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Pelican Technical Article:

Flex Disc Replacement

Time:

3 hours3 hrs

Tab:

$30

Talent:

***

Tools:

8mm, 16mm, 18mm, 19mm sockets and wrenches, hex bits, T60 Torx socket

Applicable Models:

Mercedes-Benz W210 (1996-03)

Parts Required:

New flex discs

Hot Tip:

Remove the exhaust for better access

Performance Gain:

Smooth running car

Complementary Modification:

Replace transmission mount

Flex discs serve two functions on a car. They help to absorb excessive torsional loads applied to the driveshaft under hard acceleration and deceleration. They also isolate the driveshaft from vibration while still transferring power from the transmission to the differential. As your car ages, heat from the exhaust, oil, grease and other elements cause the flex discs to degrade.

The most common visual warning signs of a failing flex disc are:

  • Cracks that appear in the face and/or webs of the disc.
  • Rubber separation from the six steel bosses.
  • Bunching, knotting or distortion of the flex disc.
  • Reinforcing cord are visible.

Sometimes, you can't see any cracks in the discs. As the driveshaft spins, centrifugal force causes the cracks to expand, usually causing an odd vibration under the center console that comes and goes depending on how fast you are driving. If it becomes serious enough, you may hear a knocking type noise that gets louder the faster you drive. Warning: If the disc fails, it will cause a variety of damage to the body of the car, transmission, driveshaft, and on some chassis, the exhaust... If you start to hear knocking or feel a vibration, climb under the car check the flex discs. If there are no cracks visible, grab the driveshaft and see if you can move the disc. Usually, you'll see the cracks at this point.

There are two flex discs on the Mercedes-Benz W210, one at the end of the transmission and one right in front of the differential. Replacement is not too difficult, but it does require that you take a few things apart to reach both discs.

Begin by raising the car off of the ground and supporting it on jack stands. Never rely on a floor jack to hold the car up. Doing so only invites the possibility for an accident. Use quality jack stands at all four jacking points under the car.

Shown here is a new OEM flex disc with all new mounting hardware for the W210 Mercedes.
Figure 1

Shown here is a new OEM flex disc with all new mounting hardware for the W210 Mercedes. There are two flex discs for the car, front and rear. Keep in mind that there are two sets of new bolts for each flex disc. Three of the bolts are slightly longer than the other three.

Begin by crawling under the rear of the car and locating the rear flex disc at the nose of the differential.
Figure 2

Begin by crawling under the rear of the car and locating the rear flex disc at the nose of the differential. There are six bolts that hold the whole assembly together. Three bolts secure the flex disc (green arrow) to the differential (yellow arrow) while the other three secure the flex disc to the driveshaft (purple arrow).

Make sure that the car is in park and the parking brake is secured.
Figure 3

Make sure that the car is in park and the parking brake is secured. You'll need to lock the driveshaft to keep it from moving as you loosen and remove each 19mm nut and bolt securing the flex disc. Loosen the three bolts you can access from below. Once removed, put the car in neutral, release the parking brake and rotate the driveshaft until you can access the remaining fasteners. Then put the car back in park and re-engage the parking brake. In order to remove the flex disc, we will need to move the driveshaft forward.

Now move towards the center of the car and remove the four 8mm nuts holding the center heat shield to the underside of the car (green arrows).
Figure 4

Now move towards the center of the car and remove the four 8mm nuts holding the center heat shield to the underside of the car (green arrows). Also remove the clips holding the oxygen sensor wiring to the heat shield. (purple arrows). Leave the heat shield in place for the time being.

You'll have to remove the rear part of the exhaust to remove the heat shield that covers the driveshaft.
Figure 5

You'll have to remove the rear part of the exhaust to remove the heat shield that covers the driveshaft. Begin by loosening and removing the four bolts that hold the front part of the exhaust to the rear. Keep in mind that the nuts are 12mm (green arrow) while the bolts are 13mm (purple arrow). If they are heavily rusted, you may want to soak them with good penetrant oil prior to removing. Sometimes you may even need to cut the bolts off if they are too rusted.

