Alright speed freaks,

I was having a discussion with a friend, and he recommends I double clutch my CL-S. He has a Supercharged RSX, and we had a run last night. Easy win with little to no effort, but he claims double clutching will make my car faster.

So, my question is. Is double clutching beneficial? And, why?

Thanks,

P.C.

 

Your friend is stupid.

 

34 and street racing, awesome.

 

Excellent!!! As long as this double clutching thing isn't important.

 

double clutching is for OLD Trucks. lol


1st gear
push clutch
put in neutral
let go of clutch
push clutch in again
shift into second


If your friend think this is faster more power to him.

 

Hmm sound to me like your friend watches too much fast and furious "not double clutching like you should" Hes prob talking about when you go to shift a gear, rev your motor slightly while you have the clutch in shifting gears, BUT that will only cause you to spin more, only time that will benefit you is when your on a race track or a drag strip and have race tires or drag slicks

 

Too much work, for zero results.

 

In his defense, he never said he was street racing.

If he was though :thumbsdow

 

Its only beneficial pretty much in a road racing environment, where you have to drop down more than 1 gear. Its not meant to make you upshift faster, its meant to make you downshift easier and smoother. It is, however, fun as hell to go from 5-2 without a hint of protest from your tranny, and to hear the engine scream instead

 

Double clutching is somewhat of a lost art, and not required on today's automotive manual transmissions. It is, however, the correct way of driving a manual. Is it beneficial? I suppose it reduces clutch and synchro wear, as well as minimizing driveline lash, but I prefer it as it makes the driving experience smoother and more rewarding.

Keep in mind that your transmission is actually in constant mesh to begin with, the synchros basically deciding what pair of gears to connect. Double clutching, although not necessary in your application, is basically depressing the clutch, taking the car out of gear and into neutral, depressing the clutch once more, putting the car into higher gear, and then releasing the clutch. The engine will have slowed down to match transmission speed. Doing it correctly is seamless. Downshift requires depressing the clutch, shifting to neutral, depressing the clutch once more and blipping the throttle to bring up engine speed while shifting into a lower gear and releasing the clutch. Does all this work make you any faster? No. Certain road race transmissions, and transmissions in heavy trucks, are not synchromesh and need to be double clutched.

Personally, I do not use my clutch for anything other than starting out or coming to a complete stop. Whether upshifting or downshifting at a leisurely pace I match revs precisely and tickle it into gear. If I use my clutch at all, it's usually no more than a quick jab. I do not recommend this unless you have a lot of experience. If accelerating quickly, however, I always use my clutch. It sounds to me that your friend may be somewhat unaware of what double clutching may involve.


Terry

 

Double clutching has absolutely nothing to do with making a car faster or quicker. It is a method to employ when downshifting and should rarely be used for upshifts. If your friend is double clutching on upshifts during a drag race, he knows nothing about drag racing or what it takes to win.

As for how you double clutch (remember, we are talking downshifting here), thsi is what you do. The scenario is a downshift from 4th to 3rd gear as one approaches a light or stop sign.

o Remove your foot from the throttle, fully depress your clutch pedal, then start the shift.
o As you enter the neutral gate, pause in your shift while at the same time letting the clutch out some (or all if you want) and blipping the throttle to increase engine speed over that where it will be in 3rd gear upon completion of the shift.
o Depress the clutch pedal and complete the shift.
o Engage the clutch.

If you do this correctly, your downshift will appear to be totally seamless with no jolts, bucking, clutch riding, or miss-matched engine-to-wheel speed.

Benefits. Double clutching and rev-matching are often confused and used when explaining the same process, but they are different. Rev-matching is similar to double clutching with one major exception. When rev-matching, you do not momentarily engage the clutch in the neutral gate while blipping (revving) the engine. The major benefit of rev-matching is matching engine speed to wheel speed in order to reduce clutch component wear. The benefits of double clutching is the same as rev-matching PLUS reduced wear on synchronizers, blocker rings and shifter forks (to name a few).

I have noticed that a few on this thread have claimed that double clutching is unnecessary with modern cars. That it's old school. This begs the question, "why" would anyone say this? Perhaps because they do not know how to do it or have never taken the time to learn the steps correctly? I have news for you people. It is just as beneficial today as it was 50 years ago. And synchronizers are not new things. Synchronized transmissions have been around since 1929 and were very common by the 50's. Double clutching significantly reduces wear primarily on synchronizers. These little clutch-like components are made of a softer metal than steel (usually brass) and are therefore more subject to wear than other components in your transmission. And yanking a manual tranny for a FWD car for a teardown and rebuild is not a cheap prospect. Doesn't it therefore make sense to do things to extend the lift of the internals for as long as possible?

