Left foot braking

[Tommy Cookers]

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.

about 50 years ago some Rovers and 2 stroke cars had true freewheels
seeming to allow downchanges as I said (on the overrun the gearbox is nominally unloaded), but eliminating 'engine braking'
now race and other motorcycles have a freewheel effect in the clutch that occurs above a threshold EB/backdriving torque (adjustable ?)
intentionally to limit EB torque

yes of course this sacrifices EB
but, as I said, on a rwd car setup balanced for optimal cornering you can't afford to have a load (EB) on the rear wheels only
you should either be somewhat trail braking or somewhat on throttle ie the EB zone should be avoided
ime track cautions led naturally to EB, but this seemed to bring the car closer to spinning
this would not apply with a road setup, that's why road setup is the way it is

anyway, some people use these motorcycle units in competition cars

[SSK]

The total longitudinal load transfer for a given car (i.e. fixed CG height and wheelbase) depends ONLY on longitudinal acceleration. To put it Mathematically: LT = Mass x LongAcc x CGheight / wheelbase.

Geometric effects like anti squat/lift/raise/dive change only the PORTION of that total load transfer which occurs more or less instantaneously through the links instead of through the springs.

Thanks. Your opinion is right. I've almost forgot the anti force is just the portion. But these force is very useful to control the body motion. Especialy aero depended cars. And the number of combination of anti force geometry is huge , so as you say, the best answer( the fastest setting) isn't one answer. I completely agree with your opinion.

[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.

about 50 years ago some Rovers and 2 stroke cars had true freewheels
seeming to allow downchanges as I said (on the overrun the gearbox is nominally unloaded), but eliminating 'engine braking'
now race and other motorcycles have a freewheel effect in the clutch that occurs above a threshold EB/backdriving torque (adjustable ?)
intentionally to limit EB torque

yes of course this sacrifices EB
but, as I said, on a rwd car setup balanced for optimal cornering you can't afford to have a load (EB) on the rear wheels only
you should either be somewhat trail braking or somewhat on throttle ie the EB zone should be avoided
ime track cautions led naturally to EB, but this seemed to bring the car closer to spinning
this would not apply with a road setup, that's why road setup is the way it is

anyway, some people use these motorcycle units in competition cars

Any upset to car balance occurs at the engagement of the lower gear during the down shift, after this the engine absorbs the energy involved.
In a manual conventional gearbox (or any manually controlled stepped ratio gearbox) this upset to car balance can be used by the driver or rider to vary other dynamic motion of the vehicle.
It is part of the drivers available car control.
As an add on to a racing motorcycle a freewheel can only be to offset the use of insufficient gears or excess power for the tyres and rider.
It is when stepped ratio down shifts are combined with electronic control that the gear changes become further removed from driver control and uncontrolled dynamics can be expected.

I used to drive a 105 Westminster years ago with a Borg Warner overdrive unit on the back of the manual gearbox.
It had a tee handle cable operated freewheel that disengaged the cone that held the freewheel clutch.
I even used this rather large car to win a couple of driving test events.
However this was at low speed and the main gain was the ability to engage reverse gear when going forwards and visa versa with the freewheel in operation.
Perhaps I should offer such a freewheel to modern driving test drivers?
The 105 with freewheel on the road used properly gave over 40 mpg.
We have not come far have we.

[Tim.Wright]

I wouldn't necessarily say that the downshift destabilises. In fact, at least historically, its the opposite and it comes back to the diff which closes slightly due to the engine drag.

These days I don't know if the electro-hyraulic diffs are torque sensitive or not. Perhaps the engine or brake drag torques are not required anymore to close the diff

[autogyro]

I wouldn't necessarily say that the downshift destabilises. In fact, at least historically, its the opposite and it comes back to the diff which closes slightly due to the engine drag.

These days I don't know if the electro-hyraulic diffs are torque sensitive or not. Perhaps the engine or brake drag torques are not required anymore to close the diff

Yes Tim, I can remember using the down shifts to straiten up the car rallying some years ago.

[Tommy Cookers]

I wouldn't necessarily say that the downshift destabilises. In fact, at least historically, its the opposite and it comes back to the diff which closes slightly due to the engine drag.
These days I don't know if the electro-hyraulic diffs are torque sensitive or not. Perhaps the engine or brake drag torques are not required anymore to close the diff

yes agreed, my bits of track activity were (afaik !) with open diffs only

in a supposedly super-handling rwd car, increasing the rear spring rate 25% was a transformation (about 6 sec/lap)
you don't know what understeer is till you have got rid of it
but then the car had oversteer throttle-off, more in lower gears (from the change in front : rear load with 'EB' axle torque)
a full/partial freewheel would eliminate/reduce this (iirc what they have in motorcycles is called a slipper clutch ?)
another car, a crude hot-hatch fwd, came this way from the factory, and would have been better with a lower rear spring rate

traditionally there is EB on corner entry, but suitable trail braking is better as the load is better distributed
that's why they do this eg in F1
without downshifting as we traditionally know it LFB is the way to go