emtmike

I was taking a patient to the hospital yesterday when I noticed one of the doctors drove his new Z06 to work. This may not seem to strange, but I live in NW Ohio, and not only do we have snow on the ground, but a ton of salt on the roads . Anyways, we were talking about our Z06's, and he was telling me that the 6st gear is governed, and that it dosen't go any faster than 5th gear . I wasen't going to volley with him in the ER, but it seemd sort of dumb that he would say that. He also said that the undercarriage is made of magnesium, and the floor boards are made of carbon fiber and that salt won't hurt it . I guess everybody has their own way of doing things . Does anybody have an answer?

Random84

There's been a tale going on about cars being "governed" for years. I don't know that a Z is speed-limited by anything more than aerodynamics, but the engine cradle is magnesium (the frame is aluminum), the floorboards are actually wood cores wrapped with carbon fiber and these things may in fact be resistant to corrosion...

but the chrome/paint/aluminum of his wheels aren't.



ETA: Oh, and a Z06's top speed is in 5th gear - but that's because 6th is numerically too weak to counteract the wind resistance at those speeds.

AzDave47

My local (AZ) Chevy dealer replaced the left Cat. recently. When they did the replacement they snapped off a bolt between the Cat. and the exhaust manifold, so they replaced that as well. They asked if it was and "eastern car" and I said yes, (bought used in VA). So they believed the bolt rusted, or that may have helped them get the new exhaust manifold covered under warranty.

Anyway, yes our cars have parts that rust, and they have other parts like carbon fiber front fenders, other composites, aluminum and magnesium pieces and the balsa wood-carbon fiber sandwich floor that do not rust.

The stock Z06 is drag limited to about 198 MPH in 5th gear with the 0.71 overdrive ratio, not even up to the 7000 rpm that would be ~217mph. I've heard that 6th gear with it's 0.51 ratio will only do 160+- MPH. Acceleration in 5th gear is much less at 160MPH than it is in 4th at that speed, again due to the 0.71 5th gear ratio.

tim414

6th gear is for cruising....it's NOT a go fast gear. In ZR1 6th IS a go gear....but NOT Z06....

The engine cradles/roof are mag. Frame aluminum. The floorboards are balsa wood sandwiched by carbon fiber.

emtmike

Wow, that's very interesting about the gearing. So the 6th gear is only to drop the RPM's down if I'm correct?. As far as the undercarrage, I guess he'll have to learn on his own . I did mention to him I could hear the salt chewing away at the aluminum frame....

Bill Dearborn

The old saying is still true: "When it is quiet out at night you can hear metal cars rusting."

Really not a lot of stuff on the road that will actually hurt a Corvette from that standpoint. I daily drove my 69 and 71 for 8 years. I put the 71 alongside the house for a little less than a year and that is when the frame rusted. Should have put a plastic sheet under the car to keep the moisture from getting into the frame.

Bill

AzDave47

In particular, the 6th gear ratio is what allows our supercars to get 28 MPG on the highway, using the low speed torque of that great 7.0 L engine.

I don't know the speeds in gears for the ZR1, but I'd bet it hits its top speed in it's 0.83 5th gear, then would drop 20-30 MPH in 6th.

JoesC5

ZR1 top speed in 5th gear is 185 MPH(don't forget it's 6500 RPH redline vs the Z06's 7,000 RPM, in addition to lower gear ratio). The ZR1's 202 MPH top speed is in 6th gear(224 MPH theoretical) where as the Z06 in 6th gear has a 325 MPH theoretical top speed. The .67 6th gear is really low compared to the Z06's .5 ratio.

At 198 MPH the LS7 is turning 4265 RPM, way off itis maximum HP rating at 6,300 RPM. The LS9 at 202 MPH is at 5835 RPM, much closer to it's maximum HP at 6500 RPM.

AzDave47

Thanks, I knew the ZR1 gearing in 5th was much better than our Z's, but forgot about the lower rev. limit. I know the ZR1 6th is a lot closer to our 5th than to our 6th gear.

One of my buddies did a calculation showing the Z at 198.2 MPH with stock gearing and 198.8 MPH at 7000 RPM using the Zr1 0.83 5th. I told him our Z's would have much better acceleration in 5th with that .83 ratio, but I wasn't yet ready to spring the $$ to change out my T6060 ratios.

The Mojave Mile just announced they will also run a 1 1/2 mile event in 2012. I guess I'll have another trip out to that lovely town of Mojave! That ZR1 5th would really help me in that event. I'll just have to settle for a good 5th of Scotch.

JoesC5

I like running at Talladega(and hope to run at Daytona later this year). Coming out of turn 2 in 4th gear at 145-150 MPH, it pulls pretty good down the 4,000' backstretch in 4th, but shifting into 5th at 158 MPH(don't want to hit the rev limiter at 162 MPH), the car is slow to get to 162MPH(my highest speed so far). That 5th gear from the ZR1 would make 5th gear a lot more entertaining, and I bet I could easily hit 167 MPH down the backstretch, maybe more. But I have to drive along way to get there, so I sure do like the .5 6th gear so I can crusie at 70 MPH and get 29 MPG.

AzDave47

At the Mojave Mile I shift from 4th to 5th at the 5/8 mile point at 164 MPH in 4th (7000 RPM and NT-05 335/30-19 rear tires) and gain less than 10 MPH in 5th for the remaining 3/8 mile. Our Z's do like to run! So far I don't think I've hit the rev limiter (7100 RPM?).

z06clif

If it wasnt for "6th gear" we'd have a "gas guzzler tax" $1300 on the ZR1

Clif

AzDave47

No question about the 6th gear mileage here. Ideal for my use would be the ZR1 5th and keep the Z06 6th, but I think if you change out the Z 5th, you need to change out 6th. I doubt I'll be doing the change out anytime soon, just dreamin' of what could be.

I get 26-28 MPG on the drive to/from Mojave and get 4MPG on the runs there. I usually get about 6.2 MPG at HPDE's.