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frenchyd
frenchyd UltraDork
11/22/18 11:51 a.m.

In reply to Tom1200 :

If you live up here in the land of ice and snow you either learn how to steer with the throttle or stay at home.  

Believe it or not I regularly do that with a 40 foot long school bus.  ( at least on icy school days ) 

iceracer
iceracer UltimaDork
11/22/18 12:05 p.m.

Is it a natural thing for us old guys?   Perhaps it is the playing around on various surfaces that it became a natural thing.

I remember talking to a long time friend at an hpde once.   He drove a fast Corvair and I drove my ZX2SR.

The subject of tb and ts came up.   He said that we had been doing it before it became a thing.

wspohn
wspohn Dork
11/22/18 12:30 p.m.

If you have run a car at the limit of adhesion in either solo or race conditions, how can you possibly NOT have observed that you can affect car attitude with throttle? If you haven't been in a nice 4 wheel drift, you aren't competing, you are just out there playing around, and if you have experience with a 4 wheel drift, and have any sense of car control, it is hard to believe that they haven't balanced the car in the corner with a combination of steering input and throttle.

I guess my 'holy crap' moment when I realized all this may just be enough decades behind me that I have forgotten what it felt like?  I guess you either develop the technique early, or just never 'get it'?

As for trailing braking, I do recall that was not a thing when I took driver training in the early 1970s - they were still telling you to complete braking in a straight line and then turn. I forget who first brought the technique to amateur racing - maybe Formula Ford brought it over from the bike guys?  Anyway, most of us immediately adopted it, as it allowed you to balance the car in terms of fore/aft weighting and 'settle' the car.

Knurled.
Knurled. MegaDork
11/22/18 1:34 p.m.
P3PPY said:

I guess I'll have to find a few explanation videos or something. I'm not getting how short of tire slip you could change the direction a car is going without changing the direction of the front tire. I'm anxious to peer into this new world though!

Tires are always slipping.  The "slip angle curve" is a curve of how much traction a tire gets relative to its angle of slip relative to angle of motion.  Likewise, a tire making forward (or braking) thrust is also slipping, and this is also on a curve.  Maximum grip comes with a certain percentage of slippage.

 

 

The fun part that we get to play with is that this curve is also affected by the vertical load on the tire.  Altering the load on the tires via braking or accelerating will affect how much grip the tires can generate.  The amount of lateral FORCE on the tires is down strictly to vehicle mass distribution.  (This is also the general idea behind how suspension tuning itself works...)

 

This is why, say, in a 911 you do not dare lift mid-corner.  You need to keep accelerating to keep the rear tires loaded down so that they can create traction so that the car doesn't swing like a hammer.  Likewise, if you are in a nose heavy car, if you aren't decelerating when turning in, you're going to have a bad time.

 

On the rallycross course, for example, if I'm in a corner and I'm starting to understeer, a quick lift of the throttle or maybe a dab of the brakes will shift weight forward and get the front tires some more bite.  Loading the tires down more vertically changes the place they are at on the vertical load vs. lateral load curve, and they generate more grip for the same slip angle, and all is well. 

 

Tom1200
Tom1200 HalfDork
11/22/18 9:03 p.m.

I was very surprised to see this many responses. 

In this age of ABS & stability control I see even less reason to use the "do all your braking in a straight line" method. I even discussed this with my student; telling them I prefer to teach standard technique striaght away rather than teach one thing then have them unlearn brake in a striaght line and then learn trail braking.

As for not rotating the car I've seen drivers who put in respectable times without any sort of throttle steering or trail braking. Most of them are sorting scratching there heads as to why they can't get that last 5-10% out of the car. This is part of why I started instructing, I just hate to see people struggle, especially when a small change in their approach can fix the issue in an instant.

There are some things I will only share with very experienced drivers; using the kerbing to rotate the car in places where you're trying to keep the throttle on (this is for underpowered wonders) or preloading the throttle under threshold braking to settle the car just before turn in as well as left foot braking (not to be confused with using your left foot to brake).

The only crunch I use as an instructor is encouraging brand new students to cruise down straightaways as it's easier to nail turn in points when you only have to slow down 10-20 mph.

Strizzo
Strizzo PowerDork
11/22/18 9:49 p.m.

I used to hoon an f150, you learn weight transfer, trail braking and steering with throttle, or you end up in the ditch.

Tom1200
Tom1200 HalfDork
11/22/18 9:49 p.m.

