Downshifting - Maintenance and Repair Forum

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Downshifting
Wednesday, February 23, 2005 2:12 AM
This is my first post here since just 3 days ago I bought my dad's 2000 Cav with 138000 km on it for 4000 Canadian. Its has a 5spd and im pretty good at driving a stick but I decided to bring up a topic thats caused some heated debate between me and my friends (most of which are mechanics or bout to become apprentice mechanics like me) considering downshifting.

I've always been told downshifting when keeping the revs in range by braking is the way to stop in a manual vehicle. One of my friends believe its best to drop to neutral and freewheel using only brakes to stop (which I find a bit dangerous since your reaction time to an accident will be slowed since you have to find the gear for your speed and let the clutch out to have control of your vehicle again). Another says to push clutch in and brake.

So why not help me out here give your thoughts on the best way to stop in a standard vehicle, so I can prevent clutch wear, since doing a clutch in a fwd vehicle sucks and I want to put that job off as long as i can.


2000 Cavalier 5spd Manual 2.2L

Re: Downshifting
Wednesday, February 23, 2005 3:11 AM
Push in the clutch, throw it in neutral, and brake to a stop. Downshifting is w waste of time imo.




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Re: Downshifting
Wednesday, February 23, 2005 3:27 AM
depends on the stop.......if im just cruising, i'll throw it in neutral and brake to a stop.....if im driving hard, i'll downshift and brake


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Re: Downshifting
Wednesday, February 23, 2005 5:00 AM
You should never just throw it in neutral and then use the brake to stop. It's harder on the brakes since you've got no engine braking helping you and there's no advantage to it whatsoever.

If you're too lazy to downshift, just leave the clutch engaged until the rpm's come down to below idle speed, then put the clutch in. Basically, you brake like you would an automatic and then put in the clutch at the end.

The proper way to brake, which will extend your brake pad life and keep you in the best control of your car, is to downshift. I'm not sure what you meant by "downshifting when keeping the revs in range by braking" though. You match the revs by using the throttle, not the brake. For casual driving, I don't often down shift past 3rd gear, though optimally you'd go to 2nd before finally putting in the clutch just before stopping.




Re: Downshifting
Wednesday, February 23, 2005 7:38 AM
Wild Weasel wrote:The proper way to brake, which will extend your brake pad life and keep you in the best control of your car, is to downshift. I'm not sure what you meant by "downshifting when keeping the revs in range by braking" though. You match the revs by using the throttle, not the brake. For casual driving, I don't often down shift past 3rd gear, though optimally you'd go to 2nd before finally putting in the clutch just before stopping.


That's what I do...but I've always heard that it's a toss up between wearing your pads down more (by not downshifting), or wearing your tranny down more (by downshifting). Although I do downshift, I do worry that in the long run, I'm decreasing the life of my tranny. I don't drive hard unless I need to (getting out into traffic, etc.), but I've always wondered....AM I affecting the tranny negatively so much that it may not be worth it? Brakes are much easier and much cheaper to replace.

Just curious...




Re: Downshifting
Wednesday, February 23, 2005 7:49 AM
I have a 2000 Cavalier and I had to replaced my clutch at 71000 miles. The clutch, like many other things, is built to withstand a certian amount of "cycles" after that period...it breaks down. Push in clutch + Let out clutch=2 cycles. You be the judge....

I upgraded my hard-to-find 2.2 clutch by the way with a SPEC Stage 3 Clutch....
Re: Downshifting
Wednesday, February 23, 2005 8:00 AM
Project Will wrote:That's what I do...but I've always heard that it's a toss up between wearing your pads down more (by not downshifting), or wearing your tranny down more (by downshifting).


If you downshift properly and get the revs right, you actually don't cause any wear to the clutch friction surface at all. The clutch is only wearing when it's slipping. With the revs right, you can drop the clutch pedal and not feel any effect on the car. Then there's no wear. The main reason I say that proper braking involves downshifting is not to save your brake pads though. The real reason is to maintain the most control over the car. Saving pads is just an added benefit.

