Downshifting On Track
Discussion
Hi all,
First post here after lurking around the boards for quite some time so firstly hi!
My question relates to track driving as opposed to driving on the road so apologies if I have posted in the wrong place.
When downshifting, I understand the need for a good heel and toe blip on the throttle to smooth the transition into the next gear. In terms of re-engaging the clutch, is it best to do this simultaneously as you or blipping or is it better to blip slightly higher up in the rev range and to then engage the clutch as the revs are dropping?
I ask as after reviewing footage from a recent trackday, I found myself not quite revving high enough to make a smooth transition on some shifts. After doing some research I couldn't work out if I should be blipping harder to getting off the clutch quicker (at the same time as the blip effectively).
My second question, is there a benefit to being fast off of the clutch or are you better to ease it out more slowly (not slipping it out but just not snapping straight off) to reduce any possible unsettling of the car?
Thanks guys!
First post here after lurking around the boards for quite some time so firstly hi!
My question relates to track driving as opposed to driving on the road so apologies if I have posted in the wrong place.
When downshifting, I understand the need for a good heel and toe blip on the throttle to smooth the transition into the next gear. In terms of re-engaging the clutch, is it best to do this simultaneously as you or blipping or is it better to blip slightly higher up in the rev range and to then engage the clutch as the revs are dropping?
I ask as after reviewing footage from a recent trackday, I found myself not quite revving high enough to make a smooth transition on some shifts. After doing some research I couldn't work out if I should be blipping harder to getting off the clutch quicker (at the same time as the blip effectively).
My second question, is there a benefit to being fast off of the clutch or are you better to ease it out more slowly (not slipping it out but just not snapping straight off) to reduce any possible unsettling of the car?
Thanks guys!
A couple of my old posts here to get you started:
Zen and the art of changing gear looks at how to develop a good technique for the road and describes the benefits of rev matching and how to achieve a smooth technique.
And this thread examines track braking in detail including a description of heel/toe gearchanges.
As for timing, you should be aiming to release the clutch just when the revs are at the correct speed for the road speed in your chosen gear. Most drivers apear to rev higher than that chosen engine speed and release the clutch as the revs are starting to drop. The dropping revs match the fact that the car speed is also dropping whilst you're braking, making the speed matching a little easier.
The alternative is to attempt to raise the revs in the way I describe in the first link above, but as part of a heel & toe technique. This takes some practice, but is possible and works well when you get it right - if the revs are raised and held, you can release the clutch at any point and the revs will match the road speed.
The clutch should be released quickly, but not sidestepped - smoothness is very important in track driving, so quickly releasing should keep things smooth, whilst sidestepping will introduce unwanted driveline shunt which could easily unsettle the car if you're close to the limits of grip.
Zen and the art of changing gear looks at how to develop a good technique for the road and describes the benefits of rev matching and how to achieve a smooth technique.
And this thread examines track braking in detail including a description of heel/toe gearchanges.
As for timing, you should be aiming to release the clutch just when the revs are at the correct speed for the road speed in your chosen gear. Most drivers apear to rev higher than that chosen engine speed and release the clutch as the revs are starting to drop. The dropping revs match the fact that the car speed is also dropping whilst you're braking, making the speed matching a little easier.
The alternative is to attempt to raise the revs in the way I describe in the first link above, but as part of a heel & toe technique. This takes some practice, but is possible and works well when you get it right - if the revs are raised and held, you can release the clutch at any point and the revs will match the road speed.
The clutch should be released quickly, but not sidestepped - smoothness is very important in track driving, so quickly releasing should keep things smooth, whilst sidestepping will introduce unwanted driveline shunt which could easily unsettle the car if you're close to the limits of grip.
Hi Reg,
Thanks for the quick reply - I have read your two articles that you linked before however a refresher is always good!!
