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CJ 02-07-2001 10:50 PM

I have a slight clunk when I put my car in D or R from P. I did a search and found lots of information leading me to think that my flex disk has finally called it a night at 171,000+ miles. What I am trying to determine is when people say the drive shaft has excessive play, do you mean that the shaft can be moved by hand front-to-back OR wiggled side-to-side? How do you pinpoint a front disk VS a rear disk. I am going to put my car on the lift in the morning and I want to make sure that I am diagnosing the problem properly.
From what I have gathered, replacing the flex disk is not that hard, it just takes time and patience.
Has anyone done a flex disk lately?

300EVIL 02-07-2001 11:22 PM

it would be side-to-side movement you are looking for. go ahead and give the driveshaft a good jerk. im shure you will find your problem. the flex disc in the front, after the trans is usually the one that goes bad first. there is also a center support bering that should also be checked.
when i reciently replaced my flex disc the mechanics said my bering didn't need to be replaced. i think they are liars. i don't do buisness with them anymore.
anyway, im not a tech but thats what i see from my experiance. hope this helps!
good luck,

CJ 02-07-2001 11:41 PM

Thanks for the info. How do you diadnose that the center bearing is going south? If I am going to be there doing the front flex disk, I do not want to pull everything else apart two weeks later.
Thanks in advance!

300EVIL 02-08-2001 12:28 AM

to check the center bering just see if there is any play in the inner metal sleve. its a sealed bering so thier so thier shouldn't be any gritty grind feeling when you turn it. also, thier is a rubber vibration grommet the goes around the bering, replace it if its cracked, brittle ect.
i think the reason my previous techs didn't want to replace it is because they had to take the drive shaft out. lazy

michael rybikowsky 02-08-2001 12:40 PM

Flex disk going bad??
Most of the time when you look at the flex disc you can see if the are failing.As far as the center bearing.They dont cost much so if you are going in there you might as well change it.Simple job.The only problem I had was the slip sleave.I did not have a wrench that would get to it so after i bounced the car up and down a few times I tightened it with a punch good luck.Michael

Johnson Chan 02-08-2001 02:44 PM

Hello CJ,

Lets say you are parked on a hill, if you use the parking brake first then shift it in park. What happens when you shift back out of it. Do you hear a clunk.

I use the parking brake all the time cause it saves on wear. If I dont use the parking brake on a hill and just use the park, when you put it in R or D, you will hear a loud clunk.

Flex disk is easy to change, just get some ramps or some way of getting under the car. They are not expensive either. It might be going out on you. Sometimes my car has loud clunking when driving fast and hard, even though i have a new tranny and flex disks, etc. so it might be normal.

Sorry if i dont make a whole lot of sense, i have been without sleep for a couple days. also your cd's are in the mail.

Crowe 02-08-2001 04:34 PM

Describe the symptoms
I have heard a lot about problems with flex disk going bad. In fact, a MBZ tech talking at a MBCA Peachtree Section meeting recently said that he sees far more flex disk and oil leak problems in the South than his collegues in other parts of the US. He thought the reason was the variable weather in the South.... this time of year it may be in the 30s one day and then a couple of days later in the 70s. Not to mention the high humidity in the Summer. Well no matter, it is still "God's Country" down in Dixie.

Describe again the symptoms of a problem with the flex disk. My 88' 300E will jerk when you first shift from Park into either Drive or Reverse. In fact, I have learned to always have my foot on the brake when shifting out of Park. It feels like some slack is being taken up before the car is ready to move. Also is there a visual or other method to confirm that the flex disk needs to be replaced?

CJ 02-08-2001 07:50 PM


brookspw 04-18-2002 11:26 AM

Maybe you guys are right, but it sure sounds more like a differential with too much play in it (worn gears, etc.). Mine has it, too. Look at the mileage on these posts and you'll see a common theme.


Matt565 05-18-2002 11:59 PM

i have the same clunking sound in my 88 260E. I put it up on the ramps today and am certain that it is the front flex disc. I ordered one today, but I haven't the slightest clue how to install it. If you are trying to diagnose it, put the car on a lift or ramps and move the drive shaft back and forth with your hand. If the shaft moves, but the disc doesn't, then that is the problem. Anyone have any ideas on how to install it?


Mick J 05-19-2002 03:37 AM

I had one replaced on my last car, an 89 230TE, at 110,000 miles. The guy said they usually go anytime after 70k depending on how the car has been driven.

Ashman 05-20-2002 03:33 AM

I had both of mine done within the last couple of weeks.

The old ones were ok, but showed some light cracking, I figured why not change them as long as the car was up on the rack and at my mechanic.


mnestor 05-28-2002 08:31 PM

flex disk r&r
yesterday I limped home, to find the flex disk almost in pieces, minus one bolt and worn oblong slot in the drive shaft. Haven't removed the disk but did undo it. Seems the shaft won't move back enought to have the disk just drop out..(some guide) So, undid the trans mount, and need to unscrew the shaft as it goes into the mid-shaft bearing. Found a new disk and bolts for 50, and a used shaft for 25. Now comes the fun.

engatwork 05-28-2002 08:44 PM

Be careful with that used driveshaft section. These units are balanced as a set. If you replace one section you will want to have the complete assembly balanced as a "unit".

meldwyer 05-26-2006 12:31 PM

w140 flex disc replacment
hello ,, evry one, i have a 1994 s420 with 225,000 mi,, i would like to replacemy front flex disc,,, is this one of does repair that one can do a diy,,,,, it look kind of simple,,, is ther any trick,s that would Help,, me to remove the disc,, and install,, new One,,, the car thuck,s when slowing down from high speed, comeing to a full Stop,, i ,like to take care of this,,, rigth away,, with replaceing this disc Help Any,,, thank,s mel dwyer 1994 S/420

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