No heel-toe no care.

 

Synchros wear out, and a clutch/throwout bearing is a lot cheaper than a transmission tear down. Sure, for daily driving, letting the synchros do their thing may not be totally bad, but if you're really stressing the car and shifting as fast as possible, double clutching will extend the life of the synchros in the long run.

Double clutching on the street is just good practice.

 

LOL double clutching is so 50's

There is absolutely no gain to be had by double-clutching. As long as you are rev matching no additional stress is applied to the clutch or tranny. The only reason to double clutch in the past was because of the lack of synchro's.

 

rev matching only gives the sensation of smooth, but still makes the synchros do ALL of the work. Double clutching puts no stress on the synchros at all if performed correctly.

But if it works for you, more power to ya.

 

If you're rev matching, are the input and output shafts not, by definition, synchronized and thus the synchros experience no wear?

 

Not if the clutch is held in. Input and output shafts are only linked if the clutch is touching the flywheel (foot off the pedal), which is why a double clutch throws in that extra "...clutch out, rev, clutch in...".


We should all just drive DSGs to remove all the guess work

 

I never said that the shafts were linked, only that they were rotating at the same speed. If the clutch is disengaged but then reengaged, with both shafts rotating at the same speed, the synchros should experience no wear. Is that not what happens when you rev-match?

 

Are you saying in neutral if you press the clutch in and out repeatedly while giving gas the clutch wears out??

 

There's far less load, so the effect isn't very pronounced.

 

The synchros only come into play when you are moving the shift lever from one gear to another. If you hold the clutch in and move the lever to the next gear, the slight moment of resistence with the shift is the synchros matching speeds for you (and you'll notice with a proper double clutch, there's no resistence in the shift since the synchros aren't doing anything). Rev matching makes the clutch engagement smooth, but does nothing for the synchros, since their work was already done when you stick the shifter in the next gate.

Go to howstuffworks.com, they have an excellent animation on how it all goes together... it's hard to explain with words (at least for me )

 

So by letting the clutch out you are spinning the clutch and the synchro before the outshaft is engaged..... Makes sense. Thanks.

 

And the supposed less wear and tear is probably so minimal as to be non-existent. By throwing in an additional cycle to the clutch you ARE increasing wear and tear.

 

It just depends on which piece of equipment you choose to put more wear on - synchros or clutch. The wear on synchros is very real, though, especially if you haven't changed transmission oil in a while.

 

Originally Posted by [graphicjoe]
A note to those who parrot the misguided advice not to downshift, saying that the brakes are to slow the car, and that brakes are less expensive to replace than clutches. [/FONT]

If done properly down shifting does not materially add to the wear or stress placed on the clutch. So long as the engine speed and transmission speed are accurately matched there is virtually no clutch wear.


[Shifting on the race track is not the same as shifting for normal use. Brakes ARE less expensive to replace than clutches and there is a fine line between a proper downshift and extensive transmission/drive-train damage.

Granted, the warranty covers the clutch and drivetrain components, in addition to the breakpads, but which one would you rather have at the end of its' life cycle immediately after the warranty expires?

There is absolutely no need to downshift a car when coming to a stop, period. 50 years ago when cars had mechanical brakes then yes they downshifted to assist the brakes, and the habit continued through the later 50's and early 60's cause people's dads said that's what they did, but this hasn't been necessary since cars started coming with front disc brakes in the mid 60's. It does nothing to add to the already extremely effective brakes of modern cars and is a waste of time, of synchros, of clutch components, and puts reverse loads on engine mounts which shortens their life. You don't want to do this to all these parts just to save your brakepads and besides, it adds nothing to the braking. Just leave the car in whatever gear you're in when you first realize you're going to have to stop ahead, then push the clutch in once you get to about 20mph and let the car coast while applying the brakes normally. You can either leave it in gear with the clutch in, or to save on the throwout bearing and pressure plate just knock it into neutral while braking for the stop.

 

Always put the car in neutral at stops, never hold the clutch peddle for more than ten seconds at most (like when reversing).

