Trailing-throttle oversteer

[redrider90]

I was reading an interesting article in the New York Times about owning older cages called "Driving Older Cars: Light on Tech, Heavy on Fun"
A subscription is required but they generally allow access I think to 5 free a month. 
https://www.nytimes.com/2020/07/02/business/driving-older-cars.html?action=click&algo=bandit-story&block=more_in_recirc&fellback=false&imp_id=609169005&impression_id=405368609&index=3&pgtype=Article&region=footer&req_id=626749158&surface=more-in-business

From that article
" In the case of the Rover, I found out that the source of my mortification was what’s called trailing-throttle oversteer: Using the brakes (or sometimes just lifting off the gas) in the middle of the turn would take some of the weight off the rear tires, causing them to lose grip and making the car spin.

Trailing-throttle oversteer was not unusual in rear-wheel-drive vehicles of the ’60s and ’70s. A driver who understood it could make the car turn more sharply. Here’s how: In the turn, lift off the gas so that the tail moves to the outside of the turn. That points the nose deeper into the turn. Get back on the gas to stop that movement. So whether trailing-throttle oversteer was a safety defect or not depended on the driver’s expertise."

I have never heard the term or this description of actually letting the rear end drift slightly and then throttling up in a car much less on 2 wheels. 
It seems it would take a bit of practice to do this. Essentially you literally are changing the angle of the front car in the turn using drifting at the rear of the car.
I always take on a curve in a car much the same as a M/C by throttling up in the curve. I can remember taking a beginners track course, Keith Code if I remember correctly and the instructor said whenever you think you are going to fast throttle it up even more and counter steer.
That said this method letting the rear end drift on a M/C seems to be asking for trouble. I would think it would be much easier to "lose it" in a curve by drifting the rear end and then throttling up.
Anybody ever do this in a car or yikes on a bike (outside of say flat track racing which allows you to have a foot on the ground)?

[Idontwantapickle]

Works in a car. You'll have a broken shoulder if you do that on pavement with a bike. High side crash.
As for the cars, they will do that trailing throttle thing but it's WAAAAYYY more fun to have enough power to just smoke the rears and oversteer! 
YMMV

Hunter

[Rough Edge racing]

Interesting,but it's  my opinion the author is making statements based on limited experience. I dove like a maniac as a young man in 50-60's American cars. Throwing cars into turns at insane speeds, car all leaned over , two ply tires howling and sliding and winding the steering wheel into the slide, the unloaded outside rear tire spinning and smoking without a limited slip...Yup just like in the Movies...the handling was sloppy but benign if you kept ahead of it. There was a slight tendency  for the ass end to come around a bit when you got off the gas pedal ,but it wasn't bad  that I remember. Cars of that period were bias to understeerig, Ford's having the most,so
you needed to power through turns to limit the front end plowing...The stiffer suspensions of the muscle cars were better but with a posi rear and slow steering the ass end could come around.....

[kingoffleece]

That particular trait caught many an inexperienced 70's 911 driver unaware as they spun their cars right off the road.   Usually with dire results.

[pressureangle]

Author=limited experience, yes.

In a rover, perhaps; a pre-CJ7 jeep, yes. Trailing throttle oversteer was a thing then on short-wheelbase vehicles with weight far forward. Pickup trucks have been this way since there was such a thing as a pickup truck.

The rest of the stuff post-1950 was engineered very specifically to understeer horrifically, because the traffic bureaucrats noticed that a car which plows straight off the road is far less likely to involve other vehicles than one that spins back into the roadway. So trailing-throttle or brake induced oversteer was no thing at all in American cars. European cars handled much more appropriately, pretty well balanced around neutral.
Throttle induced oversteer, however, was very much a thing and the balancing act between trailing understeer and throttle oversteer was the difference between life and death. Any old musclecar restoration that requires street manners includes suspension geometry changes to bring the thing more in line with modern expectations.

[Pizza Guzzi]

You soon learn never to lift off mid corner in a swing axle VW.

[lucky phil]

I was reading an interesting article in the New York Times about owning older cages called "Driving Older Cars: Light on Tech, Heavy on Fun"
A subscription is required but they generally allow access I think to 5 free a month. 
https://www.nytimes.com/2020/07/02/business/driving-older-cars.html?action=click&algo=bandit-story&block=more_in_recirc&fellback=false&imp_id=609169005&impression_id=405368609&index=3&pgtype=Article&region=footer&req_id=626749158&surface=more-in-business

From that article
" In the case of the Rover, I found out that the source of my mortification was what’s called trailing-throttle oversteer: Using the brakes (or sometimes just lifting off the gas) in the middle of the turn would take some of the weight off the rear tires, causing them to lose grip and making the car spin.

Trailing-throttle oversteer was not unusual in rear-wheel-drive vehicles of the ’60s and ’70s. A driver who understood it could make the car turn more sharply. Here’s how: In the turn, lift off the gas so that the tail moves to the outside of the turn. That points the nose deeper into the turn. Get back on the gas to stop that movement. So whether trailing-throttle oversteer was a safety defect or not depended on the driver’s expertise."