Slip the rubber exhaust hanger (green arrow) off the hook welded to the exhaust in front of the left axle (purple arrow).
Figure 6

Slip the rubber exhaust hanger (green arrow) off the hook welded to the exhaust in front of the left axle (purple arrow).

Have a helper support the rear exhaust assembly where it meets the catalytic converters.
Figure 7

Have a helper support the rear exhaust assembly where it meets the catalytic converters. Now remove the bolt that holds the rear exhaust hanger to the rear of the car (green arrow). Once this bolt is removed, the exhaust can be lowered out from under the car. Don't forget to grab the exhaust sealing ring that goes in between the front and rear pipes on the left side pipe.

With the exhaust removed, you can now pull the heat shield out from above the catalytic converters in the direction of the green arrow.
Figure 8

With the exhaust removed, you can now pull the heat shield out from above the catalytic converters in the direction of the green arrow. Be sure to unclip the oxygen sensor wiring from the shield.

Once the heat shield is removed, you'll see the driveshaft center bearing directly above (green arrow).
Figure 9

Once the heat shield is removed, you'll see the driveshaft center bearing directly above (green arrow). The driveshaft (purple arrow) is designed with a splined yoke that allows front and back movement between the two sections of the driveshaft. The center bearing secures the driveshaft in place, preventing the driveshaft from moving. You'll need to remove the two 13mm bolts (yellow arrows) that hold the bearing assembly in place to push the rear driveshaft forward. On some early cars there is a large nut that acts as a collar stop. If your car has one of these, use a large wrench to loosen the nut.

On the left side bolt, you'll find the oxygen sensor is in the way.
Figure 10

On the left side bolt, you'll find the oxygen sensor is in the way. A set of universal joint sockets comes in real handy here.

Pull the rear section of the driveshaft forward.
Figure 11

Pull the rear section of the driveshaft forward. As you do, you'll see that the differential has a centering rod (green arrow) that fits into a rubber bearing in the end of the driveshaft (purple arrow). Keep pushing until you separate the rod from the bushing and the drive shaft will fall down and away from the differential. At this point, you can remove the flex disc. You may find that the flex disc needs to be pried off the driveshaft flange depending on how rusted it may be.

Take the new flex disc and mount it with three of the small protruding metal sleeves facing into the flange on the differential.
Figure 12

Take the new flex disc and mount it with three of the small protruding metal sleeves facing into the flange on the differential. When mounted correctly, it will also leave small sleeves facing the driveshaft. As you tighten the bolts, it will push the sleeves inside both flanges. The new disc will include all new mounting bolts. The smaller, internal 10mm hex head bolts secure the flex disc to the differential as shown here. The new nuts are 18mm.

Now let's move onto the front flex disc.
Figure 14

Now let's move onto the front flex disc. This one is a bit more complicated to remove and requires the removal of the transmission mount. You'll want to use a floor jack to lift and support the transmission. Do not place the jack on the transmission pan. It will bend and possibly damage the transmission if you do so. The bell housing is strong enough as shown here. Jack up the transmission until you take the weight off the mount.

At the rear end of the transmission, you'll see the mount bracket (green arrow) that holds the transmission mount (purple arrow) which bolts to the transmission.
Figure 15

At the rear end of the transmission, you'll see the mount bracket (green arrow) that holds the transmission mount (purple arrow) which bolts to the transmission.

Unbolt the two center 13mm bolts holding the mount to the bracket (green arrows).
Figure 16

Unbolt the two center 13mm bolts holding the mount to the bracket (green arrows). Next unbolt the four 16mm bolts that hold the bracket to the underside of the car (purple arrows).

Now remove the two 16mm bolts that hold the mount to the end of the transmission (green arrows) and remove the mount.
Figure 17

Now remove the two 16mm bolts that hold the mount to the end of the transmission (green arrows) and remove the mount.

Once the transmission mount is removed, you'll see the front flex disc directly above (green arrow).
Figure 18

Once the transmission mount is removed, you'll see the front flex disc directly above (green arrow). Like with the rear disc, lock the car in gear and use two 19mm wrenches to loosen and remove the bolts.

