Is this the right clip? It's hard to see or hear what's going on. Looks like a drag or speed run. If there's clutch slippage, it's not as obvious as the previous one where the clutch is clearl slipping on the 2nd to 3rd gear shifts at a few spots on the track. In that video, the slipping is there, but it doesn't seem to get worse over time. I'm not sure if it's a weak clutch by accident, or on purpose to protect the drive train.
Is this the right clip? It's hard to see or hear what's going on. Looks like a drag or speed run. If there's clutch slippage, it's not as obvious as the previous one where the clutch is clearl slipping on the 2nd to 3rd gear shifts at a few spots on the track. In that video, the slipping is there, but it doesn't seem to get worse over time. I'm not sure if it's a weak clutch by accident, or on purpose to protect the drive train.
If you can't see / hear clutch slip from that, then you don't know what it is.
Gear change is easy to see and hear, also rpm not dropping which indicates clutch slipping as there seem not to be wheel spin, which you could easily hear/notice.
That is probably bit of power + standard clutch, but even with standard clutch you get similar slip if you shift without lifting throttle, do it enough and clutch is toasted.
Keep it cool and don't slip and you can burn tires and destroy drivetrain parts, but when you manage to slip it, by flat shifting for example, it won't bite as well until cooled down, if gone past certain point no biting.
That is how it is for typical 80's-early 90's street cars in here
Well, who cares if the engine isn't applying torque against it, during that transition :doh:, that's the whole point isn't it? Dragging the engine down, fighting only it's effective rotational inertia is nothing compared to dragging it down when it's trying to hand out hundreds of foot pounds of torque. In MOST transmissions you physically MUST remove much of the torque to even move things around anyway (unload the parts you're trying to fiddle with). So, your sequential trans related arguments are bogus. Spark cut, fuel cut, foot cut, whatever the case, it's all the same.
I thought you said much earlier that heat would not cause less grip?
BUT, Auto trans clutches are cooled by fluid, and they are band clutches. Also, as you said, there is a different combo of clutches per ratio, so you're not abusing the same bands every shift. Also, autos will fail if you're always heating them, which is why heavy duty ones have their own fluid coolers to keep the clutches (and everything else) cool.
Are there any cars with invincible rads, nonbreaking glass, no visible undercarriage IRL? Silly argument. In truth, you don't know really how the clutch will act once other related systems are in place. It's not that it's a bad addition - it most certainly is not, it's just not complete, like many other aspects of LFS.
Well, then those systems may not work right without some form of clutch modelling - I.E., you don't know the priority list, and why it is the way it is. Scawen knows, and that's all the matters.
Pardon?
More torque, and higher coefficient of friction = more heat during full throttle clutch slip, plain and simple.
Think for a sec - what generates more heat rubbing your hand at velocity and pressure x on ice or on wool? Increase the Cf on the wool at velocity and pressure x and what happens? Hand slows down, more force needed to maintain velocity - which does what - more heat.
Perhaps the temp increase over time decreases at higher temps, big deal. Still higher temps.
And why were you comparing brakes earlier? Apples/oranges. Clutch is in a sealed chamber next to an internal combustion engine, and even gets heat from transfer through crankshaft etc. BRAKES, of course are constantly cooled by ambient air flow, LOTS of it with certain types, they are drilled & vented and have ducts blowing right on them in some cars. AND the contact surface area is small by comparison AND, they still manage to get red hot sometimes AND, they still manage to be a concern for drivers. How the hell is that even remotely the same?
How many cars on Pinks have non-auto boxes? Most have transbrakes and powerglides with a shift kit, etc etc. There's the occasional manual. It's Pinks All Out that has ONE set of three passes, at the very end - and that's exactly why, because so many cars BREAK trying to do 3 hot passes. I'm sure I've seen the occasional manual, but not many (since they suck for drag racing).
