Notices
Racing & Drivers Education Forum
Sponsored by:
Sponsored by:

Do you rev match downshift (no heel/toe)

Thread Tools
 
Search this Thread
 
Old 04-29-2018, 06:41 PM
  #16  
mark kibort
Rennlist Member
 
mark kibort's Avatar
 
Join Date: Feb 2003
Location: saratoga, ca
Posts: 29,953
Received 170 Likes on 66 Posts
Default

you can get away with it, but it is a finesse move and it requires a slightly earlier braking point. sometimes it can be beneficial to give a real quick breath to the brakes between a single shift, but multiple shifts, its better to heal toe. most important is the rev matching though! (that should be priority if the pedals are not configured correctly, or you have physical issues)
Old 04-29-2018, 07:10 PM
  #17  
ProCoach
Rennlist
Basic Site Sponsor
 
ProCoach's Avatar
 
Join Date: Jun 2008
Location: Durham, NC and Virginia International Raceway
Posts: 19,150
Received 3,329 Likes on 1,891 Posts
Default

Originally Posted by Jabs1542

As you learn to get faster you will learn to trail brake, at that point you MUST heel toe in order to reach the goal of loading up the car properly (SumG, Traction Circle, etc.)
Bingo! Prioritize braking over the blip.

Most folks blip way too big, and way too early, too.

Stabs or roll of the ankle to hit the side of the shoe works, too. Rarely do I see people using only the sole of the shoe.
Old 04-29-2018, 09:46 PM
  #18  
sugarwood
Pro
Thread Starter
 
sugarwood's Avatar
 
Join Date: Nov 2014
Posts: 729
Received 31 Likes on 18 Posts
Default

Like I said, for various reasons, I will not be doing heel/toe.
No pedal extensions in my future. I just casually enjoy 1 track day a year.

Would you rev match at the end of a straight, or is that a bad idea?
Old 04-29-2018, 09:57 PM
  #19  
ProCoach
Rennlist
Basic Site Sponsor
 
ProCoach's Avatar
 
Join Date: Jun 2008
Location: Durham, NC and Virginia International Raceway
Posts: 19,150
Received 3,329 Likes on 1,891 Posts
Default

Originally Posted by sugarwood

Would you rev match at the end of a straight, or is that a bad idea?
I don't understand.

How much speed do you need to get off at the end of "a straight?"

It's more important to get the speed off in an efficient way, using the brakes, than to try and rely on engine braking to slow the car in a consistent, quick and efficient way.

If you can't or won't integrate the (multiple) downshifts with the slowing (in this case, braking), then focus on the slowing and downshift ONE TIME at the end of slowing, just before the minimum speed at the entry of the corner.

This way, the lack of rev matching (or only rev matching for the single downshift preceding the corner entry) will have a minimal detrimental effect to chassis balance, time or car attitude AT the entry to the corner.
__________________
-Peter Krause
www.peterkrause.net
www.gofasternow.com
"Combining the Art and Science of Driving Fast!"
Specializing in Professional, Private Driver Performance Evaluation and Optimization
Consultation Available Remotely and at VIRginia International Raceway






















Old 04-29-2018, 10:02 PM
  #20  
bpu699
Registered User
 
bpu699's Avatar
 
Join Date: Nov 2003
Location: racine, wisconsin
Posts: 544
Likes: 0
Received 2 Likes on 2 Posts
Default

Timely thread... not sure why, but I find heel toe blipping on the track, when you are trying to go quick, really difficult and time consuming... on the street, no problem...

braking from high high speed before a corner, and downshifting sequentially 4-3-2 while blipping really slows progress, at least for me... dang near impossible to just blip 1000-2000 rpm. Usually way over shoots or under shoots.. at least with the 930. What's the secret here?

is blipping any any worse than just rev matching? When downshifting, right foot hits the brake, clutch goes in, downshift while heel presses gas pedal a quarter inch or so, and shift...

when you you guys are downshifting 4-3-2, and heel toe blipping, the clutch is pressed to the floor the whole time? Do you lift off a bit to get the internals up to speed between gears? Double clutch?

so basically i think I do rev matching, rather than blipping... is that worse? Car seems fine, doesn't get unsettled...

