Mike in CA

Are you saying with Active Rev Matching on the Corvette that you keep your foot to the floor when upshifting, and the computer compensates? Since there is only one clutch involved, to rev match an upshift it seems it would have to interrupt power flow to blip the throttle or whatever it does. With PDK, in milliseconds, I can downshift or upshift all the way to redline without taking my foot off the gas and there is no interruption in power. If Active Rev Matching can't do that, I see little advantage to it on an upshift.

chuckbdc

Other than regulating clutch slip against traction for launch control, and requiring first to fourth shifts at certain throttle positions, I don't think there is computer involvement in Corvette 6 peed manual transmissions. If there is I sure would like to see some citation about how it works.

According to the discussion at vet forums, active rev management will be available on the C7 7 speed, apparently working like the Nissan Z car, blipping the throttle to match engine rotation the rotation of the lower gear on downshifting. Sounds similar to the 991 MT solution.

jumper5836

we'll have to see.

Mike in CA

According to several sources I found, ARM actually does do something on upshifts, unlike the 991. ARM works by monitoring the operation of the shift lever and the clutch, and adjusts engine speed to match a calibrated value. On downshifts, ARM will increase engine speed before the clutch is engaged, just as a competent driver would do when rev matching.

On upshifts, ARM will decrease engine speed before the clutch is engaged. This might help smooth shifts for inexperienced drivers, but sure doesn't seem consistent with increased performance and foot to the floor power shifting. To me, the upshift part of the feature seems like an unnecessary gimmick and is probably why neither Nissan or Porsche saw fit to include it.

chuckbdc

Do you have a url for ARM? I could not find one that was about manual trans only for automatic vetoes.

I did find a great vid of clutch work by the guy who now is the ace Porsche test driver:

Mike in CA

If you google "how does corvette active rev matching work" you'll find a number of links that talk about it to a greater or lesser degree. Here's the link where I got the description I posted above:

http://gmauthority.com/blog/2012/12/...functionality/

Walter Rohrl is awesome.....

jumper5836

The cobalt SS has NLS. It is probaly more like it.

oldman40

great point chuckbdc!

on that note...another interesting aspect of the vette/911 intertwined history: the 1965 corvette coupe ran about $4100 base msrp. the same model year 911ran about $6500. if you convert those into 2012 dollars, it's about 30k for the vette and 47k for the 911.

basically both base model vehicles now cost about twice as much as back then, inflation adjusted. what this means is--forget about on the race track--pricewise, both have kept pace with each other quite proportionately. hence contrary to popular opinion, and despite the perceived "salt of the earth" followers of the vette, both manufacturers have driven up the cost and pricepoint of their flagship sports car in a very equal way. whatever differences in performance, luxury, or branding you may perceive, it isn't because one company has under- or over-priced the other to achieve this.

so both the vette and 911 remain highly capable. not surprising, because we, the buyers, are paying dearly for it. so what attracts us to these supercars? i don't think it's just the engineering, the interior design, or the cupholders! the difference is the differing visions of gm and pag's notion of the "best" sports car they can possibly put out there for their faithful followers and to attract new generations of fans. it's the ideal that we are ultimately attracted to--- each and every one of you has been targeted by gm and pag. most of us fall into one camp or the other, some into both. fwiw.

chuckbdc

Poking around I found discussions of NLS or "no lift shift", in Vettes and Camaros. It seems to be a software based engine control so that the car won't hit the limiter and loose power (or boost) if it is short shifted (eg shifted just below the limit) and the peddle is kept to metal.

If so, it is the Vette transmissions heavy duty synchronizers that are doing the rev matching. That is quite different than rev matching where software controls rotating parts to match engine output shaft speeds to gears rotating in the transmission. The Porsche MT transaxle synchros provide the same function, but I would not bet they are as rugged as the ones in the Vette (or older muscle cars where drag racers always flat shifted), and while it could be flat shifted (not the same as "short shifted"), it would be far more likely to scramble its parts.

PDK is totally different mechanically- and so apparently will be the MT in the C7, which will do actual rev matching.

PS: At cars and coffee this morning the sentiment of the Vette folks (the ones that matter to GM are not Porsche enthusiasts) was that they liked it a lot, were happy to see the technical advances. Some were "convinced" ie, hoped, that the rear end looked better than the pictures. One guy, pointing to a 458, told me he would order his without contrasting colors so it would break up the big butt look, just like the Ferrari.

holminator

Dang this discussion is good now. I can't even figure out or have motivation to make a smart *** remark. Thanks!

LastMezger

They have a lot to be happy about:

-all aluminum frame
-carbon body panels and floor
-VVT and cylinder deactivation
-rev matching
-6-piston front brakes
-standard Michelin super sports
-improved interior...if not world class
-optional track buckets
-450+ HP
-roughly $60,000

And the styling is definitely eye catching

fast1

According to several sources I found, ARM actually does do something on upshifts, unlike the 991. ARM works by monitoring the operation of the shift lever and the clutch, and adjusts engine speed to match a calibrated value.

It seems to me that GM came up with a solution to a problem that doesn't exist. The problem is to keep the revs at the appproriate levels on downshifts; most everyone uses heel and toe to accomplish that but now there are a few companies that offer an option to do that automatically. On upshifts the revs are going to drop substantially, so I have a hard time understanding how anyone would need help when the revs drop. Of course if someone is power shifting and fails to engage a gear, the rev limiter will come to the rescue.

chuckbdc

I could find nothing at all called ARM on existing Vettes. What were the URLs for the sources you reference?

I found discussions of "NLS "no lift shift- folks trying to understand what it was about. As I understood the discussion at a Vette forum, that has nothing to do with rev matching, but to keep revs - and blower pressures- at some optimum when shifting near the top of each gear.

The press release and tech discussions for the C7 talk about auto rev matching for downshifts.

Mike in CA

From Cool Hand Luke, "What we have here is a failure to communicate." Chuck, I'm not sure if you're referring to fast1's comment which quotes my post, or my original post on the subject so pardon me if this is redundant or unnecessary. To clarify, my statement about finding references to ARM was only with respect to the 2014 Corvette, not previous models. To the best of my knowledge, ARM is available only with the new 7sp MT and didn't exist on previous Corvettes. My interpretation is that ARM is not the same thing as NLS.

Beyond that, the question seems to be whether ARM works on both upshifts and downshifts. I posted one link above that says it does. Here it is again:

http://gmauthority.com/blog/2012/12/...functionality/

Also from Autoweek:

http://www.autoweek.com/article/2013...ROIT/130119927

And this from Chevy: (the ARM info is found under "Engineering" and "7-Speed Manual Transmission")

http://www.chevrolet.com/new-2014-corvette/

chuckbdc

Well here is the official - and I think ambiguous - answer to that question (sans flat shifting, pre C7 technology and other diversions):

"An all-new 7-speed transmission complements the LT1 V8 powerhouse that propels Stingray. Rear transaxle location enables an ideal 50/50 vehicle weight balance. Intelligent sensors anticipate gear selections and match engine speed for smooth transitions during both upshifts and downshifts. Active Rev Match unencumbers the driving experience by simulating a heel-toe shifting method automatically."

That should settle the issue, right? Uhm.