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Heavy Duty Clutch & "double Clutching"


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Hi, just bought my r33 gts-t a few days ago.. Anyway, its got a VERYYY HEavy clutch.. :|

It hurts my feet when driving loll,

anyway. apparantly its worth "$2750" the guy was probably lying but i dont think he was 1 to lie as his like 60 yrs old..

anyway, whats so good about the heavy duty clutch and a normal clutch? :|

And what is "double clutching" and what are the benefits from it O_O

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heavy duty clutches can hold more power without slipping than the standard unit and can take more abuse as well. however if the clamp load on the pressure plate is high, so is pedal effort which explains why your clutch pedal is heavy. the material used for making the disc is either cerametalic or a stronger organic material so basically, it grips to the flywheel quickly the moment you reach the friction point (which can be a pain in traffic given that it is either on or off). theres nothing much you could do about the pedal effort unless you swap the slave cylinder to like a Nismo type which most say reduces pedal effort.

double clutching is a technique used to match engine revs with transmition speed?(correct me if im wrong). im not sure about double clutching but theres also another technique called heel-and-toe which does almost the same as double clutching. when you downshift, while pressing the brake pedal, you move your heel to the accelerator with your toes still on the brake pedal and press the accelerator with your heel to blip the throttle when you down the gear. when you first try it its a bit tricky as while you blip the throttle you might accidentaly press the brakes further so things can get a bit jerky on the way but keep practising.

both techniques maintains engine revs which apparently settles the car when slowing down for a corner and will stop compression lockups when you take your foot off the clutch pedal. again correct me if im wrong in any of those points.

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Double Clutching is basically pumping the clutch twice whilst changing gears to better match the engine speed to the input shaft speed on the gearbox. This was a handy technique with cars from the 1930s and so forth, that did not have a synchromesh gearbox that matches the RPMs on the gears for the gear change.

Your R33 has a dual syncromesh on 1st and 2nd gear and a single on the rest. Double clutching a modern gearbox (even a modern dog box) is a waste of time and does not really yield in any results.

Regarding the cllutch - the increased foot pressure is due to an increase in pressure in the clutch cover diaphram. You may have a twinplate clutch or similar if he paid 2750. If he has a single plate clutch, he got ripped off on the install and parts.

More info:

Wiki: http://en.wikipedia.org/wiki/Double_declutch

Video:

http://video.google.com/videoplay?docid=4002588575741675515

http://au.youtube.com/watch?v=0j-3xIZK-Bk

Race drivers fancy footwork in an AE86 - no double clutching here

http://au.youtube.com/watch?v=klMur6TPkrM&...feature=related

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Spot on man. Double clutching is where you go down a gear, but as you do so you release the clutch & blip the throttle quickly, then put the clutch in & select the gear.

Example:

Downshifting from 4th to 3rd. Push the clutch in & push the gearstick up out of 4th into neutral, let your foot off the clutch & blip the throttle quickly, then push the clutch back in, select 3rd gear & let the clutch out. With practice & doing this quick enough, you will be able to do this smoothly.

In older cars, this blipping the throttle method as you change means you can actually do it without using the clutch. I would highly NOT recommend this in a skyline though. Worked a treat in my old corolla lol.

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Double clutching is for truck drivers.

With my button clutch I have to blip the throttle on downshift otherwise it will either compression lockup (if I'm off the clutch quickly) or slip/grind/carry on if I let it out slowly). A blip of the throttle while passing through neutral makes thing a lot nicer in my case :)

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Double clutching is for truck drivers.

With my button clutch I have to blip the throttle on downshift otherwise it will either compression lockup (if I'm off the clutch quickly) or slip/grind/carry on if I let it out slowly). A blip of the throttle while passing through neutral makes thing a lot nicer in my case ;)

i agree. ;) mine does that as well whenever i let my foot off the clutch quickly (fun when its wet lol) so i got the habit of heel-and-toeing when downshifting everytime. makes me feel like a race car driver lol

Edited by R33_NICK
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nismo make a larger clutch slave cylinder this may help reduce the effort needed if its really given you drama

I think though give it some time an you will find you get quickly used to it

I get in most cars now an nearly put the clutch through the floor it seems so light compared to my 'line

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I agree. after a few weeks, getting in other cars they feel like they have no clutch. I simply blip mine going back into 2nd also & its easy as anything. Double clutching i only do once in a blue moon so i remember how to do it, no great need to practice it or anything.