Non VTEC Racer wrote:I have a 2000 Cavalier and I had to replaced my clutch at 71000 miles. The clutch, like many other things, is built to withstand a certian amount of "cycles" after that period...it breaks down. Push in clutch + Let out clutch=2 cycles. You be the judge....


That's not the clutch. That's the throwout bearing and not really true. The clutch should wear out before the throwout bearing so if you change that while you're in there anyway, then the number of times you've pushed the pedal in becomes completely irrelevant.





Re: Downshifting
Wednesday, February 23, 2005 8:13 AM
I understand all that WW, but the less you use it...the more life you get out of it. Thats all Im saying.
Re: Downshifting
Wednesday, February 23, 2005 8:27 AM
Non VTEC Racer wrote:I understand all that WW, but the less you use it...the more life you get out of it. Thats all Im saying.


Ok then... let me amend my second paragraph above to say this:

Wild Weasel wrote:If you're too lazy to downshift, or paranoid about using your clutch, just leave the clutch engaged until the rpm's come down to below idle speed, then put the clutch in. Basically, you brake like you would an automatic and then put in the clutch at the end.


Of course, I'd have to assume those in the paranoid category are the people who couldn't afford the automatic and not the ones who actually wanted to drive a manual.






Re: Downshifting
Wednesday, February 23, 2005 8:37 AM
I do a little of both while driving, depending on the mood I'm in and how lazy I do feel. I have a question along these lines though.

What harm is done to the clutch if you sit at a light with your foot on the clutch? I've read that you should let the clutch pedal out at a stop, but sometimes, if the light isn't terrible long, I'll sit in 1st with the clutch in....
Re: Downshifting
Wednesday, February 23, 2005 8:39 AM
Woah...Let me say this....every car Ive ever owned was a manual (except my '70 Monte Carlo) and I love it. I dont care how quickly my clutch/throw-out lasts. I drive my car hard and fast. Thats ME. I was just putting that out there incase he HE was worried about lifespan. I am not paranoid and I WANTED and will always want a manual.

Re: Downshifting
Wednesday, February 23, 2005 8:46 AM
use your brakes to stop, you will wear out your syncros if you continue to downshift




Re: Downshifting
Wednesday, February 23, 2005 8:47 AM
But thats not fun!
Re: Downshifting
Wednesday, February 23, 2005 9:00 AM
I learned how to drive on a stick... took my driver's test in a stick... and almost every car I've had has been a stick. When my mom taught me how to drive (and my dad agreed)... she taught me how to downshift when stopping. I have NEVER had to replace a clutch, and it does not wear out your synchros. My dad had built many a drag cars in his time and is an excellent driver. Downshifting is a good idea for many reasons, in which WW stated in his posts.

Not to mention... when I took my driver's license test in my mom's 5 spd 92 Cavalier, the driving instructor was highly impressed that I was downshifting and that earned me brownie points. (Which was good, because I was so nervous I stalled the car before my test even got started, not to mention my parallel parking job was horrendous LOL) But I still passed!

NOT downshifting, IMHO is stupid. I downshift to second when comming to a stop...




Re: Downshifting
Wednesday, February 23, 2005 9:30 AM
I downshift just cause that's what I was taught to do.. also if I wouldn't downshift and just push the clutch in on my pos Civic hatch while coming to a stop, the engine would die because the revs would drop too fast.

Rob




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Re: Downshifting
Wednesday, February 23, 2005 11:02 AM
Sean McCoy wrote:I do a little of both while driving, depending on the mood I'm in and how lazy I do feel. I have a question along these lines though.

What harm is done to the clutch if you sit at a light with your foot on the clutch? I've read that you should let the clutch pedal out at a stop, but sometimes, if the light isn't terrible long, I'll sit in 1st with the clutch in....


