Why are Clutches more fragile than Brakes?
07-30-2007, 04:01 PM
#41
Originally Posted by MrDude_1
now, if you had a "brakepad like" material that was ment to slip, and adjusted it so it did slip just right, and made the material thicker....
....then you've just re-invented the slipper clutch. the same kind of drag race clutch alot of race cars use.
next, you'll want to put some clutch material and plates together and stack em.. ooh, better yet, lets have these stacks "lock" together with some pins as it goes down the track...... you know.. just like the big drag cars.
....then you've just re-invented the slipper clutch. the same kind of drag race clutch alot of race cars use.
next, you'll want to put some clutch material and plates together and stack em.. ooh, better yet, lets have these stacks "lock" together with some pins as it goes down the track...... you know.. just like the big drag cars.
If you start adding thick brade pad like material to a street clutch, you'll warp your flywheel in a hurry, and the "give" of the material (in shear) would be rather disconcerting as well, I'd think.
07-30-2007, 07:57 PM
#42
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Originally Posted by digitalsolo
If you start adding thick brake pad like material to a street clutch, you'll warp your flywheel in a hurry,
and the "give" of the material (in shear) would be rather disconcerting as well, I'd think.
07-30-2007, 08:13 PM
#43
Originally Posted by Gary Z
I don't follow you here. Brake and clutch friction materials both experience high shear forces.
In order to make brake pad like material viable as a clutch friction, it would require a much thicker friction material then a typical, current clutch would.
The difference in "give" as shear force is applied to a 1/2" thick pad material vs. a 1/8" thick pad material is appreciable, and even with a multi-disc setup (T/F bikes have 5-6 or more plate/steel surfaces), I'd think that this will be noticable. It would be less then a sprung disc, and when coupled with one, may not even be appreciable enough to be noticable, but it would exist, and be a "different" feel, especially on an unspring disc.
On brakes, this feeling is normal, and what we've always experienced. It also doesn't particularly exist on a carbon/carbon brake setup.
Make more sense?
07-30-2007, 09:26 PM
#44
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Originally Posted by digitalsolo
In order to make brake pad like material viable as a clutch friction, it would require a much thicker friction material than a typical, current clutch would.
07-31-2007, 09:33 AM
#46
Originally Posted by digitalsolo
On brakes, this feeling is normal, and what we've always experienced. It also doesn't particularly exist on a carbon/carbon brake setup.
Make more sense?
Make more sense?
its a very... umm.. unnerving feeling. i really dont like it.
you put the brake on, and nothing. its slowing but not good.. then its suddenly "holy ****, how is it stopping this fast!?!?!" and then you've overbraked and have to let off some.
i really really really dont like how they feel... maybe on a racetrack where they're always hot they work great.. but they "change" on you..
07-31-2007, 12:43 PM
#47
it does not matter what the clutch is made from or how well its vented. centrifugal force is going to be the cause of failure. just have a good bellhousing /scattersheild when it does come apart. have had the pucks fly right thru the bellhousing and lodge themselves into the trans tunnel
07-31-2007, 03:07 PM
#48
Originally Posted by ex-SS-ve
it does not matter what the clutch is made from or how well its vented. centrifugal force is going to be the cause of failure. just have a good bellhousing /scattersheild when it does come apart. have had the pucks fly right thru the bellhousing and lodge themselves into the trans tunnel
thats always a potential cause of failure, but.... well when my stock clutch starts slipping in my beater truck, its not going to come flying out... LOL.
but thanks. i think?
08-07-2007, 10:34 PM
#49
Actually, I don't know of a single off-brand POS clutch that would fly apart at 7000rpm when free-revved. So INERTIAL failure(there is no such thing as centrifugal force) is actually a symptom of a poorly made and overheated clutch, rather than an actual problem. A good analogy would be if you went to the doctor to treat a headache, and just received painkillers instead of taking the axe out of your skull. Therefore, the entire post about Centrifugal force and parts flying through the bellhousing is wrong.
08-26-2007, 07:11 AM
#50
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Originally Posted by Sparetire
I am no engineer. I know. I tried mech engineering school and concluded that I would go insane looking at that many excel sread sheets.
But one thing stuck with me more than any other. Find a simple solution.
Why cant we just vent the bell housing better? All the ones I have seen have pathetic little plastic rigs that have an opening about 3/4 inch area tops. The clutch disk in a normal type clutch does see air on the PP side. Puck types probably get airflow between the pucks. I'll bet some airflow is happening in a multi disk too. It would not be hard to beef up ribs on the bell housing to maintain or even improve strength.
More complex but using well developed tech: Use a clutch system similar to what some LSDs use. The clutch is surrounded by heat sensitive fluid. Fluid gets hot, clutch enages, as when slippage happens. This fluid could be used a cooling system, much as some hi-po LSDs on hard core road race apps use diff coolers. It might be perfect for slipper application on the drag strip. Might be hard to do on a street car at cruise though. Some sort of lock-up system at speed might be needed so that it acts normal after you initialy start out.
Meh, I like #1. Complexity is the enemy. A nesesary evil.
But one thing stuck with me more than any other. Find a simple solution.
Why cant we just vent the bell housing better? All the ones I have seen have pathetic little plastic rigs that have an opening about 3/4 inch area tops. The clutch disk in a normal type clutch does see air on the PP side. Puck types probably get airflow between the pucks. I'll bet some airflow is happening in a multi disk too. It would not be hard to beef up ribs on the bell housing to maintain or even improve strength.
More complex but using well developed tech: Use a clutch system similar to what some LSDs use. The clutch is surrounded by heat sensitive fluid. Fluid gets hot, clutch enages, as when slippage happens. This fluid could be used a cooling system, much as some hi-po LSDs on hard core road race apps use diff coolers. It might be perfect for slipper application on the drag strip. Might be hard to do on a street car at cruise though. Some sort of lock-up system at speed might be needed so that it acts normal after you initialy start out.
Meh, I like #1. Complexity is the enemy. A nesesary evil.
You could also use a "wet" clutch as used in most motorcycles.
08-26-2007, 07:22 AM
#51
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Originally Posted by gametech
Actually, I don't know of a single off-brand POS clutch that would fly apart at 7000rpm when free-revved. So INERTIAL failure(there is no such thing as centrifugal force) is actually a symptom of a poorly made and overheated clutch, rather than an actual problem. A good analogy would be if you went to the doctor to treat a headache, and just received painkillers instead of taking the axe out of your skull. Therefore, the entire post about Centrifugal force and parts flying through the bellhousing is wrong.
First off I too disagree with the poster you are replying to here. However, I'd like to pick nits and make a point of my own:
You typed "clutch" but there are several pieces involved in a clutch assembly do you mean any part of the assembly? Just the disk?
I'm willing to bet there are clutch disks out there that will come apart at those speeds without having been abused. A solid metal flywheel would be less likely to come apart than a clutch disk with rivets holding it to a metal plate.
Just because you don't know of them doesn't mean they don't exist. I've never been to the moon but I believe it's there.
08-28-2007, 07:43 PM
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Don't know if its been mentioned already, I didn't read the whole thread, but a wet clutch like the ones on most motorcycles would be a cool idea too, for those who don't have bikes, the motorcycle wet clutch consists of alternating discs, friction, and aluminum, or steel discs.Usually 7 to 10 discs side by side. These discs are all forced together when the clutch is released, and the entire assembly spins in the engines oil. I wonder if you could adapt that sort of design inside the bellhousing and fill the housing with oil, to cool and lubricate it? Possibly add an external oil cooler just for the clutch oil......I think it would work well, def different....