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"Granny shiftin not double clutchin like you should!!"

lol just reminded me of the movie,

i dont see any benefits from double clutching unless u drive a 60 y/o truck. different to Heel toe on down shifts which is obviously effective but takes alot of practise to perfect.

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Guest 40th-edition

if you dont do it the g-box syncros are used to adjust the speeds of the meching gears. so double clutching takes the strain off the clutch and syncros.

giving a blip in between gears only spins up the flywheel

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i agree. :( mine does that as well whenever i let my foot off the clutch quickly (fun when its wet lol) so i got the habit of heel-and-toeing when downshifting everytime. makes me feel like a race car driver lol

I catch myself rev-matching in the bunky excel and I'm like "wtf are you doing?!" lol

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Double Clutching is basically pumping the clutch twice whilst changing gears to better match the engine speed to the input shaft speed on the gearbox. This was a handy technique with cars from the 1930s and so forth, that did not have a synchromesh gearbox that matches the RPMs on the gears for the gear change.

Your R33 has a dual syncromesh on 1st and 2nd gear and a single on the rest. Double clutching a modern gearbox (even a modern dog box) is a waste of time and does not really yield in any results.

+1

I have a button as well and i must double clutch every down shift, it becomes second nature and you learn to heel toe pretty quickly.

ps. double clutching and heel&toe(or rev matching) isn't the same

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Double Clutched my KE Tx3 4wd Laser everytime and no prob's with the syncros at 330,000k when I pulled the gearbox down for a look, this I found to be amazing due to the 4wd being notorious for stripping 2nd gear syncro's.

By using double clutch technique you can greatly improve the life of components in drive train but it is not a be-all & end-all. Back it up with a smoother driver style & your beastie should damn near last forever.

Many may argue the double's are not required for syncromesh gearboxes & they would be right-not required, but it is a good habit to master due to when a transfer to dogbox setups 1 missed gear change can cause all types of grief or if you ever get to drive a truck with a roadranger box you'll thank yourself you persisted with it.

I do it on every down gearchange these days when slowing or stopping

How-to

Load up gear lever slightly before pulling out of gear, press clutch whilst pulling out of gear into neutral, let go of clutch, press clutch a 2nd time & engage next gear. This is to be done to rev match ie 3rd gear 1800rpm, to 4th gear 1200rpm-while the revs naturally fall.

When coming back down thru gears ie 4th-3rd a simultaneous flick of accelerator to match gear range back-up is required slightly b4 2nd clutch push ie 4th gear at 1200rpm back-load gearlever & clutch in to pop out of gear, flick throttle so tacho rises from 1200rpm to req. 1800rpm-depress clutch & put into 3rd gear at 1800rpm-all being done whilst applying brakes at constant pressure to avoid lockup.

You will see that this is necessary when driving heavy diesel's-trucks which dont have a syncro setup on g'box

Takes a lot of practice to master & will improve stopping distance when done correctly due to engine being utilized as part of braking system-how else are you gonna stop 40ton quickly?

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  • 3 weeks later...

i beg to differ with the modern dog boxes and double clutching upshifting

my mate has a dog box in his 200 and par told him to double clutch for eg first to second go dead bang into neutral not jsut double clutch with it still sitting over to the left (from in the car point of veiw).. because short shifting flat changing with dog boxes wears away the hardner and the teeth and your forking out for a new box withing 5000kays...

he has had 10,000 kays now without failure

jsut my rant bout dog boxes

(therye cops on the street)

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Race drivers fancy footwork in an AE86 - no double clutching here

http://au.youtube.com/watch?v=klMur6TPkrM&...feature=related

Pfft - drift boy wannabe.

now watch a real race driver - the master himself http://www.youtube.com/watch?v=65iD4gkelfg...-impressed.html

Around the 1:20 - 1:40 mark they show close up footage of his feet. Notice the heel toe double declutch on downshifts? That technique is very beneficial on fast downshifts - even on more modern machinery (gearboxes haven't changed much since the video was shot - despite what the marketing blurb tells you). Main thing double clutching on downshifts does is conserves syncros, to allow faster changes(as opposed to heel - toe with a single clutch). When a works rally driver (who gets a brand new car every event) does it, I think you should really consider doing it in your road car too, if trying to do quick changes.

I've had cars with worn syncros, and it has been essential on down shifts. I have a very tight gear box in the rally car, and it's needed to allow fast down shifts. On my road cars it doesn't seem to make a big difference either way, but at the track I still do it to conserve the syncros.

Edited by warps
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