I have never heard the term or this description of actually letting the rear end drift slightly and then throttling up in a car much less on 2 wheels. 
It seems it would take a bit of practice to do this. Essentially you literally are changing the angle of the front car in the turn using drifting at the rear of the car.
I always take on a curve in a car much the same as a M/C by throttling up in the curve. I can remember taking a beginners track course, Keith Code if I remember correctly and the instructor said whenever you think you are going to fast throttle it up even more and counter steer.
That said this method letting the rear end drift on a M/C seems to be asking for trouble. I would think it would be much easier to "lose it" in a curve by drifting the rear end and then throttling up.
Anybody ever do this in a car or yikes on a bike (outside of say flat track racing which allows you to have a foot on the ground)?

It's more commonly known as "liftoff over-steer" and is most noticeable on front wheel drive cars. Anyone thats raced a FWD car will know all about it. Its basically as you described. With a front end biased car especially in fast corner with the power on if you suddenly lift off the throttle in some cases the shift of weight can be so dramatic that the car simple oversteers into a spin. It catches drivers on the track out in the above scenario when they lift off suddenly to avoid someone else's mistake and find themselves going backwards into the scenery. Never heard of it in a RWD car though. You can have an issue spinning out a RWD car if it suddenly snaps from plowing under-steer to oversteer but it's not quite the same as liftoff over-steer.
On motorcycles you often get a similar thing when you shut the throttle mid corner and the bike runs wide. worse on bikes with large section rear tyres like 180-200 sections. When you close the throttle the lack of drive from the engine through the back tyre reduces the slip angle of the tyre and then the back tyre tends to steer the front due to its greater rolling radius on the edges. Thats probably why your riding instructor advised to open the throttle in the circumstances you describe. It's a little misleading of him as it would be better to say dont shut the throttle as you'll just run wide/wider. The correct technique if running wide in a corner is to gently roll off to a neutral throttle and apply a "little" rear brake. Applying a little rear brake will make the bike either hold its line of tighten it a little depending on how much you apply. I use this technique on the track sometimes when i can see I've missed the apex a little and am going to be wider than I want to be on the exit. Instead of rolling out of the throttle I just use the rear brake to tighten the line. It's actually the only thing I use a rear brake for on the track and on the road I occasionally do the same ( usually because I've misjudged the corner) and also to hold the bike on an incline stopped at the lights. other than that it never gets used.

Ciao   

[redrider90]

The correct technique if running wide in a corner is to gently roll off to a neutral throttle and apply a "little" rear brake. Applying a little rear brake will make the bike either hold its line of tighten it a little depending on how much you apply. I use this technique on the track sometimes when i can see I've missed the apex a little and am going to be wider than I want to be on the exit. Instead of rolling out of the throttle I just use the rear brake to tighten the line. It's actually the only thing I use a rear brake for on the track and on the road I occasionally do the same ( usually because I've misjudged the corner) and also to hold the bike on an incline stopped at the lights. other than that it never gets used.

Ciao   

The technique you describe using a "little" rear brake is where I think Guzzi linked system excels at and for me that is what I like most about the linked system. It allows for a "little" more than just a "little" rear braking without the losing the bike to drifting out if not off the corner.

[pressureangle]

You soon learn never to lift off mid corner in a swing axle VW.

  folds up like George Jetson's suitcase car.

[GearheadGrrrl]

Here's an article I wrote a while back about the Corvair and 911s shared design heritage, in the mid 60s the cars in high performance form were equals but if the driver made the natural reaction of backing off the throttle in a corner taken too fast, the 911 might spin while at worst the Corvair would just plow straight ahead. Here's the link: https://gearheadgrrrl.com/2019/02/27/corvair-911-shared-dna/

[Steve Scott]

OK, some afternoon rambling on driving. First-off, we're talking street-car speeds (not "street" speeds... I'm talking about speeds a street car can attain. Think closed-course).

All unmodified street cars understeer naturally. without some intervention from the driver, the front slip-angles will increase faster than the rear with cornering sideload (the front will ultimately slide before the rear) simply because the steering tires are doing more work. This is worse for FWD because then the steering tires are also driving.

Most unmodified street cars have an oversteer threshold that is within reach when the larger slip-angles from cornering sideload are neared and the vehicle is understeering; meaning the car can be forced to transition from understeer to oversteer with some input from the driver (lifting the throttle is aided by weight shift off the rear, applying the throttle is fought by weight shift off the front, left-foot braking in a FWD etc.).No handbrake or "bootleg" turns allowed... that's just sliding! The question is how close are those two thresholds? That's much of what gives a sporting car 'feel'.

Some stock street cars cannot be oversteered without drastic efforts if at all. Mid 80s Chrysler "Omni-Rizons' come to mind. FWD, Heavy front weight bias, Much front roll stiffness, little rear roll stiffness and very soft springing made those things feel almost out of control at very low cornering sideloads. They are horrible to drive... but very safe. I don't think I've ever seen one in a one car wreck! There's lots of "SLOW-DOWN" warnings feedback to the driver long before anything is really going wrong in that car.

All bets are off with a modified car. My race car is FWD with same size tires on all four wheels (ever wonder why Porsche 911s grew those giant rear tires?), so you'd think it would want to run straight off every corner in understeer, but lots of toe-out, very stiff springing and lots of rear roll stiffness results in a car that oversteers at speed without driver input. It's manageable... comfortable even at high speed cornering, but only at full throttle near the torque peak. Lifting the throttle then is out of the question because oversteer is severe and instantaneous under those particular conditions. Alternately, In slower speed corners left-foot braking is required to get it to rotate because the torque to the front wheels is higher then. It is good on the track because everything is controlled,on the street with opposing/cross traffic, bicycles, kids, dogs, etc. it is downright dangerous.