Pictorial Rear end rebuild Part 1 - Remove Complete Assembly

[WGB]

This is a somewhat long illustration of removing the rear end assembly intact with as minimal personal risk and muscle power as I can work out having spent a day and a half making up my version of the rear support jig

First the car has to be raised and I am fortunate in having my own hoist.



The most difficult part of the whole proceedings is removing the old exhaust system - finally with the assistance of an angle grinder it was managed.



The heat shield must be removed to give access to the drive shaft and handbrake linkage



Linkage is undone and removed and the two rear cables are just left to hang

The drive shaft centre compression joint must first be loosened, The shaft has a 41mm hex on it and the compression part has a 46 mm hex.



It would probably be possible to loosen the joint with adjustable spanners but here are the two spanners I used.



The rear flex joint needs to be unbolted at the driveshaft bolts and the driveshaft supported so that the universal joints are not damaged.



The driveshaft centre bearing is then unbolted and by pushing the shaft downwards and forwards the shaft can be pulled out of the pinion flex disk, After this the centre bearing bolts are put back in finger tight and the rear of the shaft is supported as shown here.

Brakelines at the flexible line joint and hydraulic strut lower ball joints in a 6.9 are separated.



With a coill sprung rear end the shockabsorbers should be removed top and bottom (removing the rear seat) and a suitable spring compresser as shown below used to safely prevent personal injury.



Sway bar at outer ends is unbolted from rear hub carrier



The weight of the subframe is taken by the jig mounted on the transmission jack



And then the front subframe mounts



Followed by the four bolts that pass into the chassis at the rear diff mount are removed along with the connecting shaft for the the rear levelling valve.



At this point the whole assembly gracefully allowed itself to be lowered with only a little assistance needed to part the front subframe mounts,



I transferred it to my engine crane



and placed it down in preparation for work



At this point one of the reasons I went to all this trouble is immediately apparent.
The outer diagonal arm bushes are worn and allowing the inside of each outer bush to wear metal on metal and obviously not doing a lot for the rear stability or geometry as well as making a few creaking noises.

The wear points are visible in the two pictures below and it has irritated me that I have failed twice before to change these bushes with the rear in-situ.





I will post part two as and when some further work is done.

Bill

 

[-bb-]

Hi Bill,

Please let me add to the thanks you will no doubt get for posting these fabulous pictorials up. They will be a great refrence for all of us.

 

[Styria]

Hi WGB, with your permission, would you have objection if this thread, and others dealing with the work you are carrying out on the rear suspension, was to be moved to our Technical Section in due course ? In my view, it is such an excellent reference point, and it would seem a shame, and wasteful to your efforts, to have these posts simply disappear 'down the gurgler'.
At one stage, I had considered pursuing a similar transfer with the valve grind and de-coke on both Gleaming Beauty and Chris P.'s Wilhelm, but those threads have attracted sufficient interest to keep on featuring in the Top 15 section. Thus, there has been no need to transfer that thread, but any new ones would take a long time to make the top fifteen.

I always view your technical posts and pictures with a certain amount of curiosity if for no reason other than the fact that one gets the opportunity to 'look around' - as if paying you a personal visit and I find the diversity of parts and equipment, and sundries, quite fascinating. Getting to your work, I see that you have a non-standard exhaust system and its design would indicate that there would be a certain amount of 'loudness' evident at certain times. Am I correct ?...and also, is the sound noticeable or evident as a constant 'drone' when driving at various speeds ?......and how are you going to re-install it - slip joint or flanged ?

Regarding removal of the system, I must admit that I have always been disappointed that Mercedes did not fit a flanged system, such as has always been done by a 'lowly' manufacturer like the Rover Company. Those 6.9s weren't a cheap car, and you'd be forgiven for thinking that in their day of manufacture a flange system should have been a 'must'. This is something that I have done on Gleaming Beauty - the whole system is flanged, starting from just in front of the gearbox, and another in front of the rear driveshafts. I know this is going to be handy in due course if for no reason other than perhaps a possible removal of the gearbox at future times, or the removal of the rear suspension as well. I will need to drag out some pics in due course. Thank you for your contribution. Regards Styria

N.B. BTW, the amount of wear in those bushes is quite telling. Also, do you plan to replace the shackles from sway bar to top of hub in due course ? Now would be an opportune time to do so. Also, any painting of the underside of the car ?

