cold weather clutch slippage

[poly_poly-man]

I'll be the first to admit I haven't been all to nice on the clutch - learning manual on the car hasn't helped (and I'm still learning to rev-match for downshifts). However, the clutch has been alright to me - I caught it slipping once in the middle of a particularly rough bit of driving, but it caught right back up.

Then yesterday, I drove it to school (it was in the 30's out) after letting it warm up for several minutes. The whole way, I was getting problems every time I was accelerating with the clutch slipping. By the end, I was noticing it less, as I was driving extra-carefully (barely accelerating, rev-matching all my downshifts, etc.), but it still was there.

I drive it home, when it's more like 50's-60's, let it warm up about the same amount of time, and it's fine the whole way - even through I was ragging on it pretty hard.

That was the first time I've driven my car at quite that cold out. What would cause that clutch slippage when it's cold out?

[SD_GR]

I checked the temperature you mentioned, it's roughly -1 deg. Cold, but not unreasonably cold. You should not have had a problem.

The friction surface will be affected by temperature but unless I'm mistaken, it will do so in a manner opposite to what you observed. You should have had a grabby clutch instead. This means in my mind it may not be the clutch itself.

Since the clutch is hydraulic, and it is a pull type system (think old Porsche, and think I don't know what year you drive so I'm going with an 02, since that's a great choice -- my choice...) it is conceivable that the slave cylinder may be binding and causing what you described.

EDIT: The master, or the line, could have an obstruction and also cause what you described. Basically what I'm looking for is a flow fault that becomes critical as the temperature -- and so the pressure -- decreases.

[Trainrex]

Once it has slipped once, it just told you it has reached the end of its service life. Start getting ready to do a clutch job.

Now it's time for you to get some hands on knowledge instead of all the second hand regurgitated crap you've read for the last few months. Get yourself some tools and have at it!

[Trainrex]

I checked the temperature you mentioned, it's roughly -1 deg. Cold, but not unreasonably cold. You should not have had a problem.

The friction surface will be affected by temperature but unless I'm mistaken, it will do so in a manner opposite to what you observed. You should have had a grabby clutch instead. This means in my mind it may not be the clutch itself.

Since the clutch is hydraulic, and it is a push type system (think old Porsche, and think I don't know what year you drive so I'm going with an 02, since that's a great choice -- my choice...) it is conceivable that the slave cylinder may be binding and causing what you described.

A slave cylinder problem will cause the exact opposite problem. Slipping is caused by essentially one and only one problem.

[SD_GR]

A slave cylinder problem will cause the exact opposite problem. Slipping is caused by essentially one and only one problem.

My thinking is that low pressure in the slave will not allow the clutch to engage fully, so in the cold the car behaves like he's riding the pedal. Is it the opposite, like in any other system? If it's the opposite then I see what you're saying. In my Toyota when the slave acts up I can't disengage the clutch. Am I mixed up?

ED: I'm thinking about it more... So "push" and "pull" setups will both have the slave do the same thing -- DISengage the clutch. Right? I was staring at my gearbox (not that I can see the slave, or that it would help if I could) thinking.

[Trainrex]

My thinking is that low pressure in the slave will not allow the clutch to engage fully, so in the cold the car behaves like he's riding the pedal. Is it the opposite, like in any other system? If it's the opposite then I see what you're saying. In my Toyota when the slave acts up I can't disengage the clutch. Am I mixed up?

Low pressure in the slave will not allow the clutch to disengage.

A clutch's natural position is engaged. The action of the slave cylinder is to press the fingers and disengage it. Any failure of the hydraulic release system will cause the clutch to go back to it's natural position.....clamped tight.

Edit: To add a little more, a malfunctioning hydraulic clutch release system will result in a very low engaging clutch pedal and trouble shifting because there is still pressure on the dogs. A very high engaging pedal is normally a symptom of worn clutch components such as the disc, pressure plate, and flywheel. Normally the disc is the main culprit.

