::.. Double-clutching to pass...

[Qube]

::.. Double-clutching to pass...

Let's try and settle an argument I'm having.

Scenario in short... going 120kph, you want to drop to 3rd to pass. This should land you nicely in the power band. So...

I reckon that it's much quicker (and smoother) to double-clutch and accel to pass... rather than just a 'simple' downshift to 3rd and pass.

What are your thoughts?

EDIT: of course it looks a lot better if you double-clutch so you seemingly get power out of no where (no shock or otherwise jerking).

[Tiger]

Yes, that's how I drive when I drive a manual... less wear and tear on everything. When you depress the clutch, you don't step all the way in... sort of halfway to allow you to shift gear. Every car is different so the amount you have to depress varies. As little as possible without jamming the gear.

[rob101]

Yes, that's how I drive when I drive a manual... less wear and tear on everything. When you depress the clutch, you don't step all the way in... sort of halfway to allow you to shift gear. Every car is different so the amount you have to depress varies. As little as possible without jamming the gear.
x2 except i usually depress the clutch fully, after a while you notice that you can rush the clutch action a bit, so it may not be fully out when in neutral.
i don't know about faster. but it certainly feels more natural when you double clutch not like you are doing something the car doesn't want to do.:)

[Jon K]

No use double clutching just clutch in rev match and let clutch out. Did I tell you guys I walked an E46 M3 on the highwasy this afternoon ;)

[GoldenOne]

No use double clutching just clutch in rev match and let clutch out. Did I tell you guys I walked an E46 M3 on the highwasy this afternoon ;)

^^2nd...and I bet the driver of the M3 didnt expect to be walked lol

[Thayne]

I used to do this in both my E30s. :D

[Fetch]

This thread is really confusing me.
What exactly do you mean a simple shift vs. a double clutch shift?
You should be rev matching anyway , so there would be no jerks with either shift 'type'.
Double clutching is different than rev matching.

Also I don't understand another person refering to double clutching as pushing the clutch down only to disengage it, instead of all the way down. That's fine, & faster to shift, but never heard it called double clutching.


Double clutching is:
5th gear, clutch in, neutral gear, clutch out, rev match for 3rd gear, clutch in, 3rd gear, clutch out.

My definition of 'simple' would be (and this is how I normally drive):
5th gear, clutch in, while changing gears revmatch for 3rd gear, 3rd gear, clutch out.

Go ahead and tell me if I'm wrong. But I'm never wrong. (haha)

[rob101]

This thread is really confusing me.
What exactly do you mean a simple shift vs. a double clutch shift?
You should be rev matching anyway , so there would be no jerks with either shift 'type'.
Double clutching is different than rev matching.

Also I don't understand another person refering to double clutching as pushing the clutch down only to disengage it, instead of all the way down. That's fine, & faster to shift, but never heard it called double clutching.


Double clutching is:
5th gear, clutch in, neutral gear, clutch out, rev match for 3rd gear, clutch in, 3rd gear, clutch out.

My definition of 'simple' would be (and this is how I normally drive):
5th gear, clutch in, while changing gears revmatch for 3rd gear, 3rd gear, clutch out.

Go ahead and tell me if I'm wrong. But I'm never wrong. (haha)
of course you are right. :) but in order to get double clutching to work you don't really need to let the clutch all the way out in neutral.
anyway its personal preference, i try and double clutch on all downshifts. if you don't want to then don't....... but IMO if i wanted the fastest shifts possible i'd get a crash or dog box.
I think my gearbox had a hard life prior to my ownership so i am trying to extend the synchro's life by double clutching.

[Qube]

Simple would just be feathering the clutch out and let it slip to the appropriate rev... letting the synchro do the work. You know, like how most of the world shifts *gasp* :|


This thread is really confusing me.
What exactly do you mean a simple shift vs. a double clutch shift?
You should be rev matching anyway , so there would be no jerks with either shift 'type'.
Double clutching is different than rev matching.

Also I don't understand another person refering to double clutching as pushing the clutch down only to disengage it, instead of all the way down. That's fine, & faster to shift, but never heard it called double clutching.


Double clutching is:
5th gear, clutch in, neutral gear, clutch out, rev match for 3rd gear, clutch in, 3rd gear, clutch out.

