Why is rev matching an on/off situation
07-28-2013, 02:14 AM
#41
Le Mans Master
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Yep! I didn't ever want to change the clutch on my C5. Rev matching reduces wear and tear on the entire driveline. And the guaranteed smooth engagement will be the icing on the cake.
07-28-2013, 03:16 AM
#42
Le Mans Master
The suggestion was that heroic heel-and-toeing makes the rev match feature unnecessary. It also makes synchronizers unnecessary.
07-28-2013, 07:12 AM
#44
Pro
I have a 2012 GS A6 with paddles. It rev matches and works just fine. GM has had this technology for at least that long and it works great.
They are just adding the feature I have to the manual clutch C7's.
They are just adding the feature I have to the manual clutch C7's.
07-28-2013, 07:21 AM
#45
Safety Car
This is incorrect. The blip is not the computer guessing what the engine should be at or simply jabbing the throttle. It's matching the transmissions output speed to the input speed by setting the engine's RPMs to the correct speed that corresponds to the desired gear. Essentially perfect shiftting.
If you put the shifter in a gate and hold the clutch in while you're at speed, the engine will maintain the correct RPM until you let out the clutch. As the vehicle speed slow while coasting, the engine RPMs will continue to match the expected input speed on the transmission.
Nissan engineers explained that automatic rev matching indeed saves the life of the syncros and the driveline as a whole. The GM version isn't different than the Nissan version.
The engine matching the expected input speed prevents the need for the syncros to crash or spin up/down as fast. The gears mesh without the syncros working (or working hard).
If you put the shifter in a gate and hold the clutch in while you're at speed, the engine will maintain the correct RPM until you let out the clutch. As the vehicle speed slow while coasting, the engine RPMs will continue to match the expected input speed on the transmission.
Nissan engineers explained that automatic rev matching indeed saves the life of the syncros and the driveline as a whole. The GM version isn't different than the Nissan version.
The engine matching the expected input speed prevents the need for the syncros to crash or spin up/down as fast. The gears mesh without the syncros working (or working hard).
07-28-2013, 08:16 AM
#47
Le Mans Master
The two largests benefits are as stated, wear on the transmission and synchros. But also further enhancement of fuel economy. The engine will use more fuel to 'build back' the rpm after a shift. Rev matching makes this process much more efficient, thus saving fuel. It seems to me, that it's real benefit is providing a more efficient, comfortable driving experience in the daily commute as well, those times when many don't really want to heel-toe. Just my thoughts anyways.
07-28-2013, 11:29 AM
#49
Safety Car
I would have to agree that this is probably one of the main reasons it's on there. While rev matching is certainly a good selling point to auto-x ers and trackers that are not inclined to heel-toe, rev matching does more than enhance driving skills.
The two largests benefits are as stated, wear on the transmission and synchros. But also further enhancement of fuel economy. The engine will use more fuel to 'build back' the rpm after a shift. Rev matching makes this process much more efficient, thus saving fuel. It seems to me, that it's real benefit is providing a more efficient, comfortable driving experience in the daily commute as well, those times when many don't really want to heel-toe. Just my thoughts anyways.
The two largests benefits are as stated, wear on the transmission and synchros. But also further enhancement of fuel economy. The engine will use more fuel to 'build back' the rpm after a shift. Rev matching makes this process much more efficient, thus saving fuel. It seems to me, that it's real benefit is providing a more efficient, comfortable driving experience in the daily commute as well, those times when many don't really want to heel-toe. Just my thoughts anyways.
07-28-2013, 11:40 AM
#50
Le Mans Master
07-28-2013, 11:40 AM
#51
Burning Brakes
"Gimmick" to me implies that there is no practical use for it. There is certainly a use for rev matching.
GM still sells nearly have of their Corvettes with a manual last I heard (45% as of a couple years ago on the C6).
As long as they keep selling manuals anywhere remotely that often, they will not stop offering them... Although I suppose it's possible that manuals start selling so poorly in other cars that they can no longer re-use the manual from the Vette in other cars, which may at least raise the price of the Corvette's stick.
As long as they keep selling manuals anywhere remotely that often, they will not stop offering them... Although I suppose it's possible that manuals start selling so poorly in other cars that they can no longer re-use the manual from the Vette in other cars, which may at least raise the price of the Corvette's stick.
07-28-2013, 02:51 PM
#52
16 Vettes and counting…..
I seriously doubt that manually shifting an auto via paddles is the same technology.
