| STi/AE86 | 05-16-2006 02:17 AM |
How do you feel about shifting without the clutch to facilitate left foot braking?
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So eh, a couple months ago I finally got to the point where I don't have to think about double clutch heel toe downshifts and don't have any weight transfer. But now I think I'd rather be left foot braking.
Of course in a manual transmission with a clutch that's quite a problem when you need to do your gear changes in the braking zones. So I've been practicing downshifting without the clutch.
From 6th to 3rd I can do it without any weight transfer but you have to move the selector a lot slower than when you heel toe, (you still have enough time to complete your shifts in a braking zone) you also have to be very precise when matching revs but that's not too hard.
However no matter what I do from 3rd to 2nd I can't seem to get rid of the tiniest shifting of weight that comes from downshifting without the clutch. Eh, I don't know whether I should keep trying to learn this in my STi or not. I'll be getting a kart too but I like to practice things in my STi everyday.
So my question is, is this hard on the tranny even without any crunching? Cause the shifts seem pretty smooth, and do any of you do it? Can you get rid of the small shift in weight from 3rd to 2nd?
I've been watching some Walter Rohrl footbox vids (sooo cool), along with reading that once you left foot brake you completely eliminate the dead time from brake to throttle and also you have a lot more control over the longitudinal weight transfer of your vehicle with left foot braking. (Course you have to make your left foot as sensitive with the brake as your right first off.)
Also, I had someone at a CSCC event that I was at talk about how it's possible to transition from right foot braking after downshifts to the left foot but I don't understand how that wouldn't upset the balance of the car since to switch feet you would have to completely take pressure from off the pedal if even for the briefest moment. Course I never got to see him do it.
Anyway, yeah this is long, but do any of you guys do it? (Rally drivers please chime in hehe.) And how do you feel about it?
Of course in a manual transmission with a clutch that's quite a problem when you need to do your gear changes in the braking zones. So I've been practicing downshifting without the clutch.
From 6th to 3rd I can do it without any weight transfer but you have to move the selector a lot slower than when you heel toe, (you still have enough time to complete your shifts in a braking zone) you also have to be very precise when matching revs but that's not too hard.
However no matter what I do from 3rd to 2nd I can't seem to get rid of the tiniest shifting of weight that comes from downshifting without the clutch. Eh, I don't know whether I should keep trying to learn this in my STi or not. I'll be getting a kart too but I like to practice things in my STi everyday.
So my question is, is this hard on the tranny even without any crunching? Cause the shifts seem pretty smooth, and do any of you do it? Can you get rid of the small shift in weight from 3rd to 2nd?
I've been watching some Walter Rohrl footbox vids (sooo cool), along with reading that once you left foot brake you completely eliminate the dead time from brake to throttle and also you have a lot more control over the longitudinal weight transfer of your vehicle with left foot braking. (Course you have to make your left foot as sensitive with the brake as your right first off.)
Also, I had someone at a CSCC event that I was at talk about how it's possible to transition from right foot braking after downshifts to the left foot but I don't understand how that wouldn't upset the balance of the car since to switch feet you would have to completely take pressure from off the pedal if even for the briefest moment. Course I never got to see him do it.
Anyway, yeah this is long, but do any of you guys do it? (Rally drivers please chime in hehe.) And how do you feel about it?
| Th3Franz | 05-16-2006 03:02 AM |
I'd love to learn how.. I need to practice left foot braking since I think it would help.
| Calamity Jesus | 05-16-2006 08:14 AM |
[QUOTE=STi/AE86] So my question is, is this hard on the tranny even without any crunching? Cause the shifts seem pretty smooth, and do any of you do it? Can you get rid of the small shift in weight from 3rd to 2nd?[/QUOTE]
There is a US Pro Rally driver who supposedly rebuilds his 6-speed tranny after every rally weekend. He's known for his amazing clutch-less shifts.
So, yes.. I'd say it's pretty darn hard on the transmission. The 6-speed is tough, but it will eventually give way to rough driving. I would think that, even without crunching, the synchros are taking more than their share of abuse.
There is a US Pro Rally driver who supposedly rebuilds his 6-speed tranny after every rally weekend. He's known for his amazing clutch-less shifts.
So, yes.. I'd say it's pretty darn hard on the transmission. The 6-speed is tough, but it will eventually give way to rough driving. I would think that, even without crunching, the synchros are taking more than their share of abuse.
| RB5 Clone | 05-16-2006 08:51 AM |
a little time saved vs a lotta $$$ spent
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How bad to you want to win, and how much $$$ are you willing to spend to do it?
You are talking about a technique which does help shave time (a little), but definitely adds significant wear-n-tear to your gearbox.and if you blow a clutchless downshift...ouch.
if it's worth a little time saved and a bunch of $$ spent to rebuild your tranny, go ahead and keep banging clutchless downshifts.
if the STI is a dedicated race car and you have a budget for tranny work, great. If the STI is your daily driver, you're nuts to keep trying this.