My definition of 'simple' would be (and this is how I normally drive):
5th gear, clutch in, while changing gears revmatch for 3rd gear, 3rd gear, clutch out.

Go ahead and tell me if I'm wrong. But I'm never wrong. (haha)

[Fetch]

I push the clutch in enough to disengage it when I'm shifting, but am I correct to assume I am saving some of the syncros' work when I rev match without double clutching? Because that is 50% of the reason I do it, the other 50% is because I like quick smooth shifts, unlike how a lot of people I know shift manuals.
Or does that mostly just save clutch wear?

And double clutching saves clutch and syncro wear then

[Qube]

Technically, we couldn't do a good enough job to save the synchros. It's more of smoothing out the downshift not to take your passengers to the chiropractors when you're killing that M3. Whew.

If you rev match without double clutching, then you're just wearing out the throwout bearing. Or at least that's what I believe.

[Fetch]

Technically, we couldn't do a good enough job to save the synchros. It's more of smoothing out the downshift not to take your passengers to the chiropractors when you're killing that M3. Whew.

If you rev match without double clutching, then you're just wearing out the throwout bearing. Or at least that's what I believe.

I thought the throwout bearing got wear anytime the clutch was pushed in.
but, I don't know the mechanics of it, is it spinning with the engine, and therefore, higher revs will put more wear on it??

I keep the clutch out and the car in neutral at stops, etc, to save wear on the throwout bearing.

[rob101]

Technically, we couldn't do a good enough job to save the synchros. It's more of smoothing out the downshift not to take your passengers to the chiropractors when you're killing that M3. Whew.

not completely but you would reduce the wear on them through double clutching, since the wear will be proportional to the difference in speed of the section forward of the dogs and the section behind the dogs (lay shafts, tail shafts).
Do most of you people actually know what mechanically happens when you double clutch as opposed to "single clutch". rev matching in a single clutch shift does nothing for synchro wear as the section of the gearbox that is after the clutch but before the selection dogs are still not rotating at all. rev matching mainly saves your clutch . has no effect on synchros when you single shift.
whereas if you rev in neutral with the clutch out that forward part of the gearbox will be rotating. and thus the synchro has a smaller speed differential to synchronise.

[Paul in NZ]

actually isnt it double DE clutching...I dont do it,but when i go for the killer passing manouvre I rev match by not letting the throttle all the way out so as the clutch goes in the revs climb a thousand or so and smooooth downshift.actually if you have got any momentum at all you dont need third,you need third when you are down at the same speed as the truck and trailer unit,and the passing lane is short and steep.You know that the M30 in third will waste everything.And you know the cars it wont.

[angrypancake]

double clutch? rev match? wtf? i drive an auto tragic car. explain.

[ILoveMPower]

Uhhh, I blip the throttle at the exact same time I'm depressing the clutch, that way by the time I put the stick into third the clutch is already fully out and engaged. You just have to match the revs and there's no hesitation/slippage.

I really don't understand what this thread is about...

[Qube]

In that case, you're single clutch rev matching. I surmise that double clutching makes for a smoother overall shift. Of course, this is highly subjective. On the other note, this thread is about 'not' rev matching but letting the synchro take up the slack on the downshift vs. double clutching.

[Ross]

No need to double clutch on a downshift ever. Match the revs as Jon K says and dump the clutch. Rev in 3rd until valve float then powershift into 4th, repeat.

[Qube]

No need to double clutch on a downshift ever. Match the revs as Jon K says and dump the clutch. Rev in 3rd until valve float then powershift into 4th, repeat.

Match revs and dump clutch. Surely you jest on a 4 to 2 it's not logical?

Anyway, you'll need to explain valve float to me as "http://en.wikipedia.org/wiki/Valve_float" tell me the mechanics of it but isn't explaining the 'feel' characteristics of it :)

** PLEASE NOTE, I'm not trying to start an argument or flame. Everyone, try and learn from this thread what you will ;)

That aside, this fellow's post probably encapsulates how I feel:


the short answer to your question is that you are correct, the DC technique bring the input shaft up to speed directly, without relying on the
synchros.

The single-clutch technique relies on the synchros to bring the input shaft up to speed, as you say.

The above difference, in theory, seems unlikely to be the cause of any jerk, as you say.

The long answer is that for whatever reason, i could never get single clutch to work smoothly enough for me.

