Whats the difference between double de-clutching and simply matching the revs for the next lower gear?
My car does it for me :approve:
Double clutch is where you match the gearbox speed with the new gear rather than just matching the engine speed. Double de-clutch.... Who made that one up ?
Double clutch is where you match the gearbox speed with the new gear rather than just matching the engine speed. Double de-clutch.... Who made that one up ?
think about it in its literal sense?
you are de clutching twice-hence double de clutch
thats wot u need to do wen u drive trucks with twin splitter g/box'sI know I am new round here but I thought I would share my pedal pushing antics.
I ddc (double de clutch) 95% of my gear changes. I grew up watching my Father drive who had in turn watched HIS Father drive older non syncromesh gearbox's. The non syncromesh 'boxes were the reason for using ddc as the 'clutch up' extra rev allowed internal matching of gearbox shaft speeds before the gears meshed at the same/similar speed and this prevented crunching. It was used both up and down the box and if you ever see one of those old wagons on the way to a show, then have a listen as the driver ddc's up and down the box.
The very day I passed my test, I taught myself how to ddc and heel and toeing is the next natural step to follow ddc as the very first time you come to change down whilst braking, it feels like there is something not quite right.
Some people heel and toe using their foot on the brake pedal and their heel moving over to the throttle to blip the revs up to match the intended next gear speed. I am very lucky that my ankle is articulate enough to allow me to use the side of my foot to blip the throttle and this makes it a little easier.
The biggest 'thrill' about heel and toeing(h and t) is that you can not feel the gear change at all through the car. The plus side of this is that there is no jerk or slip passed to the driven wheels during a gear change and it is especially important in a RWD car as an incorrect change can cause the rear wheels to lock up and throw the car sideways.
The principal of ddc is
1 press down clutch
2 move gear lever into neutral
3 let clutch up
4 blip accelerator to the right revs of the lower gear
5 press down clutch
6 move gear lever to next lowest gear
7 let clutch up
PERFECT downchange !!
The hardest part is step 4 as it takes time and practice to get a feel for how much you should rev the car. Too much and you will sound like a bad boy at a McDonalds meet, not enough and the car will snatch on the downchange.
Get it bang on and a passenger with their eyes closed will not be able to feel the change at all-and you will have a little smile on your face.
The next step is heel and toeing. This combined with ddc allows you to carry out an absolutley perfect gearchange whilst braking for a corner.
Follow steps 1-7 above but this time whilst you are braking, allow the side of your foot(or heel) to carry out step 4. The hardest part of this is to not let your braking modulation change in the slightest as you press the throttle as this will unbalance the car. Try to be as consistent as possible and again after practice, the perfect gear change whilst under braking will be carried out.
The outside factors of the above are the pressing of the brake pedal. The initial press must be done very very gently( to settle the nose of the car and reduce weight transfer-thus reducing rear end lift and potential oversteer) and from then on progessively harder until just before the apex of the bend upon which the brake pedal must be released slowly to avoid unsettling the car again.
If you are really cheeky and have a fast reving engine and a quick foot, it is possible to add an extra little blip to the very last phase of step 7-this is really showboating, but it sounds ace!!!
After all the time it took me to write the above, ddc really does not have a place in a modern day motor as the synchros take away the need for its use.
A simple blip like this..
1 press down clutch
2 move gear lever to next lowest gear
3 Just before lifting up the clutch press the throttle to match the revs of that lower gear
4 PERFECT gear change
Now re read above and add heel and toeing to this system and you are sorted!-although you cant 'cheeky blip' on this method-lol
The last one is 'sustained change'
1 driving along a normal peice of flat road in a high gear.
2 suddenly the need to move quicker happens
3 leave throttle position EXACTLY as it was
4 Using either the above ddc method or a standard shift move the gear lever to the next lowest gear.
5 listen as the gear slots home perfectly for a PERFECT downchange
The above method is very very old school and I believe is still taught by the police driver training unit, but is also used by chauffers and the like for a seemless almost automatic feel to a downchange.
Sorry for being so anal about all of this but it is something that I have practised all my driving life (22 years) and I still count the amount of imperfect changes I make on a short trip--1 or 2 at the most:clown:....
