Left foot braking

[J.A.W.]

Yeah, A-G, that's pretty funny..

Motorcycles certainly require different dynamic inputs being single track vehicles..

But bikes had things like sequential shift gearboxes (quite capable of clutchless shifts, with skill)..
..for decades before cars got them..

& there are various bikes available with 'paddle'/auto-clutchless/linked brakes..
& etc, but they're not popular.. ..bike riders being fickle 'stick-in-the-mud' traditionalists, by & large..

IMO, it is a positive attribute to develop skilled control coordination via all 4 limbs..

[bill shoe]

For several years I was a vehicle dynamics evaluator at a largely empty proving ground. I developed high-level driving and evaluation skills. I was reluctant/conservative/stubborn to try serious left foot braking, and it didn't seem to matter.

After that gig I started doing occasional track days in street cars. This was not wheel to wheel racing, but I was driving fast in the immediate vicinity of other cars for the first time. Some of them were a bit sketchy, so I started left-foot braking to eliminate the first half-second of reaction time when they did something I didn't expect. I was surprised at how much better left-foot braking made my limit driving, even with no other cars around.

I tried to describe it in more detail but words fail me. The best I can say is that left-foot braking helps prevent pitching oscillation from getting in the way of what you're really trying to achieve with the vehicle dynamics at any given instant. You may be trying to achieve various things in terms of velocity, yaw, and dynamic weight transfer, but you never want to create a pitch oscillation. If you right-foot brake, the tiny time gap between accel-pedal and brake-pedal will always give you a pitch oscillation that takes longer to settle out than the original time gap itself. Left-foot braking can eliminate the pitch oscillation by coordinating the simultaneous letting-off of accel and getting-on of brake. The nose just smoothly goes down where you want it and stops. Turns out it's not even very difficult to do. The right-foot drawbacks can't be eliminated with an extra-quick transition between pedals or extra slow/oozing transients on the pedals. Those things just make your driving slow and lousy. The pitch oscillation is just intrinsic to right-foot braking.

[autogyro]

For several years I was a vehicle dynamics evaluator at a largely empty proving ground. I developed high-level driving and evaluation skills. I was reluctant/conservative/stubborn to try serious left foot braking, and it didn't seem to matter.

After that gig I started doing occasional track days in street cars. This was not wheel to wheel racing, but I was driving fast in the immediate vicinity of other cars for the first time. Some of them were a bit sketchy, so I started left-foot braking to eliminate the first half-second of reaction time when they did something I didn't expect. I was surprised at how much better left-foot braking made my limit driving, even with no other cars around.

I tried to describe it in more detail but words fail me. The best I can say is that left-foot braking helps prevent pitching oscillation from getting in the way of what you're really trying to achieve with the vehicle dynamics at any given instant. You may be trying to achieve various things in terms of velocity, yaw, and dynamic weight transfer, but you never want to create a pitch oscillation. If you right-foot brake, the tiny time gap between accel-pedal and brake-pedal will always give you a pitch oscillation that takes longer to settle out than the original time gap itself. Left-foot braking can eliminate the pitch oscillation by coordinating the simultaneous letting-off of accel and getting-on of brake. The nose just smoothly goes down where you want it and stops. Turns out it's not even very difficult to do. The right-foot drawbacks can't be eliminated with an extra-quick transition between pedals or extra slow/oozing transients on the pedals. Those things just make your driving slow and lousy. The pitch oscillation is just intrinsic to right-foot braking.

Very interesting and important information Bill.
My late business partner was a test driver for Vauxhall Motors for many years and I can relate exactly to what you say.
I think you were at the control level where you begin to use the gear shifts and braking dynamics to affect and vary the other vehicle dynamics you are experimenting with to the maximum.
Unfortunately modern gear shifts using electronics attempt to mask things by making the shifts faster than the drivers reaction time and without noticeable feed back.
This is workable with a road car using three pedals and the driver using conventional right foot braking but takes the driver a little further away from full car control.
In an F1 car or other with two pedals and left foot braking the electronic gear shifts, although fast can if other vehicle dynamics are extended to limits during the shift, result in control unbalance during braking.
Sorting this problem with KERS is a major driver control issue.

[autogyro]

Yeah, A-G, that's pretty funny..

Motorcycles certainly require different dynamic inputs being single track vehicles..

But bikes had things like sequential shift gearboxes (quite capable of clutchless shifts, with skill)..
..for decades before cars got them..

& there are various bikes available with 'paddle'/auto-clutchless/linked brakes..
& etc, but they're not popular.. ..bike riders being fickle 'stick-in-the-mud' traditionalists, by & large..

IMO, it is a positive attribute to develop skilled control coordination via all 4 limbs..

I offered an automatic gearbox with different control ergonomics to Honda Racing some years ago.
It promised a two second a lap saving potentially.
The only part of the system that ended up on track was the pulsed ignition gear shift electronics.
In motorcycle racing the Japanese status quo has been maintained for years now.
If it had not been the Norton Rotary would have won every race for the last ten years.

[J.A.W.]

