2011 GT 5.0: Clutch Issue: Part III
6/7/10, 06:03 PM
#1
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2011 GT 5.0: Clutch Issue: Part III
2011 GT 5.0 Clutch Issue: Part III
My issue with what appeared to be an overcentering clutch appears to be caused by a combination of tolerance stack-up and an overly strong counter-balance spring (to lighten clutch effort).
Overcentering:
When the clutch pedal is depressed the fingers on the clutch are depressed close to the center of the diaphram spring. The closer they come to going past center the lighter the spring pressure becomes until if it goes past center the force actually goes negative. At high rpm centrifugal force acting on the fingers cause increased deflection.
My Car:
In my case the clutch is not actually overcentering but we are reaching a point at which the pressure is lighter than the counterbalance spring force. When this happens the pedal goes to the floor. So even though the clutch is not overcentering the result is the same. You must wait on the rpm to drop or physically pull the pedal back up a couple of inches before it can overcome the counterbalance spring.
My car is being fitted with a revised pedal-box spring assembly which I believe to be the one now listed in the parts catalog for Job 2 (8-15-2010) cars.
If you dont have an issue dont worry about it but if you do this would be my starting point. I supect the offending spring could be eliminated completely at the cost of increased clutch effort but you go their at your own risk.
I wasnt going to post this until my car was actually fixed but the latest plan is to replace all parts at one time (they are replacing the entire clutch system im my car) so I will have no way to confirm the actual fix.
PS Could one of the mods please fix the subject line. Thanks!
My issue with what appeared to be an overcentering clutch appears to be caused by a combination of tolerance stack-up and an overly strong counter-balance spring (to lighten clutch effort).
Overcentering:
When the clutch pedal is depressed the fingers on the clutch are depressed close to the center of the diaphram spring. The closer they come to going past center the lighter the spring pressure becomes until if it goes past center the force actually goes negative. At high rpm centrifugal force acting on the fingers cause increased deflection.
My Car:
In my case the clutch is not actually overcentering but we are reaching a point at which the pressure is lighter than the counterbalance spring force. When this happens the pedal goes to the floor. So even though the clutch is not overcentering the result is the same. You must wait on the rpm to drop or physically pull the pedal back up a couple of inches before it can overcome the counterbalance spring.
My car is being fitted with a revised pedal-box spring assembly which I believe to be the one now listed in the parts catalog for Job 2 (8-15-2010) cars.
If you dont have an issue dont worry about it but if you do this would be my starting point. I supect the offending spring could be eliminated completely at the cost of increased clutch effort but you go their at your own risk.
I wasnt going to post this until my car was actually fixed but the latest plan is to replace all parts at one time (they are replacing the entire clutch system im my car) so I will have no way to confirm the actual fix.
PS Could one of the mods please fix the subject line. Thanks!
Last edited by Gene K; 6/7/10 at 06:24 PM.
6/7/10, 06:09 PM
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Thanks for keeping us posted.
Is the dealer or Ford giving you a loaner during this process or are you driving the car until they can preform the service (same day) while you wait?
Is the dealer or Ford giving you a loaner during this process or are you driving the car until they can preform the service (same day) while you wait?
6/7/10, 06:10 PM
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My issue with what appeared to be an overcentering clutch appears to be caused by a combination of tolerance stack-up and an overly strong counter-balance spring (to lighten clutch effort).
Overcentering:
When the clutch pedal is depressed the fingers on the clutch are depressed close to the center of the diaphram spring. The closer they come to going past center the lighter the spring pressure becomes until if it goes past center the force actually goes negative. At high rpm centrifugal force acting on the fingers cause increased deflection.
My Car:
In my case the clutch is not actually overcentering but we are reaching a point at which the pressure is lighter than the counterbalance spring force. When this happens the pedal goes to the floor. So even though the clutch is not overcentering the result is the same. You must wait on the rpm to drop or physically pull the pedal back up a couple of inches before it can overcome the counterbalance spring.
My car is being fitted with a revised pedal-box spring assembly which I believe to be the one now listed in the parts catalog for Job 2 (8-15-2010) cars.
If you dont have an issue dont worry about it but if you do this would be my starting point. I supect the offending spring could be eliminated completely at the cost of increased clutch effort but you go their at your own risk.
PS I wasnt going to post this until my car was actually fixed but the latest plan is to replace all parts at one time (they are replacing the entire clutch system im my car) so I will have no way to confirm the actual fix.