From what you say, I think the best method is to rev then quickly and smoothly release the clutch a split second later as opposed to rev and release at the same time. This was what I had done before and seemed the most logical however, looking at some videos (for example here - starting at 13m40 - https://www.youtube.com/watch?v=YqYeusE8ksk) it was suggested to clutch and rev at the exact same time.
Thanks again!
Thanks for the quick reply - I have read your two articles that you linked before however a refresher is always good!!
From what you say, I think the best method is to rev then quickly and smoothly release the clutch a split second later as opposed to rev and release at the same time. This was what I had done before and seemed the most logical however, looking at some videos (for example here - starting at 13m40 - https://www.youtube.com/watch?v=YqYeusE8ksk) it was suggested to clutch and rev at the exact same time.
Thanks again!
It's one of those things which many people do without giving it too much thought, but when it comes to breaking it down and describing each element, it's actually very difficult to describe.
You should definitely not release the clutch as you're revving the engine as there's a good chance you'll be applying acceleration to the driven wheels just as you're trying to reduce your speed.
It may be better if you forget about the clutch when deciding when to raise the revs. Think of it in terms of applying The throtle "blip" (or rev raise) whilst you're in the neutral phase between gears. It's not strictly necessary to use the clutch for gearchanging, but rev-matching is even more important if you're not using the clutch and on downchanges, the revs are raised whilst you're in neutral between gears.
I'm not suggesting you try clutchless changes on track, but time your throttle blip with the neutral phase, rather than your use of the clutch. For example, approaching a 3rd gear corner in 4th gear...
Clutch in - out of 4th & into neutral - raise the revs - out of neutral & into 3rd - release the clutch.
Of course, it all happens in less than a second and you need to practice carrying it all out in one smooth combined movement, but with practice it can become second nature.
You should definitely not release the clutch as you're revving the engine as there's a good chance you'll be applying acceleration to the driven wheels just as you're trying to reduce your speed.
It may be better if you forget about the clutch when deciding when to raise the revs. Think of it in terms of applying The throtle "blip" (or rev raise) whilst you're in the neutral phase between gears. It's not strictly necessary to use the clutch for gearchanging, but rev-matching is even more important if you're not using the clutch and on downchanges, the revs are raised whilst you're in neutral between gears.
I'm not suggesting you try clutchless changes on track, but time your throttle blip with the neutral phase, rather than your use of the clutch. For example, approaching a 3rd gear corner in 4th gear...
Clutch in - out of 4th & into neutral - raise the revs - out of neutral & into 3rd - release the clutch.
Of course, it all happens in less than a second and you need to practice carrying it all out in one smooth combined movement, but with practice it can become second nature.
R_U_LOCAL said:
You should definitely not release the clutch as you're revving the engine as there's a good chance you'll be applying acceleration to the driven wheels just as you're trying to reduce your speed.
That amused me - I've got an ECU map in my manual track car that automatically blips the throttle above 40mph when braking and depressing the clutch. On a few occasions it has caught me out when trail braking into a corner and accidentally glancing the clutch pedal - a good wallop of gas to the rear wheels whilst entering a corner and trail braking results in some pretty wild and messy oversteer!!Ok that makes sense - in that case I probably am doing it correct - in terms of smoothness, I can get it near flawless on the road assuming I do the big blip and am smooth with the clutch - I just wasn't sure if there was a benefit to getting off the clutch sooner with a slightly smaller blip!
In any case, thanks all for your input - that's helped to clear it up!
In any case, thanks all for your input - that's helped to clear it up!
Redline88 said:
Ok that makes sense - in that case I probably am doing it correct - in terms of smoothness, I can get it near flawless on the road assuming I do the big blip and am smooth with the clutch - I just wasn't sure if there was a benefit to getting off the clutch sooner with a slightly smaller blip!
In any case, thanks all for your input - that's helped to clear it up!
If you're too slow off the clutch the revs will die away. I'm not very good at heel and toe on the road as it's hard to do when not slamming the brakes on.In any case, thanks all for your input - that's helped to clear it up!