The only thing this will slightly wear is your throw-out bearing and not enough to be a big deal. This one is really just a matter of preference. If you're about to move again, you might as well leave the clutch pressed in until you move. If you're gonna sit there a while, put it in neutral and let it out.

The only contradicting argument to this I've heard is that you should always have it in gear with the clutch in just in case something bad happens. You can either suddenly accelerate to get away... or if you can't avoid it and get hit or something, your car won't just keep rolling if your feet leave the pedals. You'll stall and stop. Realistically though, this really isn't all that strong an argument.





Re: Downshifting
Wednesday, February 23, 2005 12:36 PM
My favorite subject, driving a manual. I prefer to downshift alot, especially slowing down for a corner.

There are three ways to stop in a stick:

1. Clutch in, shift to neutral, clutch out, coast/brake to stop.
PROS: If your lazy, this is for you, but you should probably go get an auto, no clutch wear if you don't want to develop the skill to downshift right.
CONS: Your coasting, so as mentioned above, what if you need to accelerate?

2. Brake like your driving an auto and at about 1200 rpm (or a little above idle if you have no tach) or so (in whatever gear your in), simply push the clutch in.
PROS: Better then the coast method, less wear on your clutch if you don't want to develop the skill to downshift right.
CONS: If you need to accelerate quickly you will lug the enigne unless you pull of a fast downshift.

3. The downshifting method, you run down the gears as you brake/slow down. You can go from casual to extreme with this. Casual - you downshift from 5th to 3th at 40mph, and stop there or maybe then to 2nd at around 15mph and stop. Extreme - you keep the enigne in the sweet spot all the way down (above say 3500 rpm or so)
PROS: Most control, always ready to accelerate, saves your brakes, fun, you can slow down fast on snow and ice if done right.
CONS: If you don't do it right (see below) you will wear your clutch earlier then you would if you did it right, people will think your wierd (but who cares.)

Clutch wear is an interesting thing, some people can drive 150000 + on a clutch, some only 50000. The number one reason for premature clutch wear is not knowing how to really start out (reving it and letting the clutch out real slow, or letting it out fast and jumpy.) A well worn in clutch will have a long smooth grab point, not a off/on style jumpy grab point. The second is resting your foot on the clutch while you drive.

To downshift alot without wearing your clutch you have to learn how to double clutch (reving the engine in neutral with the clutch out, also helps the syncros), simply blipping the throttle to match the rpms will not work to eliminate clutch wear. This is because the transmission input shaft/clutch is not in sync with the flywheel and bam you let the clutch out and it has to speed up to match it. If you downshift without even matching the engine speed it has to speed up both the transmission input shaft and the engine.

In fact double clutching while braking requires you to "heel and toe" which is why people who race do it.
Re: Downshifting
Wednesday, February 23, 2005 1:40 PM
No matter what speed I'm at, when I go to stop the clutch goes in, and stays in, gear goes to neutral, and I brake to stop. If I need to start accelerating again I put it in the correct gear , remove my foot from the clutch then accelerate. I've been driving a manual transmission cars for almost 14 years now, 3 chevys, 1 ford, 1 dodge, and thats how I've always done it in every car and have never once ever had any clutch problems.




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Re: Downshifting
Wednesday, February 23, 2005 5:12 PM
if im cruising, i leave it in gear, and brake, and down shift according to RPMs, if im dribing hard, i do what is called "rackin' it" which is basically doing what truckers do, and thats it down shift to slow down, this is done best by double clutching and rev matching. ive actually mastered this quite well

this is done by doing this: (scenerio as if down shifting from 5th)
let off the gas
press clutch
pull shifter into neutral, while also reving engine to an estimated matched RPMs, put into next gear (4th or 3rd) and release clutch, i have a video explaining this too if u want it


96 Sunfire, 2.4L Twin Cam 5 Spd, estimated 180hp
Re: Downshifting
Wednesday, February 23, 2005 8:12 PM
But why bother? That seems like alot of unnecessary work for nothing.