You are talking about a technique which does help shave time (a little), but definitely adds significant wear-n-tear to your gearbox.and if you blow a clutchless downshift...ouch.
if it's worth a little time saved and a bunch of $$ spent to rebuild your tranny, go ahead and keep banging clutchless downshifts.
if the STI is a dedicated race car and you have a budget for tranny work, great. If the STI is your daily driver, you're nuts to keep trying this.
| randy zimmer | 05-16-2006 10:41 AM |
"From 6th to 3rd I can do it without any weight transfer but you have to move the selector a lot slower than when you heel toe..."
So what does the stopwatch say? Does the smoothness offset the slowness?
Does this take brainpower to accomplish or is it automatic?
When racing, my brain is all about strategy, not driving the car.
Before sequentials, F1 guys skipped downshifts.
No noise doesn't mean no wear. The syncro is still working to make up that little bit of difference. It will eventually degrade to a smaller window.
It is all up to you, your lap times and your wallet.
Amazing isn't so amazing with a dogbox.
The ex-factory Audi I drove had a shift-button operated clutch for LFB downshifts.
rz
So what does the stopwatch say? Does the smoothness offset the slowness?
Does this take brainpower to accomplish or is it automatic?
When racing, my brain is all about strategy, not driving the car.
Before sequentials, F1 guys skipped downshifts.
No noise doesn't mean no wear. The syncro is still working to make up that little bit of difference. It will eventually degrade to a smaller window.
It is all up to you, your lap times and your wallet.
Amazing isn't so amazing with a dogbox.
The ex-factory Audi I drove had a shift-button operated clutch for LFB downshifts.
rz
| dch | 05-16-2006 10:49 AM |
I left-foot brake and downshift without the clutch all the time in my rally car, but I've got a dogbox. I'm not concerned at all about rev matching, I want all the weight transfer I can get, and in fact some times I have to work hard at unsettling the car to get the rotation I need for a corner. Finding neutral in my car is a bastard, even if you're using the clutch, as it wants to slide right on past into the next gear. So I can't see rev matching being an issue at all for a rally car (with a dogbox of course) and I don't know of anybody who does it off-hand. Usually when braking hard and downshifting I'm also on the throttle to keep the car settled and prevent the wheels from locking and keep the drivetrain tight. By modulating brake and throttle with small steering angles it makes it a lot easier to ride a drift all the way around a corner. So at least on gravel, it sounds to me like a rally technique is going to be pretty much the opposite of what you're trying to do on tarmac. Maybe someone with some tarmac rally experience could be more helpful.
If your gear change point is in the middle of a braking zone, there's no way I can see switching feet to clutch without releasing the brake. When I run a syncro box (spare, last choice) I usually right-foot brake into the corner as I come down gears, then switch feet when I'm in the right gear and do the final braking/corner. That implies braking a bit earlier than with the dogbox (to account for the foot switching time) and it does cost some time since you can't just go blazing in hammering down through the gears while hard on the brakes. Again the weight transfer bobble in there isn't a big deal to me, I embrace loose surfaces. :D I never shift a syncro box without the clutch, I don't want to see what happens when I err. Finishing is the first priority. However if you're perfect on the rev matching, I don't think it's any harder on the box than clutching. I just don't know anybody who can be perfect every shift so I'd have to say I agree it will be harder on your rig.
Thus chimeth in another rally driver.
Cheers,
-Doug
If your gear change point is in the middle of a braking zone, there's no way I can see switching feet to clutch without releasing the brake. When I run a syncro box (spare, last choice) I usually right-foot brake into the corner as I come down gears, then switch feet when I'm in the right gear and do the final braking/corner. That implies braking a bit earlier than with the dogbox (to account for the foot switching time) and it does cost some time since you can't just go blazing in hammering down through the gears while hard on the brakes. Again the weight transfer bobble in there isn't a big deal to me, I embrace loose surfaces. :D I never shift a syncro box without the clutch, I don't want to see what happens when I err. Finishing is the first priority. However if you're perfect on the rev matching, I don't think it's any harder on the box than clutching. I just don't know anybody who can be perfect every shift so I'd have to say I agree it will be harder on your rig.
Thus chimeth in another rally driver.
Cheers,
-Doug
| makofoto | 05-16-2006 10:51 AM |
I use to be able to do that effortlessly with a worn out VW ... but wouldn't do it with my STX WRX. If you want to do it ... using Redline MT-90 will certainly help. It will provide the extra friction to make it easier on your synchros. I use to use it ... made the 2nd to 1st shift much easier.
