Greg

I have been thinking about your hot slipping clutch ... (Oh baby!)

To the serious side and I don't think it has to do with the hydraulics.

Here are my thoughts: At rest, the clutch master/slave system should not ideally influence the clutch assembly at all. That is where the questions of free play comes in. I would still like to know the amount of free-play cold and when it slips.

My thoughts continued- if the inlet port was not being uncovered fully and thus the piston is not getting a full stroke and replenished, this would show up when using/pushing on the clutch pedal. You reported slipping when your foot is off the pedal.

This leads me to the thoughts regarding-

- the difference between when it does and does not slip. You say it slips after considerable amount of driving (time to heat up)

- the take-up (engagement point) is high off the floor. This is commonly associated with a worn clutch disk OR a bad pivot ball/clutch arm inside the bell housing.

-you said that the clutch disk thickness measures within spec, but because the measurement is at the slave cylinder and its amount of extension, a worn clutch arm pivot ball could give you a false reading.

-a failed clutch arm would also do this, but it seems very unlikely that the arm itself would fail. I have no experience to share with this part or its life/failure.

When you were under the car measuring your clutch thickness, did you get a chance to see if there was excessive movement of the clutch arm? This might be a telltale indicator of a pivot failure.

Unfortunately, I believe access to the pivot is the same as doing a clutch and once you are in there, might as well do it all.

Like you, I am hoping that the clutch disk is thick and happy, thus not needing any major work.

I could be off base on all this, but I continue to think about what is going on with your slipping hot clutch!

Haasman

[QUOTE]Originally posted by 95300YDT-A
[B]cc 260E,

95300YDT-A

Many thanks I had an older version of it.

I thought you had the official from MB.

For my findings with this problem, please see this thread:
http://www.peachparts.com/shopforum/tech-help/79447-i-hoping-one-mb-techs-had-experienced.html

Dear Greg,

I think your clutch problem is very intriguing. I never heard about that.
But a case is only lost when we give it up.
And we don't want to, are we.
So I decided to do a "brainstorming" about this with my Indy. He is a honest and modest AND independant MB specialist, ashamed to ask the prices he has just to survive.
MB-stealership in my home town goes to him to get all those 6xx rebuild ( and they have a famous MB-rebuilder just 15 miles away in the next town !).
Well, I'll try to explain what reasonable explanation he came up.
As you allready understood : English isn't my mother's language so I am sorry and please feel free to ask any questions. So here we go.
Neither of us believe your theory about the hydraulic system. Everything you told is correct but again neither of us could imagine that could cause enough force to make the clutch slipping.
You replaced the clutch by a new one, excluding the clutch as a cause.
But did you checked out the wear (the real thickness of the flywheel at the contact-with-the-clutch surface ? The wear of the plate pressing down the clutch to the flywheel ( don't know the correct name in your language ) ?
If you did't : do it.
If the contact surface on the flywheel is still OK ( or even when it's not ),
let eventually grind (mill ?) down the surface on the RIM of the flywheel, there where you bolt on the "pressing" assembly to compensate the weardown of the contact surface and you"ll see : no more slipping when hot !
What do you think of it ?
Don't forget to communicate us a follow up !
Thanks in advance and good luck,

Danny

I will not give up until I solve this!

Your English is just fine!

I'm sorry that you don't believ my theory but it's the laws of physics. Expanding hydraulic fluid can exert huge force, much more than is required to release a clutch. Without the ability to return to the reservoir, fluid expanding with temperature will displace the piston in the slave cylinder thus releasing the clutch.

I have not replaced the clutch since my measurement with the gauge suggests it is still OK. Without residual pressure in the hydraulics it certainly works OK without any slip. I think replacing the clutch and flywheel (dual mass flywheels such as that in my car should not be machined) would be a very expensive and time consuming option, especially considering that I have not diagnosed the clutch plate or flywheel to be at fault. Without perfectly convincing evidence of the cause of the problem, I would prefer to replace less expensive components such as those associated with the hydraulics which with the evidence I have to date are still the main suspect.

Please don't take this the wrong way. I am appreciative of the interest both you and your tech are showing. I will post more replies and further findings on the other thread at
http://www.peachparts.com/shopforum/tech-help/79447-i-hoping-one-mb-techs-had-experienced.html

Greg

Greg,

What are the exact measurements that you used to create your clutch disk thickness measuring tool?

I made the measuring gauge tool according to the dimensions in my Haynes W201 manual, my Haynes W124 manual and my Brooklands W124 manual. The dimensions in all the manuals agree. Unfortunately, none of my factory manuals (MB North America, W201, W124, M103, M104 but I don't have M102) depict the tool for a comparison. Without those manuals at hand at the moment I cannot quote the dimensions but if anyone is interested I will look them up again and post here. The tool seems to fit perfectly. I can feel it sliding onto the slave cylinder push rod.

Is this the tool and the dimensions you used?

Haasman,

That certainly looks like it. Again, without the manuals in front of me, I would need to verify the dimensions. Your diagram does look very much like those in my Haynes manuals, right down to not being drawn quite to scale, from memory. My Brooklands manual on the other hand, has a full size scale drawing without dimensions which can be used as a template for the tool, if my memory serves me correctly.

Greg

Updated tech article for the W124:

Mercedes-Benz W124 Brake Master Cylinder and Reservoir Replacement | 1986-1995 E-Class | Pelican Parts DIY Maintenance Article