 

[WGB]

Hi WGB, with your permission, would you have objection if this thread, and others dealing with the work you are carrying out on the rear suspension, was to be moved to our Technical Section in due course ? In my view, it is such an excellent reference point, and it would seem a shame, and wasteful to your efforts, to have these posts simply disappear 'down the gurgler'.

I would feel chuffed if you did put them in the technical section. I was planning to make one last post when all was finished with all the sections hyperlinked together.

Apart from an aide-memoir for myself I was hoping it would inspire some other budding DIYer to have the confidence to both "have a go" as well as end up with a reasonable job.

I always view your technical posts and pictures with a certain amount of curiosity if for no reason other than the fact that one gets the opportunity to 'look around' - as if paying you a personal visit and I find the diversity of parts and equipment, and sundries, quite fascinating. Getting to your work, I see that you have a non-standard exhaust system and its design would indicate that there would be a certain amount of 'loudness' evident at certain times. Am I correct ?...and also, is the sound noticeable or evident as a constant 'drone' when driving at various speeds ?......and how are you going to re-install it - slip joint or flanged ?

I have a tool collection that now goes back 44 years and as I have owned or been assiociated with M_B cars since 1973 there is some depth to that collection.

The exhaust is certainly more than audible outside the car but there is no real drone and certainly no boom periods audible inside the car. The wind noise with a soft background burble is all you hear. Having said that I feather the throttle going past any cars with chequer boards on them and on the one occasion I was stopped I turned the ignition off immediately.

The exhaust came with the car and If I have problems I will change it. It is flanged betwen the two mufflers but welded to the original Y piece which is in turn clamped to the down pipes - that is the difficult join to undo.

N.B. BTW, the amount of wear in those bushes is quite telling. Also, do you plan to replace the shackles from sway bar to top of hub in due course ? Now would be an opportune time to do so. Also, any painting of the underside of the car ?

I have no perceptible play or visible damage in the swaybar to hub shackle and as the cost of each replacement seems to be more than I paid for each new driveshaft I don't have any plans to spend any more money.

I have a long dusty gravel driveway so clean bottoms do not stay clean for long but I am toying with the idea of spraying the wheel arches Astral Silver but I might leave that until I fit the AMG rear and side skirts that I have recently collected and have a spray gun in my hand.

Bill

 

[Lukas]

This is looking very good, thanks WGB. And I've only read post 1.

You are reinforcing my tendency towards getting a hoist too.

Also, what is the car in the background (with the exposed front wheel)?

Thanks

Lukas

 

[WGB]

1938 Ford V8 Deluxe.

Bill

 

[Styria]

Regarding the exhaust system, and flanges that are fitted, these pics. are from the underside of Gleaming Beauty. This is the section just in front of the rear muffler - incidentally, this muffler is an after-market stainless steel unit with slightly smaller outlet pipes.





At the time when I had the flanges fitted, I also purchased a brand new Ch.107 intermediate muffler - witness the much flatter and probably wider size. I bought it in the hope of getting a slightly sportier exhaust note in tandem with the smaller capacity pipes rear muffler. The result is a fairly 'snarly' system, especially when you wind out the engine in the lower gears.



I regularly claean the underside of the car - doesn't make it go any faster, but it gives me satisfaction.



Regards Styria

 

[John S]

The W107 intermediate muffler is probably not helping your performance Styria. Mercedes go to a lot of trouble to get their inlet and exhaust system optimal for each engine.

 

[260ebenz]

Regarding the exhaust system, and flanges that are fitted, these pics. are from the underside of Gleaming Beauty. This is the section just in front of the rear muffler - incidentally, this muffler is an after-market stainless steel unit with slightly smaller outlet pipes.