Very nice, what on earth does this have to do with LFS clutches? Nothing. It's a 4.5 second pass for one thing, geez. So it slips like crazy for what - 2 seconds or so? Those plates (and there's a lot of them, not just ONE), wear down like crazy in those two seconds to the point they need replacing. think of how much material is being burnt off in that time. LFS does not simulate wear, just HEAT at this point - for the 30th time.
The clutches work fine in racing, and that's all that matters right now. Maybe there's some problems with the "abuse modelling", just like there is with the 100mph collisions and so forth. It's fine for now, doesn't take away from anything, acts right in the vast majority of relevant situations. It doesn't really even affect flatshifting much, so why do you keep talking about it? For all we know it's the first step to lots of other things, just wait for the "i" to be dotted before complaining.
Thanks for getting back on topic.
What I meant is you can't see if the clutch pedal was quickly or slowly released.
The inertia generated torque from these fast gear changes is huge. From the link below about seamless shifters. "The dynamic torque peaks during a gearchange can be 10 times the static torque"
http://www.speedtv.com/articles/auto/formulaone/42017
If I didn't make it clear, what I meant was that the heat wouldn't reduce the grip to the point that the clutch would start slipping from full throttle usage. Also I'm not sure if it's a friction issue or a thermal expansion issue affecting when the clutch engages, and where in the travel range and spring pressure the clutch is engaging when cold.
But I'm referring to the case where it's the same torque being genrated by a clutch with a higher coefficient of friction and a lower pressure force on the clutch.
Only to point out that with patch Y, brakes aren't fading, but clutches are.
OK. I really didn't expect this thread to get this long. The other thread was focusing on how the clutch overheating, combined with the removal of auto-cut and auto blip is adversely affecting some LFS players.
I only intended to question how realisitic this was, since I've never experienced this with any of the cars with manual shifts that I've driven.
However there have been two videos posted where it was clear that the clutches were slipping when flat shifted, and it's possible that with these clutches, constant flat shifting could cause an overheating situation. Until I saw those videos, I never saw clutches that would slip that easily, perhaps they're made that way to protect the drive train. I've already mentioned my one and only experience where a clutch on a 1987 Mustang GT was smoking while backing up a steep driveway, but showed no signs of progressively worse slippage or any issues afterwards (other than I expect 5000 miles of wear were done in about 30 seconds). So the amount of clutch slippage due to flat shifting would depend on the car. I wouldn't expect a peformance oriented car to suffer from such issues. Still as you mentioned, it's probably just a temporary fix until drivetrain damage is modeled.
What I meant is you can't see if the clutch pedal was quickly or slowly released.
The inertia generated torque from these fast gear changes is huge. From the link below about seamless shifters. "The dynamic torque peaks during a gearchange can be 10 times the static torque"
http://www.speedtv.com/articles/auto/formulaone/42017
If I didn't make it clear, what I meant was that the heat wouldn't reduce the grip to the point that the clutch would start slipping from full throttle usage. Also I'm not sure if it's a friction issue or a thermal expansion issue affecting when the clutch engages, and where in the travel range and spring pressure the clutch is engaging when cold.
But I'm referring to the case where it's the same torque being genrated by a clutch with a higher coefficient of friction and a lower pressure force on the clutch.
Only to point out that with patch Y, brakes aren't fading, but clutches are.
OK. I really didn't expect this thread to get this long. The other thread was focusing on how the clutch overheating, combined with the removal of auto-cut and auto blip is adversely affecting some LFS players.
I only intended to question how realisitic this was, since I've never experienced this with any of the cars with manual shifts that I've driven.
However there have been two videos posted where it was clear that the clutches were slipping when flat shifted, and it's possible that with these clutches, constant flat shifting could cause an overheating situation. Until I saw those videos, I never saw clutches that would slip that easily, perhaps they're made that way to protect the drive train. I've already mentioned my one and only experience where a clutch on a 1987 Mustang GT was smoking while backing up a steep driveway, but showed no signs of progressively worse slippage or any issues afterwards (other than I expect 5000 miles of wear were done in about 30 seconds). So the amount of clutch slippage due to flat shifting would depend on the car. I wouldn't expect a peformance oriented car to suffer from such issues. Still as you mentioned, it's probably just a temporary fix until drivetrain damage is modeled.
