^ Also known as the multiple times mentioned "flatshifting"

lol sorry I was being lazy and didn't read all the replies in full ^^

Interesting, very interesting.

I would like to know what differences there are in clutches used in normal road cars and proper racing cars.

I've been under the impression that in race cars you need more revs and the car is easier to stall. But is it because the clutch bites that hard, or because all the torque is on the high revs? How are clutches used in racing cars and road cars physically different, and how is the difference shown when used if there is any? Of course, then there are gearboxes... is there a thread about this already somewhere, would like to read more.

Never had guessed I would get even near this excited about some clutch thing, can't imagine how excited our real propeller heads are.

Race clutches have stronger springs, and softer materials - they wear quickly, but they transmit the torque effectively. But it means that they are difficult to balance on the biting point, and feel like they are either on or off. They are also noisier, as the plates can flutter and vibrate when the clutch is disengaged.

Road clutches are designed to be long lasting and easy to use - softer springs, built in drive cushioning, and harder more predicable materials.

Add to that a race engine is peaky (not much torque/driveability low down), and they can be tricky to move away in.

Thanks for the always so informative replay Tristan. And well, if Scawen has managed to put in all that, I must say that the time taken is more than acceptable.

Can anyone tell if clutch heat has been tried in any other sim before? I can't recall any.

Quote from tristancliffe :

Race clutches have stronger springs, and softer materials - they wear quickly, but they transmit the torque effectively. But it means that they are difficult to balance on the biting point, and feel like they are either on or off. They are also noisier, as the plates can flutter and vibrate when the clutch is disengaged.

Road clutches are designed to be long lasting and easy to use - softer springs, built in drive cushioning, and harder more predicable materials.

Add to that a race engine is peaky (not much torque/driveability low down), and they can be tricky to move away in.

Also, don't forget that the race flywheel is generally much lighter than in a standard car. This means less inertia when trying to mate the clutch plate to the flywheel which will make it much more difficult to pull away smoothly. I think this leads to more of the smoothness problems than the clutch material will. It also demands better rev matching on shifts because RPM will drop more quickly with the clutch in than it would on a street car.

Quote from AndroidXP :

^ Also known as the multiple times mentioned "flatshifting"

Yes, thus with auto clutch, we will now just not flatshift. With the computer automatically working the clutch, there is no human error in slipping the clutch accidentally, so without flatshifting, I wonder where overheating with the autoclutch will fall.

As I said, advantage still goes to auto clutchers (aka, Me )

I certainly hope to sway advantage towards the clutch users, or to fair it up anyways, the auto clutch isn't changed to be so ridiculously slow to be unrealistic like in so many other titles. Racer's auto clutch comes to mind, ridiculously and unrealistically slow. Just needing to lift on the throttle to shift doesn't sound to me to make it more even for the clutch users.

Again, I'm talking tintops and not the open wheelers. Road cars and GTRs are what I care about. I certainly hope as well that, for in the future and the possiblility of me getting a G25 (unlikely), the GTRs are not force to be sequential only. I care less about 900 degrees and better steering, clutch and h-shifter is what I want, badly.

Yes, all good points too. You win a small cookie (which you'll find at your local cookie emporium - tell them I sent you).

Quote from Bob Smith :

For anyone using the text version of LFS, the patch will add the following message:
"You become aware of a distrinctly non-rubber burning smell. What do you want to do?"

I would read a scroll of Enchant Drivetrain, while confused.


(I've been playing waaaaaay too much Nethack lately.)

Quote from mrodgers :

Yes, thus with auto clutch, we will now just not flatshift. With the computer automatically working the clutch, there is no human error in slipping the clutch accidentally, so without flatshifting, I wonder where overheating with the autoclutch will fall.

As I said, advantage still goes to auto clutchers (aka, Me )

I certainly hope to sway advantage towards the clutch users, or to fair it up anyways, the auto clutch isn't changed to be so ridiculously slow to be unrealistic like in so many other titles. Racer's auto clutch comes to mind, ridiculously and unrealistically slow. Just needing to lift on the throttle to shift doesn't sound to me to make it more even for the clutch users.

Again, I'm talking tintops and not the open wheelers. Road cars and GTRs are what I care about. I certainly hope as well that, for in the future and the possiblility of me getting a G25 (unlikely), the GTRs are not force to be sequential only. I care less about 900 degrees and better steering, clutch and h-shifter is what I want, badly.

What if when the clutch is re-engaged after a flatshift, the speed difference between the engine and drivetrain causes the clutch to slip?

Quote from Bob Smith :

For anyone using the text version of LFS, the patch will add the following message:
"You become aware of a distrinctly non-rubber burning smell. What do you want to do?"

grues would be fare more realistic for hanks track than those silly bears and octopi

Quote from mrodgers :

Yes, thus with auto clutch, we will now just not flatshift. With the computer automatically working the clutch, there is no human error in slipping the clutch accidentally, so without flatshifting, I wonder where overheating with the autoclutch will fall.

Auto-clutch does not "cure" flatshifting clutch problems - throttle cut does. The problem is not slow or sloppy engaging of the clutch, but the clutch slipping because it can't cope with the excess forces caused by the revved up engine (flywheel) that now needs to be slowed down to wheel/transmission speed again.

