Quote:
Originally Posted by CrustyNoodle
Heel-toe is not just to sound good. There are 2 key reasons why you do it: - To make the lower gear easier to engage (so really it's more of a heel-toe+double clutch);
- Reduce the chance of rear tyres loosing traction due to compression braking.
I've never experienced the Nissan system but I'm guessing that it is more for the sound of it as well as reason 2 above - which is why it would make sense to switch it off if you wanted to change down properly without putting undue stress on the syncros.
The DCT definitely only does the blip for the second reason above as it pre-engages a lower gear before you even flick the paddle (or stick) hence reason 1 doesn't get a look in. |
I never said that heel/toe was just to "sound good".
Nissans tech is not designed for sounding good, it's designed to match engine revs during gear changes on down gear accel or decel.
When coming into a turn from speed you simply concentrate on braking, and it handles the rev match.
The only reason to shut it off is so that you can practice heel/toe.
Here's a good read for it:
http://www.caranddriver.com/features...ined-tech_dept
2 different things in your post, "rev matching" and "heel/toe". Heel/toe can be used to facilitate a rev match, but you don't need to heel/toe to make a lower gear engage easier, such as when accelerating using a lower gear from the higher gear you are in.
In that situation, you don't heel/toe, you match revs with throttle control/"blip".
I don't agree about what you propose as the 2 "key" reasons for rev matching, though those are 2 things helped by rev matching.
More importantly, imo, rev matching is to protect against drive line shock, and by virtue of that, it keeps the car smooth by not unsettling the chassis, for smoother handling, and reducing stress to the drive line. Avoiding compression braking is an important part of that, as you mention.
Rev matching is not done just for slowing down. It's also the proper way to execute acceleration when downshifting a couple of gears, such as for passing. By matching the revs to the lower gear, your car accelerates smoothly instead of bogging/dragging down the engine when engaging a lower gear to accelerate.
Nissans system does all this very nicely I might add.
You really should try it out, it's awesome.
Double clutching and heel/toe are not the same thing.
Dbl clutching is a technique used in old manuals that didn't have syncro's.
Double clutching is a technique to achieve rev-matching the transmission's *intermediate shaft* to the output gear that is to be selected.
In a modern manual trans we have syncros so we don't need to double clutch.
Heel/toe is a different technique by which to rev match engine speed to vehicle speed for a given gear, when you need to brake while at the same time changing to a lower gear.
The DCT, and all other dual clutch trannies, are programmed to do what a driver would do.
The system automatically performs rev matching on decel and accel, as I'm sure you're already aware.
It just does it faster and better than pretty much all drivers.
