View Poll Results: Engine vs Rotor Braking
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Engine vs Rotor Braking
01-08-2003, 07:23 PM
#92
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I've got a question. For the record, I only read through about 75% of all the posts, it got monotonous after half an hour 
Several of you have stated, and received no debate concerning this, that you would not brake while the tranny is in neutral, or the clutch is fully depressed. why is this? I usually do this, thinking it will drop my revs down to idle and increase gas mileage. Is this causing extra stress on some driveline part? Someone also said that they would not drive through a corner with the car in neutral or clutch disengaged.
I was never formally taught to drive a manual. I was always fascinated with stick shifts, so as soon as budget allowed (i'm a college student), I bought the cheapest "fun car" with a stick I could find -- a 1984 chevrolet camaro Z28 5-speed. I'm WELL aware of the white trash associations, I'm also aware I live in Arkansas, so most of your are probably doubting my intelligence as we speak. But when you already have a vehicle (a better one at that) it's hard to justify a car payment for a second one that is, as we all know, white trash. So you save 1500 bucks and get a toy.
Anyway, I have had the time of my life learning to drive a stick, teaching my self to heel and toe (easier to do in my car than anything else I've driven, probably because I only have about 4500 rpm to work with). I have read and learned the hows and whys of double-clutching and such, and if my car could pass a tech inspection, I would be an autocrosser. Unfortunately, my fellow Arkansans only feel compelled to race around in dirt circles or a 1/4 mile at a time, not where my passions lie.
All that having been said, if anyone wants to write me a primer, feel free. I appreciate any input from those who have done all this before me.
Several of you have stated, and received no debate concerning this, that you would not brake while the tranny is in neutral, or the clutch is fully depressed. why is this? I usually do this, thinking it will drop my revs down to idle and increase gas mileage. Is this causing extra stress on some driveline part? Someone also said that they would not drive through a corner with the car in neutral or clutch disengaged.
I was never formally taught to drive a manual. I was always fascinated with stick shifts, so as soon as budget allowed (i'm a college student), I bought the cheapest "fun car" with a stick I could find -- a 1984 chevrolet camaro Z28 5-speed. I'm WELL aware of the white trash associations, I'm also aware I live in Arkansas, so most of your are probably doubting my intelligence as we speak. But when you already have a vehicle (a better one at that) it's hard to justify a car payment for a second one that is, as we all know, white trash. So you save 1500 bucks and get a toy.
Anyway, I have had the time of my life learning to drive a stick, teaching my self to heel and toe (easier to do in my car than anything else I've driven, probably because I only have about 4500 rpm to work with
). I have read and learned the hows and whys of double-clutching and such, and if my car could pass a tech inspection, I would be an autocrosser. Unfortunately, my fellow Arkansans only feel compelled to race around in dirt circles or a 1/4 mile at a time, not where my passions lie. All that having been said, if anyone wants to write me a primer, feel free. I appreciate any input from those who have done all this before me.
01-08-2003, 08:51 PM
#93
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The way that I learned to drive a manual transmission is to downshift to a lower gear in order to slow the car down and use the brakes when this doesn't slow the car quickly enough. Most of my downshifting happens when the car gets to about 2k rpm. I was never taught to rev match nor do I now. Most people that I've seen drive a manual transmission do downshift to slow down and they don't rev match. The thing that I find interesting is that those who agree with me all seem to be advocating that rev matching is critical or else you will put too much stress on your engine, transmission, clutch, and whatever else. To this I would say that the revs are matched for you. By increasing the rpm's in neutral to where the engine will be, you're just doing what it would otherwise do. Other than speculation I have not seen any real world evidence that rev matching delivers a significant wear and tear savings versus not rev matching.
[QUOTE]Originally posted by Elistan
[B]If you mean that you push in the clutch, down shift, then without giving it any gas you let off the clutch?
[QUOTE]Originally posted by Elistan
[B]If you mean that you push in the clutch, down shift, then without giving it any gas you let off the clutch?
01-08-2003, 09:14 PM
#94
[QUOTE]Originally posted by Sheister
[B]The way that I learned to drive a manual transmission is to downshift to a lower gear in order to slow the car down and use the brakes when this doesn't slow the car quickly enough.
[B]The way that I learned to drive a manual transmission is to downshift to a lower gear in order to slow the car down and use the brakes when this doesn't slow the car quickly enough.
01-09-2003, 04:01 AM
#95
Registered User
Thought I'd share my experience as well. I ALWAYS downshift when decelerating. The car I sold to buy the S was a '95 del Sol VTEC. After 128K flawless miles, that car was still on it's original clutch. I was pretty hard on the clutch, too. I took the car drag racing occasionally, and it had plenty of hard launches under it's belt. The clutch was as solid the day I sold it as it was the day I took delivery of the car. It could still chirp second at 128K miles.
