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  #1  
Old 10-22-2007, 10:27 PM
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Clicking sound in reverse?

On my '95 E320, when I back out of the driveway, there is this clicking in reverse. Sound seems to come from the automatic transmission. It's almost like the parking pawl is not quite disengaging and clicking on every notch. As soon as I shift into forward the sound disappears. Any ideas?
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  #2  
Old 10-22-2007, 11:25 PM
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Very common problem. Try a search - lots of threads on the subject.
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Old 10-24-2007, 12:35 AM
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Did a search, found nothing comparable, at least no one giving a reason why. To add to my observation, based on questions found during my search: The clicking sound is only in reverse when driving in reverse in the morning when the car is cold. (moving it out from the carport to the street) After things have warmed up, driving in reverse makes no sound. There is also no sound when just putting the gearshift lever in reverse without driving. Thank you!
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Old 10-24-2007, 12:45 AM
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Clicking in Reverse

Well, i have the same transmission as you do in my 1996 E320- and from what i can tell you, I was experiencing the EXACT same problem for a month until one day, WHAM! No reverse- $4,700 later, and a BRAND new transmission, the noise is no longer there. I don't want to scare you, but it could be the trans. You can go for a complete rebuild for less than i spent, but im just anal like that. My tranny had 115,000 on the clock when she went-
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  #5  
Old 10-24-2007, 12:50 AM
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Quote:
Originally Posted by TheEngineer View Post
On my '95 E320, when I back out of the driveway, there is this clicking in reverse. Sound seems to come from the automatic transmission. It's almost like the parking pawl is not quite disengaging and clicking on every notch. As soon as I shift into forward the sound disappears. Any ideas?
You sussed it. The pawl is just touching the ratchet. A shift linkage inspection and repair should fix it.
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  #6  
Old 10-24-2007, 08:59 AM
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Most likely the reverse clutches are worn to the point that the reverse clutch piston is hitting the 3rd gear clutch drum.. common problem.

IF you have it fixed now you won't need a new or rebuilt trans.
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  #7  
Old 10-24-2007, 11:13 AM
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Don't forget, the flex disk can be worn at the front portion of the driveshaft.
Clicking in reverse is a good indicator of this.

Have the car put up on a lift and have the flex disk inspected.
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Old 10-25-2007, 01:24 AM
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Today I put the car up and inspected the flex discs: They look like new. I also inspected the linkage from the shift lever to the transmission as Chas H suggested: It was a little off, I set it to the book. The clicking sound is still there when the transmission is cold. After driving a little, like one mile, and going back into my driveway, or any sloped road, the sound has disappeared. I'm afraid M.B.Doc is right!
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  #9  
Old 11-04-2007, 08:55 PM
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Quote:
Originally Posted by M.B.DOC View Post
Most likely the reverse clutches are worn to the point that the reverse clutch piston is hitting the 3rd gear clutch drum.. common problem.

IF you have it fixed now you won't need a new or rebuilt trans.
M.B.Doc: I'm looking at the sectional view of the transmission. It appears that the "Lamellar brake B3" has the friction plates between the transmission case and the Ravigneaux planet gearset. Therefore, when driving in any forward gear, the friction plates rub against each other at considerable speed. This results in wear, even though the reverse piston applies no force against the brake B3. By comparison, on my '69 280SL, (K4A025) there are brake bands that are relaxed in 4th gear and there is no wear. This is also true for the later transmission W4B025 used until approx. 1979. I'm asking why did MB change from a successful design?

Last edited by TheEngineer; 11-06-2007 at 11:00 AM.
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  #10  
Old 11-06-2007, 11:11 AM
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Opinions please?
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  #11  
Old 11-06-2007, 04:16 PM
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This is one from a different tangent...have you engaged your emergency brake recently? Or at least had the clicking happen thereafter?

I had to get my e-brake adjusted when I discovered a rhythimic clicking as you experienced. In my case, it happened in forward and reverse.

Also in my case, I have aftermarket rims and the lug bolts that came with them were a bit long and interfered with something in the hub.
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  #12  
Old 11-06-2007, 05:54 PM
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Engineer, I had absolutely, exactly the same symtoms on my '91 SE last summer. It was indeed the reverse (b3) clutch plates worn out. When they got thin enough, they allowed the piston to move too far in, and it began striking the K1 housing fingers. Click, click, sounded like an old speedometer cable clicking when moving in Reverse. After the tranny heated up, it expanded just enough to stop the clicking.
I bet it's kinda slow to engage reverse when shifting from Park, too?
Upon opening the tranny, I found little pieces of B3 clutch plates in the pan and filter, and I found the little rub marks on the K1 basket fingers.
This is metal-metal contact, so I would recommend you not let it go.
The b3 plates were shot, and just starting to delaminate. On the other hand, the K1 plates looked absolutely new.
I went in just as far as I dared, popped in new b3 plates, and buttoned it up. So far so good.
Do a search under some of my posts last spring (S-class Guru) for more comments.

DG
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  #13  
Old 11-06-2007, 06:15 PM
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The 722.1 trans was a "good" trans BUT very costly to make.. Shifting qualities were POOR at best!

The 722.3/4/5 trans used many cast parts & was much easier(less $$) to make...

Bottom line...more profitable transmission that shifted better!

AS S-class guru & I posted....don't wait too long or you will need a complete trans.
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  #14  
Old 11-07-2007, 10:22 AM
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Thanks Guys! The car is up in the air now and I'm looking at it. On this model ('95 E320) there is a heat shield behind the engine that blocks access to the two uppermost bolts that hold the transmission to the block. Is there a trick to get to those two bolts to take them out without removing the heat shield? The right hand bolt also holds the filler tube. The book only saysetach and remove from engine. All other fasteners are accessible.
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  #15  
Old 11-07-2007, 09:49 PM
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Ha, can't help you there; my old S-Class had enough room to crawl in there and reach all the bolts with ease. Good luck with the tranny.

DG
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