Im back if only for a short time. been doing some open wheel road racing with some friends, a Reynard indy 500 champ car. Was recently looking at a new vette wanted to know what the deal was with the z51 six speed.

 

what do u wanna know?
it has a better sway bar, some fluid coolers, better tires and taller 1st gear than the base. this equates to .1 seconds quicker 0-60 and about .1 seconds quicker 1/4 mile. It's also good for .98 lateral gs - i think the base is .94 g??

 

The deal is the ratios for the MZ6 in 1st, 2nd, 3rd, 5th, and 6th are deeper than the MM6 (non-Z51)...you accelerate quicker, and have to shift sooner because the tach gets there quicker.

If you are on the drag strip, you'll probably have to shift one more time in the quarter than the base tranny (the shift time deduct offsets most of the quicker acceleration). The bad news...all that quicker acceleration costs you a little gas mileage...a mpg or two if you're interested in that sort of thing.

 

The Z51 gearing works well on the twisties.

 

You still have to shift to 4th, I believe, with the non-Z51 to hit 115 trap speed. The Z gearing redlines at ~ 105 in 3rd. Also, I think 5th is higher to get the 186 top end, and 6th is deeper only because they wanted a bit more pickup in top gear for those who apparently are too lazy to downshift.

 

Are you talking about the getting it into first gear problems at stop lights?

 

is this difference noticable in the seat of your pants? Do you have any actual ratios. Thanks for all the info.

 

Here is one of many threads in the archives on the subject...the comparison of MM6 and MZ6 ratios are down in the middle.

Actually, I mispoke in my previous post...the MZ6 5th gear is actually a lower numerical ratio than the MM6...all other gears but 4th and 5th are deeper. Note that the thread references MN6 as the base transmission...actually the poster intends MM6; both the MM6 and MZ6 are MN6 transmissions.

http://forums.corvetteforum.com/show...N6+gear+ratios

One poster compares the MZ6 transmission to having 3.90 rear axle ratio instead of the standard 3.42...I haven't done any math to confirm his assertion. Can you feel it in the seat of your pants? Well, I can feel it!...Since my "other car" is a classic Toyota Forerunner, it's like I'm riding a tornado!

As to a noticeable difference from the MM6, I haven't driven one, but intuitively, you should be able to feel the change from a 3.42 to a 3.90 axle if the previous poster was correct. For me, the transmission ratios alone were enough to spring for the Z51 option...the coolers, the suspension, that was all gravy.

 

The gear ratios are
Base vs Z51
First: 2.66 vs 2.97
Second:1.7 vs 2.07
Third: 1.30 vs 1.43
Fourth: 1.00 vs 1.00

The final drive ratios are


3.42 x 2.66= 9.0972 vs 2.97 x 3.42= 10.1574

3.42 x 1.7= 5.814 vs 2.07 x 3.42= 7.0794

3.42 x 1.30 = 4.46 vs 1.43 x 3.42 = 4.8906

In first gear it would actually take not quite 3.90 gears but 10.1574/2.66= 3.82 gears to equal final drive ratio in first gear of the Z51. Since there are no 3.82 gears available for the Vette, but 3.90s hence the discussion that it would take 3.90 gears to equal the 1st gear acceleration capability of the Z51.

This is why those who tell you that the Z51 gearing does not make a difference are way off base. Just looking at the final drive ratios in 1st 2nd and 3rd gear should tell you that. It would take a set of 3.90 gears in a base C6 to get comparable acceleration to the Z51, traction and all else equal.



Transmissions/Final drive ratios:
Z51 MZ6 manual......*base MM6 manual.................*Base MM6 & 3.90s
1st...10.15......................*9.09............. ..............*10.37
2nd...7.07.......................*6.08............ ................*6.94
3rd....4.89.......................*4.44............ ................*5.07
4th....3.42.......................*3.42............ ................*3.90
5th....2.43.........................2.53 .............................*2.89
6th....1.95.........................1.71 .............................*1.95

 

DSOM Z51 - great info... thanks!!!

very easy to understand the last gear chart...

