Heel-toe down shifting

gomezliberty · Post by **gomezliberty** » Tue Apr 22, 2008 6:16 pm

hey
is heel-toe downshifting really worth learning? what are your ideas?

theclick · Post by **theclick** » Tue Apr 22, 2008 6:19 pm

ehh. Learn it if you wish, its not that difficult. gives you more control over your breaking, and i assume it would save your clutch a bit. If for racing, I would learn it for sure... but for road driving its not necessary.

BrennyV · Post by **BrennyV** » Tue Apr 22, 2008 6:21 pm

for what aplication?
for daily driving ur crazy

its only of use when ur doing track/race days

gomezliberty · Post by **gomezliberty** » Tue Apr 22, 2008 6:23 pm

haha just for daily driving i dont race or anythign although id like to
i just thought it would be intereseting to try/a cool trick

BrennyV · Post by **BrennyV** » Tue Apr 22, 2008 6:30 pm

you could look into it, just be sure not to try it in traffic and work your way into it as i can see it as a distraction with everyday driving.

rtcb65 · Post by **rtcb65** » Tue Apr 22, 2008 6:42 pm

I do it most of the time in ever day driving, I do it to keep practice . And i believe it does help out the clutch wear . I just replaced my clutch and the pressure plate was soft and the plate was only half worn. To give you an idea , the clutch was 6 years old . The heal toe has come in handy for me over the years. If for some reason the engine wont idle, and you come to a set of lights that are red, how do you keep the revs up to stop the engine from dieing and hold the clutch in and apply the brake.

mattims · Post by **mattims** » Tue Apr 22, 2008 8:26 pm

yep ..very handy to be able to do on cars with either no synchros left or that wont idle by themselves (or both at the same time for extra fun). But if your car is running alright i doubt there would be much difference.

bluesteel · Post by **bluesteel** » Tue Apr 22, 2008 8:55 pm

yeah really handy if you snap a clutch cable or bust a hydralic line too

AndrewT · Post by **AndrewT** » Tue Apr 22, 2008 9:59 pm

I do it all the time in everyday driving, mostly only when I'm driving "with vigor" tho (which is fairly often). I find matching the engine revs by blipping the accellerator while double clutching under braking before downshifting makes it go into gear much easier and should ultimately save the synchros if you can get the technique right.

mattims · Post by **mattims** » Tue Apr 22, 2008 10:10 pm

i do it most of the time (either that or not use the clutch at all).. but only because my L series wouldn't go into gear any other way and its the first car i learnt to drive on.

its a bit of a joke in the b4 .. synchros are so good it drops into gear before your done double clutching or rev matching.

Goon · Post by **Goon** » Wed Apr 23, 2008 6:25 am

Currently doing my HR training atm, so double clutching is important, mind you it would be a whole lot easier if the truck was less than 20 years old!!! Lookout north brissie, just missed a gear!!!!!!!!!

ToyRX · Post by **ToyRX** » Wed Apr 23, 2008 8:18 am

Blipping the throttle on downchange achieves two main advantages that I am aware of.

1) Saves the gear, particuarly for high rev change downs. Most people dont realise it but typical Subi syncro failure is due to the loading applied during these high rev change downs, not the fast upchanges. Secoundly it is kinder on the clutch.

2) In turbo cars it helps keep the boost up during change downs by keeping the gas flow going, no idea on N/A though.

discopotato03 · Post by **discopotato03** » Wed Apr 23, 2008 11:08 am

It's not just FHI gearboxes , it's ALL syncromesh gearboxes .

The facts of life are that production syncro gearboxes are just not designed for competition driving . In a pure race mechanical system constant mesh dog boxes rule supreme .

Production road cars are not intended to be driven flat out so the gear spacings are wider for relaxed low med rev use and the enines power curve is based on a broad spread of torque and limited top end .

There are no half way methods of being even halfway seriously competitive with a std engine and box - or much else unless a class rule bans mods .