When i get back to the states, i'll make a video of my driving technique after i get back into the swing of things. My heel-toe method is slightly different than what ive seen on youtube. It's pretty much self taught and since my feet are rather big, its the only way it can be done.

 

I hate to say this because I've got a Miata with a 139,000 miles on the clutch and I'm bound to jinx myself, but I've rev matched, down shifted, and heel and toed for 25 years and I've never replaced a clutch in spite of putting more than 100k miles on multiple cars. Done smoothly, the wear on the clutch is insignificant.

All this talk about using the brakes instead of downshifting misses the point. The primary point of downshifting isn't to decelerate with engine braking, it's keeping the car in the optimum gear for whatever comes next and doing it as smoothly as possible.

It's much more smooth to heel and toe into a corner and accelerate out than to brake into a corner in neutral, put it in gear and accelerate out. When you get it right it's silky smooth and a real pleasure.

 

Thanks Scott was wondering if someone was going to mention this. If you have ever Driven a Car that didn't have Synchros and you didnt rev match on down shifting the car would let you know. This is pretty much where the old saying of "If you can't Find them Grind them" came from.

Is this good for the tranny. I cant say don't really have mass data to confirm, But I can say. I have a 1980 Toyota PU with just over 1 million miles which I both Blip downshift and (what I call) Speed shift everytime I drove it. Beside replacing half a dozen U Joints and two clutches. I have never had an issue with the 5 speed tranny.

Also have a 1987 Jetta just over 280 thousand miles and did just bend a shifter fork going into reverse.

 

FYI: There are many cars with no synchros in first (the MINI has), and reverse does not have synchros.

 

Agreed... don't EVER go into a corner in neutral... that's how accidents happen.. if anyone disagrees go take a hard corner and in the middle push the clutch in.... let me know how it goes...

 

I take the corner in neutral sometimes. You don't push the clutch in in the middle of the turn. Instead you brake while in neutral when you are slowing down for a turn. Carry the speed and turn. Then put it in the gear and drive out. I do that when I am not in a hurry. It is not a dangerous manuver.

 

at speed it IS a dangerous move especially in the middle of a turn.... I made that mistake once... once... then again... maybe it applies more to a RWD drive car... <shrug> maybe you got me there.... I haven't tried it in a mini... not sure I want to either LOL

a word of note about blipping the throttle... The e60M5 with SMG blips the throttle when downshifting... every time.... I'm sure they programmed it that way... plus it makes even the average guy sound like the heal toe master with the touch of the paddle

 

Curious about the SMG unit. Can you change the tranny fluid like in manual transmission?

 

ok, now that i finally got my car, im not trying to put a lot of stress on the motor or anything... at least just yet... im at like 60 miles on the ODO.. such a long way to go before i can really drive the thing... anyway, i understand the theory of heel toeing as well as the concept, but i just feel like my foot/leg cannot bend in a way that can easily apply the brake and gas at the same time. Or at least without getting on the brakes too hard. My feet arent huge, size 11, im wearing shoes that arent fat although they arent driving shoes...

anyway, it seems like the sport button needs to be on otherwise the throttle is too unresponsive but i just cant get on the gas without digging deeper in the brake causing the car to brake pretty hard... what gives?

 

The pedals are setup perfectly for heal-toe driving, pretty much the best out of all cars I've driven, right there with a 911 turbo....I easily heal-toe and I wear size 10.....just practice.

 

In general, on the street in normal conditions, you're right, it's not a dangerous maneuver. The tires are operating no where near their limits. However I think most driving instructors would discourage cornering in neutral and changing gears mid-corner for these reasons:

1) When the car is coasting in neutral (or with the clutch disengaged), the engine is disconnected from the wheels and driver has less control of the car. If the car begins to oversteer or a truck unexpectedly gets in the way, there is no easy way to apply more throttle.

2) In a corner, if the tires are at the limit of traction holding the car in the corner e.g. ice, and the clutch is not engaged smoothly or the RPM is not exactly right, that slight difference could be enough to unsettle the car. The tires could exceed their limits and slide.

Conventional driving wisdom is to downshift in the straight before turning into a corner. Corner while in gear. Upshift in the straight after exiting the corner.