[url]http://www.cobbtuning.com/tech/gearoil/index.html[/url]
[url]http://www.cobbtuning.com/tech/gearoil/index.html[/url]
| The neck | 05-16-2006 03:34 PM |
As another left-foot-braking rally guy I'll agree with Doug that the little weight shift moving from rfb to lfb just as you turn in to the corner is no big deal and can even be useful in destabilizing the car. I think in rally we tend to brake a little earlier than road racers anyway so we have a little in reserve when the corner is not as we expect. If all goes well we can afford the extra moment it takes to change pedals. (I think this is what Tim O'Neil taught me but it may be a bad habit I developed later and I should really go back to Tim for a tune-up.)
However, in faster corners, which require less downshifting, and where weight shift would be more of a problem, I go from rfb to lfb without coming off the brake as follows:
I have a nice wide aftermarket brake pedal and as I approach the corner I am downshifting, with the left foot working the clutch, and the right is on the right half of the brake which just happens to be a good position for blipping the throttle. Once I am in the correct gear, the left foot goes to the empty left half of the brake pedal to take up the pressure, and then the right goes to the gas, and I am ready to turn.
It helps that my brakes are unboosted (intentionally) so that they really have to be pushed hard when braking into a corner because they are not so sensitive to pressure variations during the change-over.
Having said this I am strictly a rally guy, and I don't know how well this technique would work in road racing. One of the things I have admired about road racers and even good autocrossers (I think saw KC drive once) is their sensitive feet (especially rolling onto the throttle exiting the corner). I don't know that a rally guy's ham fisted pedal mashing technique's would transfer well to road racing which seems to require more finesse.
However, in faster corners, which require less downshifting, and where weight shift would be more of a problem, I go from rfb to lfb without coming off the brake as follows:
I have a nice wide aftermarket brake pedal and as I approach the corner I am downshifting, with the left foot working the clutch, and the right is on the right half of the brake which just happens to be a good position for blipping the throttle. Once I am in the correct gear, the left foot goes to the empty left half of the brake pedal to take up the pressure, and then the right goes to the gas, and I am ready to turn.
It helps that my brakes are unboosted (intentionally) so that they really have to be pushed hard when braking into a corner because they are not so sensitive to pressure variations during the change-over.
Having said this I am strictly a rally guy, and I don't know how well this technique would work in road racing. One of the things I have admired about road racers and even good autocrossers (I think saw KC drive once) is their sensitive feet (especially rolling onto the throttle exiting the corner). I don't know that a rally guy's ham fisted pedal mashing technique's would transfer well to road racing which seems to require more finesse.
| turboICE | 05-16-2006 04:12 PM |
Original poster, what type of surface are you intending to competitively utilize this technique on? (And in any case I wouldn't duplicate dogbox techniques with synchros.)
| 8Complex | 05-16-2006 04:22 PM |
Sounds impressive.
The only thing I can comment on in that entire post is the second to last paragraph. Basically, if you don't cover the entire pedal with your foot, you can switch feet without much issue. I don't left foot brake personally, but I do heal-toe all the time, and it shows in the wear on my brake pedal (all bottom right corner, down to the metal now after 91k).
The only thing I can comment on in that entire post is the second to last paragraph. Basically, if you don't cover the entire pedal with your foot, you can switch feet without much issue. I don't left foot brake personally, but I do heal-toe all the time, and it shows in the wear on my brake pedal (all bottom right corner, down to the metal now after 91k).
| rallymaniac | 05-16-2006 04:34 PM |
I can tell you that most of the rally drivers don't do LFB on the tarmac. Some hardcore ones do but it's not efficient enough to wear your brakes more than necessary on the tarmac. The line through the corner and braking in optimal spot is more important.
On the gravel, yes, it helps alot to destabilize your car and "turn" it the way you want.
On the gravel, yes, it helps alot to destabilize your car and "turn" it the way you want.
| sachilles | 05-16-2006 04:49 PM |
I'm interested to hear the answer to this.
I've autocrossed for several years and done a handfull of track and hillclimbs. Until this year I had never left foot braked.I was lucky enough to go to Team O'neil for the one day "experience" for free courtesy of a vendor from work.
I tell you, LFB is a tough thing to learn, and not all that easy to practice during everyday driving.
Had our first autox of the season, and put lfb into the equation for the first time, all I can say is I'm still learning. By the last run of the day, I was really getting the feel for it. I certainly feel the potential of it improving my times at the autocross and other events....wish I had tried it earlier.
My experience with this is exclusively in my audi A4 (I'm purchasing a wrx wagon) , and I feel that lfb is great for turbo'd vehicles....as it tends to keep the boost up. I can't wait to get my 61 mini back up to give it a shot, as I think it will benefit as well. I have yet to autox my own wrx, but I'm willing to bet it will benefit from left foot braking more so than my audi, comparing the two, it seems like boost comes on later in the wrx.
I think on pavement you will also be able to eliminate some downshifting by the act of LFB, you may be able to exit a corner in a higher gear as you will keeping your revs higher....if that makes sense?
Wish I could spend more time at Team O'neil, that was a blast.
