car talk says double clutching is bad?

[Wh33lhop]

out of context quote FTL.

he obviously meant you are upshifting during a drag race, and that double clutching would be pointless in that case. ;)

Context had nothing to do with it, I just interpreted it wrong.

Mah bad dawg.

[Wh33lhop]

Interesting information about the TOB and the disc. However, I definitely think my neighbor knows what he's talking about.

There is a difference between saying it's unnecessary and saying it's BAD for the transmission. You can trust him, I don't care. I'm saying experience fixing cars and an intrinsic physical understanding of cause and effect do not necessarily go hand-in-hand. Plenty will argue otherwise but I've talked with plenty of techs who know what they're talking about, and more than a few who are tards.

Considering the amount of people on here saying that double clutching is stupid I'm going to have to stick with that side of the argument.

Why even do it? It's slower and involves more work.

Why not? Doesn't do any harm.

I'm not sure how double clutching is "smoother." If you're driving regularly doing shifts into gears that are next to each other there is nothing unsmooth about rev matching. it just takes an ounce more effort to move the gear lever. The actual motion of the car is still smooth.

Imagine perfect synchros, no resistance whatsoever going into gear. That's what a good double clutch does, and that's why it's satisfying.

I know I sound like a character in some stupid car movie, but it's pretty cool.

[87e30]

I mean I've done it before. I have a basic understanding for the concept of how it all works. I just don't see the appeal... The ability to do it is nice, the understanding of how the car works is nice, the end result is essentially the same as a rev match though.

Although I've never double clutched really quickly, I personally just don't get the appeal of doing it every shift.

And my neighbor, I know him, I trust, him. I don't need to defend his knowledge to the internet. Maybe he just told me that exaggerated so that I wouldn't ruin my trans trying to get good at it and messing up.

[Wh33lhop]

I mean I've done it before. I have a basic understanding for the concept of how it all works. I just don't see the appeal... The ability to do it is nice, the understanding of how the car works is nice, the end result is essentially the same as a rev match though.

Although I've never double clutched really quickly, I personally just don't get the appeal of doing it every shift.

And my neighbor, I know him, I trust, him. I don't need to defend his knowledge to the internet. Maybe he just told me that exaggerated so that I wouldn't ruin my trans trying to get good at it and messing up.

It's possible.

[WlknGenius]

I mean I've done it before. I have a basic understanding for the concept of how it all works. I just don't see the appeal... The ability to do it is nice, the understanding of how the car works is nice, the end result is essentially the same as a rev match though.

Although I've never double clutched really quickly, I personally just don't get the appeal of doing it every shift.

And my neighbor, I know him, I trust, him. I don't need to defend his knowledge to the internet. Maybe he just told me that exaggerated so that I wouldn't ruin my trans trying to get good at it and messing up.

There is no appeal. I'm assuming the people who do it are either too bored driving normally or think they are badass because they are doing some sort of hardcore driving technique.

Double-clutching is retarded in this day and age. And yeah, even drivers of large vehicles such as a firetruck will not even use the clutch after 1st or 2nd gear.

[Wh33lhop]

There is no appeal. I'm assuming the people who do it are either too bored driving normally or think they are badass because they are doing some sort of hardcore driving technique.

Well, you've sure got ME pinned.

[daniel]

out of context quote FTL.

he obviously meant you are upshifting during a drag race, and that double clutching would be pointless in that case. ;)

thanks :)

I'm not sure how double clutching is "smoother." If you're driving regularly doing shifts into gears that are next to each other there is nothing unsmooth about rev matching. it just takes an ounce more effort to move the gear lever. The actual motion of the car is still smooth.

the smoothness comes in the form of the actual gear lever sliding into a lower gear easily with no reaction from the car in any way. I don't like that ounce more of effort required to use the synchros to get into gear, so i double clutch. it doesn't take much longer to do than basic rev-matching, you just have to do a little dance with your left foot.

Context had nothing to do with it, I just interpreted it wrong.

Mah bad dawg.

no problemo.

[cagedbunny]

Go ahead, try and get into first going 25mph. It's possible and I'm sure it's cool listening to the synchro spool-up whine, but it gives you the distinct impression that you're doing something wrong, and it should, because you are.