In addition, pro drivers preferred double clutch, even while stating single clutch can work if you "blip longer". So it seemed unlikely their stated preference was solely due just to a historical lack of synchros in racecars.

Seeing as you got it to work smoothly for you, and the theory also supports your position, I guess the logical conclusion is that my technique was the problem.

I'd have to observe your own single clutch technique before I could definitively say my technique sucked, or yes that was as good as it got and I still wasn't happy with it.

I did work on rev matching with single clutch quite diligently, and then had immediately better results with DC, so I dunno.

Even when I could get single clutching to work smoothly, it seemed to take longer and didn't seem to be exactly what the powertrain was looking for, if you know what I mean.

I associated single clutching with "less smooth" from my own extensive/possibly flawed experience.

SOURCE (good read!): http://forums.evolutionm.net/showthread.php?t=165808&page=1&pp=100

[Ross]

Sorry Qube, I was makin' a joke. Disregard anything I said after match revs.

Matching revs is just bringing the RPMs up to the speed they WILL be at after the downshift. The reason for this blipping of the throttle is to ease the load on the synchros which allows the gears to change easily. Have you ever tried to downshift into a lower gear and the lever is difficult to push(pull) and the gearbox makes a whirring sound? That is your synchros being overworked.
Raise the revs a bit and she slides right in. If the revs are properly matched you don't need the clutch at all.
Valve float is essentially an overrev condition where the valvesprings can no longer close quickly enough and the engine flutters at a fixed RPM, not good for it, and I really wasn't suggesting it, unless it's a rental.
Ross

[Qube]

Jeeze. How dizzying it can be it can be whilst uninformed! :) You need to put a smiley in your post so I don't go nuts trying to understand, hehe.

So anyway, back to the battle of single versus double (de) clutch downshift...

[Ross]

Double clutching is sometimes useful for upshifting and it sounds cool if done right (go rent Bullitt).but useles for down shifting.

[Qube]

but useles for down shifting.

That's quite a blanket statement. You sure you want to open it up like that? :|

Do you not agree that simply rev matching on high downshift with clutch in promotes excessive synchro wear? The keywords here are 'high downshift'. Sure, it may be better than not matching at all, but it isn't as graceful (on average), to say the least. If you rev match downshift with the clutch disengaged (non doubleclutch), you still don't match the input shaft and output shaft speeds. The clutch plate is on the input shaft and needs to be accelerated by the engine itself.

Now, don't get me wrong... you can get a great rev matched downshift without double clutch, but if so, there is still unnecessary wear on the synchros.

Where does this all tie in?

The original question was, and should be a relatively simple answer to...

It's quicker to accelerate to pass whereby one double clutch (rev-matched) than to simply downshift and let the synchro pick up the slack (non-matched). Right? We're getting a bit too deep into clutch in matching versus neutral blipping with double clutching. What do you say? ;)

[shuriken]

Sorry but I don't understand why in a modern car you'd double de-clutch. The gear leaver throw is way to long and if your driving fast and up shifting then it would just take too long. Fangio and Ascari et al would double de because there gearboxes were not syncro'd so they had to match rev whilst clutch out with gear going through neutral. If accelerating fast ( maxing it) then even the act of rev matching would waste time, all you need to do is time clutch foot and accelerater foot. All you need do is go just beyond the biting point of the clutch, only you know where that is on your car, and dip the throttle. Rev matching is for braking and decelerating, where you need the revs to be up as the engine slows down under braking so the engine is always at its power point and thus the chassis is taute and in control. Listen to any racing car and you'll hear it, but not going up the box. Having an AC Schnitzer quick shift lever would help here no end. It all seems a pointless excercise IMHO.

[Ross]

If the revs are matched the synchros do nothing. The purpose of them is to drag the driving shaft to the speed of the driven shaft.
Double clutching, that is engaging the clutch while in nuetral, allows the input shaft to slow during an upshift.
Simpl answer is it's quicker to shift once than to shift twice, which is what double clutching is.
Damn! Now I really want a car with a gearbox to thrash. Thanks for bringing it up.

