THis is on an early R107, but steering is similar to other early Benzes so asking here.

With front wheels off ground, if I turn front wheels so as to actuate the steeing linkages, I hear a groaning from the idler arm pivot.

My question is about the design of that pivot. It has steel sleeves set into rubber bushings that fit into a large tube that is attached to the chassis frame.

It looks like there is no keyway, spline or other method of locking the idler arm to the pivot bolt. (I haven't removed it to confirm that!)

Does the arm just rely on compression of the inner sleeves to lock the arm to the bolt and the metal sleeves so that the sleeves move with the arm? And if so, presumably the sleeves turn inside the rubber bushings? If so, perhaps the groaning rubber on metal sound is normal?

Somehow, I thought the arm should be locked to the bolt and it should turn inside the metal sleeves. But it doesn't look like it works like that!

By the way, on my car the bolt head is at the bottom. Same on a few other similar cars. But all parts diagrams show it as does the picture from the FSM below.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

G:

The rubber bushings have plastic liners which serve as the bearing surface in which the steel sleeves turn. There are also plastic washers top & bottom.
The picture is inverted; the arm and the bolt are on the bottom.

Thanks Frank.

Actually, the picture is correct for my 107. However, in my case the bolt head is at the bottom. Not sure if early cars were built that way because of interference with starter above when removing bolt. But later 107s are same as the picture.

I get a groaning noise out of the pivot. Today I tried tightening the bolt. Got about 1/4 turn fairly easily. Torque is supposed to be 120NM, but I doubt it was and also doubt I tightened that much lying on back under car!

After tightening the groaning was much louder but eventually diminished.

I am actually chasing a metallic clicking sound that occurs on passenger side when steering is turned almost fully. Like every time I back out of garage. Otherwise car drives and tracks perfectly with no suspension noises. I have checked balljoints, tierods, swaybar&links, wheel bearing, brakes etc as best I can in my garage as well as on friend's hoist.

I may change the idler arm bushings. But the click is probably elsewhere. I need to find a front end shop I can trust who won't throw parts at it.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

For what it's worth, I dissected my old bushings today. Might help others like me (doing this for first time), understand how the idle arm is designed.



My car did not have washer 3. Apparently that is used to set relative heights of Idler arm (2) and Pitman arm when needed. They say to put washer back if you find one.

The bolt compresses the inner flanged metal sleeves and bushing caps between the upper cup washer and the lower flat washer. The bolt is torqued to 120NM so that the when the idler arm rotates, the flanged sleeves rotate in the integral bushing metal sleeves.

The rubber caps with lips clip onto the flanged sleeves top and bottom (1 below) These caps have an internal steel washer (2 below) that bears on the chassis mounting tube. Each cap has a non-steel copper colored washer (maybe fiber)(3 below) that presumably reduces friction between the steel end-cap washers and the chassis tube.

Too many words? How about some pictures

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

I believe many indys swap the bolt orientation to make replacement easier. I just did it on my 190e and found my bolt flipped. Original orientation would mean removal of the exhaust heat shield and this way the bolts just drops out of the bottom, little weird trying to get the nut on top but I think easier overall.

I would go ahead and replace, found my bushings in multiple pieces and I think parts is all of $25.

I have ordered the repair kit. MBCanada wanted C$89, so I ordered a Lemfoerder kit for about US$25 (plus shipping to Canada!)

My SL used to have a large diameter starter not far above the head of that bolt. The newer Bosch starter is much smaller. If the bolt will go in from top, I will do that. Better if nut comes off!

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

it's a self locking nut. reversed a lot of bolts on 107s, 124s and 201s,

I just finished replacing this part on my '72 280sel as part of the overall refurbishment of the steering system. Like yours, the bolt head on mine was at the bottom. This is usually an easy job but on mine the bolt had frozen onto the inside of the upper bushing. Normally the bolt would just fall out after the nut is removed.

What a mess - I had to slam on the top of the bolt with the nut partially on. This was done from above with a long extension + socket. Got it to move down about an inch but that's all. Decided to cut the bolt head off then pry the lower bush out then hammer out the top bush from below. It all came out in pieces.

As you can see, you'll need to pop off one end of the drag link and tie rod. The Harbor Freight tool works good on this and it's under $20.

Have parts and will install tomorrow. Hoping it will be easy job.

I've had success on several cars (not tried on a 107) getting the bolt in from the top down by placing the new upper bushing on the bolt first and then placing the bushing and the bolt into the tube. It's worth a try but I've not attempted it on a 107. This method allows an approach at a steeper angle clearing exhaust components.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Changed the pivot kit today (actually because of my bad back, my young friend did it for me on his lift). Took about an hour. Actually 10 min! Rest was positioning car on hoist and talking

There were no problems really. Bolt came right out and sleeves were easily tapped out. Rubber bushing were of type with smooth exterior. They came out with a little tapping with a drift.

Back together and torqued to spec.

Bad News - Still have clicking noise from passenger side when making very slow sharp turns. (like backing out of garage). No noises while driving or even when going over bumpy roads.