Quote from mrodgers :

I certainly hope to sway advantage towards the clutch users, or to fair it up anyways,

As a clutch user, I personally couldn't give a toss. If someone is quicker than me then they're quicker than me - if that's because they're using easier controls then I need to get better with my controls.

If we give faster shifts to people with fancy hardware, we're essentially letting people buy an advantage. Currently, people with fancy hardware can still switch it off and go with two pedals and paddles if they want to and the playing field is level, but if it goes the other way then everybody will have to buy a G25 or build ghetto hardware to keep up. That would be bad.

So how will the increased engine inertia add up to this clutch/gear changing thing?

Changing gears and matching the revs is easier?

Four blade race clutch (much easier to use than 3 blade, but handles bit less torque commonly)


Normal type of clutch



See difference in contact area, typical road car clutch have big contact area which make it durable and easy to operate.
Race clutch has much less surface area, which means more pressure but also operation is more harsh as clutch bites better.
Also note that smaller surface area last less time and will warm up quicker.

Now clutch sits between flywheel (which is kind of disc of steel bolted to crankshaft) and pressure plate and is squeezed against flywheel by pressure plate springs, when you push clutch pedal down clutch disc moves away from flywheel. Flywheel rotates at engine speed and clutch rotates at speed of transmission affected by gearing and gearbox rotating speed is affected by powered wheel speed.

Now there is lot of different situations you can think about and every time you find engine and transmission to be or try to be rotating at different speed there is potential slip in clutch. Clutch resists slipping so much that it can handle torque and if you push clutch pedal you can modulate amount of torque it can handle, all the way to 0nm of torque.

Quote from JTbo :

See difference in contact area, typical road car clutch have big contact area which make it durable and easy to operate.
Race clutch has much less surface area, which means more pressure but also operation is more harsh as clutch bites better.
Also note that smaller surface area last less time and will warm up quicker.

Nice comparison pictures, and that actually makes sense in terms of physics I can remember. I think the left handed ape might have been a slight understatement, but it doesn't kill so whatever.

Quote from AndroidXP :

Auto-clutch does not "cure" flatshifting clutch problems - throttle cut does. The problem is not slow or sloppy engaging of the clutch, but the clutch slipping because it can't cope with the excess forces caused by the revved up engine (flywheel) that now needs to be slowed down to wheel/transmission speed again.

Yes, I know that about the flatshifting/throttle cut relation. Under normal circumstances, you would not have excessive heat in the clutch if driven normally and close enough to rev matching. On road cars, it is even better because of the clutch being designed to tolerate slipping due to the need for longevity. With auto clutch, the thought of rev matching and perfect clutch to flywheel engagement is done with one foot lifting the throttle and the computer working the clutch. You only need to worry about your right foot and when to change gears. But with using a G25, the user needs to worry about clutching properly with left foot while cutting throttle and switching gears, a lot more room for error. I just fail to see how you would get excessive heat in the clutch if using auto clutch.

I think that it indeed has everything to do with slow or sloppy engaging of the clutch, the human user operating the clutch and shifting poorly is the reason for the excessive forces upon upshifting. Or perhaps, I just have false understanding of the relationship of rotational speed between the output shaft, input shaft of the transmission and output shaft of the motor

We'll see come closer to Christmas how it all works out, eh?

There's been plenty of times that, due to wearing my work boots catching on the carpet mat, or whatever, that my foot has gotten stuck while letting out the clutch IRL and caused me to very excessively slip the clutch. If I had auto clutch in my real car, it would never happen, thus human error will never happen with autoclutch in a racing sim.

Well, of course there's "more to do" with auto-clutch disabled, but it's like no difference at all once you're used to it. Also, the occasional mis-shifts or not perfectly matched revs hardly contribute to clutch overheating in a significant manner. The only things that do are reaaaaally slow clutch engagement (which never happens during a race, unless you're a special kind of muppet) or flatshifting.

Auto-clutch doesn't make a difference to how screwed up your clutch gets when constantly flatshifting - what I mean is, if you keep the foot planted on the throttle then it's irrelevant how fast you release the clutch, if anything auto-clutch is making it worse due to operating the clutch slower. If you remove throttle when shifting then it's not flatshifting anymore, which was the main point as far as I can tell .

so what these changes might mean to an auto-clutch driver like myself is that IF we're effected by the clutch slip/heat issue, we may have to tweak our throttle cut settings (or become accustomed to actually lifting throttle) to shift, right? i think that's awesome...

Yes, the point is: clutch heat = no more flatshifting.

(No matter what helps you use, unless it's throttle cut, but with that enabled you can't flatshift at all anyway)

Quote from AndroidXP :

Yes, the point is: clutch heat = no more flatshifting.

Chalk up another point for the LX4 over the TBOs then.

i like that this adds a level of tunability... before there was really no point to having throttle cut enabled, but now we'll have to tune it to optimize performance without burning the clutch.

Clutch damage is possible, like when you hit clutch down then shift then hit the sift as clutch is almost fully open?

that can damage it......

Quote from tristancliffe :

Power = n x Torque x rpm, and I wanted an rpmless unit

Is it not:
P = 2(pi) * Torque * n
???

In my equation, n = constants, including gearing; in your equation n = rpm