John Z, Please Clarify
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Le Mans Master
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St. Jude Donor '05, '09, '15
John Z, Please Clarify
John
Please see your posts in the thread below. It looks like Corvettes used a bent finger diaphragm clutch with a short throwout bearing. The flat finger diaphragm was used in passenger cars with the long throwout bearing. Is there a reason one can't use a flat finger diaphragm pressure plate and a long throwout bearing in a Corvette? A 65 to be precise?
https://www.corvetteforum.com/forums...ring-size.html
Thanks
Tom
Please see your posts in the thread below. It looks like Corvettes used a bent finger diaphragm clutch with a short throwout bearing. The flat finger diaphragm was used in passenger cars with the long throwout bearing. Is there a reason one can't use a flat finger diaphragm pressure plate and a long throwout bearing in a Corvette? A 65 to be precise?
https://www.corvetteforum.com/forums...ring-size.html
Thanks
Tom
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Le Mans Master
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St. Jude Donor '05, '09, '15
Tom
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As I remember................................ ...
The straight finger clutches were subject to the clutch pedal hanging on the floor in a high rpm shift. The bent finger, not so much so.
I see no reason you can't use a flat finger/long throwout bearing in your car if that's your choice and if that McLeod clutch is built for a Chevy pass car.
The straight finger clutches were subject to the clutch pedal hanging on the floor in a high rpm shift. The bent finger, not so much so.
I see no reason you can't use a flat finger/long throwout bearing in your car if that's your choice and if that McLeod clutch is built for a Chevy pass car.
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If memory serves me I used a HD Z28 (diaphragm?) clutch from the early 70s in my 66. Worked great, never hung up. A bit stiff though. My left leg was a little bigger than my right after a few years of driving. 
And that was after a racing Sheifer clutch blew a spring out of the disc and mucked up the works! Stick with GM to be safe.
And that was after a racing Sheifer clutch blew a spring out of the disc and mucked up the works! Stick with GM to be safe.
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As I remember................................ ...
The straight finger clutches were subject to the clutch pedal hanging on the floor in a high rpm shift. The bent finger, not so much so.
I see no reason you can't use a flat finger/long throwout bearing in your car if that's your choice and if that McLeod clutch is built for a Chevy pass car.
The straight finger clutches were subject to the clutch pedal hanging on the floor in a high rpm shift. The bent finger, not so much so.
I see no reason you can't use a flat finger/long throwout bearing in your car if that's your choice and if that McLeod clutch is built for a Chevy pass car.
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Le Mans Master
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St. Jude Donor '05, '09, '15
Originally Posted by MikeM View Post
As I remember................................ ...
The straight finger clutches were subject to the clutch pedal hanging on the floor in a high rpm shift. The bent finger, not so much so.
I see no reason you can't use a flat finger/long throwout bearing in your car if that's your choice and if that McLeod clutch is built for a Chevy pass car.
As I remember................................ ...
The straight finger clutches were subject to the clutch pedal hanging on the floor in a high rpm shift. The bent finger, not so much so.
I see no reason you can't use a flat finger/long throwout bearing in your car if that's your choice and if that McLeod clutch is built for a Chevy pass car.
That is exactly correct! The flat finger will (or can) cause the the clutch pedal to remain on the floor (may occur around 5000rpm) until the rpm drops below about 4500rpm-------------------then suddenly, BAM, the pedal jumps back up. These clutches are great for grandma's mild mannered 58 4dr Chevy, but not a good idea for any performance driving which may occasionally see a little spirited engine zip.
Please forgive my persistence. Im a bit OCD, So if it had to do with high rpms did a high revving Z28 also use the bent finger style? How about an L79 in a passenger car? I'm just trying to understand.
Thanks
Tom
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I would call McLeod and ask them about the clutch you have and what RPM range it can be safely used without hanging up. It may be a special design and is good for the higher RPM.
In the early days, clutches were primarily a three finger type like B&B and Long. When the diaphragm clutch came on the scene it was flat fingered. It worked okay for the family driver, but created issues with the higher HP and higher RPM motors.
Schieffer and Hays Companies came out with the bent finger "Rev-Lok" design which pretty much eliminated the high RPM hang-up that Mike M and DZAuto mentioned. Other companies followed this design improvement. Once the design became field tested and worked well, GM and other began using them in all their cars and no longer using the 3-finger design.
One of their positive features is less pedal pressure and no longer needing the gorilla spring.
Larry
Last edited by Powershift; Feb 11, 2015 at 11:49 AM.
