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  #1  
Old 09-03-2010, 06:40 PM
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What are these and how can I change them?

Hi All,
It's been a long time for me, but I'm still driving the trusty 1986 300e W124. It's been a good car and I plan to keep it for a bit longer... But it's making an annoying squeaking sound and I can only think it's coming from these dead bushings. Attached are 2 pictures. This is a cross member at the back of the car. The greasy gross thing there is the rear differential. It's mounted to this cross member with these 2 bushings that are clearly shot and need to be replaced. By gently lifting on the differential, I can hear a squeak and see this moving. I trust it shouldn't move (or if so, not by much and it should be much firmer than it is)

So my first question is: Are these the Wheel Carrier Bushings? If not, what are they?

My second question is: Is this something that I can carefully change myself? It looks as though I simply need to remove the allen bolt there, work out that dead bushing, somehow hammer or press in a new one and put the bolt back in. I'm sure it can't be that easy... is it?

Thanks All!

Attached Thumbnails
What are these and how can I change them?-rear_end_squeek1sm.jpg   What are these and how can I change them?-rear_end_squeek2sm.jpg  
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  #2  
Old 09-03-2010, 07:10 PM
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They're not wheel carrier bushings. I would descibe them as final drive mounts/bushings.
Changing them will likely entail dropping the final drive so they can be pressed/driven/hammered out. You should contemplate renewing whatever seals are leaking as the oil will degrade your new mounts.
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  #3  
Old 09-03-2010, 07:17 PM
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Quote:
Originally Posted by Chas H View Post
They're not wheel carrier bushings. I would descibe them as final drive mounts/bushings.
Changing them will likely entail dropping the final drive so they can be pressed/driven/hammered out. You should contemplate renewing whatever seals are leaking as the oil will degrade your new mounts.
They are most commonly referred to as the rear differential mounts.
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  #4  
Old 09-03-2010, 07:35 PM
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Quote:
Originally Posted by Billybob View Post
They are most commonly referred to as the rear differential mounts.
Sounds redundundant to me. There isn't a front differential mount.
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  #5  
Old 09-03-2010, 07:47 PM
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I bet I could get a gear puller in there and work them out that way... I just need to find replacements. Could probably order them from my guy.

The grease is from a bad transmission that I've already had replaced, so I'll do a good clean up job on this differential when I'm there.
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  #6  
Old 09-03-2010, 07:59 PM
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Quote:
Originally Posted by DEPRIEST View Post
I bet I could get a gear puller in there and work them out that way... I just need to find replacements. Could probably order them from my guy.

The grease is from a bad transmission that I've already had replaced, so I'll do a good clean up job on this differential when I'm there.
Anything you can do to avoid dropping the final drive is prolly worth it. I'd clean all that greasy mess up first.
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Old 09-03-2010, 08:03 PM
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Quote:
Originally Posted by Chas H View Post
Sounds redundundant to me. There isn't a front differential mount.
It's only sounds redundant to someone who doesn't know what they are talking about. I thought I remember you mentioning you once worked on MB cars, maybe not?

On a 124 chassis in addition to the two rear mounts which attach to the differential rear cover, there is a single front differential mount that secures the forward end of the differential, it uses a 8 mm Allen head bolt which connects to a 17 mm nut which resides above it in a channel of the subframe on passenger side of the differential immediately adjacent to the differential's ABS sensor. There are upper and lower rubber disk mounts that sandwich a tab on the differential.

Last edited by Billybob; 09-03-2010 at 08:27 PM.
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Old 09-03-2010, 08:26 PM
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Originally Posted by DEPRIEST View Post
I bet I could get a gear puller in there and work them out that way... I just need to find replacements. Could probably order them from my guy.

The grease is from a bad transmission that I've already had replaced, so I'll do a good clean up job on this differential when I'm there.
The mounts in question need to be removed either in pieces ( after unbolting and moving the differential forward as much as you can, you can cut the outer shell appart with a Sawzall) or pulled in a forward direction. The area of the subframe into which these mounts fit is tapered large-small front to rear.