I'll check the link in a sec, but isn't that the kind of trans that didn't need/have any kind of cut which you posted about earlier? I believe it is, and so that just proves that flatshifting (as in power on, no cut of any sort flatshifting) is extremely hard on things - and now they've developed some kind of trans to handle it, and still, none of the LFS cars have it. But please stop confusing the subtopics of this thread by referencing out of context examples
Of course it's a friction issue; friction and temperature affect each other intimately and fundamentally.
Even though the higher Cf will grab sooner, it will still generate more heat in less time. More energy is wasted with more friction, and more heat is generated. Have a look at some basic heat/friction formulae. AJP is right about racing clutches too - not only the Cf, but they tend to have less surface area. Less surface area, more pressure, and a high Cf. Gee, that really sounds like a favourable situation for heat doesn't it? See JTs pics of a racing clutch vs a street clutch.
Is that so? Then what was this:
Seemed to me that you were saying it should be harder to heat a clutch than brakes? mm?
To which, I repeat this:Indeed, and immediately after he was done backing up the driveway, did he try a full throttle start right away? Perhaps try some flatshifting at the track within a few minutes at least? If the answer is no, then I guess you don't really know how that affected the clutch at that time whatsoever do you?
Or it could be that the drivetrain will break before the clutch overheats, meaning it's not a temporary fix 
(i know nothing about cars)
(i know nothing about cars)
(To BBT) took you long enough for your teardown? where were you?
Holiday season my friend, back to the grind today.
glad your back, but I guess your not glad to be back
in to the "grind"
in to the "grind"
Since dual clutches are banned in Formula one, they're stuck with a single clutch. There is fuel cutting, but only during the brief period when the inertia based torque is bascially the same as full throttle torque. The goal is to reduce the variation in torque during a shift; which means minimizing decreases as well as increases in torque during a very fast shift. As mentioned LFS doesn't model these, although the BMW Formula 1 car does have a system, unless the LFS version is based on an older version of the BMW race car.
Probably, but I can't be sure. Since it's metal and friction material the working temperature range is going to be relatively large (compare to tires for example). It could be that when cold, the lack of thermal expanion results in more plate pressure at the point of engagement, due to the enage position.
Friction is relative to coefficent of friction times normal force (plate pressure). I would tend to believe that with the same amount of friction and torque, caused by either higher pressure and lower coefficient of friction, or by lower pressure and higher coefficient of friction, that the heat generated will be the same, since it's the same amount of energy consumption (same torque, same rpm, so same power consumption).
In the video posted earlier, it was mentioned that the X shaped clutch with less friction area, had better cooling, apparently because air can flow between the clutch structure.
No I was was saying that slipping a clutch for a few tenths of a seconds, at a lower power than brakes experience, would generate less heat than seconds of braking from high speeds, but after doing the math with a clutch that slips like it does in the videos, I'm probably wrong. For example, consider the power consumed by braking from 140mph to 80mph in the LX6 at Blackwood in a bit over 2 seconds (aerodynamic drag must be helping a lot here). Assuming 1g of braking force, 1188lbs of car, that's 440hp of braking power at 140mph and 253hp at 80mph, for an average of 348hp during the 2 seconds. I don't know how much engine inertia there is in the LX6, but for a F1 car shifting in 30ms, it's about 10 x the engine power, so assuming a 1/3rd of a second shift time for LFS, it's 1 x times the engine power, or effectively doubles the engine power, so it would be 190hp x 2 = 380 hp for a 3 tenths of a second. The brakes consume 382,800 ft lbs of energy during the 140mph to 80mph period, while the clutch consumes 62,700 ft lbs of energy during a flat shift, 1/6th the amount of power consumed by the brakes. Then again, there are 4 brakes and only one clutch, and there are 3 shifts on that straight and just one braking zone at the end.
