clutch woes

[Jumprun]

Before I remove the clutch again on my 330 GTC I thought I would run the situation by the group in case someone has a better idea. Here's the situation;
I needed to replace my clutch due to wear, so I lightly resurfaced the flywheel, bought a new pressure plate and had the clutch disc re-lined. I also replaced the master and slave cylinder due to leakage. I put everything back together, bled the hydraulics, adjusted the MC actuating rod to the proper clearance, and properly adjusted the clutch free play. The problem is the clutch won't release until the pedal is barely off the floor. I had my assistant actuate the pedal while I looked in the inspection window and I can clearly see the lever arm and TOB moving the spring plates more than enough to release the clutch. The pedal is also nice and hard, so probably no air in the system, beside I can clearly see the springs are being adequately depressed to at least a flat condition.

The only thing I can think of is that the face of the clutch disc is wildly running out from the center spline causing it to wobble and the need for excessive travel of the pressure plate before releasing.

Fortunately removing the clutch is not terribly difficult, but I'm not looking for work either. I feel sorry for you GT guys that have to go through the interior of the car.

Any Ideas???


Best Regards, Tom in SoCal.

[DWR46]

Tom: When you resurfaced the flywheel, did you check to make sure the flywheel-to-crank bolts still clear the disc when the disc is laid on the flywheel. As material is removed from the flywheel, the disc gets closer to the heads of the bolts holding the flywheel to the crankshaft. If they touch, you need to remove material from the heads of the bolts to "thin" the head. What I have described, can cause the condition you are experiencing. You can safely remove quite a bit of the bolt head and still be able to use the flywheel.

[Jumprun]

Tom: When you resurfaced the flywheel, did you check to make sure the flywheel-to-crank bolts still clear the disc when the disc is laid on the flywheel.

I did not check for this condition, I will certainly do so, something is hanging up the clutch from properly releasing. It confirms that I will need to pull the clutch. Oh yeah, it probably has no bearing on my problem but I also replaced the ring gear on the flywheel.

Thanks for the lead Dyke, can anyone else suggest anything else to look for?

--Tom in SoCal.

[BobA]

If the clutch disk is hitting the heads of the flywheel bolts, shouldn't it make quite a scraping noise when it is being released? If this is the problem, there should be easily visible evidence, correct? Bob

[DWR46]

Bob: You will not be able to hear the scraping (at least I have never been able to hear anything). However, the bolt heads and the disc will definitely show signs of the contact. Sometimes the interference can be cured by eliminating the lock tabs under the bolt heads and using Locktite to secure the flywheel bolts. Many times this will help "lower" the bolt heads enough to clear the disc.

[afwrench]

I have seen the disc put in wrong side to the flywheel resulting in similar problems. Good luck,Mike

[Timo]

Tom (in SoCal),
Have you consulted your service manual and established your clutch specs are within given tolerances ?
Based on my (limited) experiences on Daytonas (which according to my 330 GTC service manual appear to have similar flywheel/clutch assembly, but cable instead of hydraulically operated ?) I seen multiple variables potentially contributing to clutch woes on these now 40+ year old car with who knows how many REAL miles or what type of, if any, maintenance or repairs have been performed over the years/decades.
Latest is one of the examples in the shop right now. It came in with similar problem (with previously installed NEW clutch and all !) and had been previously assembled/adjusted/disassembled several times and various (unsuccessful ?) efforts had been attempted to correct the problem.
I'm fairly sure I've got it sorted now, but due other still pending unrelated work won't have full proof until I get the engine and rest of the running gear back in and running, hopefully in few weeks.

[Timo]

P.S. One of the previously overlooked items requiring inevitable replacement is/was flywheel...

P.P.S. I still seriously dislike interweb forums where self-editing posts (even if time limited ?) is not an option for established members..;-(

[tyang]

P.S. One of the previously overlooked items requiring inevitable replacement is/was flywheel...

P.P.S. I still seriously dislike interweb forums where self-editing posts (even if time limited ?) is not an option for established members..;-(

O.K. Timo, I set the forum to allow editing for 15 minutes after your initial post for everyone!

Tom

[Jumprun]

Tom (in SoCal),
Have you consulted your service manual and established your clutch specs are within given tolerances ?

Yes I did use all the manuals and references available, but when I get it taken apart again I'll start at the beginning and measure/check everything. My wishful thinking has me wanting to believe that my dumb chief mechanic simply installed it with the wrong face forward.

oops, I forgot, I'm the chief mechanic.

Tom in SoCal.

[Timo]

O.K. Timo, I set the forum to allow editing for 15 minutes after your initial post for everyone!
Tom

Thanks Tom Y.
I know you've previously explained reasons behind your decision for not allowing self-editing, but can't remember them now.
For some one like me (with OCD) any little leeway helps, although 2-24 hr window would be even nicer as I often realize few hours later or next day how I could've expressed my views better or perhaps more appropriately...
I've even caught myself on several occasions not offering advice or opinion just for this reason. Go figure...

[Jumprun]

I removed my clutch and unfortunately I didn't find the smoking gun. I re-checked everything, the new disc and pressure plate all seem to be up to the published dimensional specs. I even had the disc oriented correctly, imagine that! I found no interference or anything else that my be dragging on the disc. The flywheel bolt heads had more than enough clearance.

I did a little experiment on the bench by rigging up a test under my drill press. I clamped the new pressure plate and disc down with the appropriate risers to simulate the flywheel and found that it takes about .200" inch movement of the throw out bearing contact ring and springs before the clutch disc is free to move. I then did the same test with my old pressure plate and new disc and I got about .175" inch before the disc was free. In both test the PP spring plate was flat and went concave when compressed to the release point. I didn't measure how much the actual PP moves but it is moving. Oh yeah, I did notice that the springs on the new PP were quite a bit stiffer than my old PP.

As a related tangent, I also did some calculations to determine what the movement of the release lever should be in relation to the required .25mm of resting clearance between the TOB and pressure plate spring contact ring. It turns out to be a ratio of 1:2.4, in simpler terms if you want to get .25mm of clearance at the TOB you can multiply that by 2.4 to see how much free travel you should have at the end (where the slave cylinder actuating rod connects) of the lever arm. So, you need to have about .24"inch of free travel of the lever arm to get the required .25mm TOB clearance. I probably had about .5"inch free travel at the lever before, so I will tighten this up but my observations say this difference will not bring the pedal up where it should be.

Sorry about the mix of metric and US measurements, my tool box and brain were filled along time ago and it's too late to replace either.

So unless someone else has some other idea I'm going to put it all back together, adjust everything and hope it's better.

Best Regards, --Tom in SoCal.