 

Particularly in 1st and 2nd where you need the deeper ratios...by 3rd, the ratio is still deeper than the MM6, but it's beginning to fade in order to equalize the intervals to 1:1 in 4th. Dam...l love this car.

Nice work posting that chart, DSOMZ51...shows everything clear as day. I was lazy and left something for the poster to research.

 

Screw the Z51, you have a Reynard? what year? Honda engine? What team was the car from? I always wanted to drive a open wheel car with 700+ hp

 

The closer ratios of the base trans make it a better choice for a road course.

 

 

Plus the base trans will handle more torque before failure making it a better choice behind a modified engine with nitrous, increased displacement, or turbo/supercharged.

 

I did a track day at Beaverun, this past Sunday. There were 4 C5 Z06s there and two of them were just burning up the course. I mean passing everybody. In that group, it was like there were no other cars out there other than those two C5 Z06s, and this was the advanced group 3 which had some very capable cars and drivers in it.

The C5 Z06 has the same exact gearing through the first four gears as the C6 Z51.

The gearing in those two cars has and continues to prove its worth on the road course.

100%. If you are going to be tearing into the engine, adding juice or a blower, then you really don't need that much gear.

But at 400hp, just like the 405hp C5 Z06, the gear ratios in the Z51 seem to work beautifully on the road course from the feedback so far.

http://www.johnnyoconnell.com/news_2006.htm

Nurburgring:
Added 9/23/06
"...Now I know all you Corvette fans were wondering if I was driving the Blue Devil, and sorry to disappoint you I wasn’t. For the first three days I trained in a 2005 Z-51 and 2002 Z-06. Both totally rocketships around the track, with really nothing out there faster. It was fun in that we were just blowing by porsches , Ferraris, and lambourghinis like they were standing still....."

http://www.caranddriver.com/features...tning-lap.html

 

What you guys (Pozzo, glass slipper) are doing...it's called rationalization.

You read how satisfied other people are with their Z51s, and read their glowing reviews of the features, and your subconscious mind says..."Dam, I could've had one of those Z51s!!!" But, then, your conscious mind can't stand to admit that it made a mistake not selecting the Z51 option, so it begins to try to realign reality with your decision.

So, between the two of you, you have eliminated the Z51 tranny as the transmission of choice for either road racing or drag racing...only the base MM6 is adequate for anything, even getting the groceries. This implies that you two think you're smarter than General Motors, because your combined assertions would mean the General designed a transmission with no purpose!

Since it's hardly likely that you two are smarter than General Motors, we can only conclude that your efforts to realign reality are based on faulty premises derived from the need for your conscious minds to constantly believe they can't make a mistake.

Keep working at it...if you have yourself believing it, that's half the battle. The rest of us, however, see through your protestations as transparently as glass. If you find yourself having doubts about your realignment efforts, professional counseling may be helpful to reconcile your subconscious and conscious minds to live harmoniously in the same brain.

 

I disagree, having run 42 laps on Road America's 4.2 mile track I have first hand experience.





The Z51 gearing allowed me to keep my RPM's just where they could generate max torque and thrust coming out of this turn and allow me to blast into the next turn. I could walk away from any non Z51 geared car.

The instructors on hand raved about the "correctness of the gearing".

Your wrong.

Tom

 

Very well said and I will certainly take your experiences to heart. . Chevy did a great job with the gearing in the Z51 C6, and the C5 Z06 before that. And with the torque curve of the LS2 its not surprising that your experiences were what you describe.

 

I simply made a statement of fact in my post just as others did when they stated that the Z51 trans with the lower gear ratios was better off the line. I did not dispute that.

I did not "eliminate the Z51 tranny as the transmission of choice for either road racing or drag racing."

"because your combined assertions would mean the General designed a transmission with no purpose! " I never said that.

You did not refute my statement about the gear ratios. Instead you continue to advance this absurd theory called Z 51 envy. If I had wanted a Z 51 I would have bought one. If I wanted one now I would go buy one.

I would suggest that it is you who need both a class in reading comprehension and professional counseling.