I was wondering if some professional drivers could give me some tips on how to luanch my Z and when i should shift at i am young and have alot to learn so any advice would be appreciated i read somewhere that shifting at redline isnt always improving ur acceleration.. thanks!

 

test

 

I did some calc's way early on where I calculated the torque applied to the road by the rear wheels, and it looks like the Z should be shifted as high in the RPM's as possible. I did the calcs at redline, but i think they could be extended to the rev limiter and still be valid.

Basically what I did was take the torque @ redline, multiply that by the gearing and divide by the radius of the tire (in ft) to get the torque applied to the rear wheels.

I would then compare that to the tourqe applied at peak torque in the next higher gear.

If the first number was higher, then it meant that you should stay in gear all the way to redline.

If the second number was higher I would need to figure out how far the RPM's would drop when shifting and then find the point at which the shift would yeild equal torque in each gear. However, on the Z, the lower gear always created more torque to the rear wheels at redline than the next gear did at peak, so therefore I didn't have to screw with the rest.

So that's the math side.

The visual side is to look at the HP curve, and realize that you want to maximize the area under the curve in each gear. Since the Z peaks at 6200, but will drop 2500 RPM's from 1-2 and 1500 RPM's on the rest, you would in theory like your shift point 1250 RPM's or so beyond peak HP for the 1-2 shift, or 750 beyond peak HP for the rest of the shifts - assuming the HP curve is symmetric around the peak HP point. Since the Z redlines at 6600 (only 400 beyond peak HP), it doesn't really matter how symetric the curve is, and you just shift as late as possible, and if you can time it correctly, you can try to shift after redline but before rev limiter.

Of course, that is for the 1/4 mile race. On a road course things may differ depending on how good you are at downshifting, how the speed changes (do you try to double downshift when going from the long straight to the hairpin, or do you take the hairpin in the higher gear, or do you take the straight in the lower gear) and other factors.

Anyhow, hope that helps.

-D'oh!

PS. I am by no means a professional driver. I am an engineer though, so the advice is only as sound as the science.

 

thanks that does help i read an article on that that had an equation to figure out where u should shift at any way is there anyone out there that knows of any shifting techniques good for the Z? also why is it when i shift to fast into second it grinds? am i just a bad driver.. this only happeneds to me SOMETMES when i am racing

 

Depending on how hard you want to be on your car there are two ways you can shift. If you want to be hard on your car but most likely get better times, keep the gas floored during the shift, quickly jab the clutch, and shift. The other way would just be shifting conventionally as fast as possible. On the 1-2 grind, just make sure you have the clutch fully depressed and don't let it out until the car is fully in gear. I noticed on the Z when you shift into 2nd it feels like it engages but you still have to pull it a bit further before it is really in gear. If you let the clutch out at that point you will get a nasty grind.
If you are planning on road racing, don't powershift. You'll want to practice double-clutching and matching revs on the downshift. I usually do it all the time now, plus matching revs and double-clutching are good for the trans/clutch.

 

i always double clutch when down shifting if not it is really hard on the syncros and what do u mean by powershifting iv hear poweshifting is just shifting with out using the clutch

 

Powershifting is when you hold your foot to the floor on the gas pedal while you shift gears. You still use the clutch (very quickly though, just enough to disengage, shift, and pop it back up).

It's hard on the car though as you can imagine. If you do it perfectly it's not too bad, but if you mess up the shift you can do some damage.

Chris

 

It's hard on your drivetrain, period....granted, like you said, if you do it right it's not that bad...but your still basically loading up the motor, then releasing it on the transmission, DS, rear end....thats going to eventually take a toll if you power shift frequently.
I'm not sure how strong the Zs trannies are...so, how knows...you might be able to drive it like that everyday for all I know

 

My Z also has a bit of a grind (more like an extended clunk, really) when going into second gear. Especially when cold and at low RPMs. When things are warm and at high RPM's it seems to shift more smoothly into second, and the rest of the gears seem fine all the time. The tranny has loosened a bit, but not much, in the 10,000+ miles I have so far. I'm geting the tranny and diff fluid changed tomorrow since I ground going into second twice (basically exactly what BigBadBuford said). I'll see what kind of synthetic the shop has, but I'll probably end up sticking with dino oil. We'll see if the new oil changes anything.

Oh, I also find the Z pretty difficult to shift smoothly. I've always driven a manual, but my other vehicles have been pickups, so the feel was quite different. At low RPMs (sub 4000) Z's engine never seems to want to drop revs as fast as the shift, so I'm always doing a little jump-and-bog when I am shifting easily. At high RPM's the engine and tranny seem much better matched and the shifting seems more natrual. Eh, it's probably just me...

-D'oh!

 

Surprisingly, I can powershift from 1 --> 2 and 2 --> 3 just fine, but I always have a problem from 3 --> 4, I usually end up just shifting as fast as I can while letting off the gas. You would think that last shift shouldn't be a problem, but for me it is.

 

Second to third is generally the hard one....I have missed 4th I think twice.....but it does happen.