Center force clutch problems
Thread Starter
Pro
Joined: May 2008
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Center force clutch problems
Any one else have problems with there center force DF clutch. I suspect the weights go off center causing intermittent drive line vibrations. Also it shutters at low speeds such as backing out of my drive way. When the car is ran at the track or auto x it does not take long for its holding ability fades. It's release point is slightly different after a long hot highway drive vs cold.
Le Mans Master
Joined: Oct 2007
Posts: 7,454
Likes: 977
From: RI, Now Franklin/Nashville TN
I consulted with my engine builder for the bottom end of my L-82 when I rebuilt it in 2014 about clutches and he suggested RAM HDX for high HP applications with stock clutch feel and I went with RAM....Might want to consider as a replacement if you go that route...real nice with stock clutch effort. I paid to have my flywheel and clutch balanced...very smooth with no vibration at mid to high rpm...I was shocked the first time I revved the motor compared to the OEM L-82/clutch/flywheel vibrations.
Last edited by jb78L-82; Sep 2, 2015 at 05:58 AM.
Melting Slicks
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From: Gulf of America
2023 C7 of the Year Finalist - Unmodified
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Had a 1976 L-82, 4-sp
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From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
I have the CF DFX. No problems with it. It does have some chatter starting off but that's because it needs to rev a few hundred rpm's higher which most times eliminates it. Also, CF does state that for street use there maybe some clutch chatter. It sure does grab! I don't have any vibration issues either.
Thread Starter
Pro
Joined: May 2008
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I have the CF DFX. No problems with it. It does have some chatter starting off but that's because it needs to rev a few hundred rpm's higher which most times eliminates it. Also, CF does state that for street use there maybe some clutch chatter. It sure does grab! I don't have any vibration issues either.
Can I remove the weights??
Race Director
Joined: Dec 1999
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From: Forked River NJ
Mine also grabs really well until lit gets really hot, but to get that hot its got to be at a track, no issues on the street, or even the drag strip. I can live with the chatter but not the vibration. I guess the weights really move around because some times it's significantly worse than other times.
Can I remove the weights??
Can I remove the weights??
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Safety Car
Joined: May 2004
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From: los altos hills california
How's this for off center! That would be the throwout bearing making these grooves.
I called them once and the tech said the weights contribute maybe 10% holding force at the RPM limit. Definitely a gimmick. If you ditch the weights which is easy to do, it is a pretty good clutch.
And yet ... a new CF clutch, with weights, in my car now works just fine. The new weight system appears to be a bit different from what I show here. It defies my understanding of centrifugal force to see how they would self center. Multiple sliding weights make for a somewhat complex dynamical system. I went so far as to try looking up their patent but was unsuccessful.
I called them once and the tech said the weights contribute maybe 10% holding force at the RPM limit. Definitely a gimmick. If you ditch the weights which is easy to do, it is a pretty good clutch.
And yet ... a new CF clutch, with weights, in my car now works just fine. The new weight system appears to be a bit different from what I show here. It defies my understanding of centrifugal force to see how they would self center. Multiple sliding weights make for a somewhat complex dynamical system. I went so far as to try looking up their patent but was unsuccessful.
Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
The weights work and they self center. When the DF first came out it was blamed for a myriad of vibration issues because when trying to solve a vibration problem the clutch was often looked at.
You can imagine how easy it was to blame the clutch when looking at it and the weights drooped downward off center. But if the fingers and weights are in good condition they will center themselves as soon as the engine starts up.
I have run the DF clutch for 10+ years and it handled power ranges from 400-600HP with absolutely no vibration or slipping. Matter of fact the same 10+ year old clutch clamps down hard on my 600HP 427ci small block on the street and at the drag strip.
I have only replaced the friction plate and the old pressure plate /clutch and the weights work perfect with 6000RPM shifts at the drag strip. That is more than enough proof I need to buy another one when and if the current one needs replacing.
You can imagine how easy it was to blame the clutch when looking at it and the weights drooped downward off center. But if the fingers and weights are in good condition they will center themselves as soon as the engine starts up.
I have run the DF clutch for 10+ years and it handled power ranges from 400-600HP with absolutely no vibration or slipping. Matter of fact the same 10+ year old clutch clamps down hard on my 600HP 427ci small block on the street and at the drag strip.