I bought a Lemfoerder repair kit. These kits are same for 107 and 123. Box it came in said made in China! Friend had a spare URO kit. We compared them. Definitely not same. There were different manufacturer markings on the rubber bushings. Only Lemfoerder also had the MB part number - 1244630066.

By the way the rubber bushing can be purchased separately. Maybe not worthwhile because you need two plus the single use lock nut.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

I have been chasing suspension noises for some time. Even after changing the idler, ball joints, control arm bushings, the noise was back today. As bad as ever.

I jacked car up and had wife turn wheel back and forth while I listened. Squeaking and clicking noise seemed to everywhere. I then tried with stethoscope. I found that it was definitely coming from the top of idler pivot. Hard to see the cause, but likely cup rubbing on top rubber insert.

Then I recalled seeing something in FSM! (Idler arm is of course at top on our 107s)


See note b) !!

I removed the pivot bolt and the lower metal sleeve (5). I compared this Lemfoerder sleeve with the original out of my car (older style without flutes on rubber). I found that the original sleeves were 0.5mm longer! (diameter was also different) Exterior surface showed kind of coarse machining marks. Original is smooth. This is the surface that turns inside the sleeve in the rubber bushing, so questionable. May be OK.

As the FSM suggested, I installed a 0.5mm shim between the metal sleeves. I tried turning the steering wheel and it does seem smoother. But still has the metal on rubber sound. Put in another shim to bring total to 1.3mm. Road tested. Still some rubber noise as well as the clicking I have been trying to chase down.

Removed Lemfoerder kit from car. It looked like the upper metal sleeve had not been turning in the upper metal/rubber insert. No doubt because of discrepancy in length of the metal sleeves. As a result the rubber bushing had been turning in the chassis tube. This would explain the noise.

Next measured the chassis tube and compared with the assembled length of the Lemfoerder kit to try and come up with a shim thickness that will work.

Chassis idler arm tube. - 83mm long +/- depending on where measured.

With upper and lower bolted up tight (using old bolt/nut), measured distance between the surfaces that bear on the chassis tube ( metal plate on inner side of rubber bushings):
Original parts removed from car: 82.5-82.9mm
New Lemfoerder parts: 80.6-80.8mm (~2mm shorter than original)
FSM says that there can be 0.5mm slack. So that would say that the distance between bearing surface could be 83mm to 83.5mm.

This means that Lemfoerder would need a 2.2-2.9mm shim between the two inner metal bushings . I made the shim from 3x0.84mm washers (2.52mm). This gave me total of about 83.22, for 0.22 slack.

With this installed, I test drove the car. No rubber squeaking or groaning. Steering feels light. None of the clicking sounds I have been chasing down when making slow sharp turns, but will test for several more days before declaring that a win because lube may be helping.

BEFORE:
Kind of poor video, but you can sure hear clicking and groaning. Watch the metal plate at the bottom of the upper sleeve - it is inside the dust cap but is separate and firmly clamped to the chassis tube. it should not move. But it does!

https://www.dropbox.com/s/capjb5omfrow5d0/Idler%20noise.mp4?dl=1

AFTER
Groaning noise in this video, taken after repair is coming from the steering column, not the idler. Not noticeable when driving. In this video, I marked the relative parts. It shows that the upper and lower rubber bushings are not turning in the chassis tube. Clicking (likely caused by the metal face of the rubber bushing rotating against chassis tube) is now gone.

https://www.dropbox.com/s/p26q9bz1jd9aev3/Idler%20noise%20after%20repair.mp4?dl=1

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

For those interested or having idler groan, cross posting this from similar discussion ion BW forums:

After chasing the idler groaning noise, I came to conclusion that if I do this again, I will not put any grease in the chassis tube or on the outside of the rubber sleeves. If they are too tight a fit, maybe a very little dish soap or Pledge or similar on just the edges of the rubber flutes so the sleeve can be pulled in. The rubber should, I believe, be a tight fit.

Where a light coating of oil or grease or dry lube might help, is between the flanged metal sleeve and the thin metal sleeve that is embedded in the rubber sleeve. Perhaps also put some grease in the gap between the rubber inserts in hope some of it may get between these sleeves.

I believe the groaning noise in my case, was the upper rubber sleeve turning in the chassis tube. This should not happen. The flanged metal sleeve should turn in the metal sleeve that is embedded in the rubber.

I believe problem starts in the end caps. The 120 NM torque should compress the assembly without compressing the washers that are on inside face of the flanged sleeve (See post #11 above items 1, 2 & 3). The FSM says, there can be up to 0.5mm slack after torqueing the bolt. If there is no slack, that flanged end cap joint can lock up and force the rubber sleeve to rotate in the chassis tube, causing the groaning. This is what led me to do the measurements and install the shims.

Could be that this is vehicle or vendor specific. I did this on my 72 107 with Lemfoerder kit. Part number is same for many Benzes from 68-95. If there is a next time, I will again measure the chassis tube and the replacement parts for fit! And probably buy the more expensive MB kit.

By the way, the rubber parts of the Lemfoerder kit have the MB part numbers and the Phoenix symbol (Company in Turkey that makes many OE MB rubber parts). The metal parts may be where the discrepancy is. It would be interesting to compare aftermarket dimensions with the MB part.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5