A-G, yes - the bittersweet story of the BSA - NVT- Norton - Roton - Wankel-mill machine is another British horror-show..

I have a `70's Kawasaki road-bike which has a gearshift shaft that projects out both sides of the gear case..
..thus offering the choice of left, or right foot actuation..
It also features a 0-1-2-3-4-5 shift pattern, which is logical, but bikes now,due to 'tradition' run 1-0-2-3-4-etc..

[bill shoe]

Very interesting and important information Bill.
My late business partner was a test driver for Vauxhall Motors for many years and I can relate exactly to what you say.
I think you were at the control level where you begin to use the gear shifts and braking dynamics to affect and vary the other vehicle dynamics you are experimenting with to the maximum.
Unfortunately modern gear shifts using electronics attempt to mask things by making the shifts faster than the drivers reaction time and without noticeable feed back.
This is workable with a road car using three pedals and the driver using conventional right foot braking but takes the driver a little further away from full car control.
In an F1 car or other with two pedals and left foot braking the electronic gear shifts, although fast can if other vehicle dynamics are extended to limits during the shift, result in control unbalance during braking.
Sorting this problem with KERS is a major driver control issue.

I think the biggest issue with transmissions is not the shift time, but rather the influence on handling balance. The extreme non-linear event known as a gearshift is terrible for limit car-control. Heel-and-toeing done PERFECTLY does not eliminate this, it just reduces it. Electronic rev-matching does not eliminate this. With enough electronic controls it's possible to eliminate all influence of gear changes, at least on a given track on a given day.

But philosophically, when it comes to high-performance driving I no longer want better gear changes, I want a really strong engine and a single drive-ratio. This is the only fundamental solution to eliminate gear change non-linearity. A secondary benefit is that for performance/race driving (i.e. not emissions and fuel-economy regulated) it's much cheaper to use a large engine and single-gear drive rather than the traditional small engine with a complex multi-speed transmission.

I suppose this is where people imagine me wearing a tinfoil hat or something...

[J.A.W.]

Cant go with you there B-S..
I really enjoy running a potently powered machine up & down via a decent gearbox..
..riding the rising torque curve, feeling the G - it ranks among those repetitive things - that are a pleasure, IMO..

& electric = anodyne..

[autogyro]

Cant go with you there B-S..
I really enjoy running a potently powered machine up & down via a decent gearbox..
..riding the rising torque curve, feeling the G - it ranks among those repetitive things - that are a pleasure, IMO..

& electric = anodyne..

Thats because you are a TS guy J.A.W.
It is that damn screaming noise they make that gives me a headache

I cant go for the big engine idea either but then a lot of what I have done in the past was in an attempt to gain performance from small power units using gearbox technology.

Sadly the gearbox is treated as an off the shelf bolt on in most applications, when in truth it is at least as important as the power unit.
Even electric vehicles benefit from a gearbox as I convinced Hewland back in 2010 for FE.
Prior to that the 'green' electric brigade mostly believed one gear was enough.
Electric vehicles do demand a new concept in gearing however, which is as yet not recognised.
With one gear the motor has to be large (and heavy) and it will use more energy for the same result.

Dont forget Bill, how effective heeling and toeing is in any application depends on the gear type and the ratio spread.

[Tommy Cookers]

I think the biggest issue with transmissions is not the shift time, but rather the influence on handling balance. The extreme non-linear event known as a gearshift is terrible for limit car-control. Heel-and-toeing done PERFECTLY does not eliminate this, it just reduces it. Electronic rev-matching does not eliminate this. With enough electronic controls it's possible to eliminate all influence of gear changes, at least on a given track on a given day.
But philosophically, when it comes to high-performance driving I no longer want better gear changes, I want a really strong engine and a single drive-ratio. This is the only fundamental solution to eliminate gear change non-linearity. A secondary benefit is that for performance/race driving (i.e. not emissions and fuel-economy regulated) it's much cheaper to use a large engine and single-gear drive rather than the traditional small engine with a complex multi-speed transmission.

agreed ! (and more meaningful than the interesting subject of what some F1 supermen can do via LFB)
even a perfect manual h&t leaves the engine as a load torque on the driven wheels that becomes larger with every downshift
this is disruptive eg to a trackday car setup for optimal cornering aka balanced (road cars by law aren't this way ex-factory)
balanced means that the back end is likely to go on corner entry
though, as Mr Andretti said, if you're not on full throttle after the downshift, why did you shift ?

CVT or torque converter transmissions tend to eliminate this problem
and offer some scope/potential/need for throttling-up against braking
'that' Chapparal was in effect a single gear car (or better) most of the time
some road motorcycles were made this way in the 70s etc, primarily for the USA
and modern torque converters seamlessly lock and unlock

having back then a RR Meteor engine (unsupercharged, detuned Merlin) the single-gear trackday car seemed a good idea
eg droppable straight into a Range Rover chassis and awd
(change the engine:propshaft ratio in the HiVo chain system, the max torque is less than with the standard engine in low gear)
slave the ignition timing to the throttle so that it retards at low powers

a 800 inch Detroit bigblock should do a good job, too

[autogyro]

agreed ! (and more meaningful than the interesting subject of what some F1 supermen can do via LFB)
even a perfect manual h&t leaves the engine as a load torque on the driven wheels that becomes larger with every downshift
this is disruptive eg to a trackday car setup for optimal cornering aka balanced (road cars by law aren't this way ex-factory)
balanced means that the back end is likely to go on corner entry
though, as Mr Andretti said, if you're not on full throttle after the downshift, why did you shift ?

