Burning the clutch when upshifting

Read the FAQ and still not sure about something? Want to shift faster? Post here.
tiptopd
Junior Standardshifter
Posts: 10
Joined: Fri Dec 11, 2015 1:08 pm

Burning the clutch when upshifting

Postby tiptopd » Wed Jan 27, 2016 3:44 pm

I am now to the point where i can archive extremely smooth upshifts by applying a bit of gas as i am releasing the clutch and then pausing the clutch at the fp just for a brief second. 8)
Now the thing is, sometimes i think i am applying a bit too much gas . I have this fear. i will put numbers to make it easer
1.Reach 2000rpm in 1st then push clutch in/let the gas out than move shifter to 2nd
*Be slow so the rpm get to idle ( for whatever reason, traffic/things, just take this as is)
2. Apply the amount of gas that holds the rpm to 1200rpm
3.Release the clutch pausing at the fp, the clutch drags the rpm to 1000rpm and i get a small acceleration but it feels nice/smooth
4.Fully release the clutch after i feel it sync
This only happens like 20% of time but still i want to know just to extend my knowledge :D
Is this the same as dragging the rpm held by rev hang (i dont have it )
Or Is this "applying power through a slipping clutch"? I have seen the videos here and that guy says you can damage the clutch in 1-2 shift because you get excited and you put the foot to the floor (i guess he means you give it full throttle or close to that)
Shortly: i fail to understand the difference between overshooting rpm by a steady throttle and overshooting them by a blip. But here is the video that doesn't think like me and it is scaring me :? https://www.youtube.com/watch?v=YRWdUhvzVpo

IMBoring25
Moderator
Posts: 3266
Joined: Wed Jun 11, 2003 5:01 pm
Location: OK, USA

Re: Burning the clutch when upshifting

Postby IMBoring25 » Wed Jan 27, 2016 7:01 pm

That's actually pretty close to perfect. If you can get it to the 1000 RPM the clutch drags it to before you let the clutch out, that would be perfect, but that's a tricky thing, especially working around a computer with some of its own ideas on how things should go.

Rope-Pusher
Master Standardshifter
Posts: 10501
Joined: Mon Mar 16, 2009 3:44 pm
Cars: '08 Jeep Liberty
Location: Greater Detroit Area

Re: Burning the clutch when upshifting

Postby Rope-Pusher » Wed Jan 27, 2016 10:06 pm

I listened to the video - not munch to watch, right? - and I don't understand what this guy is warning about. I wish he would have demonstrated it instead. You aren't going to "burn your clutch out" dragging the engine rpm down with the clutch to match the gear your upshifting into. There just isn't that much energy being dissipated. The engine rpm is going to drop down to idle eventually, so depending on how quickly you shift you might only be slipping the clutch for a fraction of a second.

Yanno, the flywheel and the pressure plate do a good job of absorbing heat from the clutch during momentary clutch slipping. It's when you slip for a long time, and turn a lot of energy into heat, that the pressure plate & flywheel heat up and loose their abilities to absorb heat from the slipping clutch. (Heat flows from hot to cold, and the rate of heat flow is proportional to the diffence in temperature, so a hot clutch friction disk will have troubles dumping its heat to other hot components, since delta T will be small). Doing a bunch of drag-race launches in a row heats the pressure plate and flywheel a lot, lot more than dragging the engine rpm down on every upshift would do.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"

vw100
Junior Standardshifter
Posts: 46
Joined: Sat Dec 27, 2014 11:18 am

Re: Burning the clutch when upshifting

Postby vw100 » Sat Jan 30, 2016 5:56 pm

Rope-Pusher wrote:I listened to the video - not munch to watch, right? - and I don't understand what this guy is warning about. I wish he would have demonstrated it instead. You aren't going to "burn your clutch out" dragging the engine rpm down with the clutch to match the gear your upshifting into. There just isn't that much energy being dissipated. The engine rpm is going to drop down to idle eventually, so depending on how quickly you shift you might only be slipping the clutch for a fraction of a second.

Yanno, the flywheel and the pressure plate do a good job of absorbing heat from the clutch during momentary clutch slipping. It's when you slip for a long time, and turn a lot of energy into heat, that the pressure plate & flywheel heat up and loose their abilities to absorb heat from the slipping clutch. (Heat flows from hot to cold, and the rate of heat flow is proportional to the diffence in temperature, so a hot clutch friction disk will have troubles dumping its heat to other hot components, since delta T will be small). Doing a bunch of drag-race launches in a row heats the pressure plate and flywheel a lot, lot more than dragging the engine rpm down on every upshift would do.

