W108 280SEL - Clunk from Rear End upon Hard Acceleration - Page 2 - Mercedes-Benz Forum

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post #11 of 24 (permalink) Old 12-27-2015, 02:25 PM
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Yeah, that big bushing isnt suppose to move any!

you can get it here for $271.15

RUBBER MOUNTING made by Mercedes Benz. #1103500675
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post #12 of 24 (permalink) Old 12-27-2015, 02:34 PM
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Once you replace it, your rear wheels will splay out when you lower it. The amount lowering will also be limited by the top the spring.
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post #13 of 24 (permalink) Old 12-27-2015, 04:03 PM
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By the way, nice looking 280SEL. I don't worry about keeping mine original. They will likely never be collectors items. I drive mine every day so I maintain and upgrade to my personal taste. Getting ready to do the megasquirt conversion. Tired of messing with 43 year old d-jet parts with 400,000+ miles of use.
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post #14 of 24 (permalink) Old 12-27-2015, 04:46 PM Thread Starter
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By the way, nice looking 280SEL. I don't worry about keeping mine original. They will likely never be collectors items. I drive mine every day so I maintain and upgrade to my personal taste. Getting ready to do the megasquirt conversion. Tired of messing with 43 year old d-jet parts with 400,000+ miles of use.
Megasquirt is a great system, once you get it tuned. I'd recommend a tuning software called TunerStudio - it does most of the fine-tuning for you....once you set up your basic AFR map and timing map, you put it in "learn" mode and go for a drive, and it adjusts on the fly!

I had a K-Jet car before this one, so I'm used to the headaches that come with old Bosch fuel injection. Once you get MegaSquirt working properly, it'll run forever!

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Once you replace it, your rear wheels will splay out when you lower it. The amount lowering will also be limited by the top the spring.
Perfect, that's what I want. I hate camber, and right now the right wheel has a bit of tilt to it. Which makes perfect sense, given the broken bushing and the way the axle is designed.



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Yeah, that big bushing isnt suppose to move any!

you can get it here for $271.15

RUBBER MOUNTING made by Mercedes Benz. #1103500675
That seems like the average price with shipping - thank you! I appreciate the help!
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post #15 of 24 (permalink) Old 12-27-2015, 05:17 PM Thread Starter
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By the way, for anyone looking for a more permanent (and more expensive) solution, it looks like an austrian company makes an aluminum replacement with a small urethane bushing...that'll probably hold it!

https://translate.google.com/transla...e30&edit-text=
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post #16 of 24 (permalink) Old 12-27-2015, 06:36 PM
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W108 280SEL - Clunk from Rear End upon Hard Acceleration

Watching the video... You lower the car (reducing outer spring height). The diff might not want to stay put for two reasons:
1) compensator spring helping to hold the axle straight and minimizing negative camber.
2) the friction of the tires on the pavement wanting to keep the axle the same overall right-to-left width, rather than bending at the differential. I bet if you roll the car back and forth a few feet after lowering it, your camber gets real negative, and the disk goes back into the trunk floor. I could be wrong.

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post #17 of 24 (permalink) Old 12-27-2015, 07:04 PM Thread Starter
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Originally Posted by Fonzi View Post
Watching the video... You lower the car (reducing outer spring height). The diff might not want to stay put for two reasons:
1) compensator spring helping to hold the axle straight and minimizing negative camber.
2) the friction of the tires on the pavement wanting to keep the axle the same overall right-to-left width, rather than bending at the differential. I bet if you roll the car back and forth a few feet after lowering it, your camber gets real negative, and the disk goes back into the trunk floor. I could be wrong.
1) I don't want negative camber, so I hope it's still doing it's job. I set the lowest height at the point where the compensator is completely compressed - so it won't go any lower than that.

2) I'll check next time I get the car out later in the week. That's a good point.
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post #18 of 24 (permalink) Old 01-05-2016, 10:21 AM
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Originally Posted by envoy_to_the_Stars View Post
Looks like this gentleman may be experiencing similar problems with the center diff mount:

Replacing diff carrier bush in w108 - PeachParts Mercedes ShopForum
Sorry, I cannot hear a clunk on that video.
You may have to do that again, this time without ANY other accompanying noises (like windshield wipers)

#130 is the differential rubber mount that takes the vibrations out.
what exactly does that metal compensator spring still do ?
It must be under more tension as you have lowered the car. There are rubber underlays (?)
Also both trailing arms are laid in rubber (#159), where they are attached to the body.

But I think Fonzi was about right.
the angles have changed and may be putting more strain on the drive shaft.
The center bushing is one, but maybe the drive shaft "donut" (front) may have cracks (some later models had them front and rear), causing some 'slop' withe the driveshaft hitting something.
It may also be as hidden as some play in the u-joint (built into the driveshaft (rear, I believe) .

TZ_280SEL described it pretty well (better than I would have)

NOW, I see there are more posts, so what I am writing /wrote maybe pointless.

But Good Luck anyway.
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post #19 of 24 (permalink) Old 01-05-2016, 11:07 AM Thread Starter
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Originally Posted by 6punkt3 View Post
Sorry, I cannot hear a clunk on that video.
You may have to do that again, this time without ANY other accompanying noises (like windshield wipers)

#130 is the differential rubber mount that takes the vibrations out.
what exactly does that metal compensator spring still do ?
It must be under more tension as you have lowered the car. There are rubber underlays (?)
Also both trailing arms are laid in rubber (#159), where they are attached to the body.

But I think Fonzi was about right.
the angles have changed and may be putting more strain on the drive shaft.
The center bushing is one, but maybe the drive shaft "donut" (front) may have cracks (some later models had them front and rear), causing some 'slop' withe the driveshaft hitting something.
It may also be as hidden as some play in the u-joint (built into the driveshaft (rear, I believe) .

TZ_280SEL described it pretty well (better than I would have)

NOW, I see there are more posts, so what I am writing /wrote maybe pointless.

But Good Luck anyway.
I have a new center diff bushing (#130) on the way, it gets here on Thursday. I'll install it this weekend and report back. My center diff bushing is totally torn through, so the diff may be getting slammed around as I accelerate and place sudden torque on it.

I don't think the driveshaft is the issue here - I have checked thoroughly and don't see any signs of it impacting anything, and it appears to be in good shape. Trailing arm bushings are in ok shape as well.

Check back on Sunday for an update, and I'll let you know what I find.
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post #20 of 24 (permalink) Old 01-09-2016, 07:13 PM Thread Starter
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PROBLEM SOLVED!

The diff support bushing was a breeze to replace. You don't even need to get underneath the back end! Totally changed the ride of the car. For those reading this in the future, you'll just need a 17mm wrench for the surrounding bolts (back two are too close to the sheet metal to use a socket, and I believe it was a 21mm socket for the center bolt.

FYI, this is what the torn up bushing looked like compared to the new one. You can see just how little support it was offering in its trashed state:

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