I've autocrossed for several years and done a handfull of track and hillclimbs. Until this year I had never left foot braked.I was lucky enough to go to Team O'neil for the one day "experience" for free courtesy of a vendor from work.
I tell you, LFB is a tough thing to learn, and not all that easy to practice during everyday driving.
Had our first autox of the season, and put lfb into the equation for the first time, all I can say is I'm still learning. By the last run of the day, I was really getting the feel for it. I certainly feel the potential of it improving my times at the autocross and other events....wish I had tried it earlier.
My experience with this is exclusively in my audi A4 (I'm purchasing a wrx wagon) , and I feel that lfb is great for turbo'd vehicles....as it tends to keep the boost up. I can't wait to get my 61 mini back up to give it a shot, as I think it will benefit as well. I have yet to autox my own wrx, but I'm willing to bet it will benefit from left foot braking more so than my audi, comparing the two, it seems like boost comes on later in the wrx.
I think on pavement you will also be able to eliminate some downshifting by the act of LFB, you may be able to exit a corner in a higher gear as you will keeping your revs higher....if that makes sense?
Wish I could spend more time at Team O'neil, that was a blast.
| turboICE | 05-16-2006 05:23 PM |
All of this is totally relevant to loose surface as has been laid out but it also all relates to intentionally unsettling the car to achieve a correct attitude around a corner. Which is why I ask the original poster where he intends on these techniques being of benefit.
It isn't entirely clear to me how with the same exit speed and the same gear you are ever going to get a higher rpm. The mechanical connection is fixed. So if LFB is allowing you to either not down shift or not down shift as low, you could do the same thing with RFB at the same exit speed, in the same gear at the same rpm. You are achieving a higher exit speed but LFB isn't getting you there when RFB couldn't.
In a turbo car, the benefit of LFB is that you can control an open throttle and maintain engine load to keep the turbo spinning and more torque immediately available as a result - but you aren't going to have more rpms in the same gear at the same exit speed.
There are limitations on where I can see LFB as a benefit on tarmac (even more limted with synchros) and ceraintly am unable to see the benefit of LFB while down shifting on tarmac. I apply LFB primarily in single gear sweepers and for the same reason as loose surface purposes to unsettle the car with the purpose of altering its attitude momentarily, just a bit though not to the extent of loose surface changes in attitude. LFB would be done when some off throttle oversteer wouldn't produce the same desired change in attitude (or if OTO would reduce load and turbo spin).
In auto-x I would expect all benefits to be keeping the engine load up and the turbo spinning - again in the same geear the whole time, certainly not down shifting with LFB.
Edit: all references to tarmac in my post mean track road course - i.e. repeated runs at speed, turn is known, no debris
It isn't entirely clear to me how with the same exit speed and the same gear you are ever going to get a higher rpm. The mechanical connection is fixed. So if LFB is allowing you to either not down shift or not down shift as low, you could do the same thing with RFB at the same exit speed, in the same gear at the same rpm. You are achieving a higher exit speed but LFB isn't getting you there when RFB couldn't.
In a turbo car, the benefit of LFB is that you can control an open throttle and maintain engine load to keep the turbo spinning and more torque immediately available as a result - but you aren't going to have more rpms in the same gear at the same exit speed.
There are limitations on where I can see LFB as a benefit on tarmac (even more limted with synchros) and ceraintly am unable to see the benefit of LFB while down shifting on tarmac. I apply LFB primarily in single gear sweepers and for the same reason as loose surface purposes to unsettle the car with the purpose of altering its attitude momentarily, just a bit though not to the extent of loose surface changes in attitude. LFB would be done when some off throttle oversteer wouldn't produce the same desired change in attitude (or if OTO would reduce load and turbo spin).
In auto-x I would expect all benefits to be keeping the engine load up and the turbo spinning - again in the same geear the whole time, certainly not down shifting with LFB.
Edit: all references to tarmac in my post mean track road course - i.e. repeated runs at speed, turn is known, no debris
| The neck | 05-16-2006 06:10 PM |
[QUOTE=rallymaniac] Some hardcore ones do [lfb] but it's not efficient enough to wear your brakes more than necessary on the tarmac. The line through the corner and braking in optimal spot is more important.
[QUOTE]
I can't really agree with that. My experience on tarmac is limited, but I have run forty or fifty tarmac stages in all kinds of conditions, and lfb was nearly as useful there as on gravel.
Driving a tarmac rally stage is more like driving a gravel stage than it it like driving a road course IMHO. Although it would be nice to brake at the optimal point and take the optimal line through every corner, its not going to happen. Firstly, it's more than likely the first time you took the corner at speed, and if it isn't, it has probably changed since the last time you went through. The surface is usually not pristine: it might be wet, or broken, or dust/mud/gravel covered and sometimes all of the above. Often the traction level can change twice or more on the way round one corner.