Still all this math is a moot point, in the cars I'm familiar with, flat shifting would break the drivetrain instead of slipping and overheating the clutch, but then there are those two videos where the cars clutches did slip, and LFS clutch slip seems to take more than 1/3rd of a second sometimes.
Ok, that's fine, but it's still not relevant to LFS or this discussion, but it is interesting nonetheless
Either way, heat is bad, and too much will cause slip. I would be willing to be a testicle that thermal expansion wouldn't have much effect towards reducing a clutch's efficacy, but I'm too tired to discuss it right now
You're not considering losses properly as far as I can tell.
Is the clutch housing vented? Otherwise, it doesn't matter much. Why would they need better cooling anyway right?
Math is never a moot point, except for your sketchy math
(j/k)
EDIT: Almost forgot - did the Mustang clutch grinder man attempt full throttle starts right after that or not? Or did he perhaps instead let his clutch rest since he toasted it, thinking perhaps that it may not be in great shape at that moment?
BUT and this is the big but you keep ignoring. Clutch heat IS in LFS and drivetrain damage is not. Why can't you accept this.
IMHO I would prefer engine heat and rad damage to come next to really crank up the pressure. That way people will have more to worry about when they do crash.
The clutch heat limits the benefit of flat shifting NOW. When drivetrain damage comes in it will make the technique even less appealing. GOOD!
I am sure drivetrain damage will come and then you will be able to argue that the drivetrain will damage first if it doesn't. Until then it is the most POINTLESS thing that you keep repeating over and over again.
I am willing to bet that if we could replace your cars drivetrain with one that will not ever suffer damage you will bugger the clutch flat shifting.
I wonder if the 1/3 second thing is auto clutch (I know you use that) and not the clutch itself. If it is caused by the auto clutch I say GOOD because its a sure fire thing to make people drive more realistic when they use it. The auto clutch appears to operates fine when used as expected.
[quote=Ball Bearing Turbo;659058][quote]X pattern clutch had better cooling that standard clutch[/quote]Is the clutch housing vented? I wouldn't know, other than there's a lot of metal to act as a heat sink. It was mentioned in this video from a previous post, the smaller clutch with shaped like an X:
http://videos.streetfire.net/v ... 339-b6f5-98aa00fe0ac1.htm
[quote]EDIT: Almost forgot - did the Mustang clutch grinder man attempt full throttle starts right after that or not? Or did he perhaps instead let his clutch rest since he toasted it, thinking perhaps that it may not be in great shape at that moment?[/quote]Actually it was my car, and my friend was the one that drove it down his dad's driveway, forgetting that due to construction, he wouldn't be able to turn the car around, so he volunteered to back it up the driveway, while I guided. He stated that there was no noticable fade while backing up and since it was night, it wasn't obvious that it was smoking till he got it to the top, where we could smell and see the smoke. I didn't do any full throttle launches, but did just drive it away. If the clutch had glazed over, there would have been a change in the feel or engagement of the clutch, but I never noticed any. I also misquoted the year, it was a 1990 Mustang GT (the 1987 Mustang was totaled when someone slammed into it while it was parked on the far side from a T intersection). It's possble that this was before asbestos based friction materials were banned in clutches and brakes in the USA.
A list of some brake materials used through out history (ceramic not listed):
http://www.roymech.co.uk/Usefu ... ive/Brake_Clutch_mat.html
Carbon-graphite can handle up to 500 C.
