changing clutch fork ball stud
Thread Starter
Racer
Joined: Feb 2009
Posts: 265
Likes: 0
changing clutch fork ball stud
Hi all,
Bought an '81 recently and knew the clutch was very heavy for having a centerforce. (I put one in my '71). Couldn't find much wrong or to adjust. Finally called centerforce, and they said the (ahem) "mechanics" that installed it didn't check the geometry and it needs a different ball stud.
Also explains the receipt that says something about fabricating a new clutch linkage to accomodate an aftermarket clutch.
Probably dumb question, but is it possible to change the ball without pulling the tranny? I'm guessing not, but just in case..... I can even see the stupid thing just looking under the car....
Thanks,
Dave K
Bought an '81 recently and knew the clutch was very heavy for having a centerforce. (I put one in my '71). Couldn't find much wrong or to adjust. Finally called centerforce, and they said the (ahem) "mechanics" that installed it didn't check the geometry and it needs a different ball stud.
Also explains the receipt that says something about fabricating a new clutch linkage to accomodate an aftermarket clutch.
Probably dumb question, but is it possible to change the ball without pulling the tranny? I'm guessing not, but just in case..... I can even see the stupid thing just looking under the car....
Thanks,
Dave K
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
no it is not possible to change the pivot ball without separating the tranny from the bell housing.
The pivot ball stud length has nothing to do with with how much clutch foot pressure is required.
The pivot ball length only varies the amount of clearance from the throw out bearing to the pressure plate fingers. Pedal pressure can only be changed by mechanical advantage of the upper Z-bar lengths or a whole new pressure plate assembly
The pivot ball stud length has nothing to do with with how much clutch foot pressure is required.
The pivot ball length only varies the amount of clearance from the throw out bearing to the pressure plate fingers. Pedal pressure can only be changed by mechanical advantage of the upper Z-bar lengths or a whole new pressure plate assembly
Thread Starter
Racer
Joined: Feb 2009
Posts: 265
Likes: 0
Are different length z-bars available or can they be altered to give different leverage?
I thought centerforce clutches were supposed to give better holding without increasing the pedal effort. I know it's a centerforce- I can see the weights thru the clutch fork opening- (it also doesn't have the rubber boot in there).
I do have a regular stock clutch from my '71 with very few miles on it. Should hold the 330 hp on my '81- I just don't feel like tearing it all apart because of this.
Thanks,
Dave K
I thought centerforce clutches were supposed to give better holding without increasing the pedal effort. I know it's a centerforce- I can see the weights thru the clutch fork opening- (it also doesn't have the rubber boot in there).
I do have a regular stock clutch from my '71 with very few miles on it. Should hold the 330 hp on my '81- I just don't feel like tearing it all apart because of this.
Thanks,
Dave K
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
To change the foot pedal required pressure to less. You need to have the fire wall rod to the very top of the Z-bar arm. The lower bar could have a hole drilled to shorten its rod attachment position.
The problem is that these changes also increase the pedal throw from engaged to disengaged.
You might just have to go to the gym and work on a leg machine!
The problem is that these changes also increase the pedal throw from engaged to disengaged.
You might just have to go to the gym and work on a leg machine!
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
If your 81 still uses the same or similar clutch hardware as the older C3s, like my 68, with a centerforce clutch you need to change to a longer clutch fork ball stud. If you try to adjust your clutch you will find yourself with the nut at the very end of the rod with nowhere else to go - unless... you can lengthen that clutch rod. This is a bubba fix, it supposedly changes the clutch geometry and is less than ideal, but it does work - there are 2 ways to lengthen the stock clutch rod. One is to substitute a Mr Gasket adjustable clutch rod. The other is to modify the stock rod to make it longer. Did both, and its worked ok for the past 7 years or so.
Thread Starter
Racer
Joined: Feb 2009
Posts: 265
Likes: 0
The lower bar could have a hole drilled to shorten its rod attachment position.
Tried that yesterday, but gave up after none of my drill bits would scratch the thing. Either that is really hard steel or my drill bits are dull and crappy, and I thought they were relatively new and good quality.
Tried that yesterday, but gave up after none of my drill bits would scratch the thing. Either that is really hard steel or my drill bits are dull and crappy, and I thought they were relatively new and good quality.
Thread Starter
Racer
Joined: Feb 2009
Posts: 265
Likes: 0
[QUOTE=PRNDL;1575690322]If your 81 still uses the same or similar clutch hardware as the older C3s, like my 68, with a centerforce clutch you need to change to a longer clutch fork ball stud. If you try to adjust your clutch you will find yourself with the nut at the very end of the rod with nowhere else to go - unless... you can lengthen that clutch rod. This is a bubba fix, it supposedly changes the clutch geometry and is less than ideal, but it does work - there are 2 ways to lengthen the stock clutch rod. One is to substitute a Mr Gasket adjustable clutch rod. The other is to modify the stock rod to make it longer. Did both, and its worked ok for the past 7 years or so.
Just so I understand you right, if I lengthen the clutch rod, that will give me a lighter clutch pedal? Or do you mean I need to make a hole further up on the lower z-bar to improve the leverage and then need the longer clutch rod to make up the difference and keep it all within adjustable limits?
Just so I understand you right, if I lengthen the clutch rod, that will give me a lighter clutch pedal? Or do you mean I need to make a hole further up on the lower z-bar to improve the leverage and then need the longer clutch rod to make up the difference and keep it all within adjustable limits?
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
kunkle, your issue may be different from the typical problem after installing a centerforce clutch in a corvette. With mine the problem was not the effort required to push the clutch pedal, it was the distance. I had to press the clutch pedal all the way down to the floor in order to shift gears. I would often hit the bright light switch while shifting gears. In order to adjust the clutch pedal I would typically adjust the upper clutch rod, but when you run out of room on the upper clutch rod the alternative is to lengthen the lower rod, pictured above. When you described the action as "heavy" above I figured you had to push the pedal all the way to the floor, BUT..... if that is not your problem, sorry, never mind, I have led you astray.
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Melting Slicks
Joined: Apr 1999
Posts: 2,010
Likes: 3
From: Moon Twp. PA USA
I have a CF II clutch on my '76. The instructions that came with the clutch give a dimension from the pivot ball to the engine. I measured mine and it was ok.
So I am running the stock pivot ball with the CF without problems.
So I am running the stock pivot ball with the CF without problems.