A rally guy (or gal) simply cannot drive every corner with the same level of commitment that I imagine road racers do (Pat Richard perhaps being an exception). The plan you develop when the co-driver calls the corner is subject to change. Modulating brakes and throttle together allows you to change your line much faster and smoother than if you had to jump from one to the other. This applies equally to tarmac and gravel stages.
Correct me if I am wrong, but road racers and autoxers are different. There is usually one fastest way through the corner, and they will be fairly commited to that fastest line very early on breaking once, and then rolling on to the throttle on the way out. If that's true, much as I love to lfb, I could see how it wouldn't help.
Regarding the brake wear in a rally, sure they get hot. I usually finish a tarmac stage with stinky smoking brakes, but I bleed them at service and change pads as needed. Efficiency be damned.
[QUOTE]
I can't really agree with that. My experience on tarmac is limited, but I have run forty or fifty tarmac stages in all kinds of conditions, and lfb was nearly as useful there as on gravel.
Driving a tarmac rally stage is more like driving a gravel stage than it it like driving a road course IMHO. Although it would be nice to brake at the optimal point and take the optimal line through every corner, its not going to happen. Firstly, it's more than likely the first time you took the corner at speed, and if it isn't, it has probably changed since the last time you went through. The surface is usually not pristine: it might be wet, or broken, or dust/mud/gravel covered and sometimes all of the above. Often the traction level can change twice or more on the way round one corner.
A rally guy (or gal) simply cannot drive every corner with the same level of commitment that I imagine road racers do (Pat Richard perhaps being an exception). The plan you develop when the co-driver calls the corner is subject to change. Modulating brakes and throttle together allows you to change your line much faster and smoother than if you had to jump from one to the other. This applies equally to tarmac and gravel stages.
Correct me if I am wrong, but road racers and autoxers are different. There is usually one fastest way through the corner, and they will be fairly commited to that fastest line very early on breaking once, and then rolling on to the throttle on the way out. If that's true, much as I love to lfb, I could see how it wouldn't help.
Regarding the brake wear in a rally, sure they get hot. I usually finish a tarmac stage with stinky smoking brakes, but I bleed them at service and change pads as needed. Efficiency be damned.
| M. Hurst | 05-16-2006 08:59 PM |
Lfb
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As a rally guy, and a total tarmac hack, I've found that LFB in an AWD car at an autocross keeps me from "buzzing" the inside front tire while accelerating and turning (loose center diff, open front diff)..keep the throttle open and brakes on enough to give the inside front some resistance the..otherwise the car would push when the inside front starts spinning. Poor man's tighter diffs..or dummy that can't back off the throttle?
...Used the same technique on ice..PGT car w/stock diffs.
FWIW..consider the source :rolleyes:
...Used the same technique on ice..PGT car w/stock diffs.
FWIW..consider the source :rolleyes:
| turboICE | 05-16-2006 09:02 PM |
[QUOTE=M. Hurst]dummy that can't back off the throttle?[/QUOTE]Hmmmm, maybe next time I auto-x I need to try this then - I drive my friends who are good at auto-x crazy refusing to get to turn grip speeds....
| STi/AE86 | 05-17-2006 06:28 AM |
Wow, I did not expect this many replies, thanks a lot to everyone for chiming in this is wonderful. I'm learning a lot.
Actually I have this technique, LFB, in mind for track work, so yeah tarmac. I sure dig rally but I've never done anything other than rallyX so I can't say I know much about gravel and the like although I can totally understand your points behind wanting to unsettle the car with gearshifts and transitioning from LFB to RFB.
However, for me I intended to learn LFB and clutchless downshifting only to get rid of that transition from brake to throttle on the track, also to help "steer" the car more effectively with the pedals. Pretty much every good professional driver I respect and is a great driver uses LFB almost exclusively. (Numerous F1 drivers, Tommi Makinen, Patrick Richard, etc.)
Done well, with a left foot as sensitive as your right for the brake and your sensitive right foot devoted strictly to being sensitive on the throttle, and overlapping throttle and brake in corners I could only see this as making you faster, my only dliemma is will even perfect downshifts without the clutch ruin my tranny. Hehe, I'm thinking that the consensus of this thread is yes it will eventually. Bummer.
Does left foot braking right now for me require brainpower, and clutchless shifts? Yeah they do, but so did heel toe at one point. But by the time I would use it in competition I wouldn't need to think about it. Just wondering if it's worth learning, well I know it's worth learning, but do I need a kart to do so heh. I am reminded of the story of how Walter Rohrl learned how to left foot brake after practicing through a storm all night in his Audi lol. Not to presume I'm that good, but I'm positive anyone can learn how to LFB and rather quickly with a good amount of the right practice.
So basically yes, all of this is meant to become more sensitive and precise thus increasing my speed.