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Re: Downshifting
Thursday, February 24, 2005 1:58 AM
Wild Weasel wrote:You should never just throw it in neutral and then use the brake to stop. It's harder on the brakes since you've got no engine braking helping you and there's no advantage to it whatsoever.

If you're too lazy to downshift, just leave the clutch engaged until the rpm's come down to below idle speed, then put the clutch in. Basically, you brake like you would an automatic and then put in the clutch at the end.

The proper way to brake, which will extend your brake pad life and keep you in the best control of your car, is to downshift. I'm not sure what you meant by "downshifting when keeping the revs in range by braking" though. You match the revs by using the throttle, not the brake. For casual driving, I don't often down shift past 3rd gear, though optimally you'd go to 2nd before finally putting in the clutch just before stopping.


Well if you dont brake enough while stopping for a stop, your wheels will be really fighting the compression of the engine causing your revs to soar when letting the clutch out and engaging the lower gear.... thats what I meant by what I said.


2000 Cavalier 5spd Manual 2.2L

Re: Downshifting
Thursday, February 24, 2005 3:36 AM
Mike M wrote:My favorite subject, driving a manual. I prefer to downshift alot, especially slowing down for a corner.

There are three ways to stop in a stick:

1. Clutch in, shift to neutral, clutch out, coast/brake to stop.
PROS: If your lazy, this is for you, but you should probably go get an auto, no clutch wear if you don't want to develop the skill to downshift right.
CONS: Your coasting, so as mentioned above, what if you need to accelerate?

2. Brake like your driving an auto and at about 1200 rpm (or a little above idle if you have no tach) or so (in whatever gear your in), simply push the clutch in.
PROS: Better then the coast method, less wear on your clutch if you don't want to develop the skill to downshift right.
CONS: If you need to accelerate quickly you will lug the enigne unless you pull of a fast downshift.

3. The downshifting method, you run down the gears as you brake/slow down. You can go from casual to extreme with this. Casual - you downshift from 5th to 3th at 40mph, and stop there or maybe then to 2nd at around 15mph and stop. Extreme - you keep the enigne in the sweet spot all the way down (above say 3500 rpm or so)
PROS: Most control, always ready to accelerate, saves your brakes, fun, you can slow down fast on snow and ice if done right.
CONS: If you don't do it right (see below) you will wear your clutch earlier then you would if you did it right, people will think your wierd (but who cares.)

Clutch wear is an interesting thing, some people can drive 150000 + on a clutch, some only 50000. The number one reason for premature clutch wear is not knowing how to really start out (reving it and letting the clutch out real slow, or letting it out fast and jumpy.) A well worn in clutch will have a long smooth grab point, not a off/on style jumpy grab point. The second is resting your foot on the clutch while you drive.

To downshift alot without wearing your clutch you have to learn how to double clutch (reving the engine in neutral with the clutch out, also helps the syncros), simply blipping the throttle to match the rpms will not work to eliminate clutch wear. This is because the transmission input shaft/clutch is not in sync with the flywheel and bam you let the clutch out and it has to speed up to match it. If you downshift without even matching the engine speed it has to speed up both the transmission input shaft and the engine.

In fact double clutching while braking requires you to "heel and toe" which is why people who race do it.


But why should double clutching and rev-matching be used in a vehicle with syncros? I know a lot of people who dont double clutch or rev match synchronized manuals and their clutches seem to be lasting a long ass time. Actually the only guy I know who ever double clutches had an old Nissan pickup and did it without even realizing why it didnt grind when he did it this way. He learned standard shift on this truck and because of the way he and the previous owner treated it would always grind in a 2-3 shift.