[rob101]

Double clutching is sometimes useful for upshifting and it sounds cool if done right (go rent Bullitt).but useles for down shifting.
yeah that was a cool movie
i strongly disagree that rev matching affects synchro load at all. when the sychro is doing its work the engine is not coupled in any way sense or form to the transmission.
that is, unless you make a habit of upshifting without a clutch. the only thing that can reduce the wear on synchros is double clutching

[rob101]

Sorry but I don't understand why in a modern car you'd double de-clutch. The gear leaver throw is way to long and if your driving fast and up shifting then it would just take too long. Fangio and Ascari et al would double de because there gearboxes were not syncro'd so they had to match rev whilst clutch out with gear going through neutral. If accelerating fast ( maxing it) then even the act of rev matching would waste time, all you need to do is time clutch foot and accelerater foot. All you need do is go just beyond the biting point of the clutch, only you know where that is on your car, and dip the throttle. Rev matching is for braking and decelerating, where you need the revs to be up as the engine slows down under braking so the engine is always at its power point and thus the chassis is taute and in control. Listen to any racing car and you'll hear it, but not going up the box. Having an AC Schnitzer quick shift lever would help here no end. It all seems a pointless excercise IMHO.
race cars use dog and crash boxes often.
so they don't use the clutch often on upshifts, should we be doing that too?
perhaps you should try it one day, before you say how "pointless" it really is
people talking about rev matching constantly here THAT ISN'T THE MAIN POINT OF DOUBLE CLUTCHING how many people that are saying its useless, can realistically double clutch?

[Ross]

Wasn't the question regarding downshifts?

[Jon K]

Guys who cares - I don't even have a clutch. F- it and drive.

[Qube]

Yes, it's about downshifts. Try not to get too emotional about it guys, heh.

[shuriken]

race cars use dog and crash boxes often.
so they don't use the clutch often on upshifts, should we be doing that too?
perhaps you should try it one day, before you say how "pointless" it really is
people talking about rev matching constantly here THAT ISN'T THE MAIN POINT OF DOUBLE CLUTCHING how many people that are saying its useless, can realistically double clutch?
I mentioned Fanio and Ascari from the 50's when the gearboxes weren't meshed so DDe clutching was a must. To do it on an up shift to go fast, on our cars gear boxes can't be quicker. On the down shift it's more relavent, and for those who can do it seamlessly, really do it, I take my hat off because it's an art form. On modern cars i stand by my statement that it's a pointless exercisein trying to go fast, unless first to second geardogs are shagged. BTW a lot of people say that that Lee H Oswald was the lone gunman too but don't make it right.. But it is just my opinion, if you can do it hats off.
How many folks can double de clutch and heal and toe on down changes? If you can then I really bow to you. That is THE real way to down shift.

[rob101]

Guys who cares - I don't even have a clutch. F- it and drive.
who needs a clutch, workmate of mine once drove home in his 4wd when his clutch cable broke. not too hard he said. personally i can't double clutch on the upshift yet though. and you have to use the starter motor to accelerate from 1st from a stop.
tricky no?

[rob101]

I mentioned Fanio and Ascari from the 50's when the gearboxes weren't meshed so DDe clutching was a must.
personally i've heard it actually easier to shift those boxes without using the clutch. not really much of a difference in what happens.
i wouldn't do that with a sychro box though.
was intention was not to attack people who are saying that its useless. it was to find out whether they could actually do it and thus actually have an opinion from personal experience. otherwise....... its not really an informed opinion.

[califblue]

Heel and Toe Downshift
By Brent Romans
Email

If you have heard of the term "heel-and-toe" downshift before, but you've never known what it means, you've come to the right place. It is the mission of this article to make you a heel-and-toe master, a proverbial Jackie Chan of downshifts. Hi-yah!

A heel-and-toe downshift refers to a specific technique used to downshift a manual transmission car. It might seem bizarre to the general populace, but racecar drivers use it all the time. Once mastered, the heel-and-toe downshift offers the benefits of reduced vehicle wear-and-tear, better driver control and faster lap times on a racetrack.

The heel-and-toe downshift is a rather complex action involving both of the driver's feet, the driver's right hand, all three vehicle pedals and the gear shift lever. The purpose of the heel-and-toe is to smoothly match engine speed to wheel speed. Here is a generalization of how a normal person downshifts a manual transmission car.

