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Vibration in rear of of 98 C280

3K views 18 replies 4 participants last post by  georgebuhr 
#1 ·
'98 C280 base model with 360,000 miles. I am original owner. Experiencing mild vibration that hits peak intensity at about 50 mph. Feels like it's coming from the rear. Seems worse when cold. Changes from a steady vibration to a cyclic vibration as speed increases but never goes away completely. Recently replaced trans with used unit w/ 100K. Recently replaced drive shaft (remanufactured). New engine and trans mounts. New front flex disc. Rear flex disc has 50K on it and dealer says it is in good shape. New Michelin AS Premiers with 10K on them. Tire balance and rotation did not have any effect. Factory shocks with about 75K are performing well.

Any ideas on the source of this vibration? It was there before the trans and driveline work but does seem more intense now - the changes seem to have exacerbated the problem. Seems to be getting worse over time. I'm stumped. Wondering if the rear end is wearing out. Could this be a rear end or rear axle problem?
 
#2 ·
Sounds like a CV joint.

does it clunk when initially putting it into gear? You can also try driving in reverse (lot of space required) and accelerating and decelerating...should be worse.
Typically an outer joint will "click" when it starts to fail, inner joints tend to cause a shudder. either way inspect the rubber boots, almost always the failing joint will have a tear, grime, greasy on the outside. inside will be dry as a bone.

Finally jack it up, get the rear tires completely free off the ground...(Make sure you chock the wheels, have the vehicle safely supported, wear safety glasses, no loose clothing or jewelry, ensure small children and household pets are not in the area, lock up all chemicals, and all the other safety crap :grin)

grab both sides of the tire (9 and 3 oclock) and see if one of them has ANY play. not rotating it, you're twisting it like you were trying to remove the tire....attempting to expose the play in the joint that should not be there.

if the joints feel good, center carrier bearing for the driveshaft?...bent rim, and 75K on the shocks....could be one failing, or the mount is bad.

I highly doubt it is the 3rd member.... they typically whine quite loudly when the ring and pinion/gears start to go. when they do eventually fail, it is a spectacular event.
 
#4 ·
Tire rotation didnt move the vibration so you can rule out a wheel assembly. Jostep is right, get it off the ground and wrestle the hell out of the tires on the back and see if they wiggle. Same thing with half shafts and drive shaft. You just got to grab them and shake the hell out of them and see where the play is. Rotating mass is most likely what is causing the vibration, so I'd focus on the tire/wheel, hub/bearing, half shaft, differential, or driveshaft. Patman is right also that it could be bushings, especially given the age.
 
#6 ·
That's why the 9 and 3 position is rec. for the diagnostic shaking. You can mimic the normal "plunge" by putting leverage on the vertical axis.... basically it could move a tiny bit if you shake it top to bottom, but not side to side. If it is worn it's really obvious once you have the weight off.

I also agree that bushings could be the culprit, that's a lot of miles. Finally it's a long shot but perhaps a warped rotor..but that should be making a telltale scraping noise and pulsing brakes. Also Give a close look at the lug nuts and ensure they are allowing a completely flush seating of the rim.

One other thing in regards to bad bearings, you can get a feathered uneven tread wear pattern on the tires...directly in the center, but that's usually when they are really far gone.
 
#7 ·
I assume you are talking about CV joints on the rear axles? That's worth a look.

There is no clunking when engaging trans and I don't hear any clicking.Rear brake rotors were replaced recently and the brakes work smoothly. Center support bearing is new - it was part of the remanufactured drive shaft. There was a shudder in 2nd gear but that went away when the driveshaft was replaced. I'm confident the drive shaft is not the problem.

Taking it in to the dealer tomorrow and I will tell them to inspect and test the hell out of all rotating components in the rear end. Seems like it should be something they can find.
 
#8 ·
Yes, rear cv joints...you don't have any in the front:grin

And you covered the bases well....rotated tires, new rotors, driveshaft, mounts, you've eliminated most potential areas ahead of the rear axle/suspension. I agree with others, has to be something rotating to be that rhythmic...

Not much else it could be except something in that area...keep us posted please, always good to know the cause of symptoms we may all encounter.
 
#9 ·
The dealer traced the problem to the inner right CV joint.

What are my options? Replace CV joint only? Replace entire half shaft? Replace both shafts?

Any recommendations on where to get the necessary parts would be helpful.