@P3PPY there is a real easy way to learn this technique. Find a big parking lot where you can drive around at 25-35 mph in a figure eight pattern. Use a mark on the pavement as your apex, use a turn in point about 50-60ft out from your apex mark, turn in under steady throttle then about half way to the apex mark roll off the throttle and note how the trajectory changes.  Now do the same thing but roll off the throttle as you turn in and note the trajectory.

If the car turns inside the mark add a small bit of throttle, if the car still isn't turning tight enough lightly drag the brakes (this is trail braking), once you get a feel for adjusting the trajectory play with your approach speed. You can do all of this with out sliding the tires.

In my wife's SUV I use throttle steering on freeway interchanges all the time, if the road tightens up I ease off the throttle a bit then as the road opens up I ease on the throttle.  

The whole point of using these techniques is that they unsettle the car far less than constant steering corrections. It's not only faster it's also smoother and consequently safer.

Tom1200
Tom1200 HalfDork
11/22/18 9:56 p.m.

@strizzo I've always felt that a muddy field and an old pickup truck should be part of mandatory driver training........you learn a lot when you suddenly find you're a passenger behind the wheel. 

Ransom
Ransom PowerDork
11/23/18 12:19 a.m.
Tom1200 said:

left foot braking (not to be confused with using your left foot to brake).

I'll have to ask you to clarify; the only left foot braking I'm familiar with is using your left foot to brake. I haven't played with it enough to get anywhere.

Fitzauto
Fitzauto Dork
11/23/18 12:57 a.m.

Steering with the pedals is something I picked up driving a stiffly spring AE86. It would either understeer or oversteer and the only way to correct it was to either apply throttle or brakes mid corner.

steronz
steronz Reader
11/23/18 11:24 a.m.

Maybe it's a testament to how much performance even pedestrian modern cars have, or maybe it's about how much grip a modern all-season can put down, but I don't think at any point in my "enthusiast" driving career I've ever been pushing a car hard enough on the street for throttle steering to be remotely necessary.  I mean, it's fairly obvious that the faster you're going the larger the radius of a turn for a given steering input, but targeting a certain slip angle and then steering with the pedals isn't something I could have seen myself picking up on without spending a few years moving up the HPDE ladder and exploring the limits of my car.

This is possibly made worse by the fact that everyone with more experience than me told me my first mod should be tires.  "Tires are everything, it's your only contact with the road!" people said, so from the get go I was putting 200TW tires on my "fun" cars, which in every case (in retrospect) just made them less fun.  You can't learn how to manage grip if you have waaaay too much of it.

iceracer
iceracer UltimaDork
11/23/18 11:30 a.m.

In reply to Ransom :

Left foot braking is used in an attempt to apply the brakes while still on the throttle in an attempt to steer the car.

Braking with the left foot is used to slow the car.

ebonyandivory
ebonyandivory PowerDork
11/23/18 12:48 p.m.

In reply to steronz :

If I hadn’t spent so many New England snowy winters with a manual two-wheel drive Ranger I might not be so good at vehicle control.

Very little steering input, lots of throttle dancing and a very light touch of the brakes.

You can learn most of the do’s and dont’s in snow covered parking lots and big developments (before the houses get built).

Iusedtobefast
Iusedtobefast Reader
11/23/18 2:19 p.m.

I have seen this mentioned already but I feel the best way to learn these skills is on the dirt. I learned from my days off-road racing about trail braking, throttle steer, and smooth inputs to all the controls. Also how to adjust each for every turn was different from lap to lap. Track would start out muddy then dust was flying by the end of the race. Ruts made you adjust your lines and you didn't always know going into the corner what line was fastest. You learn to adjust by the seat of your pants. 

dean1484
dean1484 MegaDork
11/23/18 2:47 p.m.
iceracer said:

In reply to Ransom :

Left foot braking is used in an attempt to apply the brakes while still on the throttle in an attempt to steer the car.

Braking with the left foot is used to slow the car.

Yes to all this but i also use it to change the balance of the car moving the CG forward. This changes the center of rotation of the car and I often do it while accelerating. 

 

A funny story. I was at bridghampton and had an instructor with me to get signed off for the track for an EMRA event. I was in the lightbulb and the instructor asked me to put more stearing angle in to the car I said ok and turned the wheel both ways while telling him it did not matter as I was driving the car with the throttle and actually liked it almost strait so the transition coming out into the short chute was smoother. One lap latter I was told to go to the pits.  The instructor got out and walked off. I went to my stuff in the sand box they called the pits and about 30 minuets the chief Stuart for EMRA stopped by and signed me off saying that the instructor said I was good to go but he would never get in a car with me again that day as I made him seasick.   I later found out that the instructor was of the school of maximum grip all the time for maximum speed. I later road with him and that was a fascinating study of a completely different style of driving. I ended up learning a lot from him and it taught me the balance of slip angle versus speed and brought home to me that most of the time what feels fast is slow and what seems boring is often very fast.  

buzzboy
buzzboy Reader
11/23/18 5:29 p.m.