Actually I have this technique, LFB, in mind for track work, so yeah tarmac. I sure dig rally but I've never done anything other than rallyX so I can't say I know much about gravel and the like although I can totally understand your points behind wanting to unsettle the car with gearshifts and transitioning from LFB to RFB.
However, for me I intended to learn LFB and clutchless downshifting only to get rid of that transition from brake to throttle on the track, also to help "steer" the car more effectively with the pedals. Pretty much every good professional driver I respect and is a great driver uses LFB almost exclusively. (Numerous F1 drivers, Tommi Makinen, Patrick Richard, etc.)
Done well, with a left foot as sensitive as your right for the brake and your sensitive right foot devoted strictly to being sensitive on the throttle, and overlapping throttle and brake in corners I could only see this as making you faster, my only dliemma is will even perfect downshifts without the clutch ruin my tranny. Hehe, I'm thinking that the consensus of this thread is yes it will eventually. Bummer.
Does left foot braking right now for me require brainpower, and clutchless shifts? Yeah they do, but so did heel toe at one point. But by the time I would use it in competition I wouldn't need to think about it. Just wondering if it's worth learning, well I know it's worth learning, but do I need a kart to do so heh. I am reminded of the story of how Walter Rohrl learned how to left foot brake after practicing through a storm all night in his Audi lol. Not to presume I'm that good, but I'm positive anyone can learn how to LFB and rather quickly with a good amount of the right practice.
So basically yes, all of this is meant to become more sensitive and precise thus increasing my speed.
| Patrick Olsen | 05-17-2006 09:25 AM |
I did a track event at VIR a few weeks back, and the lead instructor brought up the subject of LFB in one of our classroom sessions (I was running in the advanced/instructor group, so he was bringing this up at that level, not the track newbie level). The basic gist was that it can occasionally be of benefit, but in general it's not going to gain you much on track. Auto-x is obviously a different story, because you (generally) can put the car in 2nd and not have to touch the clutch ever again, so there's nothing to complicate the LFB. The idea of clutchless downshifting while LFB was not discussed, so maybe that would have changed his answer somewhat. With that said, I think clutchless downshifting with a synchro transmission is a bad, bad idea - you will wear the tranny out faster, and regardless of how much you practice, there's a much greater chance that you'll blow a shift and damage your tranny.
At the higher levels of motorsport LFB is widely used, but that's in cars that are specifically designed to allow for that. From what I understand, most of the F1 cars are designed such that you can't get your right foot onto the brake pedal - there's been quite a bit of talk this year about Reubens Barrichello having a hard time getting back into LFB in the Honda, that he was a RFBer in the Ferrari. If you watch the NASCAR road course events, the drivers are almost all doing clutchless up- and down-shifts, but that's because the tranny will take it (and yet they still grenade them, just because they're doing so much more shifting).
I think when it comes right down to it (IMO at least) the risk vs. gain just doesn't pay off for LFB on a road course, unless the car is set up with the proper drivetrain to allow for it. Here's a thought that just popped into my head - try asking some Spec Miata guys, or some other spec series that uses "real" cars with "normal" trannies. Those guys are as evenly matched as can be, and have to take advantage of any little thing they can to gain time. Find out how many of the top finishing SM drivers are doing LFB and clutchless downshifting.
Pat Olsen
'97 Legacy 2.5GT sedan
At the higher levels of motorsport LFB is widely used, but that's in cars that are specifically designed to allow for that. From what I understand, most of the F1 cars are designed such that you can't get your right foot onto the brake pedal - there's been quite a bit of talk this year about Reubens Barrichello having a hard time getting back into LFB in the Honda, that he was a RFBer in the Ferrari. If you watch the NASCAR road course events, the drivers are almost all doing clutchless up- and down-shifts, but that's because the tranny will take it (and yet they still grenade them, just because they're doing so much more shifting).
I think when it comes right down to it (IMO at least) the risk vs. gain just doesn't pay off for LFB on a road course, unless the car is set up with the proper drivetrain to allow for it. Here's a thought that just popped into my head - try asking some Spec Miata guys, or some other spec series that uses "real" cars with "normal" trannies. Those guys are as evenly matched as can be, and have to take advantage of any little thing they can to gain time. Find out how many of the top finishing SM drivers are doing LFB and clutchless downshifting.
Pat Olsen
'97 Legacy 2.5GT sedan
| turboICE | 05-17-2006 10:09 AM |
[QUOTE=STi/AE86]Pretty much every good professional driver I respect and is a great driver uses LFB almost exclusively. (Numerous F1 drivers, Tommi Makinen, Patrick Richard, etc.)[/QUOTE]There in lies a large part of the difference - they are at the pinnacle of their sport where every .1 of a second matters to their livlihood AND more importantly the equipment is on someone else's tab. And most don't have clutches...
I guarantee there are dozens of places where you could reduce your track times by more without the additional wear on your car.