Am also wondering how big a job this is and if I can take it on myself. I have the mechanical skills and a decent set of tools, but I don't have a lift or a hydraulic press or any other special tools.
 
#10 ·
REMOVAL

Loosen rear axle shaft collar nut.
Raise and support vehicle.
Secure assembly from turning. Remove attaching bolts and disconnect rear axle shaft from shaft flange.
Separate rear axle shaft from shaft flange by telescoping rear axle shaft in an axial direction and swiveling assembly upward.
Using a suitable puller, remove rear axle shaft. Push front end of shaft downward and remove from vehicle. Ensure universal joint end cover is not loosening when removing rear axle shaft.
Check synchromesh joints as well as the rubber sleeves and end cover for leaks and damage.
INSTALLATION

For installation of rear axle shafts, reverse removal procedure and proceed as follows:
Install new attaching bolts and collar nut, as required.
Protect flange-on surface between connecting flange and end cover to rear axle shaft against contamination.
Before installing attaching bolts, coat bolt threads with clean oil.
Tighten attaching bolts and collar nut.
Lock collar nut at crush flange to prevent nut from backing off.
 

Attachments

#11 ·
Manual states 3.2 hours with the correct tools and all the goodies a pro garage has.

It's not an impossible job, I would do it slightly different since you have a zillion miles on it. I would disconnect all 5 links, that tiny sway bar, and shock and pull the entire assembly out. Then pop the shaft off the knuckle on the bench. Replace with new bushings, new shock, perhaps a new set of brake pads.....now would be the time. Of course that requires you to do the other side as well...

Since it isn't my money, and it appears you can replace just the joint (I am used to replacing the entire shaft). And it requires some specialized tools.....I'd have the shop do it if I weren't inclined to swap over everything and use the opportunity to replace all the rubbery bits that are old enough to vote.

I haven't found the joint at autohausz or rock auto....
 
#12 ·
I have found the axle assembly at a few sites. Price range from $300 to $400. The dealer tells me only one side worn out, but I am inclined to replace both sides with the mileage that's on this car. Any thoughts?

Jostep - I cannot make out the details on that drawing you posted. Is there some way to zoom in on this? You mention using a "suitable puller" to remove the axle. It this shaft pressed in at one end or is it just a snug fit? Which end is the puller used on? Also the procedure mentions checking the synchros. I assume this has to do with the ASR function. Anyway, I'm not sure what I would be looking for. I'm not sure I would be able to identify a problem with the synchros there even if I saw it. Are these inboard of the drive shaft?
 
#13 ·
Replacing both sides.. Sure, if you plan on keeping the car a long time. The 300-400 price tag is pretty good for the new part, but it isn't exactly cheap. It also isnt a quick and simple repair as it takes special tools and time, I would be inclined to fix the problems as they arise.

The puller will remove the wheel bearing from the shaft and the hub assembly (what the wheel bolts to). The axle shaft will be held in place in the 3rd member by a splined shaft that is a slip fit and should have a seal on the axle. There were a couple special tools listed to do the job, I have not done this on our cars.... quite a few front wheel drive cars and 4x4 suv's but never an independent rear axle. Synchro's...honestly I have no idea on them, or the ASR, or how to check them.

As I said before, I would have this work done..the tools required may very well be as expensive as the total repair. Also you will be taking off the brakes in the rear...great time to replace with new parts (if you do both). I'll repost a non zoomed pic of the procedure... it was mainly to give you an idea of where the part was, and what was involved.
 
#15 ·
Clearly, having it installed at a shop is the right way to go. I'm considering a used axle. Based on the miles I've gotten out of the original, I would think an axle with less than 150K on it would work just fine for as long as I'll be driving this car. I would think a new boots would be smart, though. Will this add much labor to the installation? My car has ASR, so I believe I'll need a 1998-2000 axle. Is this correct?
 
#16 ·
As far as the boots go, if the boots are plastic and you are going used, I might not necessarily have them replaced if they look in good shape. Unless you replace them with genuine mercedes boots, they will probably be rubber which wont last nearly as long. Just a thought. I'd rather have the plastic factory boots.
 
#18 ·
You certainly could, by removing the straps and adding some grease, but if the boots are in good shape and the joints move freely with minimal play, then you shouldnt need to. You would then have to replace the straps with new ones, and to do it right you need to buy replacement straps and a special tool to tighten them on.
 
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