Pagoda SL Group
W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: Harry on November 04, 2016, 11:36:50
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For some reason, I couldn't find a previous post on the disassembly and reassembly of the torque arm bushing. Operator error no doubt. My question is on the reassembly and installation of the bushings at the rear. Do you need to use talc or something like that to squeeze the new rubber in?
Thanks,
Harry
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.../...a previous post on the disassembly and reassembly of the torque arm bushing.../..
try this; http://www.sl113.org/forums/index.php?topic=11244.msg75136#msg75136 (http://www.sl113.org/forums/index.php?topic=11244.msg75136#msg75136)
the bushings at the rear. Do you need to use talc or something like that to squeeze the new rubber in?
Definitely not grease, silicone or such... Talc is good
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I have a hydraulic shop press. I don't use it much but it takes care of that job easily.
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Thanks very much for the response and link. I understand the torque arms are specific to each side. I had mine marked then lost track. How do you identify which is for which side?
Also, what is the torque on the bolts that connect to the axle tube?
Thanks again!!
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Not a definitive answer but yes they must be specific because the L and R part numbers are different. 112 350 04 29 left and 113 050 05 29 right in edition B Nov. 1964, replaced by 110 350 10 29 left and 110 350 11 29 right in edition C Jan. 1967. I have an original axle here but could not see any obvious difference between left and right. If you find a difference I can check it on this axle.
Torque is listed at 20 mkp (196 Nm, 145 lb/ft)
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Thanks very much Dave.
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LT and RT are different and the best way to tell is by looking at the end where the stud mount is located. There's a flange on the inside edge where the bushing is mounted that points towards the driveshaft if all is assembled correctly. The parts are some times stamped with a L or R near where the arm is mounted on to the axle tube.
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OK that is a pretty obvious difference now that you mention it!
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I'm planning to replace all the rear end bushings in the next few weeks, while we're on this subject-
Which is the correct orientation of the "donut" shaped bushings?
Looking at the diagram it shows the ridged side facing up, however I recall having read somewhere that the flat side faces up....I'm confused :-\
Thanks & best,
Mike
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Small orifice uppermost. You need a special tool to insert them.
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This can be done without the special tool, but it is a lot easier with it. Tip, use wire ties to hold the rubber bushings in place while raising the assembly in place. Cut the ties and remove them after in place.
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"Small orifice uppermost"? I have installed mine (just in the arms at this time) with the ridged surface "up", i.e. pointing up when the torque arm would be in position on the car (as shown on the schematic). I had them the other way and compared them against the originals and it looked to me as though that was wrong. The cavity in the rubber is somewhat preformed with a radius in the cavity opposite the ridged side. This seems to align with the radius on the nipple protruding down from the car (with the threaded stud). I can send pictures of the originals later if it would help.
So the flange is towards the driveshaft? That's what I am also seeing from some photos that I took.
Thanks,
Harry
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Thanks for the feedback Colin & Joe, I take it that "small orifice uppermost", means flat side up against the body & ridged side facing down.
I've made my own "special tool"- l welded 2 X 22mm deep drive sockets together and fitted an M14 x 1.5mm thread nut to the top.
Best,
Mike
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It's interesting that inspecting the old doughnuts (rubber bushings for the front of the torque arms), I really couldn't tell their installed orientation. They were just too worn and formed through years of being on the car.
I called Bud's this morning and spoke with Brad, who has installed many of these. He confirmed that the ridged surface goes up towards the body of the car (flat side down). I think if you feel inside the doughnut with the ridge up, you'll feel the radius in the bore down near the bottom (flat side) that would correspond to radius on the nipple where the stud is on the car.
He also recommended using silicon to ease the installation but advised that it is difficult just the same.
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It has been awhile since I did mine but remember there being something stamped in German on the doughnut indicating which side is up or down. Would have been either "Unten" for down or "Oben" for up. Don't remember which was on there. These were Mercedes parts BTW.
Oh and btw, do NOT use grease on the OD of the torque arm bushing as was said. Grease will allow it to work it's way out of position. Ask me how I know.
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.../... stamped in German on the doughnut indicating which side is up or down.../...
OEM donuts do have "Unten" ("downwards") cast into the rubber on the ridged, large orifice side. That side goes towards the ground (i.e. flat, small orifice side goes up towards floorplate of car, just as Stick and Mike already wrote)
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It is considerably more difficult to install the bushings with the flat side up. So much so that I really have to question this procedure even though I believe it may be correct. :-\ I installed them that way on my last build and it was damn near impossible to do even with my assembly tool.
With the ridged side up, they install with some difficulty but it's sort of in the normal range of MB frustration. And, when I did install with the flat side up as advised, it made zero difference in the way the car handled.
However, your mileage my differ............ :)
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Dan, try using some wire ties to hold the rubber bushings in the arms during the install next time. Just cut the ties and pull them out when installed.
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OEM donuts do have "Oben" ("upwards") cast into the rubber on the flat, small orifice side.