Ok yeah - think we are on the same page.
Here's an example of what I had been doing - blip and the clutch release as the revs fall - is this correct?
http://youtu.be/0gBGa-oz1bM
Here's an example of what I had been doing - blip and the clutch release as the revs fall - is this correct?
http://youtu.be/0gBGa-oz1bM
hygt2 said:
Another perspective but you don't have to do my method. I default to double de-clutch heel and toe down shift for extra smoothness. I sometimes double de-clutch up shift for smoothness on road depending on what I drive
DDC is completely daft unless your gbox needs it. It's just extra faff when there is a perfectly capable synchro box available. As an academic technique for when you don't have synchros or if you are into techniques for their own sake then fine. But it's unnecessary extra actions so not an "advanced" technique.Bert
BertBert said:
DDC is completely daft unless your gbox needs it. It's just extra faff when there is a perfectly capable synchro box available. As an academic technique for when you don't have synchros or if you are into techniques for their own sake then fine. But it's unnecessary extra actions so not an "advanced" technique.
Bert
Not completely daft.Bert
If you are running on very tight track, hill climb courses, etc., you will require 1st gear more often than you think. I often need over 3,500-4,000 rpm in 1st to get through uphill hairpin quickly as 2nd gear would be outside the power bend. Also on road as well, like up zig zag hill and also some mountain roads in wales. I would DDC so that 1st will slot in very quickly and have the clutch biting point at 4,000 rpm on the N/A cars I have used.
I have observed many drivers trying to jam the gear stick into 1st at 15+ mph (or at often higher speed). These drivers take much longer to get into the detent of 1st gear and also wears the synchromesh much, much faster. OF course, this is less of a problem if you have a car with sufficient torque to haul itself from idle, like the TVR Griffith 500 I often never use less than 3rd gear
hygt2 said:
Another perspective but you don't have to do my method. I default to double de-clutch heel and toe down shift for extra smoothness. I sometimes double de-clutch up shift for smoothness on road depending on what I drive
So I took this to mean that hygt2 used DDC on all downshifts as the double in DDC was double the smoothness (which it's not). Then hygt2 said he only used it to get into first which I assume does not have synchro hence completely agreeing with me.hygt2 said:
Not completely daft.
If you are running on very tight track, hill climb courses, etc., you will require 1st gear more often than you think. I often need over 3,500-4,000 rpm in 1st to get through uphill hairpin quickly as 2nd gear would be outside the power bend. Also on road as well, like up zig zag hill and also some mountain roads in wales. I would DDC so that 1st will slot in very quickly and have the clutch biting point at 4,000 rpm on the N/A cars I have used.
I have observed many drivers trying to jam the gear stick into 1st at 15+ mph (or at often higher speed). These drivers take much longer to get into the detent of 1st gear and also wears the synchromesh much, much faster. OF course, this is less of a problem if you have a car with sufficient torque to haul itself from idle, like the TVR Griffith 500 I often never use less than 3rd gear
If you are running on very tight track, hill climb courses, etc., you will require 1st gear more often than you think. I often need over 3,500-4,000 rpm in 1st to get through uphill hairpin quickly as 2nd gear would be outside the power bend. Also on road as well, like up zig zag hill and also some mountain roads in wales. I would DDC so that 1st will slot in very quickly and have the clutch biting point at 4,000 rpm on the N/A cars I have used.
I have observed many drivers trying to jam the gear stick into 1st at 15+ mph (or at often higher speed). These drivers take much longer to get into the detent of 1st gear and also wears the synchromesh much, much faster. OF course, this is less of a problem if you have a car with sufficient torque to haul itself from idle, like the TVR Griffith 500 I often never use less than 3rd gear
BertBert said:
davepoth said:
In my experience DDC does make upshifts and downshifts markedly smoother, even on the road. Non-driving friends have remarked upon the smoothness of the drive, which is a pretty good test as far as I'm concerned.
