Lets talk about clutches
#63
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oh right, not organic.
I ran the tilton cerametallic disks when I first installed the twins. they were solid hub. I can't really say if the sprung hub would make a difference but these disks did not slip so I can't see how a sprung hub would make a difference.
that said, it's probably fine. those springs are pretty small compared to the forces in a clutch drop. I'd wager they bottom out pretty fast anyway.
I ran the tilton cerametallic disks when I first installed the twins. they were solid hub. I can't really say if the sprung hub would make a difference but these disks did not slip so I can't see how a sprung hub would make a difference.
that said, it's probably fine. those springs are pretty small compared to the forces in a clutch drop. I'd wager they bottom out pretty fast anyway.
#64
That is what I think. I don't think there is any way they could be stiff enough especially on a 1.6l size disk. The slop they have before they bottom out just serves to make it work sort of like a slide hammer and the impacts would be harsher to the drive line components during shifts and launches.
I just ordered a 4 puck solid disk.
Bob
I just ordered a 4 puck solid disk.
Bob
#65
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seriously never noticed a difference in "gentleness" going from stock sprung hub clutch to unsprung twin organic to single sprung FM level 1 clutch. it all feels the same for engagement.
#68
Got the new disk
Un-sprung 4 puck 1.6l = 1.75# for the disk
Sprung 6 puck 1.6l = 3 lbs for the disk
When the sprung 6 puck came out it was as I was thinking. The pucks were fine but the sprung center was on the verge of exploding. A couple of the rivets holding the center sprung mechanism together were pulled out from the slapping hard against the end of the spring travel. 300+ ft-lbs is too much for that small sprung center.
Bob
Un-sprung 4 puck 1.6l = 1.75# for the disk
Sprung 6 puck 1.6l = 3 lbs for the disk
When the sprung 6 puck came out it was as I was thinking. The pucks were fine but the sprung center was on the verge of exploding. A couple of the rivets holding the center sprung mechanism together were pulled out from the slapping hard against the end of the spring travel. 300+ ft-lbs is too much for that small sprung center.
Bob
#69
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Bob, any chance you could measure or calculate the spring rate?
http://www.engineersedge.com/spring_comp_calc_k.htm
calculate individual spring force:
F = T/(r*n)
(where r is the radius to the spring centerline, T is torque, n is num springs)
calculate spring displacement
x = F/k
(x = displacement at force, k = spring rate, calculated above)
and then (spring installed length - spring block height (fully compressed))
to see if the spring is partially compressed, fully compressed, or just plain smashed immediately.
ie I'm curious if they do anything.
http://www.engineersedge.com/spring_comp_calc_k.htm
calculate individual spring force:
F = T/(r*n)
(where r is the radius to the spring centerline, T is torque, n is num springs)
calculate spring displacement
x = F/k
(x = displacement at force, k = spring rate, calculated above)
and then (spring installed length - spring block height (fully compressed))
to see if the spring is partially compressed, fully compressed, or just plain smashed immediately.
ie I'm curious if they do anything.
#70
Instead of springs, my clutch disc has rubber bushings. When I flatfoot shift, there seems to be more of a thud than with the old spring hub disc. I speculate that the bushed hub would be lighter than a sprung hub.
Is that common in the clutch world to have a rubber bushed hub? Perhaps a bridge between a solid hub and a sprung hub? I can not say that I have seen it before in other discs.
Is that common in the clutch world to have a rubber bushed hub? Perhaps a bridge between a solid hub and a sprung hub? I can not say that I have seen it before in other discs.
#71
Instead of springs, my clutch disc has rubber bushings. When I flatfoot shift, there seems to be more of a thud than with the old spring hub disc. I speculate that the bushed hub would be lighter than a sprung hub.
Is that common in the clutch world to have a rubber bushed hub? Perhaps a bridge between a solid hub and a sprung hub? I can not say that I have seen it before in other discs.
Is that common in the clutch world to have a rubber bushed hub? Perhaps a bridge between a solid hub and a sprung hub? I can not say that I have seen it before in other discs.
Oh and a 1.8l SS disk is slightly lighter than the 1.6l sprung puck. The pucks themselves are heavy. The 1.6l pressure plate is lighter though. I just realized I have both 1.6 and 1.8 pressure plates out now, I will weigh pressure plates tonight for comparison.
Bob
#72
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That is an interesting observation. My guess is that the difference in durability is due to the different end of travel behavior of the two. The spring clutch eventually hits the spring lock and thus there is a sudden, big spike in stiffness (k). The rubber one essentially has its stiffness climbing continuously. It is like a bottomed out suspension hitting spring-lock instead of a rubber bump stop.
#73
Ok the pressure plate weight between 1.6 and .1.8l wasn’t as big as I thought. The Iron friction part is smaller but the stamped cover part is a bit more elaborate on the 1.6l making back some of the weight.