Most people fall into the trap of thinking that factory syncromesh is inadequate and failure prone over time . The truth of the matter is that lots of innertia in things like heavy flywheels and gears retard the engines and part of the gearboxes deceleration between changes and the more so the higher up the rev range you go .
Also you often find that emission control devices bleed air into the engine in off throttle situations because you get a momentary rich spike if the throttly closes rapidly without them .
Result ? Engine lazily slowing down and your shift hand leaning harder on the poor little baulk ring that's trying to slow down the gear train via the gears cone friction .

One of the first things you can do to help the situation is the lighten the flywheel which reduces the ENGINES revolving innertia . Against no load the engine will rev more freely and importantly will decelerate noticably faster .
Secondly (provided you never drive your car on a public road of course) back off that stupid throttle damper device so the throttle can close quickly on EFI engines .
Thirdly , use a close ratio gearbox because the rev drop between gears is less so they don't have to fall as far to engage the next gear .

Heel toeing is a bit rich on the street I think , if your corner entry speeds are that high I'm sure the constabulary would be interested in being present ...
If you want to drive spiritedly in a car or properly in a truck the aim IMO is to be in the right gear so that the engine is in the most useful part of its power range to suit the situation at the time .
My method with an 18 spd Road Ranger say approaching a tight bend is to slow down with brakes double de clutching down the box until the speed is safe and the engine is in a speed range where when I nail it the engine comes on boost and delivers sufficient torque to accelerate away if need be .
If I was driving EllieRX its similar deal though engine braking combined with being in the right gear/rev range is a lot easier because the power to weight ratio is a lot higher , the weight less and its not as top heavy as a 6WD 24T truck .
I don't rally or race but if bearing down on a tight bend doing warp 9 you'd have to wash off a lot of speed in as short a distance as possible . You'd expect to have a lot of forward weight transfer so setting up for the corner would be critical to be quick and not lethal .
If you can have a look at the in car film of Walter Rohl going balistic in the Group B Audi Quatro AWD turbo rally car , like Subaru's these were front heavy (more so with the inline 5 a long way forward in the car) . His foot action looked more like a pianist than a driver with lots of left foot braking plus the works Audi's also had a means of declutching by button - if the limit of two feet were busy with other pedals .

If into rally history get a copy of "Too Fast To Race" which is about the group B super car era . This was pretty much at the beginning of the 4WD Turbo era where to be successful the driver and the machine had to be something else .
Also there is a short 3-4 minute video called Climb Dance wich is of Ari Vatenin blasting up Pikes Peak in a tissue weight 500 Hp AWD 205 T16 .

Mind warping stuff , cheers A .

BrennyV · Post by **BrennyV** » Wed Apr 23, 2008 11:22 am

on the topic of the Audi Quattro Grp B rally car.
watch this!! my fave clip of what i think is one of the best rally cars eva built!

http://youtube.com/watch?v=FV9lFCGtwMU

Ben · Post by **Ben** » Wed Apr 23, 2008 8:20 pm

I was taught that double clutching damages synchro gearboxes as it doesn't allow them to do what they are engineered for. Non synchro boxes though, different story.

And anyone that taps the throttle with their foot on the clutch is a tool...

Ben · Post by **Ben** » Wed Apr 23, 2008 8:26 pm

discopotato03 wrote: If you can have a look at the in car film of Walter Rohl going balistic in the Group B Audi Quatro AWD turbo rally car , like Subaru's these were front heavy (more so with the inline 5 a long way forward in the car) . His foot action looked more like a pianist than a driver with lots of left foot braking plus the works Audi's also had a means of declutching by button - if the limit of two feet were busy with other pedals .

The man is a machine and the spectators are NUTS!

http://www.youtube.com/watch?v=Ts29KKhKXds

discopotato03 · Post by **discopotato03** » Wed Apr 23, 2008 11:15 pm

No he's not a machine , the machine itself is a Group B Aud Quatro Sport which was the shortened version of the Original Quatro . The man is Walter Rohl and yes he can dance on the pedals .

The spectators were nut cases and deaths amongst them and some of the crews were supposedly why Group B was banned , as the doco I mentioned before states in it's title - Too Fast To Race - the risks were thought to be too great . Manufacturers like Lancia pulled out of the sport because bad PR hurts sales .