Furthermore, the front brake pads were also original.
The rears needed replacement at 90K. I did not baby that car by any means. I drove the SNOT out of it. 
I don't believe for a second that downshifting will reduce the life of the clutch/drivetrain. I do believe, however, that it will increase the life of the brake pads.
Furthermore, the front brake pads were also original.
The rears needed replacement at 90K. I did not baby that car by any means. I drove the SNOT out of it. I don't believe for a second that downshifting will reduce the life of the clutch/drivetrain. I do believe, however, that it will increase the life of the brake pads.
01-09-2003, 06:40 AM
#96
I gave up on this thread a long time ago, but the recent rev-matching conversation is interesting.
I have no direct experience with the internals of the S2000 transmission, but from a theoretical point of view it seems to me that you will be spinning up the engine by friction in the clutch (rather than getting the engine up to speed by blipping the pedal). The interesting thing is that this friction will be coming from the other direction (i.e., the opposite part of the clutch disks from where slip normally occurs).
Probably what's going on here is that wear and heat buildup on the clutch disks is on a different "leading edge" than normal forward travel upshifts...
To be honest, I don't know if this really matches "reality" from a materials engineering point of view, but it's conceivable at least that this business about rev matching to save the clutch is not a legitimate argument. What would be fascinating is to look at the clutch disks and springs from two different driving styles and do some measurements on the materials. I wonder if such a study has ever been done.
Best wishes, guys!
I have no direct experience with the internals of the S2000 transmission, but from a theoretical point of view it seems to me that you will be spinning up the engine by friction in the clutch (rather than getting the engine up to speed by blipping the pedal). The interesting thing is that this friction will be coming from the other direction (i.e., the opposite part of the clutch disks from where slip normally occurs).
Probably what's going on here is that wear and heat buildup on the clutch disks is on a different "leading edge" than normal forward travel upshifts...
To be honest, I don't know if this really matches "reality" from a materials engineering point of view, but it's conceivable at least that this business about rev matching to save the clutch is not a legitimate argument. What would be fascinating is to look at the clutch disks and springs from two different driving styles and do some measurements on the materials. I wonder if such a study has ever been done.
Best wishes, guys!
01-09-2003, 08:10 AM
#97
Registered User
Steet driving:
Never downshift purely to brake, only to get ready to accelerate in a new gear.
Engine (compression) braking isn't hard on the engine, it's the clutch and transmission synchro wear that suffers when downshifting.
Cruising in traffic: Stay in a low gear so you can modulate your speed with the throttle and save the brakes.
Coming to a stop: Let the engine in gear while braking, don't declutch or shift to neutral until the engine slows to about 1000-1500 RPM.
Track driving: Use whatever gets you around the fastest.
Never downshift purely to brake, only to get ready to accelerate in a new gear.
Engine (compression) braking isn't hard on the engine, it's the clutch and transmission synchro wear that suffers when downshifting.
Cruising in traffic: Stay in a low gear so you can modulate your speed with the throttle and save the brakes.
Coming to a stop: Let the engine in gear while braking, don't declutch or shift to neutral until the engine slows to about 1000-1500 RPM.
Track driving: Use whatever gets you around the fastest.
01-09-2003, 10:38 AM
#98
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Well-done rev-matched downshifts are the very least mechanically stressful of all downshifting techniques. If you feel the car either surge forward or decelerate when you release the clutch, then you are stressing the clutch/drivetrain unnecessarily. If you downshift with your foot off the gas then you are absolutely torturing first the synchros, and then the clutch.
A technique that works very well on the S2K is to over-rev about 50 RPM during the downshift and re-engage the clutch just as the engine passes through the rev-match point. Very satisfying when you do it well, and zero stress on the synchros, clutch, etc. Someone suggested a shiftpoint of 2K RPM- way too low to absorb any real energy through the engine in this car. I generally use 4500-5000 RPM as the downshift point, though it can be comfortably done much higher for performance driving. If it's not getting there quickly enough, I tap the brakes to put the revs in the desired range.
This car rewards artful driving with great joy and satisfaction.
A technique that works very well on the S2K is to over-rev about 50 RPM during the downshift and re-engage the clutch just as the engine passes through the rev-match point. Very satisfying when you do it well, and zero stress on the synchros, clutch, etc. Someone suggested a shiftpoint of 2K RPM- way too low to absorb any real energy through the engine in this car. I generally use 4500-5000 RPM as the downshift point, though it can be comfortably done much higher for performance driving. If it's not getting there quickly enough, I tap the brakes to put the revs in the desired range.
This car rewards artful driving with great joy and satisfaction.