Overcentering:
When the clutch pedal is depressed the fingers on the clutch are depressed close to the center of the diaphram spring. The closer they come to going past center the lighter the spring pressure becomes until if it goes past center the force actually goes negative. At high rpm centrifugal force acting on the fingers cause increased deflection.
My Car:
In my case the clutch is not actually overcentering but we are reaching a point at which the pressure is lighter than the counterbalance spring force. When this happens the pedal goes to the floor. So even though the clutch is not overcentering the result is the same. You must wait on the rpm to drop or physically pull the pedal back up a couple of inches before it can overcome the counterbalance spring.
My car is being fitted with a revised pedal-box spring assembly which I believe to be the one now listed in the parts catalog for Job 2 (8-15-2010) cars.
If you dont have an issue dont worry about it but if you do this would be my starting point. I supect the offending spring could be eliminated completely at the cost of increased clutch effort but you go their at your own risk.
PS I wasnt going to post this until my car was actually fixed but the latest plan is to replace all parts at one time (they are replacing the entire clutch system im my car) so I will have no way to confirm the actual fix.
Last edited by montreal ponies; 6/7/10 at 06:11 PM.
6/7/10, 06:18 PM
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Im driving the car. The issue only occurs at 6400+ rpm. In daily driving its a non-issue.
Its going to take more than a day (They are replacing the entire mechanical and hydraulic system. I assume its being shipped to engineering to check all the tolerances ansd possibly bench test the assembly).
Im getting a loaner.
Last edited by Gene K; 6/7/10 at 06:22 PM.
6/7/10, 06:22 PM
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The revised part from Ford Engineering is here. Some of the regular production parts are causing a holdup. I believe they may be coming from production.
Im driving the car. The issue only occurs at 6400+ rpm. In daily driving its a non-issue.
Its going to take more than a day (They are replacing the entire mechanical and hydraulic system I assume so they can ship it all to engineering for a look see). Im getting a loaner.
Im driving the car. The issue only occurs at 6400+ rpm. In daily driving its a non-issue.
Its going to take more than a day (They are replacing the entire mechanical and hydraulic system I assume so they can ship it all to engineering for a look see). Im getting a loaner.
6/7/10, 06:23 PM
#8
MOTM Committee Member
this is cool gene and thanks for sharing. Its almost like you're lucky to have the problem cuz I'd love to chat it up with some Ford engineers. You can ask them stuff about the car no one else would know
6/7/10, 06:25 PM
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6/7/10, 07:00 PM
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The newer cars don't have the revised part yet as far as we can tell. If Ford decides to bump up the introduction date then the part site will change to reflect the earlier date. As it stands the part is slated to go online for Job 2.
7/16/10, 04:27 PM
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Here's a video that shows how the design of the 2011 pedals overcenters. It's not the clutch, but the pedals that do it.
Some more info comparing the 2011 GT pedal tree to the 2010 GT500.
By the way the Dual-mass flywheel that we heard about (and KC showed us pics of), did NOT make it into production. 2011 GT's are shipping with a standard type flywheel and clutch.
Some more info comparing the 2011 GT pedal tree to the 2010 GT500.
By the way the Dual-mass flywheel that we heard about (and KC showed us pics of), did NOT make it into production. 2011 GT's are shipping with a standard type flywheel and clutch.
7/16/10, 07:10 PM
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7/17/10, 01:44 AM
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Here's a video that shows how the design of the 2011 pedals overcenters. It's not the clutch, but the pedals that do it.
By the way the Dual-mass flywheel that we heard about (and KC showed us pics of), did NOT make it into production. 2011 GT's are shipping with a standard type flywheel and clutch.
By the way the Dual-mass flywheel that we heard about (and KC showed us pics of), did NOT make it into production. 2011 GT's are shipping with a standard type flywheel and clutch.
and im still wondering why they switched to hydraulics.. had no issues with "pedal pressure" on my 95
running a centerforce II clutch with a tremec and a fork out of and fox body with the stock quadrant.. the secret was making sure the **** cable stayed lubricated.. and pedal pressure was a light as it is on the 2011
7/17/10, 07:23 AM
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I'm guessing the design was intended to provide a lighter feel when the clutch is pressed in. Kind of like how a compound bow works. They probably just need to tweak it a bit.
7/17/10, 08:17 AM
#16
Shelby GT350 Member
Gene, sorry you're dealing with this.... but I guess we're lucky that it's you because you have been awesome about keeping everyone informed.
Thank you!
Good luck... looking forward to hearing that you car is perfect after the instalation of the revised box.
Thank you!
Good luck... looking forward to hearing that you car is perfect after the instalation of the revised box.
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