If you give it the amount of gas that holds the rpms to 4000rpm and drag them to 1000rpm with the clutch,than i guess that's how you burn it and that's what greg is warning about in the video. There is 3000rpm difference.
Now i don't know if blipping to 4000rpm and dragging them down with the clutch without feeding gas is any better :?:
Also about drag-race launches, why does that overheat the clutch ? Is it because of the rpm difference ? or does it have to do with clutch dumping ?

Rope-Pusher
Master Standardshifter
Posts: 10501
Joined: Mon Mar 16, 2009 3:44 pm
Cars: '08 Jeep Liberty
Location: Greater Detroit Area

Re: Burning the clutch when upshifting

Postby Rope-Pusher » Sun Jan 31, 2016 12:07 am

vw100 wrote:
Rope-Pusher wrote:I listened to the video - not munch to watch, right? - and I don't understand what this guy is warning about. I wish he would have demonstrated it instead. You aren't going to "burn your clutch out" dragging the engine rpm down with the clutch to match the gear your upshifting into. There just isn't that much energy being dissipated. The engine rpm is going to drop down to idle eventually, so depending on how quickly you shift you might only be slipping the clutch for a fraction of a second.

Yanno, the flywheel and the pressure plate do a good job of absorbing heat from the clutch during momentary clutch slipping. It's when you slip for a long time, and turn a lot of energy into heat, that the pressure plate & flywheel heat up and loose their abilities to absorb heat from the slipping clutch. (Heat flows from hot to cold, and the rate of heat flow is proportional to the diffence in temperature, so a hot clutch friction disk will have troubles dumping its heat to other hot components, since delta T will be small). Doing a bunch of drag-race launches in a row heats the pressure plate and flywheel a lot, lot more than dragging the engine rpm down on every upshift would do.

If you give it the amount of gas that holds the rpms to 4000rpm and drag them to 1000rpm with the clutch,than i guess that's how you burn it and that's what greg is warning about in the video. There is 3000rpm difference.
Now i don't know if blipping to 4000rpm and dragging them down with the clutch without feeding gas is any better :?:
Also about drag-race launches, why does that overheat the clutch ? Is it because of the rpm difference ? or does it have to do with clutch dumping ?

I still don't understand what the guy in the video's gripe is. Is he referring to "Power Shifting" (Keeping the accelerator pedal floored during the shift)? In that case, you would be "Dumping the clutch" after you move the shift lever to the next higher gear range. It's hard on the clutch, the driveline, the transmission, the tires, the suspension, etc. When people drive this way, they are not worried about whether the clutch is getting more than normal wear. This is done during drag racing, when time is of the essence.
The amount of energy transferred by the clutch in dragging the engine rpm up or down in order to match it to the in-gear speed after a shift is typically negligible, so don't worry about clutch friction disk wear while doing this.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"

User avatar
tankinbeans
Master Standardshifter
Posts: 3704
Joined: Tue Apr 26, 2011 9:04 pm
Cars: 17 300S, 03 Century
Location: Shakopee, MN

Re: Burning the clutch when upshifting

Postby tankinbeans » Sun Jan 31, 2016 3:40 am

I just watched and...wut? All I heard was a big fat durrrrr, don't slip clutch, bad, oggidyboogidy. Does he know a clutch is designed to slip? Is he projecting his bad practices onto others? What is happening? Perhaps with some context and a longer video we might learn something useful.
17 Mazda6
03 Century
InlinePaul wrote:The driving force of new fangled features to sell more cars [is to] cater to the masses' abject laziness!

vw100
Junior Standardshifter
Posts: 46
Joined: Sat Dec 27, 2014 11:18 am

Re: Burning the clutch when upshifting

Postby vw100 » Sun Jan 31, 2016 12:50 pm

Rope-Pusher wrote:The amount of energy transferred by the clutch in dragging the engine rpm up or down in order to match it to the in-gear speed after a shift is typically negligible, so don't worry about clutch friction disk wear while doing this.