Let's say Frank is driving his '01 Volkswagen Passat around town. He is approaching a right-hand corner while in fourth gear at 50 mph. He is going too fast to make it around the corner safely, so he starts braking until he drops the Passat's speed to about 25 mph. Frank sees on the tachometer that his engine revs are dropping too low, so he pushes in the clutch as he goes around the corner. As Frank thinks about accelerating, he realizes that the Passat is still in fourth gear, which isn't suitable for strong acceleration at such slow speeds. So he moves the shifter from fourth to second gear, lets out the clutch and motors away.

The problem with Frank's technique is that when he lets out the clutch, it is not going to be a smooth shift. The Passat is going to buck a little. Why? Because when Frank goes around the corner with the clutch pushed in, the engine revs drop to idle speed. When he releases the clutch, the mechanical locking effect between the engine and the front wheels (the wheels powered by a Passat) forces the engine revs to match the rotational speed of the rear wheels. In this case, 25 mph in second gear would mean the engine has to be at roughly 2,600 rpm. When Frank lets out the clutch after moving the shifter to second gear, his car's engine must instantly go from idle to 2,600 rpm. This sudden change causes the car to buck, as well as causing undue wear-and-tear on the clutch, transmission and engine mounts.

The simple solution for Frank would be to give the car some throttle before he lets out the clutch. Specifically, he should raise the engine speed to 2,600 rpm. This way, the engine speed is equalized to the wheel speed for second gear, making the shift much smoother. For racecar drivers, however, this technique is too slow and also means that when the car is going around the corner, the clutch is pushed in, a serious no-no in a racecar.

The racer's answer is the heel-and-toe downshift. The technique combines braking and downshifting at the same time. Using our example again, if Frank used a heel-and-toe downshift, he would have downshifted while he was braking for the corner. This way, he would have had power while he was going around the corner and he could have quickly applied more throttle once he exited the corner. These are critical elements to a racecar driver, but they can also be useful to any driver on the street.

Here is a step-by-step guide on how to heel-and-toe downshift. It will explain how to shift from fourth gear to third gear, though the technique will work for any downshift.


Begin braking for the corner with your right foot. The location of the pedals and the size of your foot will dictate where you position your foot on the pedal, but most likely it should be canted a little to the right, closer to the throttle pedal.


Push in the clutch with your left foot.


This is the hard part. With your right foot still applying pressure to the brakes, roll the outside edge of your foot outward and downward to touch the throttle pedal. The pedal design on some cars makes this easier to do than on others. Use the outside of your right foot to blip the throttle. Blipping the throttle means temporarily raising the engine rpms to match the wheel speed. The exact amount of revs needed is dependent on a variety of factors, but it is usually between 1,000 rpm to 2,000 rpm more than the current engine rpm for a one-gear downshift.


Move the shifter to third gear.


Release the clutch with your left foot.
As you can see, "heel-and-toe" is a misnomer. It actually involves the ball of your foot and the side of your foot. We'll be the first to tell you that heel-and-toe downshifts aren't easy. We've found that a good way to practice is to just sit in your car in your garage and pretend you are doing a heel-and-toe downshift with the engine off. Keep repeating the steps until you are familiar with the process. Once you are ready, try it out for real. Most likely, your early attempts will be botched. Keep trying, though. Practice each step slowly and then work your way to making them all one, fluid motion. Skilled drivers can execute a heel-and-toe downshift in less than one second.

The trickiest part is getting the correct amount of rpms to match the new gear. If you blip the throttle too much, the engine has too much speed compared to the wheels and is forced to drop down to the wheel speed when you let out the clutch. If you don't blip the throttle enough, the engine rpms are forced to rise up. Either way, you know you didn't do it right as the car will jerk a little.

You'll also know it when you did it right. A proper heel-and-toe downshift is so smooth and so satisfying that, once done correctly, you'll find yourself using the technique all the time. The great thing is that you don't have to be a racecar driver or be on a racetrack to use it. Additionally, using the heel-and-toe downshift technique on the street can improve safety. In certain emergency situations, you might be required to brake heavily and then accelerate quickly. By heel-and-toe downshifting, your car will be in the best gear to achieve maximum acceleration.

So, let's recap. It's fun to do. It improves driving safety. It reduces the amount of powertrain wear on your car. Other than the amount of time it takes to learn, there is no downside. What more could you want?

[Zeuk in Oz]

Not wanting to muddy the waters even further, but I think Paul and Rob seem to have dealt with double de-clutching well, as I understand it.

