[W126 Coupe] Transmission "Clunk" - But only when selecting Reverse Gear

[Carl Hansen]

Perhaps you could explain why it only makes a "clunk" in reverse and not in 
forward?

I do not believe the drive shaft discriminates between forward and reverse.

Carl H.


----- Original Message ----- 
From: "Dick Spellman" <spell.yy at verizon.net>
To: "Mercedes Coupes Mailing Lists" <mbcoupes at mbcoupes.com>
Sent: Wednesday, January 02, 2008 2:53 PM
Subject: Re: [W126 Coupe] Transmission "Clunk" - But only when selecting 
Reverse Gear


Hi Mike,

See if you can get the SEC up on a lift. Grab a hold of the driveshaft
while it's in Park. Roll the driveshaft from side to side while
observing the front and then the rear flex disks. If you see cracks in
the flex disks or their bolt holes, this is the likely 'clunking'
problem you describe.

If the flex disks need service, I would go ahead and replace the center
support bearing and rear pinion seal while the drive shaft is down for
this service. Any exhaust work should be done at this time as well.

Regards,

Dick

Mike Taylor wrote:

>

> On my 1988 560SEC the auto transmission (original) works great in forward 

> gears, with very smooth change-ups. I’ve had the trans fluid changed at 

> recommended intervals. But on selecting reverse gear there is a big clunk 

> and the car initially jolts backwards, sometimes quite violently, with or 

> without the brake pedal pressed.

>

> I’ve searched the archives and can’t see anything specific to reverse 

> gear. Does anyone know if there is an adjustment or anything to remedy 

> this ?

>

> I’d not want to do anything that may affect the forward gears as they are 

> currently very smooth, but appreciate any help if anyone else has had 

> this.

>

> Cheers,

>

> Mike

>

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