of interst, just started tracking a BMW z3 1.9. Car needs a lot of work, it's squirrely... but, downshifting even without rev matching is smooth as silk... that little motor poses almost no resistance to rotation...
Old 04-29-2018, 10:08 PM
  #21  
Thundermoose
Burning Brakes
 
Thundermoose's Avatar
 
Join Date: Jan 2011
Posts: 1,105
Received 103 Likes on 72 Posts
Default

Sugarwood sure is an odd poster...
Old 04-29-2018, 10:19 PM
  #22  
ProCoach
Rennlist
Basic Site Sponsor
 
ProCoach's Avatar
 
Join Date: Jun 2008
Location: Durham, NC and Virginia International Raceway
Posts: 19,150
Received 3,329 Likes on 1,891 Posts
Default

I guess I'm still confused.

The purpose of heel and toe downshifting is to MATCH THE REVS of the engine TO VEHICLE SPEED upon release of the clutch.

This is done to prevent having the revs drop so precipitously that the rear wheel speeds are HIGHER than what the engine revs WOULD be if not blipped, brought up or otherwise "rev matched."

The best downshifts I've heard have NO OVERSHOOT (revs going MUCH higher with clutch disengaged than when released) or UNDERSHOOT (chirping the rear wheels when the revs drop so much) that the engine is brought back up to speed when the clutch is released.

The goal IS to "rev match" perfectly upon release of the clutch IN THE LOWER GEAR. This allows a seamless slowing and minimal change in the dynamic platform of the chassis.

The best downshifts I've heard COMBINE the slowing of the car at the same rate as if the downshifts were NOT occuring, by effective and efficient and maximal braking BUT INCLUDING the perfect timing of rev matching, downshifting and release of the clutch in the lower gear.

When I was young and dumb, I spent a lot of time working on seamlessly matching revs as I slowed and downshifted. Not too much, not too little. Problem was, when I was on track, I wasn't slowing quickly enough this way because I hadn't integrated the proper use of the brakes in all of this! So, my early instructors and coaches helped me to prioritize braking, THEN integrate the downshifts, with precise rev matching before clutch release, WHILE MAINTAINING EVEN BRAKE PRESSURE THROUGHOUT.

In order to do this well, you need to learn WHAT the gear spacing is, practice the timing, take into account the flywheel effect of your car (heavy allows for more time to do this, light means you are more likely to "lose the revs" if you dawdle) and practice, practice, practice.

What am I missing?
Old 04-29-2018, 10:25 PM
  #23  
ProCoach
Rennlist
Basic Site Sponsor
 
ProCoach's Avatar
 
Join Date: Jun 2008
Location: Durham, NC and Virginia International Raceway
Posts: 19,150
Received 3,329 Likes on 1,891 Posts
Default

Originally Posted by bpu699
Timely thread... not sure why, but I find heel toe blipping on the track, when you are trying to go quick, really difficult and time consuming... on the street, no problem...

braking from high high speed before a corner, and downshifting sequentially 4-3-2 while blipping really slows progress, at least for me...

Do you lift off a bit to get the internals up to speed between gears? Double clutch?

True for everyone. This is not easily done well.

We used to teach "double declutching" at Skip Barber many decades ago.

This was: 1) brake, 2) depress the clutch (dip it), 3) blip the throttle, 4) select neutral, 5) release the clutch, 6) depress the clutch (dip it), blip the throttle, 7) select the lower gear, 8) release the clutch as the trevs drop to the proper speed. Rinse, lather, repeat...

But it really isn't necessary to release the clutch BETWEEN downshifts to allow the transmission shafts to come back up to speed, unless you have a very dead synchro, IMO.

Just make sure the engine revs aren't singificantly above or below the speed that matches the rear wheels in the lower gears awhen you finally release the clutch...

In the non-syncro Hewland racing gearboxes, once the car is moving, I don't even use the clutch going up OR coming down. Really nice!
Old 04-29-2018, 10:59 PM
  #24  
Thundermoose
Burning Brakes
 
Thundermoose's Avatar
 
Join Date: Jan 2011
Posts: 1,105
Received 103 Likes on 72 Posts
Default

Originally Posted by bpu699
Timely thread... not sure why, but I find heel toe blipping on the track, when you are trying to go quick, really difficult and time consuming... on the street, no problem...

braking from high high speed before a corner, and downshifting sequentially 4-3-2 while blipping really slows progress, at least for me... dang near impossible to just blip 1000-2000 rpm. Usually way over shoots or under shoots.. at least with the 930. What's the secret here?