I never do it on the racetrack. I could probably be a bit quicker if I trail braked effectively but with what I drive, meh. The better thing for me left foot braking would be to possibly help keep the turbo spooled because I'm often braking hard and late then slamming the throttle hoping that the turbo will spool when I want it too. Unless the steering angle is high there's not enough power to spin the rears. At my last race I found this to be an issue, getting my braking done too early, throttling too early and having the turbo come on boost too early and spinning the inside tire(nose heavy and no LSD).

On the street? I don't have my studs on yet and we've gotten 10-15" of snow the past 48hrs. The drive through the neighborhood to my house is 5 miles and 1300 vertical feet of twisty roads. There is plenty of time to work on some VERY low speed drifting. Scandy flick, little throttle tap, let the rear out, power down with a little oppo and boom, a perfect 15mph drift.

A 401 CJ
A 401 CJ Dork
11/23/18 6:26 p.m.

Why did they call the 930 a widow maker?  When those came out the “do all your braking before the corner” school of thought was dominant.  Is it possible that it’s disadvantageous to try and trail brake some cars?  

freestyle
freestyle Reader
11/23/18 6:41 p.m.

I've found a skidpad to be a great tool in teaching new drivers how the pedals can control understeer and oversteer. Keep the steering the same and more throttle = understeer, lift = tucks in and turns. Street Survival program. I learned autocrossing on sweepers. 

Tom1200
Tom1200 HalfDork
11/23/18 8:53 p.m.

@steronz I throttle steer my wife's SUV around freeway interchanges and trail the brakes on various on ramps.........all at perfectly legal speeds. The same goes for any high end sports car you can do this at legal speeds with great effect.  I tell people who I instruct that they can use track techniques every day to become a smoother and safer driver. 

My reason for using these techniques on a race track is it simply lets you get the maximum out of all four tires at the same time. For me this is brought home by the fact that when I finish off a set of tires all four are equally worn.

mazdeuce - Seth
mazdeuce - Seth Mod Squad
11/23/18 9:14 p.m.
steronz said:

This is possibly made worse by the fact that everyone with more experience than me told me my first mod should be tires.  "Tires are everything, it's your only contact with the road!" people said, so from the get go I was putting 200TW tires on my "fun" cars, which in every case (in retrospect) just made them less fun.  You can't learn how to manage grip if you have waaaay too much of it.

200tw tires are fast, but if your car is even half way decent you can't come close to the limit of grip on the street without being a serious a-hole. I have local corners that I can take at 40mph in my Accord and not even be close to losing grip. If I park that nd take out the Miata on absolutely terrible $35 tires I'm carefully managing understeer on entry and hanging the rear out just a few degrees by mid corner with throttle application all without exceeding 25mph. 

P3PPY
P3PPY Reader
11/23/18 9:19 p.m.

In reply to freestyle :

I'm in between flights now and I've been thinking about this a lot. Also I've not able to actually try anything out this week in my mother in laws minivan. So in a sense it seems like what's being said is basically just at a given steering input if you go slow you will turn tightly but if you go fast, your circle will be much bigger. But then there's the other reply where Dean1484 said that he could turn the wheel either way in a corner and nothing would change. I'm really looking forward to trying this out as suggested. 

 

And then theres the explanation that your tires are ALWAYS slipping. Oh man! There is so much more to this driving fast than I ever thought

poopshovel again
poopshovel again MegaDork
11/24/18 6:23 a.m.

I think it was in “Going Faster” that I read “The only thing that should handle like it’s on rails is a train.” QFT.

Also, karting in the rain will teach you how to steer with the pedals in no time.

Knurled.
Knurled. MegaDork
11/24/18 7:27 a.m.
P3PPY said:And then theres the explanation that your tires are ALWAYS slipping. Oh man! There is so much more to this driving fast than I ever thought

 

There's a lot of things in a certain GM chassis engineer's handling book that I disagree with (NOT Fred Puhn, and I cannot remember his name right now) but there are a bunch of fascinating charts with respect to slippage curves, both as a function of slippage vs. traction and load vs. slippage.  Really, slippage vs. vertical load vs. traction is a three dimensional curve, and this curve is what people are grading when they review tires.

