W126 560 SEL reverse issue / sound - PeachParts Mercedes-Benz Forum

LandYaghtLover · #1 09-23-2010, 08:21 PM

So as I mentioned in another thread, my trans shifts harsh and reverse takes forever to engage or is slipping. The harsh shifts I am working on. Probably vac issue.

I mention because I have an issue that may be related. When I reverse the car "catches" and slips. So thought it was the trans, and still do. But I also thought it felt and sounded like the parking brakes were catching. Anyone who drove with me said the same, about the parking brakes. Besides, if I engaged them and released, the lever hung low and the p=brake light was on.

So... I removed them. Pretty much just cut the lines and the y-cable and took all the hardware out. Every little spring and such.

No change! I googles and found one thread with no solution. but it really sounds like the parking brake is catching. Even feels like it. The sound is 100% proven to come from the back. Twice now I removed the rear calipers and they spread open fine.

Besides the rear calipers, what could make the noise? It seems like something is catching and with reverse slipping its really hard to back her up!

I will also try to get some audio of it.

mbdoc · #2 09-24-2010, 08:13 AM

When you put the trans in reverse & the reverse clutches are worn OUT, the reverse piston "basket" can travel too far & make contact with the 3rd gear clutch drum.

Stop backing UP!

LandYaghtLover · #3 09-24-2010, 09:06 AM

What happens if reverse is improving. Is that a bad sign? And if its slipping, should it engage at all? Because it feels more like its having a hard time engaging than slipping. Once it catches I can drive in reverse all day long.

Anyway, I do minimize backing up. But its not as bad as it was at all. And the sound is not coming from the trans.

david s poole · #4 09-24-2010, 09:28 AM

listen to what you are being told.collective experience of decades and you think that something new may be happening to your trans? we know what goes wrong in these trans and the only new thing may be in the way the symptoms manifest themselves.

LandYaghtLover · #5 09-24-2010, 09:36 AM

So... about that sound from the rear end....

david s poole · #6 09-24-2010, 12:41 PM

the sound from the rear end can be any one of a multitude of diff things not limited to but may include:drive shaft flex disc,diff mounts,cv joints,sway bar links to wheel assemblies etc. and the sound[s] you are hearing are magnified by the fact that reverse gear doesn't apply smoothly.

S-Class Guru · #7 09-24-2010, 04:38 PM

Yeah, David, that clutch basket clicks pretty loud when the plates wear down. I wonder if that's the sound he's hearing, and it just seems to be coming from farther back. The basket sound is a loud tic-tick-tick about 5-6 times per wheel revolution.

When the reverse plates wear enough, they begin to break up into chunks. When you put it in reverse, every now and then a chunk will catch and you can back up. These chunks are clogging the filter and getting everywhere. The clicking is throwing shards of aluminum from the basket throughout the tranny.
Reveres plates are the easiest thing to fix in a 722. Do it before it's too late.

DG

LandYaghtLover · #8 09-24-2010, 07:08 PM

I never hear any clicking... yet....

I need to really drop the pan, but fear doing so! The sound though is certainly coming form the rear. Just odd it only happens in reverse. The flex-disc u-joint things are new. I guess I will dive into the rear end and see what I find.