Clutch pedal feel question

So in the last two months I've had both the clutch slave and master cylinders replaced on two separate occasions. The trips to the dealer were immediately preceeded by things such as the car being difficult or impossible to get into gear.

However, the feel of the clutch pedal changed prior to each shop visit, and that's what I wanted to solicit opinions about. Both times, the first 1/3 of the clutch pedal travel (~3 inches or so) became virtual mush. Almost zero resistance. After that, I got to the point where there was resistance seemed normal. In fact, the first time the car was in the shop, the pedal would remain at that 1/3 depressed position when I took my foot off the clutch.

So now I've had my car back from those two visits for about 3.5 weeks. At first, everything seemed normal, but in the last week, the feel of the pedal has changed.

Normal = firm, equal resistance for the entire pedal travel

Now, when the car is cold, the first few inches of travel have less resistance than the rest of the travel. This condition has only happened a couple times, however. Mostly, the pedal does have less resistance at the beginning of the travel than at the end, but the increase in resistance is very linear as the pedal is depressed. It's not as if there is a sudden increase in resistance at some point in the pedal travel. Once the car is warmed up, everything goes to the above definition of "Normal."

So after all that, I get to the questions:

Does your clutch pedal have the same feel upon (cold) startup that it does 15 minutes later after the car is warmed up? If no, please describe the two conditions. Also, is this normal? I know that there are fluids involved, and fluids like to change with changes in temperature. But I never noticed ANY changes in clutch pedal feel on my old 2.8 coupe. I'm just hoping that this isn't foreshadowing another trip to the dealer.

John

Reply » Clutch pedal feel question

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Does your clutch pedal have the same feel upon (cold) startup that it does 15 minutes later after the car is warmed up?

Yes, my clutch pedal feels the same at start up as it does warmed up, with the possible exception of the engagement point changing very slightly.

I really feel for you having to jack with this whole clutch thing for so long!

Reply » Clutch pedal feel question

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An obvious question would be why did they replace the master cylinder and the clutch slave cylinder? Pressure test failed? Seems odd that they'd replace one and not test again before the car left the shop.

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However, the feel of the clutch pedal changed prior to each shop visit, and that's what I wanted to solicit opinions about. Both times, the first 1/3 of the clutch pedal travel (~3 inches or so) became virtual mush. Almost zero resistance. After that, I got to the point where there was resistance seemed normal. In fact, the first time the car was in the shop, the pedal would remain at that 1/3 depressed position when I took my foot off the clutch.

This sounds like the clutch slave cylinder was not properly bled. But...

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So now I've had my car back from those two visits for about 3.5 weeks. At first, everything seemed normal, but in the last week, the feel of the pedal has changed.

Normal = firm, equal resistance for the entire pedal travel

Now, when the car is cold, the first few inches of travel have less resistance than the rest of the travel. This condition has only happened a couple times, however. Mostly, the pedal does have less resistance at the beginning of the travel than at the end, but the increase in resistance is very linear as the pedal is depressed. It's not as if there is a sudden increase in resistance at some point in the pedal travel. Once the car is warmed up, everything goes to the above definition of "Normal."

So after all that, I get to the questions:

Does your clutch pedal have the same feel upon (cold) startup that it does 15 minutes later after the car is warmed up? If no, please describe the two conditions. Also, is this normal? I know that there are fluids involved, and fluids like to change with changes in temperature. But I never noticed ANY changes in clutch pedal feel on my old 2.8 coupe. I'm just hoping that this isn't foreshadowing another trip to the dealer.

John

It sounds to me like there's a leak somewhere, possibly in a hose. I'd check the slave cylinder hose. Have you been monitoring the fluid level in the master cylinder? Did they replace any hoses or solid lines? Any indication of a blow-by leak (at the top of the slave cylinder inside the car)? What's the state of the clutch pedal return spring (I assume you've still got the over-center spring and didn't switch to the Z3 one)?

Reply » Clutch pedal feel question

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Originally Posted by dwm This sounds like the clutch slave cylinder was not properly bled. But...

I wish it were that easy. But assuming no leaks in the system, how would the clutch pedal feel fine for the first couple of weeks back from the shop, then all of a sudden change? Maybe the air in the system works itself to a point where it's noticeable?

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Originally Posted by dwm Have you been monitoring the fluid level in the master cylinder?

No, but I will. You're referring to just keeping an eye on the brake/clutch fluid resevoir, correct?

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Originally Posted by dwm Did they replace any hoses or solid lines?

Don't know, and it's even harder to find out now considering my SA at South Bay BMW is no longer there as of the last 3 weeks.

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Originally Posted by dwm Any indication of a blow-by leak (at the top of the slave cylinder inside the car)?

Please explain this one. Can I check this myself? If so, how?

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Originally Posted by dwm What's the state of the clutch pedal return spring (I assume you've still got the over-center spring and didn't switch to the Z3 one)?

I think that the spring is fine. I'll double check, however.

Thanks,

John

Reply » Clutch pedal feel question

My clutch feels the same on start up as it does warmed up.

The entire clutch mechanism in my 3.0 was replaced in August and I had a similar problem as you experienced initially. When they installed my clutch they did not bother to align it properly since it was a self adjusting clutch. The mushy travel and difficult shifts eventually worked themselves out. However, once they did I did not experience the same differences in clutch feel with temperature.

Reply » Clutch pedal feel question

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It was explained to me that the two failures were separate instances and that it was only freak timing that they happened a few weeks apart. On both, I was told that there were internal failures (leaks) in both cylinders. I'm assuming that defective parts get returned to BMW. Do they ever do a failure analysis and if so, is it possible to track down the results?

I wish it were that easy. But assuming no leaks in the system, how would the clutch pedal feel fine for the first couple of weeks back from the shop, then all of a sudden change? Maybe the air in the system works itself to a point where it's noticeable?

I was just talking about the pedal staying 1/3 depressed. I've not had a bunch of air in my system in this car, but you're correct in assuming it shouldn't change. Unless there's a leak, in which case it's hard to say. Or water, but I have to assume there isn't a lot of moustire in the syste since you just had master and slave cylinders replaced.

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No, but I will. You're referring to just keeping an eye on the brake/clutch fluid resevoir, correct?

Yes. Of course, it'll be a slow process unless you've got a masssive leak, which you'd probably know about. Wouldn't hurt to take a good look underneath for evidence of a leak anywhere around the slave cylinder. Clean it first, drive it for a day or two, then check again.

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Please explain this one. Can I check this myself? If so, how?

Disconnect the slave cylinder from the pedal and swipe a white paper towel around the top. Max had a problem with his leaking a bit until the seal reseated/rebedded. Mine has never leaked, but I'm always very careful with it when mucking with the pedal.

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