You'll find that the nuts that hold the flex disc to the transmission flange are a tight fit, but you can just fit the end of a ratcheting wrench on there.
Figure 19

You'll find that the nuts that hold the flex disc to the transmission flange are a tight fit, but you can just fit the end of a ratcheting wrench on there. This makes the work just a bit faster.

At this point, you'll want to remove the cross brace that runs behind the front flex disc and above the catalytic converters.
Figure 20

At this point, you'll want to remove the cross brace that runs behind the front flex disc and above the catalytic converters. This gives you a bit more room to move the driveshaft enough to remove the disc. There are two 13mm bolts that hold this in place. This picture shows the 13mm bolt on the right side of the car (green arrow).

And here is the 13mm bolt on the left side of the car.
Figure 21

And here is the 13mm bolt on the left side of the car.

Now manipulate the front section of the drive shaft until you can remove the old flex disc.
Figure 22

Now manipulate the front section of the drive shaft until you can remove the old flex disc. It may take some time to find the optimum angle in which to move the shaft in order to remove the flex disc.

With the discs removed, you can clearly see the cracks that had formed (green arrows).
Figure 23

With the discs removed, you can clearly see the cracks that had formed (green arrows). In this picture, you can see how centrifugal force affects the disc. The cracks start from the inside and work outwards, eventually cracking through and destroying the disc.

Now place the new disc inbetween the transmission and the driveshaft.
Figure 24

Now place the new disc in between the transmission and the driveshaft. Torque the new nuts and bolts to 50ft-lbs. Now just reattach the transmission mount, brackets and center bearing, the heat shield and exhaust and you're finished.

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Comments and Suggestions:
Q Comments: Can a bad front flex disc stop car from going into drive 2000 e320 4matic 168000 mile
October 31, 2016
  Followup from the Pelican Staff: Not likely. Unless it is broken. - Nick at Pelican Parts  
sanele Comments: I want to which gear box that is same as the gear box of mercedes alegance v6 model 1999 automatic
October 22, 2016
  Followup from the Pelican Staff: I’m not the best with part numbers.


Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need. - Nick at Pelican Parts
 
Carlos0422rg Comments: What's the degree of difficulty for replacing the driveshaft center mount and bearing on a 126?
July 25, 2016
  Followup from the Pelican Staff: depends on your experience. 4 or 5, due to the amount of disassembly. - Nick at Pelican Parts  
Leo L Comments: Hello, What an awesome site. I just purchased a Mercedes-Benz C230 Kompressor. Found a bad front flex disc. This site was Kustom made. Thanks.
May 5, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
roliver Comments: Hi Guys

I suddenly developed a low frequency rumble and vibration from under the centre console, on my 1997 c230.I have replaced the transmission end flex disc and mount. It doesn't seem to made much of an improvement - any ideas on where else I could try. Many thanks.
April 8, 2016
  Followup from the Pelican Staff: I would check the center support bearing. - Nick at Pelican Parts  
goldwing70 Comments: I have 1999 E320 4matic wagon. Front and rear flex discs are on both the front and rear driveshafts? Are the discs all different, ie 4 different part numbers?
April 5, 2016
  Followup from the Pelican Staff: They are likely different.

I’m not the best with part numbers.

Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Dennis Comments: Are there 2 disks on the 2001 E430. I'm asking because some manufactures only sell the front for this year and model.
March 29, 2016
  Followup from the Pelican Staff: I think there are two.

Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need. - Nick at Pelican Parts
 
goldwing70 Comments: Do you have an article on replacing the front drive shaft on W210?
March 25, 2016
  Followup from the Pelican Staff: All W210 articles are here:

http://www.pelicanparts.com/techarticles/MBZ_Tech_Index-W210.htm

We don't currently have that tech article. If we get a chance to perform the procedure, we will be sure to document it.