Say you downshift without revmatching and the clutch has to spin the engine up to 4000rpm from idle. Just like you wouldn't recommend letting the clutch spin the engine 3000rpm up (from idle to 4000) on a downshift, he is recommending don't let the clutch slow the engine too much. He isn't saying you will burn the clutch immediately the first time you do that, just that it isn't a good practice, this is how i see it.
Anyway i do downshift without revmatching most of the time, but so that the engine has to spin up to 2000rpm in the next lower gear no more than that. So the clutch takes the engine from idle to 2000rpm, i feel guilty about that, is that still negligible ? Than why do so many people care about rev-matching, is it only for smoothness ?

vw100
Junior Standardshifter
Posts: 46
Joined: Sat Dec 27, 2014 11:18 am

Re: Burning the clutch when upshifting

Postby vw100 » Sun Jan 31, 2016 1:06 pm

IMBoring25 wrote:That's actually pretty close to perfect. If you can get it to the 1000 RPM the clutch drags it to before you let the clutch out, that would be perfect, but that's a tricky thing, especially working around a computer with some of its own ideas on how things should go.

but he said the car is accelerating while the clutch is still slipping, isn't that bad :?:

Teamwork
Senior Standardshifter
Posts: 482
Joined: Fri Jan 15, 2016 9:49 pm
Cars: 2015 VW GTI

Re: Burning the clutch when upshifting

Postby Teamwork » Sun Jan 31, 2016 1:09 pm

vw100 wrote:Anyway i do downshift without revmatching most of the time, but so that the engine has to spin up to 2000rpm in the next lower gear no more than that. So the clutch takes the engine from idle to 2000rpm, i feel guilty about that, is that still negligible ? Than why do so many people care about rev-matching, is it only for smoothness ?

I would say that I am the opposite (that I rev match my gears most of the time) but I posed a question about down shifting without rev-matching in the below thread "Refining techniques...". I was essentially asking if it's negligible in the sense that when I'm yielding to traffic conditions and need a lower gear then what is required if it's okay to not rev-match when I'm only going from idle rpm 800-900 rpm to about 1100-1200 rpm in the lower gear. I don't feel anything abnormal or even really a jerk at all in terms of engaging a lower gear in this practice.

On a whole though I do try and rev-match anytime I feel that it would benefit me in a smoother transition. I'm sure it reduces stress on the driveline and it prevents forward weight transfers that can make you feel out of control. I'm not expert- I'm new and asking a ton of questions in my other thread but whenever I'm in doubt I usually rev-match a downshift when I can and I probably do more times then not. The above scenario is literally one of only ones I can think of when I don't- and if someone told me otherwise I would attempt too.
Last edited by Teamwork on Tue Feb 02, 2016 7:22 am, edited 2 times in total.

IMBoring25
Moderator
Posts: 3266
Joined: Wed Jun 11, 2003 5:01 pm
Location: OK, USA

Re: Burning the clutch when upshifting

Postby IMBoring25 » Sun Jan 31, 2016 1:35 pm

vw100 wrote:
IMBoring25 wrote:That's actually pretty close to perfect. If you can get it to the 1000 RPM the clutch drags it to before you let the clutch out, that would be perfect, but that's a tricky thing, especially working around a computer with some of its own ideas on how things should go.

but he said the car is accelerating while the clutch is still slipping, isn't that bad :?:


It's a question of degree. You don't want to deliberately accelerate the car while the clutch is slipping (except starting from a stop where it can't be avoided) but in this case the slight acceleration is just a byproduct of the engine being dragged down to the car's speed. 1200-1000 RPM is a less-significant difference for the clutch to take up than if no throttle were used and the vehicle's momentum had to pull the engine up from 600 RPM. As I said, it would be better to nail 1000 on the money, but perfection, especially with a computer-controlled car, is a tricky thing.

vw100
Junior Standardshifter
Posts: 46
Joined: Sat Dec 27, 2014 11:18 am

Re: Burning the clutch when upshifting

Postby vw100 » Sun Jan 31, 2016 1:49 pm

IMBoring25 wrote:It's a question of degree. You don't want to deliberately accelerate the car while the clutch is slipping (except starting from a stop where it can't be avoided) but in this case the slight acceleration is just a byproduct of the engine being dragged down to the car's speed. 1200-1000 RPM is a less-significant difference for the clutch to take up than if no throttle were used and the vehicle's momentum had to pull the engine up from 600 RPM. As I said, it would be better to nail 1000 on the money, but perfection, especially with a computer-controlled car, is a tricky thing.

i completely agree with you :wink: What greg is saying in the video is the same : You don't want to deliberately accelerate the car while the clutch is slipping. Now how do you do that ? When you go crazy with the throttle so the clutch has to work too much to bring the rpm down to where it is needed in the higher gear. But rp i confusing me, as far as i am understanding, he is saying that it is negligible.