2000 Cavalier 5spd Manual 2.2L
Re: Downshifting
Thursday, February 24, 2005 5:50 AM
For those who said when they're braking they just put in the clutch, go to neutral, and then just use the brakes... that's absolutely wrong and there's no benefit to it at all. As I mentioned... if you're too lazy to do anything else then you just leave it in gear until you get down to idle rpm's and then put the clutch in. There is no more or less wear on the clutch than going to neutral and coasting but you still maintain the benefit of some engine braking.

Double-clutching has nothing to do with saving your clutch. It simply allows you to engage your gears easier and saves some wear on the synchros.

Rev-matching is what saves wear on the clutch and is necessary if you want to drive the car properly and downshift smoothly without messing up the car's attitude. If you don't rev-match and you do downshift then you WILL wear your clutch faster. And if you try to downshift to accelerate out of a corner and you don't rev-match then you could potentially upset the car enough to invoke enough understeer to throw you right out of the corner. If you don't understand this stuff, then you don't know how to properly drive a manual.





Re: Downshifting
Thursday, February 24, 2005 6:07 AM
OK...now maybe I'm not understanding this, I'm not extremely technically inclined, and don't race so I don't know the terminology....but...

You seem to be talking about rev-matching and heel-toe like they were different things? I thought that in order to rev-match you had to heel-toe with the brake and accelerator.

Explain to a non-newb newb? Please?





Re: Downshifting
Thursday, February 24, 2005 10:16 AM
Let me predicate this by saying you can never double clutch or rev match and get good life out of the clutch. As for the synchros, double clutching will help them as well, but the worse thing you can do to them is speed shift or power shift so I'm sure we have all at one time or another put some wear on them.

Quote:

Rev-matching is what saves wear on the clutch and is necessary if you want to drive the car properly and downshift smoothly without messing up the car's attitude. If you don't rev-match and you do downshift then you WILL wear your clutch faster. And if you try to downshift to accelerate out of a corner and you don't rev-match then you could potentially upset the car enough to invoke enough understeer to throw you right out of the corner. If you don't understand this stuff, then you don't know how to properly drive a manual.


You are correct about making downshifts smooth, and about downshifting in a corner. But I think you should reconsider whether rev-matching alone will save the clutch and make your downshift smoother. A real life scenerio: Forget braking for a minute here, your going 60 mph in 5th gear and you see a curve ahead you want to start at 40 mph and end at 50 mph (accelerating though the curve), so you downshift to 3rd as you come up to it, there are three ways to downshift: 1. Just down-shift and let the clutch out, 2. Rev-match the engine with the clutch in, down-shift and let the clutch out, and 3. Clutch in, shift to neutral, clutch out, rev the engine about 750 rpm higher then you need it, clutch in, shift to proper gear (3rd) clutch out. Then take the corner in the right gear. Below is an approx. table of rpms of your powertrain as let the clutch out in 3rd gear (for ease of calc assume 4th gear (1.00:1) even though we want 3rd.)

Engine RPM Trans Input RPM Diff. input RPM
(flywheel RPM) (clutch RPM)
Normal Downshift - 1500 1500 3500
Downshift w/ Rev-Match - 3500 1500 3500
Downshift w/ DC & Rev-Match - 3500 3500 3500

With the double clutch all the components of the powertrain are at roughly the same speed, with just a rev-match (no spinning the trans up with a double clutch) your transmission is freewheeling at around the speed that you were spinning it in 5th. Since a clutch (and synchros) are devices that get two things to go the same speed as each other using friction, the closer they are in speed to begin with, the less wear on the device (clutch or synchro.) It also will make the downshift smooth.

To brake while doing this requires you to operate three pedals with two feet. You do this by rolling the right side of your right foot on to the gas while braking (can be tricky.) This is called a "heel and toe." Anymore its not what your really doing, but at the beginning of the 20th century the gas pedal in race cars was in between the clutch and brake, and a driver would brake with the right foot and use his heel to rev it.
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