I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 
Rudolf Comments: @ Moe, I had a same problem with yours. My car is Merc W210 E320 1996. I found fuel leaking from the fuel hose between the fuel filter and fuel pump. I replaced the fuel hoses and fuel filter and works great run now.
March 4, 2016
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
Hal Comments: Hi..
I have a 97 e420 with 83K miles. Transmission is slow to engage when cold. Not often occasional hard shift under acceleration.
Will a service help or do I have bigger trouble?? Thanks in advance you site and advice seem really good
December 7, 2015
  Followup from the Pelican Staff: Could be worn parts, like clutches, seals, etc. First check the transmission fluid level to be sure it is correct. Then check the transmission ECM for fault codes. If the system is not working properly, a fault code will be set. This will be your best bet when diagnosing.
- Nick at Pelican Parts
 
burn side Comments: I have a 1999 Mercedes e320 and I love to do my own repair work and I love too read book about cars
November 29, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Dennis Comments: Trying to locate correct rear flex disc for 1951 Mercedes Benz 220. The one I received from MB Classics in CA did not fit. The part number they had was 186-411-01-15 replaced by
189-411-01-15.Part was too big. Any suggestions?
August 28, 2015
  Followup from the Pelican Staff: I am sure we can figure it out. Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Joel Comments: When I install a rear flex disc it last about 2 weeks and it self distrust. What im I doing wrong 02 cl500
May 12, 2015
  Followup from the Pelican Staff: What vehicle?

The driveshaft angle could be wrong or the flex-disc is loaded improperly or installed backward. - Nick at Pelican Parts
 
dandaman Comments: Ive got a 2004 e500 and slow speed turning it feels as if the front tires drag and now has a grinding /clunk sound coming from under neath. Any ideas as of what to ck
I cked cv shafts,ball joints, tierods, all seem ok. Thanks
May 11, 2015
  Followup from the Pelican Staff: Check if the brakes or the wheel bearings are binding. - Nick at Pelican Parts  
Rich Comments: Thank you so very much...
I'd say that you can add R129 SL600 on the list of applicable models. It's the same deal of removing the back end of the exhaust, removing the heat-shield to expose the center bearing to loosen it, supporting the gearbox to remove the support bracket, etc,...
I installed Febi replacements, they come with all new nuts/washers/bolts...
April 3, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Moe Comments: Hi i have a 1996 S320 mercedes and when I accelerate in my car it takes off fine but then it starts to bogged down like I'm losing power but then it picks up again and then it does the same thing repeatedly can someone plz. Help
February 7, 2015
  Followup from the Pelican Staff: Is the check engine light on? Sounds like an engine misfire. I would check spark, fuel and compression on all cylinders.
- Nick at Pelican Parts
 
Zeikgeiz Comments: This applied well to my 2004 w203. Thank you.
January 27, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Rob Comments: My 2008 S550 4matic, 104k mile car has developed a vibration when accelerating. I press the pedal down slightly and a vibration occurs and lasts between 1/4 - 2 seconds, regardless of speed. Not every time, but often. No trans codes and engine mounts are good. Any thoughts are appreciated. Thanks.
January 16, 2015
  Followup from the Pelican Staff: Sounds like you may have a faulty drive axle. Check the front drive axles for binding. - Nick at Pelican Parts  
twinturboE320 Comments: what is the part number of the mount bracket in figure 15 my 1996 e320 due to this issue being untreated allowed the bracket to snap I had it welded together but it unfortunately didn't work as well as I hoped and this one part is holding me back from completion.
December 27, 2014
  Followup from the Pelican Staff: I am not the best with part numbers. Give our parts specialists a call at 1-888-280-7799 and they can help figure out which part or repair kit you need.
- Nick at Pelican Parts
 
Treetops Comments: Is it safe to assume this applies to 99 e300 too?
November 10, 2014
  Followup from the Pelican Staff: The tech article applies to:
W210 E320 (1996-02)
W210 E300 (1996-97)
W210 E420 (1997)
W210 E430 (1998-99)
W210 E55 (1998-02) - Nick at Pelican Parts
 
