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Old 06-18-2004, 05:47 PM   #1
Ki2AY
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Why does a stick stops faster than a Auto?

can someone explain to me why does a manual transmission vehicle stops faster than an automaitc?
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Old 06-18-2004, 05:55 PM   #2
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??? About the only thing I can come up with is that most stock automatic cars continue to drive the wheels even though you've let up on the gas. But at impending lockup with no throttle applied, the transmission has zero to do with stopping ability. Only mass (how much weight you have to stop), brakes (how much friction you can generate), and tires (the actual interface with the road that stops you).

Automatics should not affect stopping ability in ANY car.
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Old 06-18-2004, 06:04 PM   #3
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I find that shoving the car into 1st gear while doing a brisk 80mph on the freeway brings the car to a complete stop about 45 feet sooner than using conventional braking techniques. Kind of like a poor man's Anti-lock braking system.

Just kidding of course!
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Old 06-18-2004, 06:29 PM   #4
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idunno.. my uncle says stick's stops faster, and another time, me and my friend was driving down on a freeway and he wasnt paying attention to the road, he didnt realize the car on front of us went on a sudden brake and i yelled out loud to step on the brake! luckily we didnt hit the car on front of us, but he did say, "if his car was an automatic we would've hit the car".
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Old 06-18-2004, 06:32 PM   #5
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Quote:
Originally Posted by Ki2AY
idunno.. my uncle says stick's stops faster, and another time, me and my friend was driving down on a freeway and he wasnt paying attention to the road, he didnt realize the car on front of us went on a sudden brake and i yelled out loud to step on the brake! luckily we didnt hit the car on front of us, but he did say, "if his car was an automatic we would've hit the car".


you can use engine breaking with manuals, but you probibly can with some autos, most just free wheel. As bav said if you dont have ABS then manual is more handy in slipery conditions.
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Old 06-18-2004, 06:50 PM   #6
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Originally Posted by cinqyg
you can use engine breaking with manuals, but you probibly can with some autos, most just free wheel. As bav said if you dont have ABS then manual is more handy in slipery conditions.

Is that what I said?
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Old 06-18-2004, 06:51 PM   #7
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Quote:
Originally Posted by cinqyg
you can use engine breaking with manuals, but you probibly can with some autos, most just free wheel. As bav said if you dont have ABS then manual is more handy in slipery conditions.

whats "engine breaking"?
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Old 06-18-2004, 06:54 PM   #8
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Originally Posted by ChrisV
??? About the only thing I can come up with is that most stock automatic cars continue to drive the wheels even though you've let up on the gas. But at impending lockup with no throttle applied, the transmission has zero to do with stopping ability. Only mass (how much weight you have to stop), brakes (how much friction you can generate), and tires (the actual interface with the road that stops you).

Automatics should not affect stopping ability in ANY car.

ChrisV
I have read a lot of your posts here on CF and I love the knowledge and eloquent style you bring to the board. I have always agreed with most of what you say. However, I disagree with you on this one. An automatic transmission is connected to the transmission through a fluid coupled unit called a torque convertor. This unit provides about 5% slippage between the engine and the transmission. This is the reason you can come to a dead stop with an automatic and not kill the engine. A manual transmission uses a clutch to form a solid attachment between the engine and transmission. Using a technique called "engine braking", or downshifting, you can add the power of the engine to help slow the momentum of the car. Automatics will do this to some extent down to about 25/30 mph where all the hydraulics unload. This is bad abuse for an automatic though. Back in my day (hum- hummp), this led to a technique called double clutching, in order to match the speed of the crank to the speed of the transmission input shaft to accomplish selection of a lower gear. I still do it out of habit, a lost art I think. No fancy synchronizers in those days. The addition of engine power to help stop the car is a great advantage. Just ask any truck/lorry driver.

Did you notice that UK word I put in there? See what reading that foreign stuff does to ya.
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Old 06-18-2004, 07:02 PM   #9
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Originally Posted by jcutsh
ChrisV
I have read a lot of your posts here on CF and I love the knowledge and eloquent style you bring to the board. I have always agreed with most of what you say. However, I disagree with you on this one. An automatic transmission is connected to the transmission through a fluid coupled unit called a torque convertor. This unit provides about 5% slippage between the engine and the transmission. This is the reason you can come to a dead stop with an automatic and not kill the engine. A manual transmission uses a clutch to form a solid attachment between the engine and transmission. Using a technique called "engine braking", or downshifting, you can add the power of the engine to help slow the momentum of the car. Automatics will do this to some extent down to about 25/30 mph where all the hydraulics unload. This is bad abuse for an automatic though. Back in my day (hum- hummp), this led to a technique called double clutching, in order to match the speed of the crank to the speed of the transmission input shaft to accomplish selection of a lower gear. I still do it out of habit, a lost art I think. No fancy synchronizers in those days. The addition of engine power to help stop the car is a great advantage. Just ask any truck/lorry driver.

