Left Foot Braking

[wst]

Before we begin, this is not a conversation about where LFB is/isn't to be used, it's purely a conversation to improve my understanding (and hopefully other peoples') of the effect it has on the car/driving. A dynamics kind of question.

I was on Youtube and I tripped over this ancient video by a certain Mr Harris and it got me thinking - what is happening at the driven wheels when the brake is applied while the engine is also providing drive? What's different about the reaction a car with a torsen diff has to one with an open diff? Is it still useful to LFB with an open diff? What other diff types are there where it has a positive/negative/neutral effect?

I was partly thinking of the old chestnut of a car stuck with one wheel on ice and another on tarmac - could LFB be used in a car to make it able to move?

[wst]

R_U_LOCAL said:

Left-foot braking was developed by rally drivers in front-wheel drive cars as a way of controlling understeer, particularly in tighter corners, where there is a tendency for front-wheel (and many four-wheel) drive cars to push on under heavy throttle application on loose surfaces. Modern stability systems effectively do the same thing by quelling understeer through application of individual brakes.

All this makes me sound like a real advocate of left-foot braking. I am - but not on the road. But that would be breaking the first rule of your original post. So I won't go there!

I guess with the ability to control an open diff it'd have minor effectiveness on an open-diff'd RWD as well, if it didn't have systems to do that for you - never thought of those computerised systems as things doing the same job!

And yeah, I was a spoilsport just to keep the thread concise really, no amount of arguing will change peoples' behaviour away from the forum (eg when driving) so let's not go there

[wst]

Yes, with my current lack of driving talent I think any attempt at LFB on a road or track or wherever in snow, with my lack of ABS just helping things a bit, would result in me going in a perfectly straight trajectory, either with rotation (oversteer) or not (understeer), and the art would be in hitting the tree nice and straight.

[wst]

From the first post...

wst said:

Before we begin, this is not a conversation about where LFB is/isn't to be used, it's purely a conversation to improve my understanding (and hopefully other peoples') of the effect it has on the car/driving. A dynamics kind of question.

It's been flogged to death and isn't relevant to the thread. You wouldn't push a button that says "do not push"... wait, you would? st!

Tales of driving a ridiculous Focus ST with an open diff, however, are! I'm supposing that it scales down to a puny shopping hatchback on a frozen ice lake. Do you reckon it can help with cornering traction when the car hasn't the ability to spin up the inside-front? (FWD/AWD)