At the time when I had the flanges fitted, I also purchased a brand new Ch.107 intermediate muffler - witness the much flatter and probably wider size. I bought it in the hope of getting a slightly sportier exhaust note in tandem with the smaller capacity pipes rear muffler. The result is a fairly 'snarly' system, especially when you wind out the engine in the lower gears.



I regularly claean the underside of the car - doesn't make it go any faster, but it gives me satisfaction.



Regards Styria

Looking very neat and tidy underneath your Mercedes Styria job well done!

 

[Styria]

Hi JohnS, to be perfectly honest, I am not sure if you are correct, or otherwise. I take your point regarding design by Daimler, but I guess only a comparable dyno test would verify any differences. As it is, I don't think that the 350 muffler is all that much smaller - if at all. I know it's narrow to the extreme, but it is also quite wide.

Seat of the pants feeling, as I remember it, would probably indicate that power is still quite strong. I am also quite surprised at the difference in engine note between Gleaming Beauty's "dirty" engine (read high compression) and Australian delivered 6.9s with the lower compression engine. Regards Styria

 

[Oversize]

Looks like it was a huge job to update the driveshafts to W126. I'm wondering if it'd be easier to just replace the entire differential & driveshafts? Obviously more expensive, but would it give access to a wider range of ratios? Do the 6.9 diffs suffer from any common problems? I know at least one of mine doesn't hook up as well as I'd like & spins only one wheel if I'm too heavy on the throttle.... Is the 6.9 diff & driveshafts stronger than those from say a W126 560SEL?

 

[WGB]

It is no harder to put in flanges and 560 drive shafts than it is to change the old driveshafts and hopefully it will be a permanent fix as I have already attempted a repair on the RH axleshaft and had no wish to replace old for old and possibly dodgy.

It also allows me to remove a shaft with relative ease in the future if there are any maintenance issues - hopefully there never will be.

My LSD works well and the only diff problem I had was a leaking pinion seal.

I also did not wish to change the ratio if for no other reason than speedo calibration but I believe there are a couple of taller ratios that were used in 126's.

Another reason for dropping the rear end is that I have changed the RH driveshaft in-situ before and while it is possible it is actually easier to drop the lot.

http://www.topklasse.org/forums/showthread.php?t=372&highlight=driveshaft

The other reason was to replace the diagonal arm bushes for which the subframe needs to be lowered in some way.

Bill

 

[Styria]

I hope this meets your approval, Bill, but I am now in a position to perhaps "piggy-back" some of my recent efforts to perhaps assist future do it yourselfers who don't have access to a car hoist and gearbox jack - such as myself.

As Bill says, the first initial problem that arises relates to the removal of the slip jointed exhaust system. If you don't have oxy at your disposal, removal can be downright frustrating and hard work. Of course, if one sets to it with an angle grinder, you still have the task of re-fitting and also joining the system - I don't think Bill made it clear how he carried out that job. My solution is to take the car to exhaust fitters, and have them install flanges, such as illustrated hereunder.



In this instance, I found it necessary to assemble the two halves on the bench (floor !) due to the fact that the exhaust fitters carried out a rather slovenly job, prior to refitting to the car. Removal of the complete rear axle assembly is straight forward - merely a nut and bolt operation, as long as the car is up high enough and a good quality garage jack with a steel platform to support the differential. I also drained all the diff oil, because the back cover needs to be removed in order to release the circlips that retain the driveshafts. Also one needs to take good care and note position of the thrust washers for the driveshafts - where they fit into the diff splines.

In my opinion, the biggest headache as far as removal is concerned relates to the handbrake cables. Once you get the hang of it, dismantling the cables from the cranking lever located in the gearbox tunnel is fairly straight forward. However, on the hubs themselves, the expander (activator) is a tight fit, but this has been covered in other sections of the forum. More of this work in the next post. Regards Styria

 

[Styria]

With the complete assembly removed from under the car, this afforded the opportunity for some serious cleaning and painting - if you are inclined that way. I am.







Of course, once the assembly is removed from the car, one can also carry out some additional serious cleaning, painting and refurbishing - and I am just not referring to a lick and promise. With the differential having its cover removed, it affords a real opportunity to fill with petrol and give it a good clean out. Also, with the assembly removed from the car, I took the opportunity to remove various rubber bungs from box sections and filled those with Fish Oil as a rust preventative. Refitting of the assembly is again fairly straight forward, once you know how it is done - trial and error beforehand, however, is the order of the day.

