Clutch engagement question
Thread Starter
Instructor
Joined: Aug 2006
Posts: 151
Likes: 1
From: Dupont WA
Clutch engagement question
I drove a car today that I really like. I have a question about the clutch engagement, though. The Vette is a 96 with the 6 speed. The clutch doesn't begin to engage until the very top of travel. That is, it disengages for shifting with just a little downward travel and reengages at the same place. It works well, but I've never had a clutch with that kind of feel.
I also drove a 90 manual today and its clutch worked more like I'm used to (like in my 03 Jetta Turbo and other cars I've owned/driven). You push it all the way to the floor and it disengages and when letting it back out, it starts to reengage just a little bit off the floor.
Is one of these conditions more "normal" or usual? Since it is a hydraulic clutch, I wouldn't think this would have anything to do with clutch wear, but does it? Is this something to be concerned about or just a matter of preference and what I'm used to? Is this adjustable? If this is a sign of a worn clutch, what does a clutch job run on a LT-4/6-speed combo?
Thanks!
rob
I also drove a 90 manual today and its clutch worked more like I'm used to (like in my 03 Jetta Turbo and other cars I've owned/driven). You push it all the way to the floor and it disengages and when letting it back out, it starts to reengage just a little bit off the floor.
Is one of these conditions more "normal" or usual? Since it is a hydraulic clutch, I wouldn't think this would have anything to do with clutch wear, but does it? Is this something to be concerned about or just a matter of preference and what I'm used to? Is this adjustable? If this is a sign of a worn clutch, what does a clutch job run on a LT-4/6-speed combo?
Thanks!
rob
Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
Originally Posted by CentralCoaster
New oem clutches are $240-$300. Flywheels are $1000. Dunno about labor costs.
As for the engagement, I'm curious as well.
As for the engagement, I'm curious as well.
CC,
We've both done ZF-6 TransPlants on our early C4s. Mine's an 84. My clutch engages just off the floor. I used a Fidanza AL FW with an SLP sprung hub disk. What about yours? My friend =Jeff= thinks I may have a bent clutch pedal.
BTW, pulled the slave off mine yesterday after I started losing hyd fluid. Although the seal was correctly installed on the slave cylinder plunger, the micro ridges were pretty well shot.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Originally Posted by Dominic Sorresso
CC,
We've both done ZF-6 TransPlants on our early C4s. Mine's an 84. My clutch engages just off the floor. I used a Fidanza AL FW with an SLP sprung hub disk. What about yours? My friend =Jeff= thinks I may have a bent clutch pedal.
BTW, pulled the slave off mine yesterday after I started losing hyd fluid. Although the seal was correctly installed on the slave cylinder plunger, the micro ridges were pretty well shot.
We've both done ZF-6 TransPlants on our early C4s. Mine's an 84. My clutch engages just off the floor. I used a Fidanza AL FW with an SLP sprung hub disk. What about yours? My friend =Jeff= thinks I may have a bent clutch pedal.
BTW, pulled the slave off mine yesterday after I started losing hyd fluid. Although the seal was correctly installed on the slave cylinder plunger, the micro ridges were pretty well shot.
Race Director
Joined: Mar 1999
Posts: 12,597
Likes: 237
From: Bartlett Illinois
my 89 with a ZF starts to engage about 1 to 1.5 inches from the floor, with full engagement near the top of the pedal. This is correct according to Bill B. (www.zfdoc.com) I have a brand new Clutch with a Fidanza Al. FW, Carolina Stage 1 disc and Centerforce Pressure Plate. I am planning on converting to a RAM push type setup in the next year or so.
My hydraulics are new. neither are leaking after 3 months of fighting with them..
Oh and dominic, your Micro edge seals on your slave were non existant.. LOL
My hydraulics are new. neither are leaking after 3 months of fighting with them..
Oh and dominic, your Micro edge seals on your slave were non existant.. LOL
Racer
Joined: Feb 2002
Posts: 390
Likes: 0
From: St. Louis MO
Hmmm......I've just replaced my OEM clutch with a Carolina Clutch replacement and the pressure point has moved from the very top end of travel (OEM clutch) to ~2 inches off the floor. I'm wondering the same thing about "normal". The old clutch wasn't worn all that badly (really didn't look like it needed replacing but since I had the tranny down.......) the new pressure point is difficult to get accustomed to - I keep killing the engine off the line!
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Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
Originally Posted by -=Jeff=-
my 89 with a ZF starts to engage about 1 to 1.5 inches from the floor, with full engagement near the top of the pedal. This is correct according to Bill B. (www.zfdoc.com) I have a brand new Clutch with a Fidanza Al. FW, Carolina Stage 1 disc and Centerforce Pressure Plate. I am planning on converting to a RAM push type setup in the next year or so.
My hydraulics are new. neither are leaking after 3 months of fighting with them..
Oh and dominic, your Micro edge seals on your slave were non existant.. LOL
My hydraulics are new. neither are leaking after 3 months of fighting with them..
Oh and dominic, your Micro edge seals on your slave were non existant.. LOL
Jeff not only solved the mystery of the leaking slave cylinders, but he also found out that the clutch pedal "stalk" will bend. That's my problem. The stalk is bent down causing the engagement point of the clutch to require pushing pedal to the floor. Clutch engages just off the floor. Jeff doesn't like driving it cause he kills the motor.
Thread Starter
Instructor
Joined: Aug 2006
Posts: 151
Likes: 1
From: Dupont WA
I traded a couple of email with Bill Boudreau at zfdoc.com about this. I don't want to post the entire messages without his permission, but the gist is as follows:
With a 6-speed C4 Corvette clutch hydraulic system which is actuating a stock clutch system, disengagement should begin at the first 1.0 – 1.5 inches of travel downwards. The clutch pedal must be depressed all the way to the floor when shifting all gears. Reengagement should begin at the first 1.5 – 2.0 inches of travel upwards. Wear-rate of the (engine-to-transmission) clutch is not affected by a problematic clutch hydraulic system. The clutch hydraulic system is self-adjusting as the clutch wears.
When I pressed him for what is the most-likely cause for the clutch pedal condition I experienced, he said:
It is a clutch hydraulic problem. Plan on buying a new master and slave hydraulic cylinder if you buy the vehicle.
So...thank you very much Bill!
Rob
With a 6-speed C4 Corvette clutch hydraulic system which is actuating a stock clutch system, disengagement should begin at the first 1.0 – 1.5 inches of travel downwards. The clutch pedal must be depressed all the way to the floor when shifting all gears. Reengagement should begin at the first 1.5 – 2.0 inches of travel upwards. Wear-rate of the (engine-to-transmission) clutch is not affected by a problematic clutch hydraulic system. The clutch hydraulic system is self-adjusting as the clutch wears.
When I pressed him for what is the most-likely cause for the clutch pedal condition I experienced, he said:
It is a clutch hydraulic problem. Plan on buying a new master and slave hydraulic cylinder if you buy the vehicle.
So...thank you very much Bill!
Rob
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
That sounds like b.s.
The only way a clutch is going to disengage early is if the fork is somehow preloading the t/o bearing, or the pressure plate spring is weak.
The only way a clutch is going to disengage early is if the fork is somehow preloading the t/o bearing, or the pressure plate spring is weak.
Team Owner
Joined: Jun 2005
Posts: 46,295
Likes: 2,596
From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
Mine started out and is still engaging about 1/3 of the way off the floor. There is about 1/2-1 inch of free play at the top. Otherwise, it works fine. Oh, it is an LT4.