Website with some ceramic compound brake materials, short term temperature maxes of 800C:
http://www.moto.lt/index.php?s_id=43&lang=en
http://videos.streetfire.net/v ... 339-b6f5-98aa00fe0ac1.htm
[quote]EDIT: Almost forgot - did the Mustang clutch grinder man attempt full throttle starts right after that or not? Or did he perhaps instead let his clutch rest since he toasted it, thinking perhaps that it may not be in great shape at that moment?[/quote]Actually it was my car, and my friend was the one that drove it down his dad's driveway, forgetting that due to construction, he wouldn't be able to turn the car around, so he volunteered to back it up the driveway, while I guided. He stated that there was no noticable fade while backing up and since it was night, it wasn't obvious that it was smoking till he got it to the top, where we could smell and see the smoke. I didn't do any full throttle launches, but did just drive it away. If the clutch had glazed over, there would have been a change in the feel or engagement of the clutch, but I never noticed any. I also misquoted the year, it was a 1990 Mustang GT (the 1987 Mustang was totaled when someone slammed into it while it was parked on the far side from a T intersection). It's possble that this was before asbestos based friction materials were banned in clutches and brakes in the USA.
A list of some brake materials used through out history (ceramic not listed):
http://www.roymech.co.uk/Usefu ... ive/Brake_Clutch_mat.html
Carbon-graphite can handle up to 500 C.
Website with some ceramic compound brake materials, short term temperature maxes of 800C:
http://www.moto.lt/index.php?s_id=43&lang=en
500 C is not even hard to reach
Video of a Caterham in action, being powershifted (2nd half of video), and the clutch isn't overheating.
from http://www.jackals-forge.com/lotus:
donny2005.wmv
from http://www.jackals-forge.com/lotus:
donny2005.wmv
In the video he is power shifting properly, but he is definatly not flat shifting. Power shifting is not hard to do and it doesnt heat the clutch up that much, its just the flat shifting that causes the clutch fade.
Indeed, I can powershift all day in LFS
What is the difference here? The throttle is being pressed before the clutch is released, causing the clutch to slip and force the engine rpms down to match the gear on the upshifts, as seen in the second part of the video.
Of course, the difference is in the fact that even though there is some slip with "power shifting", there is not as much slip or shock as there is with "flat shifting".
I supposed theoretically if you flat shifted fast enough, it wouldn't be that much different but that would be tough with synchros unless you're he-man, and like wrecking things.
In LFS, I can power shift indefinitely. Flat shifting can still be done for quite a long time before it leads to overheating.
I can't imagine the jerk the car would have if the clutch had enough force to not slip during a flat shift, where the clutch was quickly engaged. The RPM change on the drive terrain would jerk the car and would be very uncomfortable.
If you 'flat shift' by the time you declutch the engine speed will have risen greatly and going up a gear reduces the engine speed without slip for your given speed. It is declutching, not clutching that does all the harm, it's like doing a racing start on every gearshift, would you expect a clutch to last 100 racing starts in quick succession (which would be about 4 or 5 laps worth)? Real cars often struggle to do one.
The rev-limiter in an engine prevents this, since shift points in real cars are usually done close to the point where the rev-limiter kicks in, the engine speed will not have risen "greatly".
In this video of a drag run by a guy named Ranger in a stock Corvette Z06 with drag radials, he mentions one early shift, in the run. The goal was to shift at 7000 rpm, and the rev limiter kicks in at 7100 rpm. He also does burnouts with stock brakes, he's not using a setup that locks up the front brakes only.
http://www.youtube.com/watch?v=469NvIOiz7U
Ranger again, on stock tires:
http://www.youtube.com/watch?v=6Y-Fq306rzI
Its not jut RPM that causes the clutch to slip, but also the resistance to drop RPM by being full throttle. The engine could be at 1200 RPMs with 0% throttle and there would be little to no damage to the clutch, however if the engine were to counter the force from the driveterain through the clutch with too much torque will cause the clutch to heat up too much.
In the videos does he "flat shift"?
In the videos does he "flat shift"?
I have just done a quick searched on "flat shifing" in google. Do you realise that EVERY single link I follow mentions the HUGE damage that is done using the technique. It rips the teeth off the gears.
Yes drag racer might use it but with cars BUILT TO DO IT. They do not care about damage, their race is seconds, not minutes or hours. WE ALREADY KLNOW THIS. How many more unrelated drag things are you going to bore us with.