Bill refers to the fitting of the differential to the rear subframe with four mounting points. The two parts need to be offered to each other in a square and level fashion - if the angle is incorrect, the studs of the diff housing will not pass through the holes of the subframe. Once you have the assembly complete, i.e. subframe, differential and trailing arms, you're dealing with considerable weight.



The following picture shows the assembly to be in the upside 'down' position. It was the only method that I could come up with to fit the two trailing arms without losing two liters of useless sweat, and cramps in both arms and one of the legs....



My solution was to use three rolling jacks - the main with steel platform to support the centre of the assembly, and to small jacks supporting the feft and right front of the subframe/trailing arm. Initially I had offered just the subframe and diff. to approximate locations under the car, but I did not have the physical strength to the attach the trailing arms to the subframe. Just too heavy, and the newly fitted bushes reulted in a stubborn fit. So I pulled everything back out, turned diff. and subframe upside down, and fitted the trailing arms from the top. I actually needed a slid hammer to place the trailing arms in the correct position on the subframe. I then turned the whole assembly back into its position, fitted the jacks under the respective locations and rolled the assembly back under the car.

A couple of hints here - when attaching the diff. mount to the plate of the diff., just leave it very loose and flexible. This makes it easy to attach the mount to the body by means of the four bolts. Also another potential bug bear or time waster - ensure that the prop shaft is offered to the diff. flange as you are jacking up the whole assembly because, once the diff. is in the correct position, you can no longer hook up the drive shaft. That's it for the time being - there may be a little more to come once I gather my thoughts and review the work that was carried out. Regards Styria

 

[WGB]

Thank you for continuing the posting with your experiences Styria.

As regards the exhaust slip joint I always get very frustrated with these.

Heat with oxy and extreme violence with a hammer and various implements helps but from memory I used an angle grinder to cut each pipe lengthways and then prised the pipes away from each other. Then I welded the lengthwise cut before re-fitting.

One of the problems is that these joints in this car are dual so they interfere with each other.

I appreciate that I am very lucky to have space as well as a hoist which was donated gratis by a grateful patient and collected and assembled in my shed by family members after lunch one Easter. Without it this advancing frame would not be so industrious.

Bill

 

[Oversize]

Well done guys on completing such a job and for posting such detailed pics / text in order to help others (or for just some interesting reading). Styria why did you drop your rear subframe? BTW it looks very nice all cleaned and painted.... Yes I think exhaust flanges are a far better proposition than the original slip joints. And a single system may be better than two pipes running side by side. Plus it's seems quite difficult to maintain an even gap between the two pipes, making for a rather ugly system (Styria you must have found a GOOD exhaust fitter)!

 

[Styria]

Hi Bill, I am glad that you don't mind my "piggy-back" ride. I guess the more info is available, the better achieved is the purpose of the topklasse forum.

Hi Mark, it is necessary, and as indicated by Bill, to drop the subframe in order to gain access to the bolts that secure the trailing arms to the subframe. Besides, going to all the trouble of replacing subframe and trailing arm bushings, it is almost just as easy to remove the whole lot or, shall we say, as much as possible. I am so glad I did as it gave me the opportunity to carry out a really good clean up. Mightn't make the car go any better, but it sure pleases the eye and my propensity for cleanliness. I know, I know...the first lot of rain.......

Another item to bear in mind - it is imperative to disconnect the rear flexible joint and move downwards with the lowering of the diff. - unless the flexible drive is removed, it is not possible to remove the right inner bolt that secures the trailing arm to the subframe. Regards Styria

 

[WGB]

Also if you have an axle shaft replacement it is actually easier to drop the whole subframe or remove a rear hub to get that shaft out. This was one of the reasons I changed to 126 type shafts and flanges.

So long as you have 41 and 46mm spanners you can collapse the driveshaft quite easily by loosening the central slip joint which makes removal and fitment of the driveshaft quite easy.

Bill