Rev matching yes, DDC no. Since a well rev matched gear change is perfectly smooth, DEC cannot make it more so. I think there are confusion on the meaning of "downshifting". I shall break this into 2 parts:
1) Lifting the clutch pedal pass the biting point, which rev match (not DDC) will add smoothness. DDC is irrelevant with regards to the clutch operation when the gear stick has already been "shifted" into the new gear.
2) Shifting of the gear stick with DDC will definitely add smoothness (or the ease) of moving the gear stick from neutral into the lower (or higher) gear.
From my observation of the discussion so far, I think more drivers are concern with the smoothness of lifting of the clutch pedal pass the biting point, and therefore the rev match. My observation of this discussion (small sample size I admit) is that less drivers are concern with the ease of / smoothness on the shifting of the gear stick itself, and therefore see there is no need for DDC.
IMHO, both are important but you don't have to agree with me.
1) Lifting the clutch pedal pass the biting point, which rev match (not DDC) will add smoothness. DDC is irrelevant with regards to the clutch operation when the gear stick has already been "shifted" into the new gear.
2) Shifting of the gear stick with DDC will definitely add smoothness (or the ease) of moving the gear stick from neutral into the lower (or higher) gear.
From my observation of the discussion so far, I think more drivers are concern with the smoothness of lifting of the clutch pedal pass the biting point, and therefore the rev match. My observation of this discussion (small sample size I admit) is that less drivers are concern with the ease of / smoothness on the shifting of the gear stick itself, and therefore see there is no need for DDC.
IMHO, both are important but you don't have to agree with me.
waremark said:
davepoth said:
In my experience DDC does make upshifts and downshifts markedly smoother, even on the road. Non-driving friends have remarked upon the smoothness of the drive, which is a pretty good test as far as I'm concerned.
Rev matching yes, DDC no. Since a well rev matched gear change is perfectly smooth, DEC cannot make it more so. I'll admit that I'm no Fangio, but I can heel and toe properly. For smoothness however, DDC knocks it into a cocked hat. It's most obvious in low gears - try a downshift to first at 10mph and see which feels smoother.
davepoth said:
waremark said:
davepoth said:
In my experience DDC does make upshifts and downshifts markedly smoother, even on the road. Non-driving friends have remarked upon the smoothness of the drive, which is a pretty good test as far as I'm concerned.
Rev matching yes, DDC no. Since a well rev matched gear change is perfectly smooth, DEC cannot make it more so. I'll admit that I'm no Fangio, but I can heel and toe properly. For smoothness however, DDC knocks it into a cocked hat. It's most obvious in low gears - try a downshift to first at 10mph and see which feels smoother.
waremark said:
DDC may reduce wear on the synchro. I don't understand why you think it adds to perceived smoothness.
What do the synchros do? They allow you to change gear even when the relative speeds of the gears are far apart, which causes wear on them. The greater the difference in speed, the more wear. DDCing is the ultimate technique for matching the relative speeds of the gears in a manual gearbox, and if you do it properly the speed differences are minimal. Because the gear speeds are already pretty much matched, the difference in torque between the input and output shaft is minimised as much as is possible, since torque is a turning force.
Where does that torque difference go if you don't bother matching the input shaft to the output shaft, or do it badly? Some of it is turned into heat by the clutch, but some of it manifests as undesired acceleration or deceleration. That's what's jerky, and that's what is minimised by DDCing.
I agree with one of the above posts, it's kind of tricky to explain just how to do it right... With practice you yourself just know when it's right!
If I ever try to do it on the road, I find it very jerky, almost like I'm briefly pressing the brake pedal too much. On track though, under heavy braking and higher speeds it feels perfect.
If I ever try to do it on the road, I find it very jerky, almost like I'm briefly pressing the brake pedal too much. On track though, under heavy braking and higher speeds it feels perfect.
Gassing Station | Advanced Driving | Top of Page | What's New | My Stuff