Some folks have stated they have been able to move the differential forward just enough to remove the mounts and to install new mounts, I have never witnessed that being done.


I unbolt the axles the driveshaft and the mounts and drop the differential, using a puller or a large bolt/large socket/large washer arraingment remove the old mounts and install new mounts into the same position.

I unplug the differential ABS sensor behind the rear seat and push the pigtail and grommet out under the car. I do that because if you try to unbolt the ABS sensor and remove it letting it hang, it is common for the sensor to be damaged in the process, even if you do get the ABS sensor out without damaging it you will need a specific very thin O-ring to get it resealed without leaking, most common O-rings are too thick and will not allow you to reinstall the sensor.

The grime on the rear cover is most likely is from differential fluid escaping the vent because it looks like it is on and possibly coming from the top of the differential, although the drive flange seals are often leaking after 150,000 miles. With the differential on the bench you can open it up, remove the clips which secure the drive flanges in place, pull the flanges out and replace the seals. If the front pinion seal is also leaking you can change that but it's a more involved process because you need to ascertain the preload and then replicate that upon re-assembly.

The rear muffler section can be dropped and allowed to hang, allowing more space on the drivers side when dealing with the axle on that side.
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Old 09-03-2010, 08:26 PM
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Quote:
Originally Posted by Billybob View Post
It's only sounds redundant to someone who doesn't know what they are talking about. I thought I remember you mentioning you once worked on MB cars, maybe not?

On a 124 chassis in addition to the two rear mounts which attach to the differential rear cover, there is a single front differential mount that secures the forward end of the differential, it uses a 8 mm Allen head bolt which connects to a 17 mm nut which resides above it in a channel of the subframe on passengerside of the differential immediately adjacent to the differential's ABS sensor. There are upper and lower rubber disk mounts that sandwich a tab on the differential.
The differential is enclosed in the center assembly, according to the Mercedes workshop manual. As such it has no mounts. Using the term "differential" to describe other than the part the ring gear bolts to is a common error among neophytes. Furthermore, there is only one differential in the subject car, at the rear of the car. There is none at the front.
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  #10  
Old 09-03-2010, 08:58 PM
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Originally Posted by Chas H View Post
The differential is enclosed in the center assembly, according to the Mercedes workshop manual. As such it has no mounts. Using the term "differential" to describe other than the part the ring gear bolts to is a common error among neophytes.
Semantics! Just admit it you don't know how the differential's "center assembly" is secured to the subframe! You though you where getting in a cheap shot and only exposed your own shortcomings.

I clearly spoke to the parts reference as "commonly referred to"

Quote:
Originally Posted by Billybob View Post
They are most commonly referred to as the rear differential mounts.
It is interesting that when you attempted to take your cheap shot you failed to mention your nomenclature objection when you only claimed redundancy when arguing there where no "front differential mounts"!

Quote:
Originally Posted by Chas H View Post
Sounds redundundant to me. There isn't a front differential mount.
If you where consistent regarding the nomeclature you would have refered to the assembly in question as the "center assembly" in your previous posts to this thread rather than as the "final drive" which you did twice!

Quote:
Originally Posted by Chas H View Post
They're not wheel carrier bushings. I would descibe them as final drive mounts/bushings.
Changing them will likely entail dropping the final drive so they can be pressed/driven/hammered out. You should contemplate renewing whatever seals are leaking as the oil will degrade your new mounts.
Quote:
Originally Posted by Chas H View Post
Anything you can do to avoid dropping the final drive is prolly worth it. I'd clean all that greasy mess up first.
As this thread is of a technical nature regarding the actual parts of the original poster's vehicle and you have already removed any doubt as to the extent of your lack of firsthand knowlege regarding the arrangement of those parts; I'm going to cease embarrassing you as long as you cease to embarrass yourself. In the interest of the actual concerns of the original poster and the repair operation in question let's agree to confine further commentary to the circumstances in question. The poster is no doubt more interested in repairing his vehicle than your "attempted food fight"!