The rally class that followed was FIA group A and then to WRC or World Rally Car . With constant development WRC cars are now faster point to point than the Group B cars .

As for the Quatro , it was a pretty wild thing and very difficult to drive competitively . Its AWD system was crude and agricultural by todays standards but more than a match for anything when it first appeared . Most of its problem was the long in line 5 cylinder engine set mainly over the front wheels - very front heavy .
Peugeot ended up beating them with their 205 T16 which was lighter , more nimble and had much more even weight distribution .

Lastly double declutching a syncro box won't hurt it if you do it properly , if the speed difference of the selected gear and coupling sleeve is reduced the cone clutch isn't working as hard so engagement is a little quicker and the engine revs will be closer to where you want them when you release the clutch . Its only really necessary if you need a rapid down change or the baulk ring is worn out .

Cheers A .

AndrewT · Post by **AndrewT** » Thu Apr 24, 2008 12:09 am

It really is useful on the street in certain situations. I think I have good "mechanical sympathy" and I feel I can almost sense how much easier it is on the gearbox.
I should try and take some videos of taking the same corner with different downshifts, double clutching with a blip of the accelerator when the clutch is out in neutral really helps things along. It just has to be done correctly or I could see it causing damage.

dibs · Post by **dibs** » Thu Apr 24, 2008 6:49 am

when you learn that foget the clutch.i got trucks and rarly use the clutch .do it sometimes in the brumby .never in the forester (auto )..lololol

dibs

discopotato03 · Post by **discopotato03** » Thu Apr 24, 2008 9:46 am

I don't want to start arguments but I will say that changing any syncro box clutchless is hard on it wear and tear wise - if its synchromesh is in good condition .

The reason why is that the chamfered splines on the sides of the gears and inside the coupling sleeve are small and greater in number that the big chunky dove tailed "dogs" in a constant mesh dog box . Because they are chamfered to a small point they are easily burred if abused ie forced into engagement . If the front section of the gearbox is not unloaded (clutch disengaged) engine inertia easily beats the cone clutch (baulk ring) and the splines on the coupling sleeve/side of uncoupled gear grate past one another making that grinding noise .
Truck gearboxes are very different because the shafts and gears are larger (and heavier) to withstand the higher torque loadings of a bigger engine hauling more vehicle mass . Also big diesels operate over a much narrower rev range than petrol car engines so gearbox revolutions are usually a lot less .
The dog boxes need to be double declutched because they have no means of synchronizing their coupling sleeves and gears - other than innertia and an experienced driver . Plus the dogs being dove tailed to a degree pull themselves into mesh and stay in gear on drive and over run . The real trick with a big box like a Road Ranger is to not miss the rev/road speed "window of opportunity" because if you do its often difficult to make any gear engage - highly inconvienent to have to stop and start all over again .

OT but just in case you ever wondered how the pattern work on a Fuller Eaton 18 spd RR box imagine this .
They a not common these days but the Porsche pattern 5sp box has 1st to the left and back with 2-5 in the normal "H" pattern . The 18 spd RR is the same but 1st is really a crawler gear . On the gearstick you have an up/down flip switch which does the low/high range air shifted change over . So you go 1-5 in low range , flip the switch and go back across the gate fom where 4th to 1st would be in a H pattern 4spd . They only change ranges if the stick is moved across the neutral gate as well . So 12345 - flip - 6789 . These boxes have a splitter as well so you can split any of the 9 ratios up or down and that gets you the 18 speeds . Being fairly close ratio means you can keep Mr turbo diesel right in the meat of its torque curve , its also necessary in the truck I occasionally pedal because it redlines at ~ 1700 and pulls from ~ 900-1000 revs . The two speed transfer case has an open but lockable center diff , plus there's three cross axle diff locks and a power divider lock because its a bogie rear drive system . Like the L AWD system if any of its wheels (6) loses grip it sits and spins that wheel alone .

Some people pride themselves in driving trucks clutchless but the reality of the matter is that they can't be bothered pushing the clutch pedal . If you drove the same vehicle daily and over long distances it becomes easy to know its traits but if the driver is paying for transmission rebuilds he learns to look after it .

Your gearbox your money your call , A .