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Discussion Starter · #1 ·
Hi all
We have had our 2015 CLA 200 Auto for around 6 months now , I have noticed an annoying whine from the transmission when on the overrun and coasting which is worse between 35-40 mph as the car is used around town a lot this whine is very noticeable and unlike mercedes , the car was put into the selling dealer for investigation but the response was "there is nothing wrong they are all like that" so if that is true how many more of us are tolerating noisy transmissions?
 

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Might be a bad bearing??
Consider sticking a small microphone under the bonnet ... or at least try an in cabin recording??
 

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Discussion Starter · #3 ·
I'm taking the car back to road test with the dealer technical specialist next week so I will record the noise as a back up but it does it all the time so we'll see what they say, I've worked for BMW , MB, and Volvocars in the past and driven lots of those models and never heard such a thing on a car with only 8000 miles up so for the dealer to say, no to its fine makes me think they are not interested in even looking at the problem, of course the second they agree it is noisey they then have to sort it.
 

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I'm taking the car back to road test with the dealer technical specialist next week so I will record the noise as a back up but it does it all the time so we'll see what they say, I've worked for BMW , MB, and Volvocars in the past and driven lots of those models and never heard such a thing on a car with only 8000 miles up so for the dealer to say, no to its fine makes me think they are not interested in even looking at the problem, of course the second they agree it is noisey they then have to sort it.
A noisy bearing may bust before warranty expires ... though collatorals will be bad
 

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Discussion Starter · #5 ·
UPDATE:-
This noise referred to by Mercedes as (Howling noise between 60 km/h and 80 km/h in acceleration and deceleration mode) is a known issue going well over a year
with some DCT7G transmissions , - it is simply cured by the installation of a resonance damper on the short drive shaft , have now tested the car and
the howling noise has gone.
A quick fix indeed ,very pleased the car did not req to have the transmission taken out , it is now enjoyable to drive :)
 

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Glad to hear of the well documented fix ...
As to the "why" a resonance suggests some mechanical design parameter (eg rotational harmonic) violation due to material and density variances ... though "where" they installed that damper may be indicative ... towards the engine or towards the wheel or smack in the middle?
 

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Discussion Starter · #8 ·
Ok, This is what I know from a MB tech info document,

The gearing of the spur gear excites the side shaft at its natural frequency > a howling noise can be heard
The damper is fitted close to the cv joint , effects a few variants diesel or petrol.

hope this info helps anyone else dispairing at the thought of living with a noisey transmission , it might just be a ten minute fix
 

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Ok, This is what I know from a MB tech info document,

The gearing of the spur gear excites the side shaft at its natural frequency > a howling noise can be heard
The damper is fitted close to the cv joint , effects a few variants diesel or petrol.

hope this info helps anyone else dispairing at the thought of living with a noisey transmission , it might just be a ten minute fix
Thats good info to know.
Some time when you feel inquisitive perhaps you can upload a picture of this said fix?
We are a curious sort ... ?
And do you have the number for the service bulletin for this fix? It might be printed out on your repair order.
 

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Honda's use them for many years
 

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Honda's use them for many years
None of my 3 Acura (well Honda Japan) drive lines had any external harmonic balancers ... instead the x-sections had minor mods (done and painted over at the factory) so those were dynamically balanced parts. Not sure if the American Honda lines did that though ...
 

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It's a round rubber bushing going around the inner part of the axle.
My old Honda had one.
Auto part
 

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It's a round rubber bushing going around the inner part of the axle.
My old Honda had one.
Yup ... I have seen those external harmonics modifiers ... and luckily in my cases they balanced
the metal shafts themselves instead ... those were the good o' days ... :cool:
 
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