If you want to do it, by all means absolutely do it, the exhibition of that skill is very impressive and your ability to do it will be impressive. But don't kid yourself into thinking that is where you have the most room to improve your lap times. When clutchless downshifting is where you can most improve your times you will have the proper equipment for it and it will be someone else paying for that equipment.
I guarantee there are dozens of places where you could reduce your track times by more without the additional wear on your car.
If you want to do it, by all means absolutely do it, the exhibition of that skill is very impressive and your ability to do it will be impressive. But don't kid yourself into thinking that is where you have the most room to improve your lap times. When clutchless downshifting is where you can most improve your times you will have the proper equipment for it and it will be someone else paying for that equipment.
| rallymaniac | 05-17-2006 11:17 AM |
[QUOTE=The neck][QUOTE=rallymaniac] Some hardcore ones do [lfb] but it's not efficient enough to wear your brakes more than necessary on the tarmac. The line through the corner and braking in optimal spot is more important.
[QUOTE]
I can't really agree with that. My experience on tarmac is limited, but I have run forty or fifty tarmac stages in all kinds of conditions, and lfb was nearly as useful there as on gravel.
Driving a tarmac rally stage is more like driving a gravel stage than it it like driving a road course IMHO. Although it would be nice to brake at the optimal point and take the optimal line through every corner, its not going to happen. Firstly, it's more than likely the first time you took the corner at speed, and if it isn't, it has probably changed since the last time you went through. The surface is usually not pristine: it might be wet, or broken, or dust/mud/gravel covered and sometimes all of the above. Often the traction level can change twice or more on the way round one corner.
A rally guy (or gal) simply cannot drive every corner with the same level of commitment that I imagine road racers do (Pat Richard perhaps being an exception). The plan you develop when the co-driver calls the corner is subject to change. Modulating brakes and throttle together allows you to change your line much faster and smoother than if you had to jump from one to the other. This applies equally to tarmac and gravel stages.
[/QUOTE]
I'll have to check who does and who doesn't use LFB in WRC on Tarmac.
I think Panizzi is the one who doesn't which could explain why he wasn't great on gravel.
[QUOTE]
I can't really agree with that. My experience on tarmac is limited, but I have run forty or fifty tarmac stages in all kinds of conditions, and lfb was nearly as useful there as on gravel.
Driving a tarmac rally stage is more like driving a gravel stage than it it like driving a road course IMHO. Although it would be nice to brake at the optimal point and take the optimal line through every corner, its not going to happen. Firstly, it's more than likely the first time you took the corner at speed, and if it isn't, it has probably changed since the last time you went through. The surface is usually not pristine: it might be wet, or broken, or dust/mud/gravel covered and sometimes all of the above. Often the traction level can change twice or more on the way round one corner.
A rally guy (or gal) simply cannot drive every corner with the same level of commitment that I imagine road racers do (Pat Richard perhaps being an exception). The plan you develop when the co-driver calls the corner is subject to change. Modulating brakes and throttle together allows you to change your line much faster and smoother than if you had to jump from one to the other. This applies equally to tarmac and gravel stages.
[/QUOTE]
I'll have to check who does and who doesn't use LFB in WRC on Tarmac.
I think Panizzi is the one who doesn't which could explain why he wasn't great on gravel.
| ghschirtz | 05-17-2006 01:35 PM |
LFB can be learned-I drive an automatic trans that way all the time. I think LFB, if you don't have to shift and have a series of linked corners on the track, would be better, but driver workload goes up and chance for error. as someone said, you have to be alert to tactics and other stuff all the time, so it may not be the best choice of where to put your effort.
I would not shift a synchro box without using the clutch, or I would plan for the box to be torn down and rebuilt a lot more often to head off failure in competition. Straight-cut gears and no synchros, a clutch actually gets in the way, a little. In F1, with the computers, servos and electronics doing all the work to shift and match revs, of similar situations, clearly LFB would be the way to go.
My $.02 worth.
George
I would not shift a synchro box without using the clutch, or I would plan for the box to be torn down and rebuilt a lot more often to head off failure in competition. Straight-cut gears and no synchros, a clutch actually gets in the way, a little. In F1, with the computers, servos and electronics doing all the work to shift and match revs, of similar situations, clearly LFB would be the way to go.
My $.02 worth.
George
| djviper | 05-17-2006 09:12 PM |
ill be honest i only use left foot braking where i only need to scrub off minimal speed rest of the time i just use heel and toe
as mentioned if you have a dog box go for it, otherwise unless you have shares in syncro and baulk ring production best not clutchless either way lol
as mentioned if you have a dog box go for it, otherwise unless you have shares in syncro and baulk ring production best not clutchless either way lol
| BHawk | 05-17-2006 09:37 PM |
Clutchless downshifting in a synchronized car is probably a bad idea for all the reasons listed above.
