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-   -   240d stiff hard clutch pedal (http://www.peachparts.com/shopforum/diesel-discussion/396246-240d-stiff-hard-clutch-pedal.html)

petecooke 11-28-2018 01:00 PM

240d stiff hard clutch pedal
 
I have a 82 240d manual tranny with 350k on it and an 83 240d with 270k miles.

I recently replace the clutch master and slave cylinder(master was leaking fluid) on the 82 but the clutch is still much harder to push in than the 83.

I'm thinking it's the throw out bearing but I'd rather not pull the tranny if I don't need to since it's getting very cold in MD and I don't have a garage to work in. Any way to test the throw out bearing?

Any ideas what could be causing this?

Thanks,

pete

Diesel911 11-28-2018 01:21 PM

On other vehicles if the Throw Out Bearing is bad it makes noise when you step on the Clutch.

Sugar Bear 11-28-2018 01:41 PM

It is probably not the throwout bearing unless it is dry/gummed up where it slides over the front bearing housing or at the fulcrum/ball stud where the fork pivots. The splines where the friction disc slides on the transmission input shaft can also become dry.

The variation in the force needed is more likely in the different spring tension and possibly the design of a different brand pressure plate between the two cars.

As stated, throwout bearings make noise when they are bad due to the pressure/load applied when depressing the clutch. If the clutch is not depressed and there is noise it can be a worn clutch fork or front input bearing in the transmission.

Good luck!!!

petecooke 11-28-2018 01:55 PM

I'm not hearing any noise so I guess it's not the throw out bearing. Not sure when the last time fluid was changed so I plan on doing that soon.

Could low fluid or old fluid possibly cause the clutch pedal to be harder to press?

Thanks,

Pete

moon161 11-28-2018 02:23 PM

I've got a hard time imagining how the release bearing could contribute any resistance to the travel. It's got a loose fit over the input shaft which turns with the flywheel when the clutch is engaged. Any resistance to translation over the input shaft would also resist it's rotation and get hot real fast. The ball that the yoke is attached to at the far end has no leverage to present meaningfull resistance, same with the operating rod at the other end.

You might be feeling the internal boot on the receiving cylinder, but I think it's likely a stiffer pressure plate on the clutch.

Sugar Bear 11-28-2018 04:26 PM

Low or old fluid cause the problem? I do not see how it could.

Good luck!!!

petecooke 11-28-2018 06:09 PM

I guess I will wait until I have to replace the clutch plates.

Any recommendations on which clutch plates has the least tension?

Thanks,

Pete

barry12345 11-28-2018 06:38 PM

Might want to examine the pedal assembly for any form of binding.Or less than free top bushing. I cannot see a really strong finger spring effect of the pressure plate. It would be hard to even find one for this model with them I would expect.


Unusual issue for this model. Is the line between the brake master and slave really open well? Since the system is hydraulic you may have some form of partial check valve in the old rubber hose.

moon161 11-29-2018 09:29 AM

Quote:

Originally Posted by barry12345 (Post 3865575)
Might want to examine the pedal assembly for any form of binding.Or less than free top bushing. I cannot see a really strong finger spring effect of the pressure plate. It would be hard to even find one for this model with them I would expect.


Unusual issue for this model. Is the line between the brake master and slave really open well? Since the system is hydraulic you may have some form of partial check valve in the old rubber hose.


^That's a good idea, you can have a blockage in a brake line like this.

optimusprime 11-30-2018 09:03 AM

They make 2 types of slave cylinders for your car make sure you have the right one fitted the cylinders are the same its the arm in the centre that has 2 sizes long and short .Might be you have the long one fitted !

vwnate1 11-30-2018 10:50 AM

Clutch Pressure Places / Covers
 
A diaphragm typ will always have less pedal effort but I'd be amazed of Mercedes even offered a rockford typ clutch cover .

moon161 11-30-2018 01:03 PM

Quote:

Originally Posted by optimusprime (Post 3865913)
They make 2 types of slave cylinders for your car make sure you have the right one fitted the cylinders are the same its the arm in the centre that has 2 sizes long and short .Might be you have the long one fitted !


If this was the case, I think the clutch would not engage at all.

97 SL320 11-30-2018 04:28 PM

Quote:

Originally Posted by petecooke (Post 3865460)
I recently replace the clutch master and slave cylinder(master was leaking fluid) on the 82 but the clutch is still much harder to push in than the 83.

What is the history of this car? Did the pedal get stiffer immediately after cylinder changes? Did you compare old / new bore diameters?


Quote:

Originally Posted by petecooke (Post 3865460)
I'm thinking it's the throw out bearing but I'd rather not pull the tranny if I don't need to since it's getting very cold in MD and I don't have a garage to work in. Any way to test the throw out bearing?

A throw out bearing won't cause this issue however, if the trans nose where the bearing slides is dry, there will be much friction that could cause stiff pedal. This isn't a common failure mode.
Quote:

Originally Posted by petecooke (Post 3865460)
Any ideas what could be causing this?

In another thread, someone had a stiff clutch / very narrow range of release. They would push the pedal to a certain point, clutch would be released but if they pushed farther, it would drag. Turned out clutch disc center springs came apart and were wedging disc to cover.

97 SL320 11-30-2018 04:33 PM

Quote:

Originally Posted by vwnate1 (Post 3865936)
A diaphragm typ will always have less pedal effort but I'd be amazed of Mercedes even offered a rockford typ clutch cover .


A Rockford clutch ( AKA Twin Disc ) is an over center clutch commonly used on industrial engines and old mechanical punch presses.

The two common automotive non diaphragm clutches are:

Long These have a very narrow forged release arm with a wear / finger height adjustment bolt at the levers tip. Uses coil springs for pressure

Borg and Beck . These have wide stamped steel release lever. Uses coil springs for pressure.

Junkman 11-30-2018 08:25 PM

People use dual disk clutched in the Cummins world - for towing. They generally wouldn't be necessary and likely unavailable unless custom built for a 123.

I had an MGB with an extra return spring on the brake pedal that caused problems being too stiff until I found the correct weight spring.


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