 

"Responsive" tires will have a very steep initial curve as you can generate high grip levels with low slip angles, while "forviging" tires will not drop off a cliff after peak grip occurs.  Generally speaking, the lower the sidewall profile, the more responsive but less forgiving the tire.  And high section width bias-plies?  Since a bias-ply is always skidding/slipping even when rolling neutrally in a straight line, the difference between no forces and max forces is low, so they have very shallow broad curves, which is where you see photos and footage of 1950s sports car racing where it looks like they are pitched way sideways, but this is actually where "maximum grip" is.  Or close enough to it to work, racing wasn't as much of a science then as much as it was having fun and growing big brass ones, and the tires were very forgiving anyway.

 

"Drifting" in the JDM-yo sense can be thought of as driving so that the rear tires are past the peak of the grip curve and the chassis is controlled by transferring load fore and aft with the throttle and brake..  ("Drifting" in the American ricer sense is just doing a burnout around a corner and is nothing very technically interesting)

Tom1200
Tom1200 HalfDork
11/24/18 7:08 p.m.

Both my cars run on bias ply tires; the Datsun is on Hoosier vintage TDs and the Formula 500 on Hoosier R25 slicks.

The vintage TDs are such that you can play with the backend of the car all day long. 

The Formula 500 on is a different ball game. The much lower/stiffer  sidewall makes for a very small window between maximum slip angle and total breakaway.  This may seem backwards but with the F500 you cannot as aggressively steer with the pedals as you can with the Datsun. This I'm sure is down to design of a slick over a semi threaded tire, the lack of tire wind up in the slick means they don't spring back like the vintage TD does.

So going back to steering with the pedals; with a treaded tire be it radial or bias ply that spring back in the tire can be used to great effect. Take a 30 degree left into a 90 right, you can trail the brakes into the 30 right to the point of a hair beyond maximum slip angle in the rear, then wait for tire to spring back. If coordinated perfectly this will start rotating the car into the 90 right making the transition much quicker then could possibly be done with the steering. Think along the lines of Scandenavian flick but in a very slow motion version.

One of the analogies  I use is bending a wood dowel. If you grab both ends and bend it quickly it won't bend to far before breaking. In contrast if you slowly pry on the dowel you can bend it very far. When we turn the steering wheel we're trying to bend the tire and using the pedals allows you to slowly bend the tire. Trailbraking allows you to use less steering as well as getting the rear tires to rotate the car thereby bending all four tires at once. Just using the steering wheel on entry as well as mid corner bends the tire rapidly and snap you go past maximum slip. This also brings about a tendency to wind on more lock to overcome the intial sometimes near undetectable understeer, once the fronts do grip they're  turned more then they need to be and that leads to the car essentially being chucked into a corner, which of course leads to a brief bit of oversteer. So you end up scrubbing speed on corner entry then a bit more transition from entry to mid corner.

Hopefully all of the above makes sense; I know it may not be technically correct but again hopefully it provides a good visual for the mind's eye.

snailmont5oh
snailmont5oh Dork
11/25/18 5:05 p.m.
Strizzo said:

I used to hoon an f150, you learn weight transfer, trail braking and steering with throttle, or you end up in the ditch.

I grew up driving mid 70s full-sized Fords, and a '70 F100 2wd. My first 4wd was an '86 F150 short-bed 6-cylinder/4-speed OD, with a fiberglass cap (read: 350 pounds as high on the chassis as you can get it).  On anything but dry pavement, that truck *would not turn* unless you transferred weight to the front tires first. 

In 2wd, you would let off the throttle and turn the wheel, which would cause the back end to come around. I would let the truck rotate a little, then add some oppo and feather the throttle to manage the drift angle, which I preferred to be "pointed down the next straight".

4wd was where things got interesting. Hold on to the throttle for at least a second longer than would cause death in 2wd. Pop off throttle, and when the nose *slammed* down, turn the wheel. Truck pivots around a point about a foot behind the driver, in the centerline of the truck. Allow pivoting to continue until truck is pointed down the next straight, then snap the wheel straight, and kick the throttle to the floor as hard as possible. Truck then continues to slide sideways around the turn, and, by some sort of magic, when there's road in front of it, shoots off in that direction. 

This was the truck that, on a wet 2-lane road, would do a Dukes of Hazzard style bootlegger turn, using only the service brakes, without leaving the pavement. Push clutch, put in a *lot* of brake, turn wheel, pop clutch, throttle up, gone. Fun truck. 

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