Did you notice that UK word I put in there? See what reading that foreign stuff does to ya.

yeh, ive heard of this technique called "double clutch" my boss actually mentioned it the other day, she said the same thing u said which i still dont understand , maybe its the fact that im not a stick driver. and she also did mention about the fact that people used the "double clutch" technique back in the days with old manual cars, she said most people dont use that technique anymore because of some kind of new system MT cars have now.
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Old 06-18-2004, 07:17 PM   #10
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Quote:
Originally Posted by Ki2AY
yeh, ive heard of this technique called "double clutch" my boss actually mentioned it the other day, she said the same thing u said which i still dont understand , maybe its the fact that im not a stick driver. and she also did mention about the fact that people used the "double clutch" technique back in the days with old manual cars, she said most people dont use that technique anymore because of some kind of new system MT cars have now.
Sounds like my kind of gal.

If you are interested I will write it up. But I need to know where to put it on the board. Maybe the admin's could start a thread called school or something where we could place articles about basic training in elecrtical, hydraulics, etc.
I would be glad to write some.

John
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Old 06-18-2004, 07:32 PM   #11
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Quote:
Originally Posted by jcutsh
Sounds like my kind of gal.

If you are interested I will write it up. But I need to know where to put it on the board. Maybe the admin's could start a thread called school or something where we could place articles about basic training in elecrtical, hydraulics, etc.
I would be glad to write some.

John

id appreciate that, whats wrong with posting it here? i just want to know what is "engine braking" and how does it work.
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Old 06-18-2004, 07:42 PM   #12
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Originally Posted by Ki2AY
id appreciate that, whats wrong with posting it here? i just want to know what is "engine braking" and how does it work.
It would take me time to write it correctly. and that kind of effort should have a special place on the board where it can be found by those who seek information. This article would be longer than the 1500 character limit.

John
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Old 06-18-2004, 07:51 PM   #13
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It would take me time to write it correctly. and that kind of effort should have a special place on the board where it can be found by those who seek information. This article would be longer than the 1500 character limit.

John

I think the 1500 character limit is for the PM's...I've seen quite large posts in the past...well over 1500 characters.

We used to have a section called Gearhead Garage where this kind of stuff was placed. It was "manned" by member vwhobo which left the forum and subsequently that section was removed. Saved somewhere, I'm sure. The best I can offer is to make it a sticky and lock it so as not to make it a thread that goes on and off topic.
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Old 06-18-2004, 07:53 PM   #14
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There's 444 characters in the above post including spaces, but excluding the quote.

360 actual characters.
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Old 06-18-2004, 08:53 PM   #15
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Originally Posted by Ki2AY
id appreciate that, whats wrong with posting it here? i just want to know what is "engine braking" and how does it work.


Well i would have a go but i would probibly get shot down.

Over the course of time like anything else manual transmissions have developed. The origional type which still exists in some situations is a crash box or dog box. The more modernt type atleast for car aplications is the syncromesh gearbox.

What is a syncromesh?
When you start to engage (any) gear the synchro ring and hub create friction as they begin to mesh as they are both spinning at different speeds.
Once they match they engage with the dog teeth onto the drive gear.
This means all the gears are turning in order to get them to mesh inot what ever gear you select.

The dog teeth are oftern very small number of splines to help them mate up quickly, on dog boxes you some times have to mate a 15 spline gear with a 25 spline gear, if you get it wrong you will hear the crunch and a shiver will run through your spine.

What is a crash/dog box?
This is basically means that the gearbox doesnt have any syncros so to change gear so you have to line the gears up to change up or down, the only effective way of doing this is to double declutch.


Double de clutching
Double de clutching involves stopping in neutral and letting the clutch up with the engine at idle to slow the gears down. You then step on the clutch and move the gear stick from neutral to the next higher gear. On Down shifting, you stop in neutral and let the clutch out and throttle to speed up the gears before stepping on the clutch and then going from neutral to the lower gear.

So why would you want a crash box?
Well they are stronger than a syncro box, they are oftern used for truck, tractors, and race boxes.

The main reason for using them on tractors and trucks is the number of gears that you would a have to mesh typical truck has 16-20 gears and a tractor has 40+ forward and the same in reverse.

On race cars there are other reasons, as we have mentioned they are stronger, for the syncros to work then they have to equilise there speed this takes time, so it is quicker to double declutch. In terms of power transfer becuase there are less operations and componets then the power trasner is more efficent.(well its a point to debate)


If you have any coment pm me and i will edit as you so wish
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