Hello,
04/67000km on it.
I recently changed my clutch pedal assembly/coils/plugs/wires.

Here is my problem

When I step on my gas to get acceleration, my rpm goes up then comes down then my car accelerate. (feels like my clutch is not 100% engaged) (here clutch slipping)

When I just start my car and start to drive, my clutch is soft (easy to press), no clutch slipping problem what so ever, and then after I started to drive for about 15mins~30mins, my clutch gets really hard (hard to press), then the clutch slipping problem kicks it.

I tried to adjust the clutch pedal, problem does not go away.
Is this mean I need a new clutch??
Please help, I hate this problem.

 

I would hate to start off by saying you need to replace anything with the clutch since you just got done replacing the clutch pedal.
Makes me think you should start there.

Now what did you adjust on the pedal?
Was it the pedal stroke or play?
If you adjusted the play, did you move the rod out (towards the cylinder) or in (away from the cylinder)?
Does the clutch pedal rod appear to be centered in the clutch pipe or is it inserted at an angle?

When the clutch pedal because harder to press, does it spring back normally?
Hell, I might even take the pedal back out and reinstall it just to make sure it wasn't something overlooked during the reinstalling.
Remember, according to what I've gathered, this occurred after you replaced the pedal.

Now couple other things to consider if we rule out everything with the pedal assembly.
1) Bleed the clutch line. This may not be it, but its something to try before you start disassembling something (always start with the easy eliminations).
2) Throw-out bearing is seizing on the spline for whatever reason (maybe lack of grease).
3) Something wrong with the pressure plate diaphragm.
4) Excessive grease is flinging onto the surfaces where the disc is touching and causing it to slip at the beginning (this is less likely since your pedal gets harder to push after a while).

That's all I can think of at the moment.

 

I tried both taking the rod out and in.
Both did not work.
and it is not in the angle. It goes in directly.
and the clutch springs out right away.

 

Bleed your Brake Fluid, Fully.

When I say Fully, follow this order : Bleed MC, Slave Cylinder, Front Left, Front Right, Rear Left, Rear Right. Then Repeat from MC again for one more time.

Use Dot 3 or 4 Fluid. I prefer 4, find some Fully synthetic(which one is not anyway) with a high wet and dry boiling point. Do NOT use DOT 5

Why? cuz "cold start = soft clutch/brakes then after warm up = hard" usually means your Brake Fluid is full of Water ---- means its time to change.

 

how's the brake fluid relates to the clutch pedal being hard??
can you explain to me more detaily??
I don't understand the dot 3/4/5 fluid thingy

 

Because your hydraulic clutch uses the same fluid as your brakes.
You'll see the master clutch cylinder to the right of the master brake cylinder.

Wiki to the rescue:
http://en.wikipedia.org/wiki/DOT_3

 

okay okay, i understand it now.
What is MC? he mentioned me saying Bleed the MC, does that stands for master cylinder?? am i correct??
and also how to I grease the throw out bearing?
don't I have to take out the transmission??
Because also when I take off my foot from the clutch, there is this weird sound coming out. It sounds like really high pitch sound, but it goes away as I step on the clutch.
Also when the clutch is soft, there is the same sound. However, when the clutch gets hard, the sound goes away.

 

Yes.
MC = Master Cylinder

Yes, the transmission needs to be dropped.

The Release Bearing (aka Throw-out Bearing) is number 4 in the pick above.
And you don't grease the bearings themselves, but the spline it rides on.
If there are bad bearings, you replace the whole release bearing.

This is likely not a sign of a bad release bearing (as some people think for some reason) because its not in use until the pedal is pressed in.
What you hear is gear rollover.
A bad release bearing is MORE noticeable with the pedal in (meaning, you'll likely hear sound with the pedal in and out... just more with the pedal in).

Let me explain why and refer to the pic above:
When you press down on the clutch pedal, the fluid is pushed from the master clutch cylinder to the slave cylinder (#1 in pic above).
The top on the slave cylinder is connected to the clutch release fork (#5) and pushes the fork back.
Because of the fork's pivot when you push the top back, the bottom of the fork moves forward.
Attached to the fork is the release bearing (#4) but its not in contact with anything (just riding on the spline) UNTIL the fork pushes it forward (when you press the pedal in).
When the fork pushes the release bearing forward it compresses the diaphragm fingers on the pressure plate (#6).
Same concept as the fork (basically), pushing the bottom of the spring fingers forward moves the top of them back.
The top of the spring fingers is a surface that pushes the clutch disc (#7) against the flywheel (#11) when the pedal out.
With the clutch pedal in (and following with what was explained above) the release bearing pushes on the fingers, which allows the disc to become separated from the flywheel.

So now that you have an understanding on the whole clutch assembly, hopefully this will help you troubleshoot this better.
But bleeding the line is something you should do first.

 

Found this on YouTube:
http://www.youtube.com/watch?v=6BaECAbapRg
Should help explain what I was talking about.

 

thx so much for the great help!!
I will try to bleed the lines first and put in new brake fluid.
Hope that will fix my clutch slipping.
But how do i fix the high pitch sound that is coming out from the clutch when I depress the clutch??

 

No problem.
I always tell people that the best way to troubleshoot something is to first understand how it is supposed to work.

Hard to say if you have a legitimate problem.
Gear rollover noise is common with our car since the transmission is so close.
Might be perfectly fine.
Do you have anyone near you that drives an RX8 that you can compare to?
Maybe if you can take a video clip of what you're hearing we can attempt to hear if its normal.

 

ah ha!
i won't be able to work on my car due to my final exams.
I will post up videos for the sound coming out of my transmission soon.
thx you again

 

Really, GREAT Information.. It helped me alot understanding how it works.

And maybe it's going to help me better debate my problem with my dealership and I certainly hope you guys can help me too troubleshoot this PITA problem:

Mazda replaced 80% of my transmission/synchros/forks in feb under warranty. They also advised to change the clutch since it was pretty worn out and since the tranny was already disassembled, it was only a 100$ extra for labour.

I followed their advise and bought an ACT ZM8-HD-SS clutch. They installed it.

First impression : excellent. Completely new car feeling. my clutch before was really soft and not precise.

BUT: a week after, it went back the way it was before. again, soft, long, no feeling whatsoever of the point of friction.

Complained 3 times at Mazda : I was told there was nothing wrong with it and that actually ACT clutch aren't that good and that the pressure plate is softer than the OEM. Basically, it was a downgrade clutch-wise...

After 1000KM, last week, at a traffic light, suddenly I can't get in any gear. Im stuck in neutral. When I turn off the engine, I can get in some gears though it's hard to shift.

Got it towed to Mazda and before they even get it in the garage for inspection they tell me thats its certainly the release bearing and they need to disassemble the tranny again to take a look and obviously, I will need to pay for that.

My clutch is barely 1 month old and they're telling me that my release bearing is dead. They never questionned/admitted their clutch's installation they put me full responsible of this problem.
Well the last problem i expected now was a clutch problem after it was just replaced though never worked properly.

Now I was advised to check my clutch pedal as it might be broken and causing this problem though I dont have the feeling this is the problem.

Any idea, tips?

Is it realistic to check it myself and remove the tranny to get to this bearing considering Im a very average DIYer with little expertise (and no expertise at all with tranny) ?

Help please

 

gtommy,

did you ever find out the problem? If not, my guess would have been the clutch pedal going out. I had problems getting in/out of gears (especially reverse) and it fixed the problem.