rear end too.

Lifted in.

Then the prop shaft.

Then hubs.

...and then springs.

Shocks, anti roll bar etc.

 

I removed my prop shaft first before removing the rear suspension, it made removal and replacement of the subframe/suspension much easier.

I only partially assembled the rear end too..........

After 2 hours of frustration, I'm going to remove the propshaft. After its all said and done and after looking at that beautiful undercarriage, its time to pull the propshaft. The only reason I was reluctant to do so, was beceause I already connected the front flex disc. I'll get to work now and check in later. Thanks so far everyone for the great advice.

 

I only removed the rear section. If you do that remember to mark up both sides of the splines so they go back together balanced.

 

My apologies for jumping into your discussion, but I'm seriously stumped and am hoping someone who've been down this path might have some sage insight to help me out.

I just finished up rebuilding the front 1/2 of my 83 300SD, springs and all. With that completed, I'm onto the rear 1/2 rebuild. I'm stalled trying to work out how to separate the rear braking rotor plate assembly from the CV spline.

I've removed the rotor/drum, caliper, sway bar connections are all separated. I've also removed the small center bolt securing the brake hub assembly to the CV, and from what I can glean on this forum and others, the two parts should simply slide right off. I've used a slide hammer and I still cannot separate the two.

I would love to drop the whole sub-frame but I'm doing this while on my back - no lifts here.

Any thoughts would be deeply appreciated.

 

You're talking about sliding the axle out of the wheel hub? The wheel hub is held in by a castle nut on the inboard side, and you don't want to remove that unless you're needing to replace the bearings. If all you want to do is remove the axle from the wheel hub, what I'd suggest is raising the trailing arm until the xle is straight, then trying to pull the axle back from the hub. If you can't do that, you can try threading the hub center bolt back into the axle a turn or two and then hitting it with a plastic or rubber mallet to try to knock it loose. If the trailing arm is down against the stop, the axle has to move at an angle and binds more easily than if it's straight.

 

Hey Jay, wow! Thanks for such a fast reply!!

You're correct, I am attempting to replace the rear wheel bearings along with the trailing arm bushings, shocks, springs, etc.. The whole enchilada.

I hadn't considered trying to align the wheel hub (perpendicular) with the cv joint and differential. To be clear, what I'm reading from you is that, there shouldn't be anything (nuts, bolts, clips, etc.) beyond the small wheel hub center bolt (see below (thanks to PeachParts for the w123 rear end images)).

 

Alright, I've tried to align the hub and axle as closely as possible. I've given the slide hammer a couple of serious smacks and nada. I am a little reluctant to beat on it too much for fear of damaging something.

 

You shouldn't be trying to be removing the hub from the axle that way. You need to press the axle out of the hub. Drive the axle into the hub with a brass drift, after you take the center bolt out of course. The axle should compress enough to clear the splines.

 

I'm awaiting the delivery of a 14mm allen for the diff's drain plug. But I'm about to just pop the diff cover before draining it which should allow me to pull the 'C' clips on the diff side of each CV joint. But even with those clips out, I'm not sure that it advances my goal of dismantling the whole rear axle.

 

Right. That bolt, along with the washer, are what hold the axle end into the wheel hub. With the bolt and washer removed, it should slide right out. Lining things up will make it move more easily. You can also wiggle the axle up and down at the wheel end to get it to unstick.

In my case, the axle wouldn't quite slide enough to clear the inner end of the wheel hub. I was able to get it out with enough fiddling, but I couldn't get it back in until I unbolted the inner trailing arm mounting bolt and swiveled the arm a little around the outer bolt to provide the extra clearance.

 

@roncallo is right. Th axle slides out of the hub, with the hub still securely mounted to the trailing arm. Don't try to pull the hub out of the trailing arm with the slide hammer.

 

Jay, Thank you for your time and help on this. I sincerely appreciate the weekend support.

I think I'm missing something fundamental. I may also be confusing some of our terms.

In your experience, when you've had a rear axle (cv joint) splined with the wheel hub (the part with 5 bolt holes which the tire mates with), did you separate the two with just using a mallet on the back side of the rotor's backing plate rather than my sliding-hammer attached to the front of the wheel hub?

This has been a California car for its entire life. There's no rust or corrosion anywhere so I'd be a little surprised if the axle and hub are rusted together. But anything is possible.

-j

 

You're trying to pull the wheel hub off of the axle. That's backwards: you need to pull the axle out of the wheel hub, inboard toward the centerline of the car. (Or push it from the outboard side of the wheel.)

Forget what you know about American cars. Germans do things differently. (See my signature.)

 

You're correct - I've been trying to pull the hub off, rather than gently tap the cv joint's spline inward, toward the differential.

I've yet to perform this step, but it now makes sense to me. I'll assume that there's enough space in the joints that it'll collapse and clear the back of the hub. I'll want to tie up (support) the wheel side of the cv joint before tapping the spline, to avoid it dropping to the ground.

Thanks again for your patience with the backward questions. I think I've got it now.

Enjoy your weekend!
Jeff

 

Jay, the spline is out. The birds are chirping once again and the sky has cleared.

I have the car's full weight on the rear tires and, for this discussion, the top two nuts, rubber bushing and large flat washer, for the driver's side shock are removed and I'm about to liftd the car allowing the entire shock to be removed.

My question: I've read conflicting reports regarding using a spring compression tool, or not. At this point, can I simply jack up the car and allow the a-arm to drop sufficiently to allow the coil to be removed under no spring tension?

Or do you recommend a compressor? I have the plate type I used on the front wheels, but if I can avoid using it... my feelings would remain intact.

Jeff

 

My question: I've read conflicting reports regarding using a spring compression tool, or not. At this point, can I simply jack up the car and allow the a-arm to drop sufficiently to allow the coil to be removed under no spring tension?

If' you've got the plate compressor, use it. The trailing arm will come down against a stop, and that will not let the spring tension completely release. OTOH, having it down against the stop means you won't have to compress the spring as much to get it out as you would if the arm was in the normal position. Make sure to jack the car up so the arm does go down against the stop.

 

Hey Ron,
Thanks for your help/post. My mental model was definitely backwards.
My earlier W126 challenges taught me that when things don't make sense, initially, there are usually engineering details that are quite sound. Just gotta love German engineering!