If you want to "left foot brake" you should try learning to do the "windshield wiper". This will be used when transitioning from LFB to RFB so that you can perform your standard heel - toe downshift. You will be starting out in the LFB position with your left foot over the brake and your right over the throttle. Just imagine that the heels of your feet are attached to something and can't move. Simply rotate the toes of both feet to the left so that your left foot is over the clutch and your right foot is over the brake pedal and your right heel should still be in good position for the blip of the throttle you will need. Once you have finished braking in a straight line and have turned in you just do the reverse and switch back to left foot braking. Once mastered this can all happen very quickly and you are unlikely to lose any time doing it. Not to mention that you will also save wear and tear on your car.
If you want to "left foot brake" you should try learning to do the "windshield wiper". This will be used when transitioning from LFB to RFB so that you can perform your standard heel - toe downshift. You will be starting out in the LFB position with your left foot over the brake and your right over the throttle. Just imagine that the heels of your feet are attached to something and can't move. Simply rotate the toes of both feet to the left so that your left foot is over the clutch and your right foot is over the brake pedal and your right heel should still be in good position for the blip of the throttle you will need. Once you have finished braking in a straight line and have turned in you just do the reverse and switch back to left foot braking. Once mastered this can all happen very quickly and you are unlikely to lose any time doing it. Not to mention that you will also save wear and tear on your car.
| adhowe70 | 05-17-2006 11:18 PM |
I agree with BHawk... the "windshield wiper" for the win! I know accomplished LFB drivers (with good credentials on gravel and on tarmac) that do this move seamlessly.
| ghschirtz | 05-18-2006 02:10 AM |
^Now I find out my novel idea is already in practice...sigh, but good on you. I noticed in traffic that keeping the heels planted seems to help...now I have an informed opinion, andthank you.
George
George
| patr | 05-18-2006 03:46 AM |
maybe you guys dont understand the right way, but since my name was mentioned (thanks for the props!):
YOU DONT NEED TO CLUTCHLESS SHIFT TO LFB
there are multiple ways to do this, but essentially you can swap feet left to right and right to left without unweighting the car if you do it right, and you can also heel toe style with the clutch/brake. The point is, "braking with the left foot" does not equate to "left foot braking". But you mainly brake with the left foot unless you need to shift, and still at that point, you can heel/toe the clutch brake or you can swap feet onto the brake pedal with no weight jiggling at all (practise). Anyone who has done any "true" studless ice rallies on a synchro box with any amount of pushing HAS to do this, because whenever you hit the brake pedal without the gas, you can stall the engine, and whenever you shift, you can stall the engine, and any glitches in your technique, will stall the engine/induce slides. Maybe that is why most people DNF the ice rallies. Go figure.
But also, you CAN clutchless down shift but you dont need to unless you are really in a jam and are losing it and dont want to swap feet. But anyways, the time to do this is not during the max braking moment (max longitudinal Gs) but once the tires are already laterally loaded, again this wont upset the car if you do it right. You can compensate for the driveline wiggle with your feet, so that there is no wiggle at all. But anyways, you dont need to, just need to get your feet moving.
You can see the foot cam video if you want to see a lot of LFB, but in any case, you should always clutch on the upshifts to save the thing. That video is here: [url="http://www.rocketrally.com/managed/mod-CMpro-listpages-subid-41.phtm"]http://www.rocketrally.com/managed/mod-CMpro-listpages-subid-41.phtm[/url]
-Pat
YOU DONT NEED TO CLUTCHLESS SHIFT TO LFB
there are multiple ways to do this, but essentially you can swap feet left to right and right to left without unweighting the car if you do it right, and you can also heel toe style with the clutch/brake. The point is, "braking with the left foot" does not equate to "left foot braking". But you mainly brake with the left foot unless you need to shift, and still at that point, you can heel/toe the clutch brake or you can swap feet onto the brake pedal with no weight jiggling at all (practise). Anyone who has done any "true" studless ice rallies on a synchro box with any amount of pushing HAS to do this, because whenever you hit the brake pedal without the gas, you can stall the engine, and whenever you shift, you can stall the engine, and any glitches in your technique, will stall the engine/induce slides. Maybe that is why most people DNF the ice rallies. Go figure.
But also, you CAN clutchless down shift but you dont need to unless you are really in a jam and are losing it and dont want to swap feet. But anyways, the time to do this is not during the max braking moment (max longitudinal Gs) but once the tires are already laterally loaded, again this wont upset the car if you do it right. You can compensate for the driveline wiggle with your feet, so that there is no wiggle at all. But anyways, you dont need to, just need to get your feet moving.
You can see the foot cam video if you want to see a lot of LFB, but in any case, you should always clutch on the upshifts to save the thing. That video is here: [url="http://www.rocketrally.com/managed/mod-CMpro-listpages-subid-41.phtm"]http://www.rocketrally.com/managed/mod-CMpro-listpages-subid-41.phtm[/url]
-Pat
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