07-28-2013, 03:00 PM
#53
Le Mans Master
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"Gimmick" to me implies that there is no practical use for it. There is certainly a use for rev matching.
GM still sells nearly have of their Corvettes with a manual last I heard (45% as of a couple years ago on the C6).
As long as they keep selling manuals anywhere remotely that often, they will not stop offering them... Although I suppose it's possible that manuals start selling so poorly in other cars that they can no longer re-use the manual from the Vette in other cars, which may at least raise the price of the Corvette's stick.
GM still sells nearly have of their Corvettes with a manual last I heard (45% as of a couple years ago on the C6).
As long as they keep selling manuals anywhere remotely that often, they will not stop offering them... Although I suppose it's possible that manuals start selling so poorly in other cars that they can no longer re-use the manual from the Vette in other cars, which may at least raise the price of the Corvette's stick.
The number fell to less than 10% manual.
In 2009 Ferrari made the California with the new DCT and no manuals as an option for the first time. The Tifosi were outraged. So, in the second year, they made a manual possible.
They sold 2.
Then it went to 0% manual with the 458, much to the displeasure of the 6-10% of the buyers out there that still wanted manuals.
They still have about a one year waiting list 3 years into production.
Whenever the DCT is introduced, a large percentage of manual owners give it up in favor of the DCT. Those are real historical numbers.
It's not the manufacturers who are driving this. It's owners. The many complaints from people on this forum about a lack of DCT in the C7 proves it.
Last edited by Sin City; 07-28-2013 at 03:03 PM.
07-28-2013, 03:55 PM
#55
Le Mans Master
For instance, if you are in 3rd gear and push the clutch pedal in at 20 MPH and let the engine come to an idle, you can put the transmission into 1st gear without any grinding, so the syncos did their job.
Likewise, if you are going 60 MPH is 4th gear and you push the clutch in and coast for 10 seconds with the engine at idle, you can easily shift to 6th gear with no gear grinding. You don't need to "double clutch" if the syncros are working right. Of course you would want to rev the engine back up some to "rev match" the speed of the transmission input shaft so the clutch engagement is nice and smooth ... this is what "rev matching" is all about.
07-28-2013, 04:28 PM
#56
Le Mans Master
Reliance on the synchros to work miracles is also why on most used sports cars they're completely trashed.
07-28-2013, 06:18 PM
#57
Team Owner
better question, why are the on/off switches separate and in such a weird location?
07-28-2013, 06:19 PM
#58
Le Mans Master
I Love how some of the folks can get so easily derailed from one little word and go completely off topic in debate over the most insignificant detail.
Okay, rev match is not designed to save the synchros. However, the synchros job is bring the input shaft to engine speed during gear change. Now if rev match brings engine speed to the desired rpm, this makes the synchros job easier, right? So rev matching saving the synchros from wear might be overstated as a benefit, maybe more a side effect.
Okay, enough tunnel vision of the insignificant. Carry on.
Okay, rev match is not designed to save the synchros. However, the synchros job is bring the input shaft to engine speed during gear change. Now if rev match brings engine speed to the desired rpm, this makes the synchros job easier, right? So rev matching saving the synchros from wear might be overstated as a benefit, maybe more a side effect.
Okay, enough tunnel vision of the insignificant. Carry on.
07-28-2013, 06:39 PM
#59
Safety Car
I Love how some of the folks can get so easily derailed from one little word and go completely off topic in debate over the most insignificant detail.
Okay, rev match is not designed to save the synchros. However, the synchros job is bring the input shaft to engine speed during gear change. Now if rev match brings engine speed to the desired rpm, this makes the synchros job easier, right? So rev matching saving the synchros from wear might be overstated as a benefit, maybe more a side effect.
Okay, enough tunnel vision of the insignificant. Carry on.
Okay, rev match is not designed to save the synchros. However, the synchros job is bring the input shaft to engine speed during gear change. Now if rev match brings engine speed to the desired rpm, this makes the synchros job easier, right? So rev matching saving the synchros from wear might be overstated as a benefit, maybe more a side effect.
Okay, enough tunnel vision of the insignificant. Carry on.
07-28-2013, 06:50 PM
#60
Le Mans Master
Without double-clutching, the engine isn't even involved. Only if you blip the throttle in neutral with the clutch engaged (i.e. foot off pedal) can the engine alter the speed of the input shaft to match the destination gear.
If the system only blips the throttle when your foot is on the clutch, that doesn't do a thing for the synchros one way or the other.