Inconsistent engage point / noisy clutch

[steve91tt]

I have had an inconsistent engage point on my clutch since I installed it last fall. Some times it engages right off of the floor and some times half way through the throw of the peddle. It wouldn't bother me so much but lately when it's engaging half way through the peddle I hear a wooshing/grinding noise coming from the clutch area. The sound is also quite inconsistent (ca. 20% of the time). It happens more when the car is in gear and less when in neutral.

I have tried rebuilding the master, replacing the master, replacing the slave, replacing the rubber line and this weekend I dropped the transmission to take a look but all appears normal. I am using a 240mm center force II clutch, aluminium flywheel and longer clutch collar.

I'm heading up to Texas Motor Speedway for a track weekend in 2 weeks so I need to determine if I should trust the clutch or make other arrangements. Thanks in advance for the help.

[steve91tt]

Just a quick update on this thread in case anyone has the same problem in the future.

I am still suffering with the inconsistent clutch described above but I think I might be making progress. Since I first posted I discovered that the clutch master was not consistently releasing pressure in the system when I took my foot off of the pedal. This results in the master acting like a pump. When it does not release pressure the master adds pressure and fork travel with each time I press the pedal. Thus, the inconsistent clutch pedal.

I first tried removing the stops on the top and bottom of the pedal box and adjusted the push rod to get the clutch to engage very near the floor in an attempt to get as much room at the top of the pedal travel as possible. This seemed to help for a while.

I next tried a smaller slave cylinder to shorten up the engage point and again give me more travel at the top of the stroke to help the master release. This did not help.

Next, I took the master out of the car and found that even on the bench the plunger needed to be 100% disengaged before any pressure could be bled back to the reservoir. Even moving the push rod side to side slightly closed off the communication between the reservoir and the clutch line.

I then took the master apart and found black material in the piston bore. I assumed that this was rubber from the seals and pressure release value. The master is less than 1 year old so I'm guessing that the fluid I'm using is eating the seals (ATE Original Super Blue Racing DOT 4 Brake Fluid).

I cleaned it up and put it back on the car with different fluid in it (standard DOT 3). This seemed to help for a day or so but the problem came back.

I pulled the master again and once again found black material in the bore. My working hypothesis is that the original brake fluid had swollen the rubber on the release valve to the point that it would not longer work consistently so I ordered a new master.

While waiting for the new master to arrive I filed 1/8" off the the end of the master push rod to allow the cylinder to move back further in the bore in hopes of getting the sticky valve to release. This definitely helped but it still sticks from time to time.

Still waiting for the new master to arrive from Rockauto. I'll keep this thread updated with the results.

Anyone else seen similar?

[austinnelson117]

I actually had this exact problem on my old Explorer. Everyone I talked to told me I was crazy and nothing was wrong. I changed every single component involving the clutch and tranny except the master. I ended up giving up and selling the car to a friend and a month later everything was fine. Let me know how it turns out

[austinnelson117]

Also, I know it's off topic but what is the paint code on your 240? Is it the same one that they use on 350z's? I'm picking up a 240 in a week or so and that's the exact color I want to go for.

[steve91tt]

The paint code is 901.

Update...

I replaced the master. The engage point became nicely consistent but I still had the issue of intermittent gear grinding.

I replaced the clutch with a "Brute" brand (recommended by Dave Rebello as being the best value stockish clutch out there). The Brute kit came with a new clutch collar, bearing and bushing so now everything is matched and new (at least with the mechanical part of the clutch). The car shifts much better now. No more grinding into gear but the engage point is on the floor even with the upper and lower stops removed. If I adjust the clutch peddle to move the engage point off of the floor the master does not fully release and I get the inconsistent peddle again. I bench bled the master three times and still no change. I'm getting about 1" of throw at the slave as it stands. The car is drivable but the clutch peddle has a HUGE throw. Feels like driving a tractor.

At this point I believe that my problem is something to do with the geometry of the flywheel. I am running an aluminium, Forenza unit. I could pull the trans again and put the stock flywheel back but I love the responsive nature of the lightweight aluminium.

Any suggestions?

[Pop's Z]

Hi Steve, Did you check the pivot point of the clutch pedal? I have seen the pivot hole wallowed out and the pin and the pedal would move in weird ways. I have also found pivot pins being worn out causing the symptoms you describe.FWIW.

Cheers, Mike

[steve91tt]

I hadn't thought of that but unfortunately I don't think thats the issue as the clutch peddle and pivot look good.

[cygnusx1]

The Fidanza flywheel is infamous for people tightening the bolts that hold the clutch...BUT the bolts actually bottom out in the tap hole and don't fully clamp the clutch in place. It's very deceiving. You need to use shorter-than-stock screws or grind them shorter. Washers work too, but I prefer using shorter screws, no washers, and locktite. Fidanza also did not tap the blind holes all the way down, consistently, which exacerbates the problem. Get a metric bottom-tap and finish their job for them, so that all the bolts can fully seat. This may or may not be your issue but it was worth mentioning here.

[steve91tt]

Wow. I had no idea. If my flywheel nuts are bottomed out would that cause the extra long engage point I am experiencing?

[cygnusx1]

I am not entirely sure what symptoms it may cause, but I would think decreased clutch capacity would be one symptom. Inconsistency, might be another side effect. BTW It's not the flywheel bolts, it's the bolts that hold the clutch to the flywheel, that are the issue in the cases I have seen.

Edited September 9, 2011 by cygnusx1

[beermanpete]

I suspect it could cause a low pedal engagement. It could also cause bolt failure, which you don't want.

[coop]

Not clamping the clutch all the way down with the clutch bolts can cause slipping and short or early clutch activation, not foot to the floor activation.