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Mercedes Gear Shift Troubles

Symptoms of an Abnormal Chassis Flex Disc in a Mercedes

Posted on November 2, 2019 by smikyautomowp

Mercedes are well known for high-performance engines and ingenious features. However, without the proper care, even the most well-made parts can begin to become faulty. One such part that can be negatively impacted by time, use, and poor maintenance is the chassis flex disc. In this article, we will take a closer look at this part, learn about what is does, and discuss the signs and symptoms of abnormality.

What is a flex disc and what does it do?

The flex disc, which can also be called a “guibo,” is a coupling device that is made of reinforced rubber bolted to either side of the flex disc and input and output shaft flanges. These connect to the transmission shaft, the drive shaft, and the differential via their connection to the flex disc.

Mercedes vehicles have both a front and rear flex discs. The front flex disc is responsible for connecting the tranny to the driveshaft and is difficult to access, requiring investigation under your vehicle to locate. The rear disc is responsible for connecting the driveshaft to the differential and is much easier to find.

The flex discs have 2 distinct purposes,

1. To absorb the extra torque inflicted on the shafts when accelerating or decelerating.
2. To isolate the driveshaft from the vibrations caused by the tranny.

Flex discs have a long life span and will often last your vehicle’s life span. With peak maintenance, they should only start degrading after around 200,000 miles.

Symptoms of an Abnormal Flex Disc

You can usually inspect your flex discs for visual signs of abnormalities. While some issues are invisible to the naked eye, more noticeable problems can be spotted such as:

• Cracks to the face or webbing of the flex disc
• Rubber separating from the bosses
• The flex discs overall appearance seems distorted

When a Flex Disc Is Damaged Beyond Repair You’ll notice…

• The drive shaft will move excessively, and there will be abnormal vibrations in the center floor.
• You’ll feel a rougher gear shift when the car is put into reverse or shifted to drive.
• They’ll be knocking noises coming from under your Mercedes which will become louder when accelerating.

Symptoms of Flex Disc Damage or Wear

If you notice the following symptoms you should make sure to deal with them as soon as possible. Sorting vehicle problems early can help reduce the amount of damage caused as well as ensure repairs are cheap and more straight forward. Therefore, if you notice any of the following symptoms you should seek the advice of an expert mechanic.

A Vibration-Heavy Uncomfortable Journey

Excessive vibrations and overall ride discomfort are a clear sign that one of your flex discs is damaged. This issue is most commonly caused by an insecure drive shaft.

Trouble Shifting Gears

Struggling to change from park or reverse to drive can be a sign of an abnormal flex disc. This can also signal transmission issues, so it’s worth checking over both parts.

Causes of Flex Disc Abnormalities

There are 3 main reasons as to why one or both of your Mercedes’ flex discs have developed faults which are:

1. Age of Car: The older a car gets, and the more it passes the 200,000 mile lifespan, the most likely your flex discs are to degrade.

2. Heat: Heat can really degrade your flex discs, so it’s best to avoid sharp accelerations or engine overheating.

3. Drivetrain Alignment: A misaligned drive train can cause the flex disc to excessively stretch, which results in expedited wear.

Mercedes Chassis Flex Disc Repair

Replacing the Flex Disc

The flex disc is a relatively affordable component, costing around $100. The real cost comes in changing out the part as the front flex disc is particularly difficult to access. For quality repairs, you should expect to pay between $300-500 dollars in total. Of course, you can try to save money and replace it yourself, but unless you’ve had some experience with vehicle repair in the past, you’re likely to do more harm than good while trying to repair this part.

St. Matthews Imports is your quality repair shop for all Mercedes needs. If you live in or near Louisville, KY, then look no further. We have multiple repair shops, including our Hubbards Lane location, and will provide you with trusted automotive service, maintenance needs, and reliable repairs. Call us today to schedule an appointment or stop by for a consultation.

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