I have only replaced the friction plate and the old pressure plate /clutch and the weights work perfect with 6000RPM shifts at the drag strip. That is more than enough proof I need to buy another one when and if the current one needs replacing.
Safety Car
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From: los altos hills california
Care to explain why? And don't just answer "centrifugal force". The centrifugal force is omega-square x R, so the further out on R you are, the more the force. Hence the off center weights that are further out want to stay there. The only thing I can surmise is there is an offsetting force because the weights nearer the center are denser and their combined density makes it work. Also because the weights are sliding on the fingers which is not perpendicular to omega there is a vector component there. Perhaps a free body diagram, or .....
Clearly too my severely stuck weights require some sort of explanation. That was a fairly new clutch.
Clearly too my severely stuck weights require some sort of explanation. That was a fairly new clutch.
Racer
Joined: Jan 2015
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From: Vernon B.C.
If it were me I and the pressure plate is still in good shape I would take the weights off and try it. I think the weights are a bit of a gimmick on that type of clutch myself. On racing pressure plates the weights are tunable and I don't see any of that on these. Just my 0.02 cents.....
Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Care to explain why? And don't just answer "centrifugal force". The centrifugal force is omega-square x R, so the further out on R you are, the more the force. Hence the off center weights that are further out want to stay there. The only thing I can surmise is there is an offsetting force because the weights nearer the center are denser and their combined density makes it work. Also because the weights are sliding on the fingers which is not perpendicular to omega there is a vector component there. Perhaps a free body diagram, or .....
Clearly too my severely stuck weights require some sort of explanation. That was a fairly new clutch.
Clearly too my severely stuck weights require some sort of explanation. That was a fairly new clutch.
with increased holding capacity as RPM increase.
Many things can cause a clutch failure and I didn't I didn't design the clutch nor did I install it in your car ( which could easily be the problem), phone this number and ask why your weights stuck : 928-771-8422
I know mine self center not sure about yours
Safety Car
Joined: May 2004
Posts: 4,364
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From: los altos hills california
Sorry, I am not trying to yank your chain. Lots of discussion on this in previous posts including in part by me
https://www.corvetteforum.com/forums...ce-clutch.html
I can see that as the clutch spins up, the weights will all move outwards, and, because of the angle on the pressure plate fingers, they will exert additional clamping pressure. After thinking about this some more I'm guessing that if the restraining wire that passes through all of the weights was too short, all the weights can't fly out equally as far and that creates an imbalance, maybe? My conjecture about the mass density of the weights is probably overthinking things a tad.
I still have the clutch in the picture but seem to have lost the baggie full of weights that I removed so I can't check on that. Clearly my weights were badly stuck and for a completely stock clutch setup, throwout bearing, bell housing and all the linkage.
And the new clutch in my car, with a new weight configuration works just fine. No imbalance that I can detect.
Here's the new clutch. Notice that these weights are already out near the perimeter, so maybe that's all there is to it, not enough free play in the old design? You can see where the restraining wire ends at about the 1:00 position.
https://www.corvetteforum.com/forums...ce-clutch.html
I can see that as the clutch spins up, the weights will all move outwards, and, because of the angle on the pressure plate fingers, they will exert additional clamping pressure. After thinking about this some more I'm guessing that if the restraining wire that passes through all of the weights was too short, all the weights can't fly out equally as far and that creates an imbalance, maybe? My conjecture about the mass density of the weights is probably overthinking things a tad.
I still have the clutch in the picture but seem to have lost the baggie full of weights that I removed so I can't check on that. Clearly my weights were badly stuck and for a completely stock clutch setup, throwout bearing, bell housing and all the linkage.
And the new clutch in my car, with a new weight configuration works just fine. No imbalance that I can detect.
Here's the new clutch. Notice that these weights are already out near the perimeter, so maybe that's all there is to it, not enough free play in the old design? You can see where the restraining wire ends at about the 1:00 position.
Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Not sure if you can see it but the weights have an abnormal amount of crap around them. I can see that clutch getting out of balance very easily. The weights can't move because of all debris around them.
Safety Car
Joined: May 2004
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From: los altos hills california
If you look at the new clutch, CF has added another feature. Look carefully, after every three weights there is a sliding stop on each lever arm. Look at 6 o'clock for instance. I assume that is to keep the weights from getting out too far. Probably another band aid to prevent what happened in the first version.