May 16, 2013 at 9:20 pm #41662
Looks like a great car but why do American car manufacturers persist in installing 6 speed manual gearboxes which are in effect 4 speeds as 4th gear is 1 to 1. I know the rear end ratio is 3.91 but surely a car intended for track use would have benefited from 5th being 1 to 1 and 6th being .85 or close. Thoughts anyone?
May 17, 2013 at 9:14 am #41668
GM Authority StaffModerator
Well, the new Corvette C7 has a 7-speed manual… and Hyundai has a six-speed in the Genesis Coupe, as does VW in the Golf R, Subaru in the WRX/STI, and Audi in all S models availbale with a manual gearbox. Hence, it’s not just Americans that offer up six-speed sticks in their performance offerings.
I don’t see this as a problem at all… heck, how often does one shift above fifth on a track anyway?
May 19, 2013 at 12:53 am #41716
Alex you missed my point. Many other manufacturers do indeed offer 6 and now 7 speed manuals in their sports models. Lets run through some of the cars you mentioned: Genesis Coupe, 5th is 1-1. VW Golf, 5th is 1.110. My point is that GM are marketing this as a track orientated performance car. Closer ratio gears allow maximum acceleration. The Tremec TR6060 in the Z28 has a.74 5th and a .50 6th which are unusable unless you happened to be at Daytona. In a perfect world GM would have installed a twin clutch transmission with paddle shifters, I’m sure cost would prevent that though. As for the new C7 with a 7 speed, I believe 4th is still 1-1, they can’t be serious.
May 19, 2013 at 8:22 am #41717
The over drives and the multiple gears are what will keep a V8 and higher powered engines more viable longer. Hell anyone can sell a good old 4 speed today and most people would have no issue with it.
The fact is that the extra gears are what deliver the MPG in the more powerful engines by letting them run bigger gears and still letting them lumber down the road for the higher EPA and Emission numbers.
If there were no EPA numbers to meet and CAFE mandates by the government we all would just be fine with a 5 speed with on over drive gear.
Today you may want to note with most cars you drive they all lumber around 1600-1800 RPM down the highway. This is why GM puts in sound canceling in the Nox and a few there cars as the Ecotec has a drone at that RPM. It is a matter of meeting the RPM you need and then tailoring the gear box and car to meet it to get your numbers.
I have put enough skip shift removers in Corvettes so we do not have to deal with that. And most performance car I drive today I only see 5th and higher on the freeway.
June 5, 2013 at 6:37 pm #42677
GM Authority StaffModerator
Ultimately, if you’re having fun with a Z/28 or the Corvette on a track (road corse, not an oval), you’ll only be in 1-3 most of the time, in 4th some times, and very rarely in 5th. I still don’t see a problem…
August 26, 2013 at 11:17 am #46277
I used to have a 1985 Corvette with the Doug Nash 4+3 transmission. It had electronic overdrives on 2nd, 3rd, & 4th gears. It worked well on the street being if you came up on traffic you could manipulate speed without up or down shifting a gear using the clutch, you just pushed the botton on the shifter. I understand the writers concern for a manual tranny with more ratios greater than 1-1, and ultimately Alex your point of ratios which allow these Big V-8’s to run at drastically reduced rpms allowing great fuel economy serve the greatest number of owners. Of course if you really want to play you do what I did back in 1974. I slipped a completely blueprinted 1970 LT-1 engine into my ’68 Z/28. I pulled the tranny and installed a custom geared M-22 “rockcrusher” and a 3:88 12-bolt rear end. My LT-1 engine could pull 8,000 rpm. That combo allowed me to witness many dumbfounded expressions on several LS-6 Chevelles and Hemi or 440 Roadrunners as I walked away from them with my little 302 Z.
Here’s the specs on the Doug Nash 4+3 transmission 1984 thru 198888 Z51 cars are…* indicates the elect OD ratio:
1 : 2.88
2 : 1.91
2 : 1.30*
3 : 1.34
3 : 0.90*
4 : 1.00
4 : 0.68*
July 3, 2015 at 3:15 am #97259
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