Terry mentioned that a manaul transmission is in constant mesh and that is correct and is why they are called constant mesh transmissions. When you are shifting gears, you are not really shifting any gears at all (bet some of you didn't know that). The gears in the transmission are in fixed positions and do not move when you move the shifter. What you are doing is moving hubs along splined shafts to mechanically connect with collars which are fixed in gear sets. These hubs have dog teeth which fit into female openings in the collars. This is what you are doing... moving these parts together. The synchronizers engage first to try to bring the speeds of these shafts into "sync", then the blocker rings lock together for the final insertion of the dog teeth. The synchonizers have the most work to do because they have to match speeds of items of mass and overcome the inertia of those items. So don't let anyone tell you that double clutching is old school or just for trucks or not necessary with modern transmissions because what they are telling you is not at all the case.

I would suggest to those who belittle double clutching to learn how a manual transmission operates.. as well as the clutch assembly. Understand what goes on in there and you'll gain not only a better appreciation of the mechanics but also understand why you should do and not do some things.

 

Southernboy as always, another excellent writeup on MT operation. When did you become a moderator?

 

Thanks, Legend.

A couple of months ago, though I don't believe I'm doing much good at it. I have a lot of things on my plate on both the work and home fronts, so there never seems to be enough time to really be effective. Watch them kick me out.

 

Nice writeup!

Oh, and congrats on the MEGA status!

 

They won't kick you out, you are too much information to be shown the door.

Honestly, thumbs up once again for a great write-up on how to correctly drive a manual transmission.

 

nice write up... always good to read up on these things

and to the OP... pretty sure its double clutCHing, not "double cluthcing"

 

This...

 

Thanks for the write up Southernboy, and Teranfon. Double Clutching isn't something I have ever tried, and it will take practice and to get the technique down to where the shifts and revs are seamless, but I will give it shot and see how it goes.

Yeah... I noticed the thread title a bit late. I blame it on Fat finger typing.

 

....and SB and terenfon show why they're mods. SB, after reading your post, I feel like I need to bring my S2000 and me down to VA for shifting lessons from the master.

 

Do you ever wish your CTS-V was a manual? I would love to have one of those. I keep toying with the idea of "maybe after I retire", but we'll see.

 

You're most welcome and yes it certainly does take some practice. I was very fortunate in that I learned this technique when I was a teenager and every car I've owned since then has benefited from this. You will find that the two things which will stand in your way as you learn this are timing and feel. Timing deals with getting everything to mesh so that it all comes together in a fluid and seamless motion. Feel is the natural feel you will develop so that it becomes as normal as breathing. You will know when you have gotten there when your passengers don't even realize you have made a downshift.

Here are two videos which depicts what we're talking about. The first one has one part of it with which I disagree and that is were the driver says to the effect that double clutching is not all that necessary because modern synchronzers are so good. Yes, they are very good, but they are still wear items. What has helped is that the transmissions themselves have become smaller with lighter components which reduces the inertia load on the synchros. But I would be hard pressed to believe that the manual in our TL's is better than a Muncie 4-speed of the mid 60's. That, my friend, was a masterpiece.

http://video.google.com/videoplay?do...88575741675515

http://www.youtube.com/watch?v=pI3cH...eature=related

 

I do agree technically that is true, but to put it in perspective we're talking about making the synchros in your manual transmission last 300,000 miles instead of 200,000. Then you can get into all the semantics regarding clutch and throw-out bearing wear, will that require a clutch job sooner vs. later, etc. etc.

As one of the few people out there that actually knows how to double-clutch (isn't it called double de-clutching?) I'll still put myself in the camp that it really isn't necessary on modern transmissions. I've taken several cars way past 100,000 miles and they shifted just fine all throughout.

Abusing any transmission though, will accelerate wear and if you're a butcher with the shift lever, that transmission is gonna wear out a lot faster.

Just my , no more, no less.

Oh yeah, and I definitely agree about the Muncie transmissions. The M-21 in my Camaro with a Hurst stands to this day as the best shifting transmission I've ever used. Fast, positive, perfect.

Oh yeah, and to the OP, your buddy is wildly mis-informed, as noted several times above.

 

My pop owned a '79 V-8 Jeep CJ-7 with a 3 speed manual that was every bit as easy to shift without the clutch as with it. I probably did half and half.

 

Is that a trick question? Um, YEAH I wish I'd bought a manual! However, I use the car to travel sometimes and the wife has to able to drive it in a pinch.

Luckily, the automagical tranny in this car is REALLY good, and I just purchased a transmission tune (waiting for it to arrive in the mail) to increase responsivity to throttle input.

 

It could be argued that rev-matching versus double clutching is a matter of degrees. Degrees the operator is of a mind to accept in favor of or as a trade off for wear. I double clutch my downshifts, and occasional upshifts which I will explain, for several reasons. First and foremost is because in the purest sense, it is the correct thing to do. But also because it smooths my shift and makes the shifter almost feel as though it is being pulled into gear. Also I must admit to a touch of vanity here. I know that most manual drivers do not do this because they have either never heard of this technique and/or they do not know how to do it and have no intention to learn. When I do this I know I am in a rather small group of drivers.

Now for double clutching on upshifts. The only time I find this necessary is when during an upshift, something occurs which delays my shift momentarily but enough to allow engine speed to move close to or back down to idle. Then double clutching is a good thing.

