Term understanding...
#11
Originally Posted by EBMCS03' post='248955' date='Mar 2 2006, 07:10 PM
And on the DB9 note... I think it was a SMG type gearbox wasnt it? so thats why he said whatever he said...
Oh and not just the M5 Rev matches... regular cheapie production SMGs rev match too.
Oh and not just the M5 Rev matches... regular cheapie production SMGs rev match too.
Yeah, rev-matching on downshifts was one of the cool features of SMG when it first came out. Now, I'm not so sure ...
After all, rev-matching can be found on lots of slushboxes ... even a cheapie auto gearbox in the Infinit G35 rev-matches on downshifts (does it pretty well too).
#12
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Originally Posted by ipse dixit' post='248989' date='Mar 2 2006, 10:54 PM
After all, rev-matching can be found on lots of slushboxes ... even a cheapie auto gearbox in the Infinit G35 rev-matches on downshifts (does it pretty well too).
http://forums.e60.net/index.php?showtopic=22879
#13
Originally Posted by jet190rs' post='249007' date='Mar 2 2006, 08:21 PM
Dude! When I drove the Infiniti M35 and downshifted, the clutch was fried! :thumbsdown:
http://forums.e60.net/index.php?showtopic=22879
http://forums.e60.net/index.php?showtopic=22879
M35 =/= G35
I am not familiar with the transmission setup in the M.
#14
Originally Posted by sdente' post='248892' date='Mar 2 2006, 08:15 PM
You are all partialy right. Double clutching was a technique designed to enable smooth downshifts and prevent gear damage. Double clutching was and is used for downshifting cars with straight cut gears and no syncros. These days all street cars and almost all race cars have syncro transmissions so true double clutching is not required to protect the transmission. However, when driving at the limit of a car it is still neccesary to match the revolutions of the engine to the speed the wheels are turning in order to not upset the balance of the car when you engage the gear. You do this with the heel/toe method as follows.
1.) Begin braking
2.) Depress the clutch with your left foot
3.) While keeping the brake depressed with the toes of you right foot you use the heel of the right foot to depress the throttle (blip) so that the engine RPMs exceed the point you need to match the revs of the wheels. As you release the throttle you also release the clutch.
This results in a down shift that does not upset the car and puts no strain on the transmission.
When done right you will not feel the car speed up or slow down due to releasing the clutch. You will never be a quick driver until you master this technique.
I am always amazed by drivers who slam the car down a gear making lots of noise while using the engine to slow the car down. Engine and transmissions are expensive compared to brakes. Remember, the only reason you downshift is to ensure you are in the proper gear to accelerate after you are done braking.
Here is a link to a video that show Heel and Toe done properly
www.radicalmotorsport.com/gallery/mv_feet.mpg
Enjoy!!!!
1.) Begin braking
2.) Depress the clutch with your left foot
3.) While keeping the brake depressed with the toes of you right foot you use the heel of the right foot to depress the throttle (blip) so that the engine RPMs exceed the point you need to match the revs of the wheels. As you release the throttle you also release the clutch.
This results in a down shift that does not upset the car and puts no strain on the transmission.
When done right you will not feel the car speed up or slow down due to releasing the clutch. You will never be a quick driver until you master this technique.
I am always amazed by drivers who slam the car down a gear making lots of noise while using the engine to slow the car down. Engine and transmissions are expensive compared to brakes. Remember, the only reason you downshift is to ensure you are in the proper gear to accelerate after you are done braking.
Here is a link to a video that show Heel and Toe done properly
www.radicalmotorsport.com/gallery/mv_feet.mpg
Enjoy!!!!
DOUBLE DE-CLUTCHING IN AN AUTO!
The db9 has padles on the steering wheel that are connected to an automatic gearbox. Just like hobi did with it's modification for the steptronic. Using the padels is the same thing as you would use the stick in manual mode.