Yea! My memory isn't as bad as I thought. Is that on ALL parts or just the MB supplied ones?
I do also remember that I made a tapered install tool and it was still very difficult. Quite an achievement when it was on.
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.../...Is that on ALL parts or just the MB supplied ones?
Just the OEM. Repro donuts lack this writing (and quality of the rubber may be ?)
I do also remember that I made a tapered install tool and it was still very difficult. Quite an achievement when it was on
A general tip is that the rear axle should be close to horisontal (not scissored). Also, the whole axle with the radius arm may need to be nudged rearwards; install tool should fit into the middle of the donut hole (as best possible)
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Thanks for all of the dialogue! I looked at my new bushings and they absolutely have "unten" on the ridged side. So I looked again at the ones that I removed and I do believe that they were installed accordingly. I guess that's what I'll take on this weekend. All good. Love these cars! Thanks again!!
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Good luck Harry and let us know how it goes. I'll be tackling this in the next week or 2....
Best,
Mike
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A general tip is that the rear axle should be close to horisontal (not scissored). Also, the whole axle may need to be nudged rearwards; install tool should fit into the middle of the donut hole (as best possible)
Thanks for the info Hans.
I get very nervous about shifting the axle and the unintended consequences of that.....
If one were to first remove the rear springs, then install the rubber donuts as well as the bushings at the rear of the arms, would that not make installation easier? And then reinstall the springs after all this is done?
I ask this as last year I replaced the rear springs by using a spring compressor without disconnecting the trailing/torque arms (I should have done all the bushings then)....
Best,
Mike
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The interesting thing about MB work shop literature is that one often has to back in time to find the correct info. You really won't find how to position piston rings on pistons or which way is up on the trailing arm bushings in the BBB because MB expected their mechanics to already know this info as part of ongoing training . This info is found in the 190 sedan work shop manual from about 1955 which shows clearly that the bushing goes in with the ridge upwards.
And the piston rings? Top ring is gaped towards the manifold side directly over the piston skirt, second ring gap is towards the spark plug side directly over the piston skirt ( 180 degrees ) third ring gap is towards the front of the engine and oil control ring is gaped towards the back of the engine. On oil control rings that come in two pieces, position the top ring 180 degrees away from the ring gap above it, and the second ring directly below, 180 degrees away from the one above it. The idea being that you want the longest path of resistance to compression gas losses that you can make - keeping in mind that we aren't talking about pistons, of course. ;D
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I made a simple tool to compress, remove and install the rear trailing arm rubber at the axle. A little welding was required to make the tool. As an alternate method, three strategically placed "C" clamps will also work to compress and release the clips also.
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Genius as always.
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I thought that I would follow up post installation. I have now completely reassembled the torque arms to the car/axle. Recall that my initial reason for getting into the rear end was to replace the boot on the differential. As usual, this forum of persons experienced with this work was invaluable.
First, the torque arms. I installed the bushings with the ridged side up. Although there were differing viewpoints on the forum, I was ultimately swayed by the advice provided by Bud's Benz, the inner contour of the bushings best matching the contour of the mating feature on the car when in this orientation, the exploded diagram of this assembly (on the forum and in other places) depicting the same, and the experience noted on the level of difficulty installing them in the opposite orientation. Never-the-less, I very much appreciate the assistance and advice provided by everyone.
I will say that this is a two person job. I can't imagine doing this alone. I didn't use a specialty alignment tool. I used a mirror, and straps on the axle to pull/align the torque arm such that the hole in the bushing remained aligned over the mating feature. It was a slow and deliberate process. As long as I had maintained this alignment, I was able to jack the torque arm right into place without any real incident. I did use silicon spray to "encourage" the process.
Relative to the boot, I followed much of the guidance from the forum and removed the fuel tank and compensating spring. The amount of accessibility with these out of the way was well worth the additional work. The compensating spring is the challenge here. I couldn't quite get enough travel with the shocks disconnected for each axle to drop to the point where the spring was unloaded. Almost but not quite. The brake lines were the issue - there wasn't enough available travel with those connected. I started to disconnect those (figuring these should be replaced anyway) but they were not about to come loose without a fight. I chose not to take those on in addition to everything else. The spring came out easily enough but I had to make a simple tool (also found on the forum) to compress the spring in order to reinstall it.
The grand news is that the rear end has all new rubber, except the lateral adjustment. I didn't feel that I could get to that easily with the exhaust in position. They do need to be replaced (I have the parts) and I will replace them but I didn't want to take on the exhaust right now. I haven't had it on the road but I will in the next few days. I'm anxious to see/feel the results.
So thanks very much. I hope that I am able to also offer helpful advice for others doing this job in the future. It is not a job for the feint of heart or newbies. It is very involved, and anytime you are working with springs and heavily loaded suspension members, it can be dangerous.
Harry
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Thanks for the feedback Harry! I'm going to tackle the torque arms next week and replace donuts & bushings.
I've been busy renewing steering components yesterday and today....
Best,
Mike