I actually have serious doubts if the technique is possible with auto-clutch in LFS at all. It requires you to pull the stick out of gear without the clutch, then just blip the clutch enough to poke it into the next gear. So I would like to know how you plan to do this with your two joysticks and macros? This will be a great read BTW
http://en.wikipedia.org/wiki/Powershift states that the clutch takes a lot of abuse using the technique for instance.
I am not sure if the technique is 100% possible anyway. Not sure if you can pull the car out of gear with your foot planted and no clutch. Will try later. If not its fully impossible to do correctly in LFS so hardly a supprise you cook the clutch no?
This is exactly the point of my thread. When flat shifting, drivetrain damage is realistic, clutch slipping isn't, at least for most cars, but there are exceptions.
Based on two videos posted earlier in this thread, some cars do have clutches that slip when flat shifted, either on purpose to protect the drive train, or because the clutches are just relatively weak, or because they are worn. Note that the slippage in those videos didn't appear to worsen over time, so although there was a lot of slippage, it didn't generate enough heat to worsen clutch grip to the point that the clutch actually failed.
No he doesn't, you can hear that he's lifting during shifts, but he does chirp the tires on the 1st to 2nd gear shift, although this can only be heard on the noiser drag radials used in the first video, and not the stock tires used in the second video. In those Z06 drag videos, the engine rpms aren't going to drop much, but with 505hp (SAE minimum) on a 3150lb car, chirping the tires on the 1st to 2nd gear shift will happen on a fast shift, even with drag radials. It should be pointed out that the Z06 has an always active maximum torque limiter that reduces engine power if excessive torque is detected, to protect the drivetrain. The Z06 drag racers say that it's only noticable with drag tires, and not stock tires. Still the torque limiter can't prevent inertia related effect; if some idiot went full throttle and dropped the clutch while in 5th gear from a standing still position, I'm pretty sure something in the drivetrain would break as mentioned above, since the clutch in a Z06 isn't going to slip like the clutches in the cars from those two earlier videos did.
My point of linking to those drag videos was to note the drivers comment that desired shift points were only 100rpm less than where the rev-limiter kicks in. Regarding flat shifting, if flat shifts are made made near redline, then the rev-limiter acts as an "auto-cut" during such flat shifts. As far as I know, there are no racing series that ban the usage of rev-limiters.
It's a stock Corvette Z06, with a stock clutch. Ranger uses drag radials on an otherwize stock Z06 in the first video for a 10.85 ET, and uses the stock OEM Goodyear runflat in the 11.22 ET run. In the first video, he does chirp the drag radials on the first to 2nd gear shift. Again my point of those drag videos was the drivers comment about shift points close to max rpms from the rev-limiter.
Regarding auto-cut and auto blip, companies such as Motec, make data aquisition systems and engine management systems with features such as clutchless, no lift shifts (via auto-cut, using pressure sensors on the gear shifter) with standard transmissions. These products are used by even casual racers that simply do fun runs on track days as oppose to real racing. I assume that there are some racing series that ban the use of no lift shift systems, but I don't know which series do and don't allow these.
http://www.motec.com/products.htm
The bottom line for some here seems to be that yeah, clutch slipping from flat shifting isn't realistic, but until drive train breakage is modeled in LFS, clutch failure was an alternative method to discourage flat shifting. Since LFS has a reputation for being realistic, I was surprised that the developers simply didn't wait for the drivetrain damage model to be incorporated into LFS rather than patch Y's unrealistic (to some here) clutch model as a means to discourage flat shifting.
The combination of removing auto-cut and auto-blip, and adding clutch failure to Patch Y has obviously been an issue for some S2 license owners, based on the complaints about this in the other thread. In my case, it's not an issue because I simply took the "Motec" route and programmed auto-cut and auto-blip in to my controller's "scriptable" driver to replace the now missing feature in LFS.
How realistic is clutch overheating?
(258 posts, started )
FGED GREDG RDFGDR GSFDG