Track driving question - turbo lag, left foot braking
Discussion
Does anyone use left foot braking to overcome turbo lag when driving on track or is this something that requires so much finesse that it's not worth bothering with? I'm just thinking about how rally drivers used to gain time by using the left foot method. The point I'm thinking this might be useful is somewhere mid-corner, when getting back on the throttle and the turbo-lag means that the weight transfers to the back gently and causes more understeer, rather than getting instant punch resulting in making the rear tyres work slightly harder and if anything, getting a little oversteer on exit.
I've assumed a RWD turbocharged car in this theoretical situation.
I've assumed a RWD turbocharged car in this theoretical situation.
Mad Chemist said:
Don't get much lag in my mapped TTRS
Thanks.From reading around here, people do use LFB on track, usually in the context of correcting the line of FWD cars. But it's a valid technique for a turbo car; whether it will make you quicker is very much down to the car, and how well you can LFB.
It's a valid technique what ever drivetrain you have! I LFB pretty much all the time, as my road car is an auto, and my rally car is paddleshift sequential. But even when you have a conventional manual, getting good at LFBing is a worthwhile thing to do, as you can subtly adjust the trajectory of the car in the middle of a corner without having to adjust the power setting, and as it works on all 4 wheels, it's much less likely to effect the cars balance and weight transfer as you do it.
BertBert said:
davepoth said:
BertBert said:
How are you planning on working the clutch whilst you lfb?
You don't want to be changing gear while balancing the car on the throttle (and brake).I'm wondering if I can get on the throttle about mid-corner, but use left foot braking so as not to get that initial gentle laggy push and instead get more punchy thrust when lifting off the brakes to try to help neutralise any understeer.
bennyboysvuk said:
Does anyone use left foot braking to overcome turbo lag when driving on track or is this something that requires so much finesse that it's not worth bothering with? I'm just thinking about how rally drivers used to gain time by using the left foot method. The point I'm thinking this might be useful is somewhere mid-corner, when getting back on the throttle and the turbo-lag means that the weight transfers to the back gently and causes more understeer, rather than getting instant punch resulting in making the rear tyres work slightly harder and if anything, getting a little oversteer on exit.
I've assumed a RWD turbocharged car in this theoretical situation.
I don't think rally drivers use left foot braking in response to turbo lag. Remember that brake biase is heavily to the front, so will be more 'braking' force there than at the back. I don't think all the front wheel braking is going to help you mid corner (assuming RWD)I've assumed a RWD turbocharged car in this theoretical situation.
Edited by balls-out on Monday 26th November 10:41
I use it on the road in a BMW auto to compensate for the throttle response. Not exactly turbo lag, however the effect is similar.
Ironically I do it to control the weight transfer to the rear by slowing it down. When the car decides to respond and apply power to the wheels I can blend off the brake and on to the throttle at the point I want to accelerate rather than when the car wakes up.
This is really just something I have developed to get around the initial, none linear, response of the throttle and the delay, presumably due to the torque converter, of the drivetrain. I have only ever tried it on the road therefore not as a limit technique more to promote smoothness and balance.
Ironically I do it to control the weight transfer to the rear by slowing it down. When the car decides to respond and apply power to the wheels I can blend off the brake and on to the throttle at the point I want to accelerate rather than when the car wakes up.
This is really just something I have developed to get around the initial, none linear, response of the throttle and the delay, presumably due to the torque converter, of the drivetrain. I have only ever tried it on the road therefore not as a limit technique more to promote smoothness and balance.
I've used it to "move the brake bias backwards" on snow (with some success ...and lack of success). You can perform nice tail-out pirouettes in a FWD car.
I've also used it to "limit the slip" of the front diff to aid traction on loose surfaces.
It's probably too confusing for me to use safely on the road in a a manual, though, without a lot of practice -It's too easy to stamp on the brake instead of the clutch.
I've also used it to "limit the slip" of the front diff to aid traction on loose surfaces.
It's probably too confusing for me to use safely on the road in a a manual, though, without a lot of practice -It's too easy to stamp on the brake instead of the clutch.
bennyboysvuk said:
I'm wondering if I can get on the throttle about mid-corner, but use left foot braking so as not to get that initial gentle laggy push and instead get more punchy thrust when lifting off the brakes to try to help neutralise any understeer.
It feels pretty challenging to me in terms of footwork. On the brakes (right) on the approach, get to the right gear, turn in, off brakes (right), on brakes (left), on gas (right), off brakes (left).I can't convince myself that it's going to end up in anything other than a spin (both feet in).
Bert
It can be done...by some people
As demonstrated here with some skill Although I'm not convinced that the pedal footage in the video coincides with a rally stage.
I remember seeing this footage on TV years ago. Watch the spectators
As demonstrated here with some skill Although I'm not convinced that the pedal footage in the video coincides with a rally stage.
I remember seeing this footage on TV years ago. Watch the spectators
Edited by MC Bodge on Monday 26th November 19:16
BertBert said:
It feels pretty challenging to me in terms of footwork. On the brakes (right) on the approach, get to the right gear, turn in, off brakes (right), on brakes (left), on gas (right), off brakes (left).
I'm not sure that, on tarmac, braking for a corner whilst going down through the gears would ever warrant using your left foot, unless you suddenly wanted to adjust the car's line mid-corner once you'd got back on the power. As said, in terms of lag in that situation, you'd make sure you were in the right gear (i.e low enough to have your revs high and avoid any lag when you get back on the throttle). I see it as being useful (if you're skilful enough - I'm not) to be able to trim the line of a car without coming off the gas - e.g. for a fast kink where you might lift to help turn-in, but stay in the same gear, you instead left foot brake whilst maintaining some throttle. This would help eliminate any turbo lag as your revs would be higher than if you'd lifted, as well as reducing understeer.
ETA - If you're driving a Group B Monster on loose surfaces, it may be a different story, but again, Rohrl seems to be doing his hard braking with his right foot, then just making corrections using his left foot.
Edited by _Neal_ on Wednesday 28th November 13:15
On Track I havnt found that left foot braking has helped me too much because it over complicates things and I find I can adjust teh car quite well with the throttle. However, my daily driver isn SMax with an auto type box and that is very easy to left foot brake and i do it all the time now as eth pedal position is so poor that in order to get comfortable with my right foot on throttle, then I would be too close to the brake pedal so its nicer to have my left foot angled in to cover the brake pedal, if that makes sense.
I have found that teh transition from throttle to brake is now seemless and also back to throttle and this has noticable benefits to th eweight transfer of the car. I have noticed that I can brake deeper into a corner and tehn get straight on to the gas and again this is safer and faster. (Yes I do drive quickly on the road when conditions allow).
None of this is quite as simple in a manual car and I dont get enough time on track to fully develop this skill.
I have found that teh transition from throttle to brake is now seemless and also back to throttle and this has noticable benefits to th eweight transfer of the car. I have noticed that I can brake deeper into a corner and tehn get straight on to the gas and again this is safer and faster. (Yes I do drive quickly on the road when conditions allow).
None of this is quite as simple in a manual car and I dont get enough time on track to fully develop this skill.
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