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?

Very common problem. Try a search - lots of threads on the subject.

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!

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- :confused:

You sussed it. The pawl is just touching the ratchet. A shift linkage inspection and repair should fix it.

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.

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.

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!

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?

Opinions please?:rolleyes:

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.

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

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.

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 says:Detach and remove from engine. All other fasteners are accessible.

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

Should have bt an S-Class! Schucks! - they don't make a wagon. So, anyone out there that has had a wrench on those two top bolts? On my 280SL there is a hole in the transmission tunnel to stick a wrench thru.

Looks like I can join the clicking in reverse transmission club.
I guess it was just a matter of time before the transmission was going to give me trouble. Seems to be par for the course on the later 124's.
I suppose I should count my blessings...another member didn't have his transmission make it to see 166k miles. I think his didn't even make it to 100k miles. Nice job MB bean counters! (not).

Hi Larry: It appears that every 722.3 transmission has this problem. I educated myself a little on the subject. The reverse laminar brake is anchored to the case and to the rotating core. While it is only energized during reverse, the discs make some contact during regular driving and that wears them thin. When the stack becomes thin, the piston that compresses the stack in reverse, begins to bottom out. The piston has radial ridges. What you hear is each ridge touching. At first, it happens only when the transmission is cold. If you replace the laminar plates at that time, no damage has been done. If you wait, you get metal debris that migrate and you have to completely overhaul the transmission. The nice thing about it is, that you get a warning. Are you going to do the job yourself?
Please note: If there is anyone who finds that my understanding is wrong, please correct me !

Thanks for the insight!
I don't think I will do anything myself on that transmission. I have a mystery leak as well, and this is just the icing on the cake that I needed to push me into looking for a transmission. I don't know of any shops around my area that I would trust, so I will likely be buying one from a rebuilding shop out of state.

If you are planning to get a rebuild unit there would be no reason to do anything now. You can go for years with a clicking noise in reverse with no performance issues whatsoever, forward or reverse - unless you just don't like clicking for some reason. These are very stout transmissions - way better than the 722.6s and later.

It took me years to come to this conclusion: When you have a Benz you had better be doing all the work yourself. Whenever I get my hands on a used one - and I can't afford new - I find that wherever mechanics have been, there are broken or missing parts or screws overtightened or not tightened or cross threaded. It never fails. And I have watched them: They will not clean an engine before they work on it and not repair/replace things that now are accessible because they have taken something off. (like the radiator). I bought a car that had "unrepairable" oil leaks. The previous owner had it at two repair places and it still leaked a lot. He sold it, to end his problems. I found - after spending a lot of time - a loose screw. It looked ok, but wasn't. I really hate to remove that transmission, I really do. But I'm convinced that the shop would screw up. Furthermore, I'm convinced that many other guys have had the same experience.:mad:

Yes - an old thread - but I wanted to tack on my experience thus far to an existing one that had a post that might be relevant to my situation. See above - post #11 in this thread.

Yesterday I was returning from a 40 mile drive. Backed into the driveway as I always do. Transmission obviously in REVERSE. I'm hearing a clicking sound as I roll down my driveway - slightly downward incline. Sound reminiscent of a playing card hitting bicycle spokes. For the younger crowd who may not be familiar with this - kids used to hook up a playing card to a spot near the wheel spokes and let the spokes run across the card. 50s era entertainment.

So I drove up the driveway and backed down several times - each time hearing this clicking sound. First time I've experienced this. Internet search brings up all sorts of bad news.

I took the car out again this afternoon for another drive and on return rolled down the driveway with foot off the gas this time. I usually feather the brake pedal a bit. No clicking sound. Repeat - up and down the driveway many times - foot off gas - no clicking sound.

I then went thru a series of backing up feathering the brake pedal. Each time I'm hearing the clicking sound when feathering the brake. Let the car roll down w/o braking and no clicking sound.

In the days ahead, I'll pull the transmission pan and check for chunks of things that don't belong. As with many of these older MB sedans, there is a slight delay going from PARK to REVERSE. Maybe a secs. - has been doing this for many years.

Will also examine Emergency braking system and the brakes in general. All fwd. gears are smooth including shifting from one gear to the next.

If I find anything worth mentioning - I'll report back to this thread.

The trans have more numbers that 722.3 Like 722.3xx Is any of this specific to those later numbers xx?