is blipping any any worse than just rev matching? When downshifting, right foot hits the brake, clutch goes in, downshift while heel presses gas pedal a quarter inch or so, and shift...

when you you guys are downshifting 4-3-2, and heel toe blipping, the clutch is pressed to the floor the whole time? Do you lift off a bit to get the internals up to speed between gears? Double clutch?

so basically i think I do rev matching, rather than blipping... is that worse? Car seems fine, doesn't get unsettled...

of interst, just started tracking a BMW z3 1.9. Car needs a lot of work, it's squirrely... but, downshifting even without rev matching is smooth as silk... that little motor poses almost no resistance to rotation...
I don't believe it is necessary to blip in between 4-3-2 shifts with clutch depressed the entire time. That would have no effect as the purpose of the blip is to match engine speed with transmission speed at the point that clutch is released. At VIR for example, I'll downshift 5-4-3 but only make a single blip when I make final release of the clutch. Some folks with heel toe after each downshift, but I think that is more out of habit. As Peter says, braking is the most important part. Perfect rev matches are nice, but as long as wheels don't chirp the only thing you really give up with a poor rev match is some clutch wear.
Old 04-29-2018, 11:46 PM
  #25  
TXE36
Drifting
 
TXE36's Avatar
 
Join Date: Feb 2013
Location: TX
Posts: 2,943
Received 191 Likes on 128 Posts
Default

Originally Posted by bpu699
Timely thread... not sure why, but I find heel toe blipping on the track, when you are trying to go quick, really difficult and time consuming... on the street, no problem...
I dunno, track or street I do without even thinking. If I drive the street M3 for a while (5-speed) I'm even tempted to heel-toe the Jag which makes no sense given that it is an automatic.

Now, one thing I did do is I mimicked the pedal setup of the M3 in my driving simulator including the floor hinged gas pedal and using a load block for the brake (so that it responded to pressure). I modified the pedals that came with my Logitech G25. I used that setup to practice heel-toe whenever I was simracing and I think it helped.

The rev matches don't have to be all that high if you are patient to wait for the end of the braking zone or to space out multiple downshifts during the braking zone. Timing of the blips is more important than the magnitude of the blips.

-Mike
Old 04-30-2018, 12:28 AM
  #26  
911ted
Instructor
 
911ted's Avatar
 
Join Date: Aug 2017
Posts: 183
Received 40 Likes on 25 Posts
Default

With all due respect:
This thread needs to have a 915 tranny caveat.
It also needs a NO ABS caveat too. Constant pressure just gets you flat spots. My size 13 braking foot pulses like a mad man when hauling down my G bodied car with race slicks.
Today's modern car gives more forgiveness than you can get from a priest in confession
Old 04-30-2018, 08:05 AM
  #27  
Jabs1542
Rennlist Member
 
Jabs1542's Avatar
 
Join Date: Nov 2015
Location: Northern VA and Central FL
Posts: 1,137
Received 145 Likes on 88 Posts
Default

How about a different approach? Let's discuss the goal and how we prepare you for it.

You are going very fast down a long straight and approaching your brake point. Let's say at this moment you are going 130 mph in 5th gear. Now the question is, what gear do I need to be in when I exit the corner? For this example let's assume you take the corner at 50 mph and your best gear to exit and accelerate out is third. So as you brake and slow down the car you will want to be in third by the time you get through the corner and back onto the throttle. Heel-toe is the method you use to make sure THE CAR REMAINS PERFECTLY BALANCED AT ALL TIMES while performing the downshift. At this point you are dealing with two dimensions, braking (longitudinal) and turning (lateral). Screw one of those up while your tires are screaming at you and bad things are likely to happen.

Ok, you've heard this before... so what? When you begin your track education you are taught to brake hard, then downshift, then turn, go through the corner, and then accelerate at track-out. But as you get better you will start to brake later, and later, and eventually trail that brake all the way into the corner. When you get really good you will trail brake into the corner at high speed, induce a little trail brake oversteer, rotate the car, and be back on throttle BEFORE you reach the apex (on a good day in a proper corner).