I'm sure you can find something I'll post elsewhere to be disagreeable with and vent your vitriol.

Last edited by Billybob; 09-03-2010 at 09:27 PM.
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  #11  
Old 09-03-2010, 11:00 PM
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Yes, those with scant knowledge often refer to the final drive as the differential. Fact is the final drive might not contain a differential. Or sometimes we find a differential in the transmission/transfer case of AWD vehicles.
It's not a case of semantics, but one of intelligence and knowledge.
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  #12  
Old 09-03-2010, 11:23 PM
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Quote:
Originally Posted by Chas H View Post
Yes, those with scant knowledge often refer to the final drive as the differential. Fact is the final drive might not contain a differential. Or sometimes we find a differential in the transmission/transfer case of AWD vehicles.
It's not a case of semantics, but one of intelligence and knowledge.
Come on now, your continued ranting just makes you sound confused and desperate if you don't stop the family will take the keyboard away from you. The original poster just wanted the information to fix his car, no need for you to get frustrated and agitated!
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  #13  
Old 09-04-2010, 07:03 AM
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Boys, take your playground spat outside. The OP just asked for a little help identifying these parts. Typically called differential bushings, but EPC refers to them as rubber mounts for the axle housing to rear subframe. The photos tell me yours are overdue for replacement. P/N 124-352-77-65
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Last edited by Cal Learner; 09-04-2010 at 07:19 AM.
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  #14  
Old 09-04-2010, 08:19 AM
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the mounts/bushings in your photos actually look pretty good. the left one is a bit off-center but for instance the ones in my car are much worse. and when they're bad they don't normally make a squeaking noise, more of a clunk. i think the squeak is coming from somewhere else.
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  #15  
Old 09-04-2010, 08:50 AM
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I'd say if he can duplicate the noise by pressing up on the final drive, he's found his problem.

On the "semantics" episode, I was siding with ChasH until the statement, well here, I'll quote it:
Quote:
Fact is the final drive might not contain a differential.
Ummm, can you give an example of that, I'm confused and will readily admit it. I might be missing something, something that will give me an "Oh, YEAH!" moment. I love those.

And as far as the battle itself, if this would help get peace talks to ensue, in a Mercedes shop, if someone has worked on Mercedes for awhile, with prior mechanical experience, eventually you see the term "final drive" used enough that you start using that instead of the more generic term "differential". Before i was exposed to Mercedes, I know this is the term that was used, either that or just "rear axle". Of course I'm a little older and these terms were used regarding rear wheel drive American cars, before Chevy shocked the world with the Citation!

Anyways, when you start to work on Mercedes, the "final drive" name is used a lot, especially in the maintenance sheets, ie "check final drive oil".

In the REPAIR info, such as the microfiche sheets, it is usually referred to as the "Center Section".

I will also use the term "Punkin' " (pumpkin), ie "don't drop that punkin' on your head!"

Some of these terms might be used more or less frequently due to location, maybe? I don't see the big fuss in correcting each other, there are lots of terms like this, differntial, rear axle, final drive, hey you know what is being talked about, big deal. For some reason, I would be more apt to use the term "final drive" when talking about the fluid change, but if I had to REMOVE it, I would say something like "ah crap, the center section has to come out!" It's always strange for a guy who is used to solid rear drive axles to start working on IRS, to me that was always high tech Jag or Corvette stuff, it was a real leap to go into IRS.

If someone would ask about the differential though, I knew what was being talked about, no need to do a correction, sort of like if someone offers me a soda, and where I live they always call it "pop" instead, no reason to say "huh?", I know what it is! (and usually I want to say "only if you're out of BEER!").

Gilly

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