That's why i asked more how is it possible for an auto to double de-clutch? From what he describes, and from what i;ve seen and heared, my steptronic also "double de-clutches". If you're in a high gear at low rpms and you blip the throttle it will change down a gear, press it harder to reach the kick down it will change actually 2 gears. Then i find myself with a rev-matched engine/transmission. Is that correct? Is that what he ment? And if yes, what autos don't "double de-clutch" to say the aston's gearbox is so special and amaizing?
#15
Originally Posted by jet190rs' post='248985' date='Mar 2 2006, 10:49 PM
I guess its a British thing, or maybe just a Jeremy Clarkson thing...but he should've said it "blips the throttle" or "rev matches" or maybe even "heel and toe" instead of "double de-clutches". These are the correct terms in American English.
BTW, we also just say "double clutch" instead of "double de-clutch"
BTW, we also just say "double clutch" instead of "double de-clutch"
#16
Originally Posted by BetterMakeWay' post='249100' date='Mar 3 2006, 09:47 AM
That might be the explanation.
The other posts are right in that it simply allows the driver to bring the engine speed up (or down) to match the transmission speed for the gear that you are about to engage.
If you don't use this technique in a gearbox without synchromesh then you rip the gearbox to bits V.Quckly.
Heeling and toeing also matches to the revs of the engine / gearbox, so it is kind of the same, but it is also different in that it allows you to change gear WITHOUT using the clutch at all (like in rally cars and fast motorbikes) - I used to while away many happy hours practising this in my manual coupe.
What Clarkson meant was that the DB9's gearbox was clever enough to replicate the effect of heeling and toeing and I believe he called it double de-clutching cause he is a proper old fashioned brit.
#17
Originally Posted by needforspeed' post='249104' date='Mar 3 2006, 05:03 AM
What Clarkson meant was that the DB9's gearbox was clever enough to replicate the effect of heeling and toeing and I believe he called it double de-clutching cause he is a proper old fashioned brit.
#18
Originally Posted by BetterMakeWay' post='249128' date='Mar 3 2006, 10:43 AM
Yes...and i ask again: what auto desn't do that now? My steptronic also does that. Why did he say that gearbox is so special? Maybe because he said that the sequential gearbox in the vanquish is rubbish and it doesn't work and it brakes all the time.
http://www.triumphspitfire.com/healtoe.html
If you heal and toe right you don't need to use the clutch (try it next time you have a hire car).
"The DB9 is one of the first cars in the world to use a shift-by-wire automatic gearchange. The conventional PRNDL gear lever has been replaced by a system of buttons that select park, reverse, drive or neutral.
"It's easy to use and gets rid of the clutter associated with the automatic gear lever on the centre console," says David King.
Those choosing the ZF automatic can drive the car in full auto mode, or can change gear manually using the paddle shifts. The paddles are made from lightweight magnesium and are directly behind the steering wheel, at the 10-to-two position. They allow instant Touchtronic gearchanging."[color=#FF0000]
I THINK the shift-by-wire technology means that the gearbox actually has a clutch (just like a manual) and not a torque convertor and that the gear changes are initiated electronically.
The 7 series gearbox is also 'shift-by-wire'.
#19
Very informative discussion. Bravo to all!.
I have little input on this because i am an automatic 'addict' (I encounter too many traffics light daily)
That is all i have to say about that.
I have little input on this because i am an automatic 'addict' (I encounter too many traffics light daily)
That is all i have to say about that.
#20
I need to have some terms made clear for me..
What is "depressing the clutch"? Is it the "pushing your feet down" thing?
What's engaging/disengaging the clutch? Hell I know what they mean but I'm not that sure about which is what
One more question: In the video the link which sdente provided, why doesn't the driver umm... depress the clutch in order to upshift?
Thank you
What is "depressing the clutch"? Is it the "pushing your feet down" thing?
What's engaging/disengaging the clutch? Hell I know what they mean but I'm not that sure about which is what
One more question: In the video the link which sdente provided, why doesn't the driver umm... depress the clutch in order to upshift?
Thank you