What your instructors are teaching you are the basic foundation principles to prepare you for more advanced driving. This started with the whole concept of threshold braking (which includes cars with no ABS) and then moves into heel-toe rev matching (throttle blip is a method of rev matching). So to get really fast into corners you must; a) master threshold braking, then as you get better b) master heel-toe downshifting, then as you get better c) master trail braking (which brings both of those concepts into your turn in point), and eventually d) you will be trail braking deep into the corner thus maintaining mid-corner speed and getting back on the throttle earlier.

Sorry for the long post but it seemed like a few of the readers needed some context to understand why you even care about this funky ankle twisting maneuver your instructors insist you master.
Old 04-30-2018, 08:11 AM
  #28  
ProCoach
Rennlist
Basic Site Sponsor
 
ProCoach's Avatar
 
Join Date: Jun 2008
Location: Durham, NC and Virginia International Raceway
Posts: 19,150
Received 3,329 Likes on 1,891 Posts
Default

Originally Posted by 911ted
With all due respect:
This thread needs to have a 915 tranny caveat.
It also needs a NO ABS caveat too.
With all due respect, here's evidence that that is NOT the case, if done properly and well.

915 gearbox, 3.0-liter carbureted engine, no ABS, R7 Hoosiers. Listen and weep, or learn...

Old 04-30-2018, 08:18 AM
  #29  
Veloce Raptor
Rennlist Member
 
Veloce Raptor's Avatar
 
Join Date: Aug 2006
Location: All Ate Up With Motor
Posts: 41,863
Received 1,690 Likes on 872 Posts
Default

Originally Posted by ProCoach
With all due respect, here's evidence that that is NOT the case, if done properly and well.

915 gearbox, 3.0-liter carbureted engine, no ABS, R7 Hoosiers. Listen and weep, or learn...

Dat's da fact, Jack
Old 04-30-2018, 10:09 AM
  #30  
wanna911
Race Car
 
wanna911's Avatar
 
Join Date: Apr 2005
Location: With A Manual Transmission
Posts: 4,728
Likes: 0
Received 2 Likes on 2 Posts
Default

Originally Posted by Jabs1542
How about a different approach? Let's discuss the goal and how we prepare you for it.

You are going very fast down a long straight and approaching your brake point. Let's say at this moment you are going 130 mph in 5th gear. Now the question is, what gear do I need to be in when I exit the corner? For this example let's assume you take the corner at 50 mph and your best gear to exit and accelerate out is third. So as you brake and slow down the car you will want to be in third by the time you get through the corner and back onto the throttle. Heel-toe is the method you use to make sure THE CAR REMAINS PERFECTLY BALANCED AT ALL TIMES while performing the downshift. At this point you are dealing with two dimensions, braking (longitudinal) and turning (lateral). Screw one of those up while your tires are screaming at you and bad things are likely to happen.

Ok, you've heard this before... so what? When you begin your track education you are taught to brake hard, then downshift, then turn, go through the corner, and then accelerate at track-out. But as you get better you will start to brake later, and later, and eventually trail that brake all the way into the corner. When you get really good you will trail brake into the corner at high speed, induce a little trail brake oversteer, rotate the car, and be back on throttle BEFORE you reach the apex (on a good day in a proper corner).

What your instructors are teaching you are the basic foundation principles to prepare you for more advanced driving. This started with the whole concept of threshold braking (which includes cars with no ABS) and then moves into heel-toe rev matching (throttle blip is a method of rev matching). So to get really fast into corners you must; a) master threshold braking, then as you get better b) master heel-toe downshifting, then as you get better c) master trail braking (which brings both of those concepts into your turn in point), and eventually d) you will be trail braking deep into the corner thus maintaining mid-corner speed and getting back on the throttle earlier.

Sorry for the long post but it seemed like a few of the readers needed some context to understand why you even care about this funky ankle twisting maneuver your instructors insist you master.
Not sure I understand c) . I don' think Trail braking involves heel toe as your downshifting should be done by turn in, thereby separating it from the trail braking portion of the turn. Besides, trying to use the limit of grip on turn in while shifting braking and turning is too much going on (it used to be a bad habit of mine) and a miss would be disasterous. Ideally you should want to get the shifts done(at least the last one) early so that you can use all of your focus on maximizing entry/mid/exit speed. Obviously, there may be outliers but for the most part shifting should be done by turn-in.


Quick Reply: Do you rev match downshift (no heel/toe)



All times are GMT -3. The time now is 11:56 PM.