I recently installed an exedy twin disk carbon clutch and things have been working great for about 300miles.

• Yesterday on the way home from HI RIB meet the clutch pedal refused to come back up after being pushed down. I had to manually push it up with my left foot.
  
• If I hold the clutch slightly i feel some pressure but then it drops rapidly and the clutch can Easily be tapped to the floor where it will stay until I manually bring it up again. This was a terrible PAIN when stuck on a hill...I tried to rev up and get it to keep the gear but it would not want to come up. So after a 4000prm dump it kept the gear...i manually brought up the clutch and shifting into 2nd was easy...for shifting into 2nd gear I pushed the pedal down selected the 2nd gear and manualy brought the pedal back up...I drove it home (thank god for no red lights) and didn't want to dump the clutch again. So when I got to my garage I turned it off and rolled it in.
  
• This sounds like it could be 3 things...

I havn't had time to lift the car up and do a manual check for leaks but I will get to it soon.

I'm open to all input or comments that can help me resolve this issue! Thank you for your time!

 

dude i have the same problem......i am stumped so once you figure it out please let me know...thanks

 

Or, in add'n to your list, a broken clutch-release fork - often happens with aftermarket clutches which require higher force to disengage.

 

I'm very sure its not the fork because if it was the fork the clutch would not work at all...it does work just manual engagement is required. I am leaning towards hydraulic type of failure. I will check the res tank and line tmrw after work and report back on the issue.

 

Obviously I didn't understand your symptoms correctly.

So, the clutch will disengage, but then won't re-engage w/o pulling up the pedal? If it is a hydraulic problem, it usually won't disengage, or stay disengaged for long.

Hmmm...

Dave

 

If I'm understanding it right, it sounds like the pp isn't able to push the slave cyl piston back in for some reason. Either the slave or master is stuck and pulling the pedal back frees things up. If I was to guess (and I am) the master has an issue. Some of the information is confusing though.

Good luck. It'll be interesting to hear what it ends up being.

gary

 

This happened to me as well, I topped of the fluid and it hasn't happened since.

 

update : 01

• I'v checked Fluid level and its where I left it, at the top. I don't have any soft lines in the system...(fd comes with hard lines and just 1 line that is soft from factory but I'v replaced it with a stainless steel one long ago)
  
• I got my friend to pump the clutch and I tried to look through the inspection cover to see if the slave cylinder is doing its job (pulling the pressure plate) and its doing it.
  
• I'v tried looking for leaks while he's manually pumped the clutch and all the lines are bone dry.
  
  
• Back to square one...still no idea what's wrong...I need to get a gauge to see where I'm losing pressure...Master cyl, lines, slave (doubt it since I see it working just fine under fast pumps)
  
• What it could be according to a local mechanic is that the clutch master cyl has worn our parts inside causing it to leak and the leak is going back into the line that is why I'm not seeing a physical leak. He says to get a gauge and test it...

Onward way my son time to lose you'll find

 

1. If the slave is pulling the pressure plate, AND IT STAYS PULLED, AND DOESN'T COME BACK by itself while the clutch is depressed, then it's NOT a hydraulic problem.

2. If it doesn't stay pulled while the clutch id depressed, and there is no external leakage, then the master is bad (internal leakage past the piston).

If #2 is correct, then replace both the master & slave, since if one is bad, the other usually soon follows.

Dave

 

I recorded our tests and here's the data (rounded to show whole numbers..10 is really an 8 etc..)

After 100 pushes:

• 10 the pedal came back on its own...(don't know why but it would spring back up)
• 60 the pedal stayed pressed in dead on floor and I had to bring it back up with my foot
• 30 of the time it kind of comes back but stops 2inches on its way back up and I'd use my foot to bring it up again.

 

Again, if the slave is pulliing the pressure plate, and it stays pulled every time, it's NOT a hydraulic (slave, master, or line) issue.

If the slave retracts while the pedal is still pushed, even 1 time out of 100, and there is no external leakage, then the master is bad.

EDIT: I don't see data to define the answer to these questions (statements that I just made). If you can confirm or contradict what I said, the cause of the problem should be apparent.

Dave

 

I'll take your advice and replace master and slave..i'm done tinkering

I will update this page again to let you guys know if the problem was solved.

 

Which Dot No. of brake fluid in used

 

Totally sounds like a problem with clutch hyraulics. My old TII had the exact same problem - an internal leak in the clutch master cylinder. The heavier new clutch probably put more load on the clutch hydraulics and started blowing by one of the internal seals. You've got enough of a seal to build pressure, but it will leak down quickly, and sometimes not hold at all.

As said, it's a wise idea to do both the master and slave at the same time. Most likely the root of the problem is the master, but when you have a new master with fresh seals, the line pressure will go up a good deal and put a load on the old seals in the slave. Just get both new and be done with it.

I'm glad you already have a stainless clutch line - that's a necessity with heavier clutches. Not to mention it eliminates a failure point.

The hydraulic parts are reasonably priced, too. Make SURE to get NEW parts and not a rebuild kit or the like - you really have to get new parts to do the job right. Might want to call some of the local auto parts places - there's a place here in town that carries the Tokico components (they make the parts for Mazda) so they're OEM-grade parts without the Mazda markup.

Dale

 

I use MOTUL Racing Brake Fluid 660

http://www.motorspotstore.com/morabrfl660.html

 

Thanks DaleClark for the reassurance on the issue It makes sense since the twin carbon disk exedy uses a much heavier pressure plate than factory. DaveW was right from the get go about it and I just wanted to make sure it wasn't anything else.

I'd rather use Mazda parts rather than anyone else..unless I can get a porsche gt3 master cyl

 

Thanks for yr info of Dot 4, ask because I had ever used Endless CCM brake pads with A Brand of Racing Brake Fluid Dot 5.1 thought the best.
After 4 months of rainny season in Bkk. Changed both master and slave cylinders.
I'm not surprise about the effect from Dot No. of brake fluid over specs...haha

 

works very well =)

 

same problem here.. I am installing a new clutch, master and slave Monday.. G

 

this is such a PIA job

 

You really think so? Ihor and I just installed the Exedy carbon twin disc in a teeny tiny garage (no lift), and the car is an RE Amemiya widebody so finding safe jack points was interesting. I think it's a breeze, just mind over matter

 

you guys are welcome to come and help me out...mine is large, heated, beered up and food galore... =-)

 

Update::

Installed new clutch master cyl and while installing the slave cylinder we found another problem.

The slave is attached using a clutch release support triangular metal plate, part number:

N315-16-921 and in the book as 41-925,

this piece is aluminum and the bolts holding in the slave are steel so what had accrued was when the slave pushed on the plate it stripped the support plate so well that the bolts came lose when you push the clutch. We took the bolts out to see the inside is completely stripped away. I'm ordering a new clutch support release plate now.


another update : i also took this time to install racingbrake lines on all 4 and the pedal feel has really changed a lot:

http://www.racingbrake.com/Brake_lin..._p/bl005-t.htm

 

Hey Yuri,

Acosta installed the clutch, right? Sounds like they stripped those out by over tightening......

 

Yea looks like it and over time they just gave up holding the pressure.

The part number N315-16-921 will run you $45.95 plus tax and shipping. Not exactly what I was expecting to pay for such a small piece of aluminum but no other way around it. I took the piece to a machine shop and they said they can make new threads for a larger bolt in case mazda ever stops making the part.