[SD_GR]

Low pressure in the slave will not allow the clutch to disengage.

A clutches natural position is engaged. The action of the slave cylinder is to press the fingers and disengage it. Any failure of the hydraulic release system will cause the clutch to go back to it's natural position.....clamped tight.

Edit: To add a little more, a malfunctioning hydraulic clutch release system will result in a very low engaging clutch pedal and trouble shifting because there is still pressure on the dogs. A very high engaging pedal is normally a symptom of worn clutch components such as the disc, pressure plate, and flywheel. Normally the disc is the main culprit.

I highlighted where I made my error in my thinking. This is my problem. Since they don't affect the natural state, either push or pull setups just affect the effort required to DISengage the clutch. They do the same thing with different links, and either clutch defaults to engaged.

Thank you TR!

[Trainrex]

I highlighted where I made my error in my thinking. This is my problem. Since they don't affect the natural state, either push or pull setups just affect the effort required to DISengage the clutch. They do the same thing with different links, and either clutch defaults to engaged.

Now you have it!

Thank you TR!

Anytime

[SD_GR]

Aha! OK, and so since the OP even started off saying he'd had the clutch slip when the car was warm, there is no cold clutch slip mystery anyway. His disc is likely worn.

[Trainrex]

His disc is likely worn.

That is correct. This is a wonderful opportunity for him to apply some of his reading knowledge to a real world application.

The first job I ever performed on a car was a clutch job all by myself circa 1992ish. Hours on end in the garage checking off the steps in my Haynes manual one at a time while using my brandy new Craftsman tool set, jack and jack stands. I learned volumes that day. I could have read the book all day long, but I didn't truly understand how it all worked until I did the job with my own hands.

[poly_poly-man]

It really only slipped once, and that was in the middle of a session in which I was pretty rough on it - I thought the point of organic clutches was that they would give you heat-related issues, until you let them cool down, when, unless you glazed them or something, they pop right back to their original state... am I wrong?

Also, WHY would the clutch be significantly worse during a cold morning, and pop right back to being a good clutch that same afternoon?

[Trainrex]

It really only slipped once, and that was in the middle of a session in which I was pretty rough on it - I thought the point of organic clutches was that they would give you heat-related issues, until you let them cool down, when, unless you glazed them or something, they pop right back to their original state... am I wrong?

Also, WHY would the clutch be significantly worse during a cold morning, and pop right back to being a good clutch that same afternoon?

You are incorrect. Any overheating or glazing of a clutch does permanent damage to the disc, the pressure plate, and the flywheel. A clutch is simply a braking system in a different configuration. Abuse will wear down the friction material (just like brake pads) and do damage to the pressure plate and flywheel (just like brake rotors). Once the friction material is damaged and/or depleted, the clutch can no longer provide the clamping force necessary to prevent slipping.

Your clutch slips worse when it's cold because of thermal expansion. Things expand when they warm up. Your slipping problem will start to get significantly worse as the little bit of remaining friction material wear away. Right now there is just enough left that it stops slipping when the disc, pressure plate, and flywheel expand enough to help it clamp.

[SD_GR]

If it's getting really cold in NJ you'd be best off doing this sooner then rather than later. With three guys we did a clutch in a half day, but it's always warm or at worst chilly here. I'd get two buddies and a garage plus definitely jack stands.

[Trainrex]

If it's getting really cold in NJ you'd be best off doing this sooner then rather than later. With three guys we did a clutch in a half day, but it's always warm or at worst chilly here. I'd get two buddies and a garage plus definitely jack stands.

You forgot the most important thing.......alcohol!!!

There is nothing like drunk wrenching with your friends!

[poly_poly-man]

drunk wrenching at 17? not recommended, I'd imagine

I have some mechanic uncles who can help me out, no problem.

I was thinking that, if it were possible, I would want to wait until I got a bit more power/torque into the car before I did the clutch, then go exedy stage 1 organic. Would it be terribly ill-advised to go with that clutch before I did the power mods?