Reverence
Senior Standardshifter
Posts: 264
Joined: Sat Jan 16, 2010 12:46 pm
Cars: Peugeot 307 2L
Location: Beijing, China

Re: Burning the clutch when upshifting

Postby Reverence » Mon Feb 01, 2016 11:48 am

vw100 wrote: Than why do so many people care about rev-matching, is it only for smoothness ?

there are some funky misquotes in here, LoL :lol:
depends really why you are downshifting. If it is because you are coming to a stop, then just use the brakes, no need to downshift. If it is to pick-up power, rev match to get in gear faster. If it is to slow down with probable consequent acceleration, rev match for smoothness.
in general:
1) to limit clutch wear (negligible)
2) to be ready in gear faster, instead of waiting in no man's land
3) smoothness

Many of us do the DC Rev Match to go easy on the synchronizers too, besides caring for the clutch> you will slide in gear like butter, without any resistance. When you get good at it, it is faster than SC rev matching.

Rope-Pusher
Master Standardshifter
Posts: 10501
Joined: Mon Mar 16, 2009 3:44 pm
Cars: '08 Jeep Liberty
Location: Greater Detroit Area

Re: Burning the clutch when upshifting

Postby Rope-Pusher » Mon Feb 01, 2016 11:33 pm

Teamwork wrote:
vw100 wrote:
Rope-Pusher wrote:Anyway i do downshift without revmatching most of the time, but so that the engine has to spin up to 2000rpm in the next lower gear no more than that. So the clutch takes the engine from idle to 2000rpm, i feel guilty about that, is that still negligible ? Than why do so many people care about rev-matching, is it only for smoothness ?

I would say that I am the opposite (that I rev match my gears most of the time) but I posed a question about down shifting without rev-matching in the below thread "Refining techniques...". I was essentially asking if it's negligible in the sense that when I'm yielding to traffic conditions and need a lower gear then what is required if it's okay to not rev-match when I'm only going from idle rpm 800-900 rpm to about 1100-1200 rpm in the lower gear. I don't feel anything abnormal or even really a jerk at all in terms of engaging a lower gear in this practice.

On a whole though I do try and rev-match anytime I feel that it would benefit me in a smoother transition. I'm sure it reduces stress on the driveline and it prevents forward weight transfers that can make you feel out of control. I'm not expert- I'm new and asking a ton of questions in my other thread but whenever I'm in doubt I usually rev-match a downshift when I can and I probably do more times then not. The above scenario is literally one of only ones I can think of when I don't- and if someone told me otherwise I would attempt too.

I think I was misquoted there. I don't believe I wrote any of that which was quoted to me. Please be more careful in how you cut-n-paste.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"

Teamwork
Senior Standardshifter
Posts: 482
Joined: Fri Jan 15, 2016 9:49 pm
Cars: 2015 VW GTI

Re: Burning the clutch when upshifting

Postby Teamwork » Tue Feb 02, 2016 7:23 am

Rope-Pusher wrote:
Teamwork wrote:
vw100 wrote:

I would say that I am the opposite (that I rev match my gears most of the time) but I posed a question about down shifting without rev-matching in the below thread "Refining techniques...". I was essentially asking if it's negligible in the sense that when I'm yielding to traffic conditions and need a lower gear then what is required if it's okay to not rev-match when I'm only going from idle rpm 800-900 rpm to about 1100-1200 rpm in the lower gear. I don't feel anything abnormal or even really a jerk at all in terms of engaging a lower gear in this practice.

On a whole though I do try and rev-match anytime I feel that it would benefit me in a smoother transition. I'm sure it reduces stress on the driveline and it prevents forward weight transfers that can make you feel out of control. I'm not expert- I'm new and asking a ton of questions in my other thread but whenever I'm in doubt I usually rev-match a downshift when I can and I probably do more times then not. The above scenario is literally one of only ones I can think of when I don't- and if someone told me otherwise I would attempt too.

I think I was misquoted there. I don't believe I wrote any of that which was quoted to me. Please be more careful in how you cut-n-paste.

Editted- sorry not sure how that ended up happening. Original quote was from 'vw100'.

Rope-Pusher
Master Standardshifter
Posts: 10501
Joined: Mon Mar 16, 2009 3:44 pm
Cars: '08 Jeep Liberty
Location: Greater Detroit Area

Re: Burning the clutch when upshifting

Postby Rope-Pusher » Wed Feb 03, 2016 9:42 pm

Let's blame it on Mud Chiggers and let it go at that.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"


Return to “Manual Driving Tips”

Who is online

Users browsing this forum: No registered users and 2 guests