I find it most useful in downshifting, especially more than 1 ratio at once.

In normal driving though, I only rev match without double de-clutching as that is usually smooth enough and I rely on the synchromesh to do its job.

I did find this concept hard to teach my kids though, as they have not known some of the more agricultural gearboxes of my youth. I actually took my licence test in an EH (1964) Holden Premier Station Wagon with a 3 on the tree gearbox that had very little synchromesh so I was forced to double de-clutch up and down for every gearchange during the test - hadn't got around installing a replacement gearbox at that stage - and besides, first didn't have any synchro anyway. I think the poor tester felt sorry for me and passed me first go.

In my opinion, the only way to get experience with double de-clutching and also the heel and toe technique is to practise and practise until it comes without effort.

Modern gearboxes make us all lazy ! :)

[rob101]

i've never really thought double clutching is teachable
its more of a case of telling them how to do it, then letting them practice. I must say so though i had no hope of learning on my e28, the flywheel inertia is too low. once i got the m50 though, i found it much easier to learn, as the revs don't fall as quickly due to the flywheel haviing more inertia.
Neither of my parents can double clutch so they couldn't ever hope to teach me!

[Paul in NZ]

do people really drive like frank?Drive round corners in 4th gear with the clutch in?>I ahve only driven with one person who did that.Imagine
Coasting around the corner clutch in car in top.Driver is feeding the steering whel fromone hnd to the other a little at a time
jerkily
most times clutch is released with car in too high a gear.....
I tell you that was scary
My brother double de clutches with ease.
ex truck driver

i've never really thought double clutching is teachable
a good double declutch takes hardly any more time than not,gear lever is paused in neutral clutch is partly released as throttle is blipped,clutch pushed bock in gear lever resumes movement, new gear selected,cluth released

Hows that Rob?

[Paul in NZ]

Actually rev matching allows smooth shifting of a manual without the clutch.
down shifts are easier
release throttle so car is coasting,gear lever easily moves out of gear,now put a little pressure on the gear lever and push down on the throttle so the revs rise slowly as the revs come up to the point where the revs match the gear/road speed it wll slip into gear easily wthout a sound...
Upshifts are a bit harder but will work too....just let the revs drop away and when the revs/speed are right it will slip in to gear just the same.

[rob101]

a good double declutch takes hardly any more time than not,gear lever is paused in neutral clutch is partly released as throttle is blipped,clutch pushed bock in gear lever resumes movement, new gear selected,cluth released

Hows that Rob?
um..... how's what?
what i meant is you tell someone how to do something, but its a coordination thing. which means practice practice practice.
and yes in case you missed it i am in the pro double clutching team. I've got no problem with rev matching, but you can do that with a single clutch and double clutch shift. so it really is a moot point as there is no point of difference between the two in respect to rev matching it can be done equally well with both.
but that isn't the main point of double clutching is it? i mean it means you can shift a box without using the synchromesh at all, thats the main difference isn't it?

anyway the last part isn't directed at you Paul. I just wanted to clarify my previous points. I see this crap posted on forums all the time, and its always people who can't double clutch who say blah blah its too slow just clutch once. and to be honest, synchromesh is slow! if you want fast changes get a crash box. and then guess what? you'll have to double clutch.

[Michael999]

in my manual 242GT i double declutch on uphill corners under acceleration.
I found that just slipping the clutch a little to be much easier and almost as smooth.
For an actual drive, ill double clutch, but for commuting to work daily in traffic i just got bored of it, and when doing it i tended to speed, because it put me in a racey mindset :P

[The Bigfella]

My first car ('58 VW Beetle) had no synchro on first and it was essential to double de-clutch for the 2nd to 1st shift whilst moving. These days its probably about as useful as 4" chrome exhaust tips on standard pipes.

I was doing it again for downshifts in the M5 while I had a problem with the engine dying - which can get nasty on twisty roads as the car will kick sideways if the engine dies and recatches as the clutch comes out. Its much easier to do when the brake pedal is adjusted to the right height too.

[shuriken]

Califblue....
Nice post that mate. Rally drivers heal and toe all the time as do F1 racers, with the exception of Barrachello, he left foot brakes I think?
I'm not having a pop at anyone on here either. But I was stating my personal view. This whole threads been an interesting one too. Yeah lorry drivers will DDeC with easy.