No lift shift ??

[radz28]

Originally Posted by 1st Gen Forever

So at the risk of sounding stupid, when performing no-lift shifting, do you use the clutch or does the ignition cutout provide enough reduction of load to permit the synchros to mesh? Is it the movement of the shift lever that triggers the ECU or the clutch movement?

I would imagine at least a slight clutch pressure is still needed but maybe not all the way to the floor?

No stupid questions around her, friend

You still use the clutch to removed the mechanical connection from the engine to transmission. However, it sounds like the PCM limits fuel/spark to control over'rev'ing during the shift. It seems to me that as soon as you go into red-line (6200), this function happens - I'm not going to call it a feature, per se (and though GM might), because unless I find out that it's different than just hitting the rev' limiter, to me - it's about the same. I do have a feeling I've missed something, or don't remember something more specific. I'm sure there's programming to keep the RPMs optimal to up-shift to the next gear, but I can't remember...

I would definately still apply full pressure to the clutch; this is not a DSG-gearbox or something - there's still a mechanical connection to release, and the computer can't do that.

[GoldenBear]

Originally Posted by radz28

No stupid questions around her, friend

You still use the clutch to removed the mechanical connection from the engine to transmission. However, it sounds like the PCM limits fuel/spark to control over'rev'ing during the shift. It seems to me that as soon as you go into red-line (6200), this function happens - I'm not going to call it a feature, per se (and though GM might), because unless I find out that it's different than just hitting the rev' limiter, to me - it's about the same. I do have a feeling I've missed something, or don't remember something more specific. I'm sure there's programming to keep the RPMs optimal to up-shift to the next gear, but I can't remember...

I would definately still apply full pressure to the clutch; this is not a DSG-gearbox or something - there's still a mechanical connection to release, and the computer can't do that.

I'm not an expert on No Lift Shift, but from reading the Corvette forums, on a vehicle with NLS, I think that one doesn't want to let the engine hit the red line, as if the red line is hit, the fuel/spark control timing is different (less optimal) than when the engine is below the red line and the clutch is pressed and released quickly without lifting the throttle. Maybe someone with actual Corvette NLS experience can weigh in on this.

[radz28]

Originally Posted by GoldenBear

I'm not an expert on No Lift Shift, but from reading the Corvette forums, on a vehicle with NLS, I think that one doesn't want to let the engine hit the red line, as if the red line is hit, the fuel/spark control timing is different (less optimal) than when the engine is below the red line and the clutch is pressed and released quickly without lifting the throttle. Maybe someone with actual Corvette NLS experience can weigh in on this.

See - that makes a lot more sense. So maybe fuel cut-off is 6200, but NLS engages sooner, because cutting fuel and spark abruptly seems counter-productive to keeping all the positive momentum for maximum acceleration (I really didn't try to make that sound technical...). What I mean is, it seems like stopping all the inertia from the powertrain, from crankshaft to tires, by cutting power would make it less effective than somehow, kinda', pausing it. That didn't sound good either... It seems like instead of running an F14 into a net on a carrier to stop it is better than putting up a wall for it to crash into to stop it. The net will absorb most of the inertia and still enable a relatively safe stop, while the wall - not so much. I see the NLS as the net and the wall as the rev' limiter.

My head hurts... Just don't read that...

[69NMYSS]

Originally Posted by IcePick06

All the magazine reviews I have read describe this function while referring to PTM Mode 5 (more specifically LAUNCH CONTROL), so I'm going to say "YES" it's only available when using LAUNCH CONTROL via PTM Mode 5

Launch Control is available in all modes of PTM as is the no lift shift. In addition to keeping the engine from revving through the limiter, it keeps the S/C spooled up, so upon entering the next gear, your RPMs and S/C are loaded for optimum acceleration. Mode 5 is known as 'Race' Mode with suspension set to 'Track'. While Mode 5 does have a special L/C for VHT prepped drag strips, it is not the only mode with L/C.

[snapp32e]

Does it not have a shift light in the HUD. Would it be possible the light indicates perfectly timed shifts according to what the programmed algorithm determines to be the best shift point for optimum power and rmp alignment for the next gear? Most shift lights are just programmed to illuminate at a pre determined rpm, maybe Chevy has developed a "smart" shift light.

[radz28]

If I remember correctly, there is a shift light in the HUD.

[69NMYSS]

Originally Posted by snapp32e

Does it not have a shift light in the HUD. Would it be possible the light indicates perfectly timed shifts according to what the programmed algorithm determines to be the best shift point for optimum power and rmp alignment for the next gear? Most shift lights are just programmed to illuminate at a pre determined rpm, maybe Chevy has developed a "smart" shift light.

Yes there is a shift indicator located in the HUD, it appears as a series of dots that move closer to each other as shifting is required, as the dots merge it blinks and its time to shift.

[snapp32e]

Right, so it makes sense that the shift light will recommend shifting prior to reaching red line and allowing the ECU to intervene with the over rev protection. Hitting the rev limiting would really decrease performance times i would think.

[69NMYSS]

Originally Posted by snapp32e

Right, so it makes sense that the shift light will recommend shifting prior to reaching red line and allowing the ECU to intervene with the over rev protection. Hitting the rev limiting would really decrease performance times i would think.

I would say you are correct. Wish you could adjust the shift indicator.

[Blue Menace]

Wow, productive and informative thread!

[Russell James]

Where has it been said that any Corvette or ZL1 has a No Lift Shift feature?

I've driven ZR1's and Z06's.... lifted during every shift. Seen too many people scatter drive train parts trying to speed shift a Tremec and IRS. Violent wheel hop is often the result.

Is there actually some programming there that is intended for wide open shifts?

[snapp32e]

So i wonder if a guy utilized the NLS and instead of grabbing the next gear just held the cluth in and allowed the car to coast if it would lower the RPM to match the next gear synchronization in relation to the cars speed or if it would hold optimum RPM according to power and allow you to side step the clutch at 4000 RPM when the next gear ratio demands a 2000 RPM sync speed?

[69NMYSS]

Originally Posted by snapp32e

So i wonder if a guy utilized the NLS and instead of grabbing the next gear just held the cluth in and allowed the car to coast if it would lower the RPM to match the next gear synchronization in relation to the cars speed or if it would hold optimum RPM according to power and allow you to side step the clutch at 4000 RPM when the next gear ratio demands a 2000 RPM sync speed?

Wow, now you are getting way to technical for me

[snapp32e]

Lol...this car is going to be my guinea pig.