Why would I try to engage first gear at 25mph? Because I hate my transmission and motor? Whatever point you're trying to make is lost on this one.

Bottom line is, double-clutching downshifts on an E30 is a waste of energy. If you want to do it because it makes you sleep better at night, then by all means, go for it. But there are a hundred parts on your 20 year old car that are going to wear out sooner than your synchros, assuming you're not some ham-fisted retard banging gears. And curbs.

[Wh33lhop]

Why would I try to engage first gear at 25mph? Because I hate my transmission and motor? Whatever point you're trying to make is lost on this one.

First gear turns, downshifting for a stop light and thinking you're awesome, etc.

[WlknGenius]

Well, you've sure got ME pinned.

I'm that good.

[nando]

First gear turns, downshifting for a stop light and thinking you're awesome, etc.

there isn't much point in downshifting past 2nd really. You get overrun fuel cut down to ~1500rpm with the stock computer, which is slow enough in 2nd gear that you're almost stopped anyway.

the only time I ever needed 1st for a corner was an extremely tight autox, which was very rare. I hated doing it too, although it surprised me a bit when it just slipped right into gear. Otherwise, yah, you're just beating up on your car for no good reason..

[Wh33lhop]

there isn't much point in downshifting past 2nd really. You get overrun fuel cut down to ~1500rpm with the stock computer, which is slow enough in 2nd gear that you're almost stopped anyway.

the only time I ever needed 1st for a corner was an extremely tight autox, which was very rare. I hated doing it too, although it surprised me a bit when it just slipped right into gear. Otherwise, yah, you're just beating up on your car for no good reason..

To each his own. Not all of us have high compression 2.8 strokers that put out any torque below 3500rpm though. :p

[txtorquemade]

I would suspect you are doing putting more wear in both the throw out bearing and the clutch by double clutching. In double clutching, you are engaging the clutch twice during each shift. The clutch and the flywheel will be spinning at different rates and every time the clutch squishes up against the flywheel, you are going to get wear.

Rev matching is the ticket. If you minimize the speed difference between the clutch and the flywheel and you minimize the length of time the clutch spends spinning against the flywheel, the less wear you are going to have. Think about it: you burn a clutch up by trying to feather the clutch while accelerating. You get more wear by doing that than you do if you rapidly engage the clutch causing a bit of a jerk (which can be eliminated with good rev matching). But the clutch spins less so you are doing as much to it. Anyway, that's just my take on it.

Kinda think I agree with that. From a purely physics standpoint, it makes sense. :);)

[z31maniac]

my zf320 has 95k miles on it, and the clutch has about 15k miles on it w/ a lightweight flywheel.

I was talking about mine.

[Wh33lhop]

I would suspect you are doing putting more wear in both the throw out bearing and the clutch by double clutching. In double clutching, you are engaging the clutch twice during each shift. The clutch and the flywheel will be spinning at different rates and every time the clutch squishes up against the flywheel, you are going to get wear.

Rev matching is the ticket. If you minimize the speed difference between the clutch and the flywheel and you minimize the length of time the clutch spends spinning against the flywheel, the less wear you are going to have. Think about it: you burn a clutch up by trying to feather the clutch while accelerating. You get more wear by doing that than you do if you rapidly engage the clutch causing a bit of a jerk (which can be eliminated with good rev matching). But the clutch spins less so you are doing as much to it. Anyway, that's just my take on it.

The only extra wear you are putting on the clutch is when you're using the clutch to spin the input shaft. I'm not exactly sure what the moment of inertia the input shaft has, but suffice it to say it's under 1% of the comparable equivalent moment of inertia the entire car would have in first gear. You are saying a clutch that's designed to start a 3000lb car from a rest hundreds of thousands of times before it wears out is going to be worn by a 15lb 12" disc and a 5lb 1" diameter input shaft? Get real. That is beyond negligible, I don't care how much more you have to rotationally accelerate the input shaft than the car.

And as for the throwout bearing, that is worn more based on how long and to what extent the clutch is depressed, not on how many times. Think about it.

You want to state that double clutching is unnecessary since synchros will last forever? Fine, not only are we on the same page, but I agree with you. But what you are posting is immaterial.