1.6l ACT Extreme PP 8.25 lbs.
1.8l ACT HD pressure plate 9.25 lbs.
What is going in my car,
1.6l Fidanza Flywheel----7.5 lbs.
1.6l 4 puck unsprung disk ----1.75 lbs.
1.6l ACT Extreme pressure plate ----8.25 lbs.
Total rotating assembly 17.5 lbs. For me it is streetable and it holds 300+ ft-lbs of torque reliably at the lowest weight available before stepping up to the 949 twin.
Bob
1.6l ACT Extreme PP 8.25 lbs.
1.8l ACT HD pressure plate 9.25 lbs.
What is going in my car,
1.6l Fidanza Flywheel----7.5 lbs.
1.6l 4 puck unsprung disk ----1.75 lbs.
1.6l ACT Extreme pressure plate ----8.25 lbs.
Total rotating assembly 17.5 lbs. For me it is streetable and it holds 300+ ft-lbs of torque reliably at the lowest weight available before stepping up to the 949 twin.
Bob
#77
Since we are talking cluthes, I know that there is also a 5.5" diameter clutch available. I talked to a Gentleman at Prather racing about it. We did not go into specifics, but I believe it is used in some of the unlimited naturally aspirated classes like E prod and such. Still uses the stock fork.
I have my doubts that a 5.5" would cut it in my application, but would love to drive a car with one just to see what it was like. I can only imagine blipping the throttle of a wildly modified BP with that clutch.
I have my doubts that a 5.5" would cut it in my application, but would love to drive a car with one just to see what it was like. I can only imagine blipping the throttle of a wildly modified BP with that clutch.
#78
Since we are talking cluthes, I know that there is also a 5.5" diameter clutch available. I talked to a Gentleman at Prather racing about it. We did not go into specifics, but I believe it is used in some of the unlimited naturally aspirated classes like E prod and such. Still uses the stock fork.
I have my doubts that a 5.5" would cut it in my application, but would love to drive a car with one just to see what it was like. I can only imagine blipping the throttle of a wildly modified BP with that clutch.
I have my doubts that a 5.5" would cut it in my application, but would love to drive a car with one just to see what it was like. I can only imagine blipping the throttle of a wildly modified BP with that clutch.
FWIW Mazdamotorsports sells 3 versions of flywheels for the 5.5" clutch. Steel with an aluminum ring gear ~4 lbs for the flywheel. A Tilton ceremetalic twin Rally clutch to fit it weighs 6.1 lbs and holds 500 ft-lbs.
I suspect getting the car rolling from a stop would often involve some wheel spinage with that setup.
Bob
#79
That is a lot of torque capacity. Much more than I thought.
I am not to concerned about street drivability. I just want it to be fast.
Many have told me that a light clutch and flyweel is not good for drag racing, but the higher big budget cars have pretty darn light clutch and flywheel combos. In my experience, lighter seemed to be better. In saying that, I would have to think that eventually you get to a point that the weight of the clutch would affect a drag car's 60' time enough to actually lower total elapsed times.
I hate to invest that kind of money only to find out it just does not work. However, if a clutch expert says to go for it, then I might. I wish I could get my hands on one to try without ponying up.
I am not to concerned about street drivability. I just want it to be fast.
Many have told me that a light clutch and flyweel is not good for drag racing, but the higher big budget cars have pretty darn light clutch and flywheel combos. In my experience, lighter seemed to be better. In saying that, I would have to think that eventually you get to a point that the weight of the clutch would affect a drag car's 60' time enough to actually lower total elapsed times.
I hate to invest that kind of money only to find out it just does not work. However, if a clutch expert says to go for it, then I might. I wish I could get my hands on one to try without ponying up.
#80
That is a lot of torque capacity. Much more than I thought.
I am not to concerned about street drivability. I just want it to be fast.
Many have told me that a light clutch and flyweel is not good for drag racing, but the higher big budget cars have pretty darn light clutch and flywheel combos. In my experience, lighter seemed to be better. In saying that, I would have to think that eventually you get to a point that the weight of the clutch would affect a drag car's 60' time enough to actually lower total elapsed times.
I hate to invest that kind of money only to find out it just does not work. However, if a clutch expert says to go for it, then I might. I wish I could get my hands on one to try without ponying up.
I am not to concerned about street drivability. I just want it to be fast.
Many have told me that a light clutch and flyweel is not good for drag racing, but the higher big budget cars have pretty darn light clutch and flywheel combos. In my experience, lighter seemed to be better. In saying that, I would have to think that eventually you get to a point that the weight of the clutch would affect a drag car's 60' time enough to actually lower total elapsed times.
I hate to invest that kind of money only to find out it just does not work. However, if a clutch expert says to go for it, then I might. I wish I could get my hands on one to try without ponying up.
Bob