Dan h Comments: Thanks for the info had to change a pair in my auto class it really helped my teach didnt knpw what to do.
October 27, 2014
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
rab Comments: can anyone tell me a how to remove the last part of the drive shaft that is in the trans and if i can do it with out having to buy a pin wrench socket
September 15, 2014
  Followup from the Pelican Staff: You should be able to counterhold the flange while loosening the center nut. Then remove the flange from the transmission. - Nick at Pelican Parts  
Fred Comments: Excellent article I take that these do apply to my 2002 e430?
September 6, 2014
  Followup from the Pelican Staff: The article applies to:

W210 E320 (1996-02)
W210 E300 (1996-97)
W210 E420 (1997)
W210 E430 (1998-99)
W210 E55 (1998-02) - Nick at Pelican Parts
 
Pike pole Comments: Replaced the flex joint couple on my wife's 2001 E320 wagon in May 2014 with Dorrman parts. She has put about 1000 miles since repair. The new one are distorted and damaged. The Parts store is replacing them,but i'am not happy doing the job again, have you ran into this happen before? We have owned the car since new 110,000 miles on car
August 17, 2014
  Followup from the Pelican Staff: Not personally. However, I would check that the part was installed correctly. - Nick at Pelican Parts  
Boss Hog Comments: I want to know if you guys have a DIY for replacing the motor mounts, transmission mount, flex disc for the 2000 E430 Sport? I guess when I accelerate sometime I'm getting a sort of rumbling noise from underneath. I think it might be motor mounts or one of the above. Also, I was thinking it could be the control arm bushings too. Anyhow, do you have the parts to fit my car or should I be looking for special parts number on these parts before ordering? I need the tool for removing the wires on this same vehicle and was wondering if the one you advertise for the E320 will work on the E430.
August 12, 2014
  Followup from the Pelican Staff: We don't currently have an article for your vehicle. I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-77 - Nick at Pelican Parts
 
Big d Comments: I was driving my car and it shut down on me the engine was still run-in.the gear on my car would not Change. I had to turn the car off then put it back on the car stated back on got two block the car shut off again on me took it to the shop and thy said it was my transmission thy said the disc were slipping. Thy said 6,200 to fix it my car.
July 16, 2014
  Followup from the Pelican Staff: If the fluid is full, your transmission may be faulty. I would go with the shops suggestion. If you want, get a second opinion. - Nick at Pelican Parts  
jw Comments: I have a '99 w210. When we accelerate, there is a clicking, slapping noise. but only when we are moving. any ideas? I just replaced the rear flex disc and and the sound is not as loud. what could this be?
May 21, 2014
  Followup from the Pelican Staff: COuld be a drive shaft coming in contact with something or a bad joint. I would inspect the driveline for rubbing, marks or binding. - Nick at Pelican Parts  
Kevin Comments: It looks like you guys also replaced the bolts on the drive shaft.
What other bolts would you recommend replacing when doing this fix?
Can you give me specifics as to what types of bolts they are?
March 5, 2014
  Followup from the Pelican Staff: I would replace any self-locking or torque to yield bolts. Give our parts specialists a call at 1-888-280-7799 and they can help figure out which fasteners or bolt kit you need.
- Nick at Pelican Parts
 
Robert Comments: Thank you! By using your simple to understand directions I was able to do the work myself in no time, and saved a couple of hundred. Will be looking for this site every time I have to do a repair on my car. Again THANK YOU.
January 17, 2014
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help. - Nick at Pelican Parts  
Amalowze Comments: Hi,

I intend to order parts from you and replace the trans and engine mounts and flex discs on 2008 S550, non 4matic. Are the any differences in the procedure from the one outlined above? And please if you could give me those for the mounts too, will be very appreciated. Thank you.
January 8, 2014
  Followup from the Pelican Staff: This article applies to:
W210 E320 (1996-02)
W210 E300 (1996-97)
W210 E420 (1997)
W210 E430 (1998-99)
W210 E55 (1998-0

We don't currently have a tech article for your model.- Nick at Pelican Parts
 
Eddy A Comments: You guys saved my life...
Excellent job!!!
I could not thank you enough for this documentation.

Warmest regards,

Eddy A
October 18, 2013
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help. - Nick at Pelican Parts  

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