When you are pressing on, especially on a track, there is no better way of smoothing a change using the heel and toe method. When racing there is absolutely no point in wasting precious time in ddc but matching your revs on a downchange will save you money on driveline components, make your car a lot smoother and of course sound better
Next time you go to watch clubman racing, choose a downhill tight bend and listen to the amount of racers that actually match their revs between gears. The ones that dont, will leave a little black mark on the circuit and their cars will be shuddering as the drive train tries in vain to catch up different rotational speeds.
The other thing that is possible to do, is whislt braking in a turbocharged car, use the same principle of heel and toeing to keep the revs up. So for example brake hard but at the same time use the side of your foot to keep the revs up-it is similar to left foot braking(which I am not going to go into as my fingers are tired) but without the need to use the left foot as an extended handbrake-thus keeping the turbo on the boil and the car smooth!
People that can afford cars that blip the engine automatically between downchanges are very very lucky(and I hope that is me one day) but ultimately they are missing out on a little driving pleasure!!
Cheers
FE.
i dont see the point in normal driving, also double clutching has to be the slowest wat to change gear, it just makes no sence to me.
dont understand any of this wot dus blip mean
The whole point of this thread is education.
No one 'has' to heel and toe or double de clutch.
If you understand how to do either or BOTH then you are enhancing your options as a driver.
Heel and toeing IS THE MOST EFFECTIVE WAY of changing down a gear smoothly with a modern gearbox whilst braking FACT!-unless software and solenoids are doing it for you.
Simply changing down and dropping the clutch is a very brutal way of gear changing and can cause upset to a cars balance(especially under braking)
Like I said in my first post, have a listen to anyone that has studied or enjoys driving or a decent trackday/racing driver, and they will all match the speed of their engine to the speed of the next gear down to be selected.
Its not about sounding good or drawing attention to yourself or messing about, its about knowing you have perfected the smoothest way to change gear.
Smooth is everything when driving a car-and the faster you go, the smoother you must be!:approve:
to make the change smoother by matching the free revs with the revs of the next, lower engaged gear??
Ive started doing this as I think its better for the clutch and puts less stress on the synchro mesh. Am I right??
The whole point of this thread is education.
No one 'has' to heel and toe or double de clutch.
If you understand how to do either or BOTH then you are enhancing your options as a driver.
Heel and toeing IS THE MOST EFFECTIVE WAY of changing down a gear smoothly with a modern gearbox whilst braking FACT!-unless software and solenoids are doing it for you.
Simply changing down and dropping the clutch is a very brutal way of gear changing and can cause upset to a cars balance(especially under braking)
Like I said in my first post, have a listen to anyone that has studied or enjoys driving or a decent trackday/racing driver, and they will all match the speed of their engine to the speed of the next gear down to be selected.
Its not about sounding good or drawing attention to yourself or messing about, its about knowing you have perfected the smoothest way to change gear.
Smooth is everything when driving a car-and the faster you go, the smoother you must be!:approve:
The whole point of this thread is education.
No one 'has' to heel and toe or double de clutch.
If you understand how to do either or BOTH then you are enhancing your options as a driver.
Heel and toeing IS THE MOST EFFECTIVE WAY of changing down a gear smoothly with a modern gearbox whilst braking FACT!-unless software and solenoids are doing it for you.
Simply changing down and dropping the clutch is a very brutal way of gear changing and can cause upset to a cars balance(especially under braking)
Like I said in my first post, have a listen to anyone that has studied or enjoys driving or a decent trackday/racing driver, and they will all match the speed of their engine to the speed of the next gear down to be selected.
Its not about sounding good or drawing attention to yourself or messing about, its about knowing you have perfected the smoothest way to change gear.
Smooth is everything when driving a car-and the faster you go, the smoother you must be!:approve:
look who the original post is by........ its so he can get to the tanning salon quicker! .
Sorry lusty.:star:
I can do it with my road car, but cant do it for the life of me on my rally car.
Think it is a combination of pedal placement, pedal height, the gearbox and concentrating on not hitting anything that screws it up
Plus you cant just blip that engine, you have to give it a good prod.
i think we need some threads explaining how to do this and doube declutching for the weaker drivers amongst us lol
dont understand any of this wot dus blip mean
jeez, four pages of detailed explanation, and you type 'wot dus blip mean'.
g
Not weaker drivers-everyone drives differentlyi think we need some threads explaining how to do this and doube declutching for the weaker drivers amongst us lol