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Thread Starter
Le Mans Master
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From: Maryland
St. Jude Donor '05, '09, '15
Yes…………..both of the cars you mentioned used the bent finger diaphragm clutch plate.
I would call McLeod and ask them about the clutch you have and what RPM range it can be safely used without hanging up. It may be a special design and is good for the higher RPM.
In the early days, clutches were primarily a three finger type like B&B and Long. When the diaphragm clutch came on the scene it was flat fingered. It worked okay for the family driver, but created issues with the higher HP and higher RPM motors.
Schieffer and Hays Companies came out with the bent finger "Rev-Lok" design which pretty much eliminated the high RPM hang-up that Mike M and DZAuto mentioned. Other companies followed this design improvement. Once the design became field tested and worked well, GM and other began using them in all their cars and no longer using the 3-finger design.
One of their positive features is less pedal pressure and no longer needing the gorilla spring.
Larry
I would call McLeod and ask them about the clutch you have and what RPM range it can be safely used without hanging up. It may be a special design and is good for the higher RPM.
In the early days, clutches were primarily a three finger type like B&B and Long. When the diaphragm clutch came on the scene it was flat fingered. It worked okay for the family driver, but created issues with the higher HP and higher RPM motors.
Schieffer and Hays Companies came out with the bent finger "Rev-Lok" design which pretty much eliminated the high RPM hang-up that Mike M and DZAuto mentioned. Other companies followed this design improvement. Once the design became field tested and worked well, GM and other began using them in all their cars and no longer using the 3-finger design.
One of their positive features is less pedal pressure and no longer needing the gorilla spring.
Larry
Tom
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use a clutch pedal to the floor stop to prevent the sticking pedal from over centering the clutch. jack up the rear of the car,put the car in gear,have some one slowly push in the clutch while you try and turn the back tire. at the point you can turn the tire have the guy pushing the clutch in see how far off of the floor the clutch pedal is. install the clutch pedal stop to prevent the clutch pedal from going any farther. https://www.corvetteforum.com/forums...edal-stop.html
Last edited by PAmotorman; Feb 11, 2015 at 03:32 PM.
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On the other hand, I have had two of the flat finger clutches hang up but I fixed the problem like Clem suggested above by preventing the clutch from going over center on the pedal stroke.
All I remember is, the early flat finger clutches would hang up. I'm thinking some of the later ones didn't due to a design change internal to the pressure plate besides the fingers. That's been too many years ago though.
Thread Starter
Le Mans Master
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St. Jude Donor '05, '09, '15
use a clutch pedal to the floor stop to prevent the sticking pedal from over centering the clutch. jack up the rear of the car,put the car in gear,have some one slowly push in the clutch while you try and turn the back tire. at the point you can turn the tire have the guy pushing the clutch in see how far off of the floor the clutch pedal is. install the clutch pedal stop to prevent the clutch pedal from going any farther. https://www.corvetteforum.com/forums...edal-stop.html
I just took the clutch out of an original '66 L 79 that was in a Chevy II. I think it was flat finger but I'm not sure and I'm not home to check. That engine wouldn't rev but 5900 (according to a Sun tach) and it never hung to the floor on me.
On the other hand, I have had two of the flat finger clutches hang up but I fixed the problem like Clem suggested above by preventing the clutch from going over center on the pedal stroke.
All I remember is, the early flat finger clutches would hang up. I'm thinking some of the later ones didn't due to a design change internal to the pressure plate besides the fingers. That's been too many years ago though.
On the other hand, I have had two of the flat finger clutches hang up but I fixed the problem like Clem suggested above by preventing the clutch from going over center on the pedal stroke.
All I remember is, the early flat finger clutches would hang up. I'm thinking some of the later ones didn't due to a design change internal to the pressure plate besides the fingers. That's been too many years ago though.
Thanks
Tom
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What model number clutch do you have?? I have looked thru the McLeod clutch lineup for Chevrolet and do not see a straight finger clutch being offered. They are all bent finger diaphragm or B&B……or ultra high HP specials.
Larry
Larry
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http://www.mcleodracing.com/index.ph...pns-30559.html
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75225. It shows a bent finger in the pic but it's not.
http://www.mcleodracing.com/index.ph...pns-30559.html
http://www.mcleodracing.com/index.ph...pns-30559.html
I would not worry if it will hang up at high RPM. You can ask McLeod, but it is probably specially constructed for 7000 RPM or so without issue. McLeod is an excellent company, and they would not sell a track clutch that is good to 4500 RPM.
Just make sure you have the correct length TO bearing………..whichever length McLeod states for your car. You don't want to pull the trans to replace it later. You have to rely on them for their special product.
Larry