As for the Muncie, my '66 SS396/360 Chevelle had an M21 close ratio box. That 2.20:1 first gear was the ticket with 3.73's out back and even better with 4.10's (the wide ratio, 2.52:1, worked better with 3.55 and higher gears). There is no way the manual in a TL could even hope to match a Muncie in terms of strength and durability. Those transmissions were superb.

 

The thing about a manual that so many people who don't have or want them don't realize is the feeling of immediate and a one-to-one direct power translation from the engine to the driver's lower back when he tips into the throttle. With a serious car, and yours is a perfect example, this is so prevalent and consuming that one does not have to nail the throttle every time they drive the car.

I hear this a lot. "Why do you need so much power? You can't use it on the streets". When someone says this to me, it is clear that they haven't a clue and I will most likely not be able to sway or convince them otherwise. I have only owned two really quick cars in my life and that feeling of a throttle opening to driver sensation is sheer pleasure to me. A manual magnifies this in my book. I have ridden in four cars that were quite a bit quicker than the new CTS-V (sorry, but it's true: 1967 L71 Corvette, 1998 modified Mustang SVT Cobra, 1969 detuned Camaro drag machine, Factory Five replica of a 1966 427 Shelby AC Cobra). The sensation of acceleration is amazing so I know your "V" is a super machine and in my mind, perhaps the best of its kind the world has to offer.

 

I certainly know how to do this but never recommend it unless the driver has no choise (broken cable/hydraulic system). To easy to damage the dog teeth. I prefer to do things as they were intended.

 

I should clarify something here. There are times when I do not perform this maneuver entirely correct. Something distracts me or upsets my timing or some similar thing and my downshift looses its smoothness. It happens. Also, i freely confess to using my tach often when doing this, and for upshifts as well, because with the stock exhaust system very little engine noise makes it into the cabin. So nothing is perfect or absolute with this technique. Most of the time, but not always.

 

I will typically try to blip the throttle ever so slightly on shifts to rev match (especially if im lax and let the tach drop a little before shifting) I have never had a issue with my manuals lasting (syncros) beyond 250k. I will double clutch when driving slower and conservative(which isnt often) I find my self using 2nd A LOT on my TL since the 6 speed swap for starting out (if i had to guess 80% of the time) My clutch now has 100k on it and going strong.

 

Respectfully SB, I have to disagree with you here. Although one needs to be VERY aware how to do it properly, it can be done without any damage. One of my pickups has 380 000 kilometers, or about 250 000 miles, on it and still retains it's original clutch and gearbox. It has been shifted for the most part without using the clutch while moving. My Accord, collector cars, and other vehicles have all been driven in the same manner without ever experiencing any problems. It does take, however, a very precise technique.

BTW: M21? smooth? Ford toploader FTW! You can't convince us Ford boys otherwise!


Terry

 

That's why I never recommend doing this. Not that this technique can't be learned and mastered, which it most certainly can. It's just that when people ask me about it, I recommend against. I do not wish to be someone who encouraged another to do this only to find out sometime later that he trashed a gearset.

I have done and I know how to do it, but even so I chose not to for the simple reason that I would hate to have that one time arise where I did and lost my timing as well as a few dog teeth.

But to each his own both in terms of cars and money.

 

Yeah, the Jeep in question definitely lent itself to that kind of operation, it was very easy to get the revs right and butter it right into the next gear. On some other cars, particularly cable-shifter FWD ones, its darn near impossible to do on a consistent basis....so no go.

Much love for the top-loader Terry, that's a terrific gearbox as well.

 

Interesting; 2.20 first gear with a 3.55 ring is exactly what I had in the Camaro; it worked pretty well because I like having a really tall overall 1st gear ratio.

Although my double-clutching technique is very good, I'm essentially a throttle blipper 99.9% of the time. When I double-clutch its mostly for fun and to keep the technique sharp.

I actually use a blip on upshifts in certain cars for the same reasons you mention, although in the Camaro I did it a lot more because the flywheel was light enough that an extra blip on upshifts made them smoother in normal driving. Otherwise, you had to be right quick with the clutch and the lever.

Cheers,
-Mirror

 

I rev match and occasionally shift without using the clutch, works fine for me!

 

We generally considered 3.55's to be the middle ground between going for a wide ration (2.520) or a close ratio (2.20). Lots of variables here. Engine displacement and state of tune. Car's weight and chassis configuration (dynamics)... just to name a few. I ran shorter tires on my '66 Chevelle which made my 3.73's work out to a 3.91. My engine was turning 4000 RPM at 70 MPH in 4th gear with that setup.

Remember periodically checking your toeplay to make sure it was to spec and then making the adjustments where the rod connected with the release fork? Did your Camaro have a Holley carb? The stock carb that came with my Chevelle was a single feed 660CFM Holley. When I installed my headers and straight thru exhaust, I replace that carb with the R3310 780 dual feed (center pivot) Holley. Great carburetors and so easy to work on.