Properly applied gearbox control on down shifts, rather than unbalancing the car, can be used to dynamically position the car in all planes of moment to improve entry speed and speed through the corner.

CVT or torque converter transmissions tend to eliminate this problem
and offer some scope/potential/need for throttling-up against braking
'that' Chapparal was in effect a single gear car (or better) most of the time
some road motorcycles were made this way in the 70s etc, primarily for the USA
and modern torque converters seamlessly lock and unlock

CVTs and to a lesser degree torque converters use to much energy to keep cones and discs applied and to dissipate heat in oil (torque converters), to be efficient enough.
They both reduce feedback to the driver and remove almost all 'feel'.
Removing the torque converter was the first thing I did when applying automatic transmission technology to racing.

having back then a RR Meteor engine (unsupercharged, detuned Merlin) the single-gear trackday car seemed a good idea
eg droppable straight into a Range Rover chassis and awd (just change the engine:propshaft ratio in the HiVo chain system)
a 800 inch Detroit bigblock should do a good job, too

My friend John Dodd used a RR Meteor in his monster RR car.
It used a much modified GM Turbo 400 automatic three speed gearbox.
It was nearly as fast through the quarter mile as my Mustang but much heavier and useless for corners.
I have also modified a number of Range Rovers with the Detroit V8 diesels.
Much too large for the chassis and the gearbox on the Range Rover would never take the torque for long if used hard.
The gears are OK, it is the flimsy casing that lets go.
For off road there was no room between the front diff and the sump, so it was no longer any use for that purpose.
As a track day car, it would be way to front heavy and have the wrong suspension.

[Tommy Cookers]

the Meteor without gearbox is no heavier or bulkier than the V8 with gearbox
the engine would be well back anyway to pickup the stepacross chain drive, this engine position would be good for balance also
(yes, a crossmember would need moving)
the beauty of having no gearbox is that the matching of motor to load is at the stepacross, ie you don't need truck size axles, diffs
the torque delivered to the propshaft/cwps/diffs is no more than the max the standard engine and gearbox could deliver in low gear

this idea was not for a road car, and so it's unlike the Dodds car
as bill said, you don't need a gearbox to drive trackdays
on track there would be a stop pedal and a go pedal and LFB could be applied or not

now if you want a bad idea, I did talk to the owner of the works Allard that finished high at Le Mans in 53 or so
he wanted to install in it a 60 series Merlin (ie 2 stage supercharged)
that would be over twice the weight and bulk of a Meteor and hardly have more power at sea level (than a derestricted Meteor)

[bill shoe]

Tommy, if you ever get a Meteor in a Range Rover I will volunteer for a ride. It might make the airplane seem boring by comparison.

[J.A.W.]

T-C, FYI, back in `44 when ol' Adolf's diabolical V1 cruise-missiles were raining down on London,
Merlins were cleared to run +25lbs boost - at sea-level - on 150 grade petrol - to give those Spits a bit of pep..

http://www.spitfireperformance.com/merlin66_18_25.jpg

An old ex-tank mill would have to be running pretty exotic fuel to get anywhere near that kind of output..

[Tommy Cookers]

crudely, the centrifugal supercharger tends to deliver according to the square of its rpm
so the highly boosted Merlin is 'top-endy' (no problem in its normal use as the load is similarly proportioned)
there will be notably low torque and power at relatively low rpm
though a single speed engine would probably be better as the auto throttle would in such an engine not act until quite high rpm
either way your 1700 hp or whatever would only be consistently accessible on the track by using a gearbox

the Meteor is the opposite, being N/A and with further 'bottom-endy' mods, ie reduced valve motion and induction system
so it tends towards the ideal, the 'constant-power' engine, having its max torque at relatively low rpm
(in lap time terms 'constant power' is the best way to use a given amount of energy)
and has no need for a gearbox in track driving
remove the 2450 rpm governer (made for the benefit of the tank transmission) and there's 800 hp (on 80 Octane)

ideal to eliminate the gearshift issue and focus on the LFB aspect of track driving
(however, I no longer have this engine, so suggest the stretched Detroit big-blocks as a practical alternative)

apart from CVT or so-called torque converters, there's also traditional freewheels and modern motorcycle-type overrun clutches
potentially enabling non-disruptive downshifts (the freewheel/overrun condition allowing downshifts without clutch or throttle action)
what do the users of motorcycle-engined competition cars do in using (or disabling) their overrun clutches ?

[autogyro]

Where in the power train would you put the free wheel/over run clutch?
You definitely will not simplify any gear shift.
You will lose over run braking and feel.